Howland Island National Wildlife Refuge Comprehensive Conservation Plan

              Howland Island National Wildlife Refuge Comprehensive Conservation Plan
FONSI-i
FINDING OF NO SIGNIFICANT IMPACT
Howland Island National Wildlife Refuge
Comprehensive Conservation Plan
Unincorporated U.S. Territory, Central Pacific Ocean
The U.S. Fish and Wildlife Service (Service) has completed the Comprehensive Conservation
Plan (CCP) for Howland Island National Wildlife Refuge (Refuge). The CCP will guide
management of the Refuge for the next 15 years. The CCP describes the Service’s preferred
alternative for managing the Refuge and its effects on the human environment.
Decision
Following comprehensive review and analysis, the Service selected Alternative B in the
Environmental Assessment (EA) for implementation because it is the alternative that best meets
the following criteria:
􀂄􈑁 Achieves the mission of the National Wildlife Refuge System.
􀂄􈑁 Achieves the purposes of the Refuge.
􀂄􈑗 Will be able to achieve the vision and goals for the Refuge.
􀂄􈑍 Maintains and restores the ecological integrity of the habitats and plant and animal populations
on the Refuge.
􀂄􈑁 Addresses the important issues identified during the scoping process.
􀂄􈑁 Addresses the legal mandates of the Service and the Refuge.
􀂄􈑉 Is consistent with the scientific principles of sound wildlife management.
􀂄􈑃 Can be implemented within the projected fiscal and logistical management constraints
associated with the Refuge’s remote location.
As described in detail in the CCP and EA, implementing the selected alternative will have no
significant impacts on any of the natural or cultural resources identified in the CCP and EA.
Public Review
The planning process incorporated a variety of public involvement techniques in developing and
reviewing the CCP. This included three planning updates, meetings with partners, and public
review and comment on the draft planning documents. The details of the Service’s public
involvement program are described in the CCP.
Conclusions
Based on review and evaluation of the information contained in the supporting references, I have
determined that implementing Alternative B as the CCP for management of Howland Island
National Wildlife Refuge is not a major Federal action that would significantly affect the quality
of the human environment within the meaning of section 102(2)(C) of the National
Environmental Policy Act of 1969. Accordingly, the Service is not required to prepare an
environmental impact statement.
Howland Island National Wildlife Refuge Comprehensive Conservation Plan
ToC-i
Table of Contents
CHAPTER 1: INTRODUCTION
Introduction................................................................................................................................. 1-1
The U.S. Fish and Wildlife Service ............................................................................................. 1-1
National Wildlife Refuge System ................................................................................................ 1-1
National Wildlife Refuges in the Pacific ..................................................................................... 1-4
Refuge Establishment, Purpose and Boundary............................................................................ 1-6
Regional and Ecosystem Conservation Plans ..............................................................................1-9
Refuge Vision Statement ........................................................................................................... 1-10
Refuge Goals............................................................................................................................. 1-11
CHAPTER 2: PLANNING PURPOSE, NEED, AND ISSUES
Planning Process .......................................................................................................................... 2-1
Purpose and Need ........................................................................................................................ 2-1
Planning Issues and Opportunities............................................................................................... 2-2
CHAPTER 3: MANAGEMENT DIRECTION
Overview..................................................................................................................................... 3-1
Goals, Objectives, Strategies, and Rationale ............................................................................... 3-4
CHAPTER 4: REFUGE AND RESOURCE DESCRIPTION
Geographic/Ecosystem Setting .................................................................................................... 4-1
Climate........................................................................................................................................ 4-1
Global Climate Change................................................................................................................ 4-2
Geology and Soils........................................................................................................................ 4-7
Hydrology ................................................................................................................................... 4-9
Air and Water Quality.................................................................................................................. 4-9
Environmental Contaminants....................................................................................................... 4-9
Terrestrial Vegetation and Habitats ............................................................................................. 4-9
Terrestrial Wildlife..................................................................................................................... 4-10
Marine Habitats, Fish and Wildlife............................................................................................ 4-12
Threatened and Endangered Species ......................................................................................... 4-16
Invasive Species ........................................................................................................................ 4-17
Wilderness Resources ................................................................................................................ 4-17
Archaeology and Paleontology.................................................................................................. 4-17
Recent Cultural History ............................................................................................................. 4-18
Socio-economics ........................................................................................................................ 4-21
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ToC-ii
APPENDICES
Appendix A. Glossary of Terms and Acronyms
Appendix B. Species Lists
Appendix C. References
Appendix D. Planning Team Members
Appendix E. Quarantine Protocol
Appendix F. Wilderness Review
Appendix G. Statement of Compliance
Appendix H. Plan Implementation and Costs
Appendix I. Consultation and Coordination
Appendix J. Responses to Comments
LIST OF FIGURES
Figure 1.1 National Wildlife Refuges in the Pacific…………………………………………1-5
Figure 1.2 Howland Island National Wildlife Refuge: Geographic Location and Boundary..1-8
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Chapter 1 - Introduction 1-1
Chapter 1: INTRODUCTION
Introduction
This document is a Comprehensive Conservation Plan (CCP) for Howland Island National
Wildlife Refuge (Howland). It will guide management of refuge operations, site visitation, and
habitat restoration for 15 years. Guidance within the CCP is in the form of goals, objectives,
strategies (Chapter 3), and wilderness study findings (Appendix F). The CCP was revised as
appropriate based upon public comments. The refuge manager of the Pacific Remote Islands
National Wildlife Refuge Complex (Remotes Complex) in Honolulu, Hawaii, is responsible for
implementing the CCP.
The U.S. Fish and Wildlife Service
Howland is managed by the Fish and Wildlife Service (Service), within the U.S. Department of
the Interior. The Service is the primary Federal entity responsible for conserving and enhancing
the Nation’s fish and wildlife populations and their habitats. Although the Service shares this
responsibility with other Federal, State, tribal, local, and private entities, the Service has specific
trust resource responsibilities for migratory birds, threatened and endangered species, certain
anadromous fish, certain marine mammals, coral reef ecosystems, wetlands, and other special
aquatic habitats. The Service also has similar trust responsibilities for the lands and waters it
administers to support the conservation and enhancement of all fish and wildlife and their
associated habitats.
National Wildlife Refuge System
President Theodore Roosevelt established Pelican Island, Florida as the first national wildlife
refuge in 1903. Since that time, the number of refuges has expanded to include 548, totaling
approximately100 million acres. These refuges, found in every state and several U.S. Territories,
are administered collectively as a national system of lands with the specific mandate of
managing for “wildlife first.” This System is the largest collection of lands specifically managed
for fish and wildlife conservation in the Nation and perhaps the world. The “wildlife first”
mandate of the System means the needs of wildlife and their habitats take priority on refuges, in
contrast to other public lands that are managed for multiple uses. The following is a description
of some of the most relevant acts and policies that guide the management of the System.
National Wildlife Refuge System Administration Act of 1966, as amended
The NWRS Administration Act defines a unifying mission for all refuges, including a process
for determining compatible uses on refuges, and requiring that each refuge be managed
according to a CCP. The NWRS Administration Act expressly states that wildlife conservation
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1-2 Chapter 1 – Introduction
is the priority of System lands and that the Secretary shall ensure that the biological integrity,
diversity, and environmental health of refuge lands are maintained. Each refuge must be
managed to fulfill the specific purposes for which the refuge was established and the System
mission. The first priority of each refuge is to conserve, manage, and if needed, restore fish and
wildlife populations and habitats according to its purpose. The Service has statutory authority
under the NWRS Administration Act to regulate activities that occur on water bodies “within” a
refuge. The NWRS Administration Act requires a CCP be completed for each refuge and that
the public has an opportunity for active involvement in plan development and revision. It is
Service policy that each CCP is developed in an open public process.
National Wildlife Refuge System Mission and Goals and Purposes (601 FW1)
In July 2006, the Service issued a policy (601 FW 1) which included the NWRS mission
statement and NWRS goals, and described how refuge purposes are determined.
The NWRS Administration Act established the following statutory mission for the System:
“The mission of the System is to administer a national network of lands and waters for
the conservation, management, and where appropriate, restoration of the fish, wildlife,
and plant resources and their habitats within the United States for the benefit of present
and future generations of Americans.”
The administration, management, and growth of the System are guided by the following goals
(601 FW 1, July 2006)….”
• Conserve a diversity of fish, wildlife, and plants and their habitats, including species that
are endangered or threatened with becoming endangered.
• Develop and maintain a network of habitats for migratory birds, anadromous and
interjurisdictional fish, and marine mammal populations that are strategically distributed
and carefully managed to meet important life history needs of these species across their
ranges.
• Conserve those ecosystems, plant communities, wetlands of national or international
significance, and landscapes and seascapes that are unique, rare, declining, or
underrepresented in existing protection efforts.
• Provide and enhance opportunities to participate in compatible wildlife-dependent
recreation (hunting, fishing, wildlife observation and photography, and environmental
education and interpretation).
• Foster understanding and instill appreciation of the diversity and interconnectedness of
fish, wildlife, plants, and their habitats.
Lastly, the NWRS Administration Act describes refuge purposes, and how these guiding
principals for the refuge are located and documented.
Appropriate Refuge Uses (603 FW1)
This policy (603 FW 1), published in July 2006, provides a national framework for determining
appropriate refuge uses. Serving as a “prescreening” for proposed uses of a refuge prior to a
compatibility determination (see below); this policy requires—for most uses—a written finding
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of appropriateness by the refuge manager based on 11 criteria. Findings of appropriateness
require State concurrence for refuges located within State boundaries. These criteria include:
• Promotes safety of participants, other visitors, and facilities.
• Promotes compliance with applicable laws, regulations, and responsible behavior.
• Minimizes or eliminates conflicts with fish and wildlife populations or habitat goals or
objectives in a plan approved after 1997.
• Minimizes or eliminates conflicts with other compatible wildlife-dependent recreation.
• Minimizes conflicts with neighboring landowners.
• Promotes accessibility and availability to a broad spectrum of the American people.
• Promotes resource stewardship and conservation.
• Promotes public understanding and increases public appreciation of America’s natural
resources and our role in managing and protecting these resources.
• Provides reliable/reasonable opportunities to experience wildlife.
• Uses facilities that are accessible and blend into the natural setting.
• Uses visitor satisfaction to help define and evaluate programs.
Compatibility (603 FW2)
Lands within the System are different from other multiple-use public lands, in that, with few
exceptions, they are closed to all public access and use unless specifically and legally opened
(603 FW 2). No refuge use may be allowed unless it is determined to be compatible. A
compatible use is one that, in the sound professional judgment of the refuge manager, would not
materially interfere with or detract from the fulfillment of the mission of the Service or the
purpose of the refuge. The NWRS Administration Act identifies six wildlife-dependent
recreational uses: hunting, fishing, wildlife observation, photography, environmental education,
and interpretation. When compatible, these six uses become priority uses of the System. As
priority public uses, they receive special consideration over other general public uses in refuge
planning and management.
Biological Integrity, Diversity, and Environmental Health (601 FW3)
The NWRS Administration Act directs the Service to “ensure that the biological integrity,
diversity and environmental health of the System are maintained for the benefit of present and
future generations of Americans…” This policy (601 FW 3) is an additional directive for refuge
managers to follow while achieving refuge purpose(s) and System mission. It provides for the
consideration and protection of the broad spectrum of fish, wildlife, plants, and their habitat
resources found on refuges and associated ecosystems. When evaluating the appropriate
management direction for refuges, refuge managers would use sound professional judgment to
determine their refuges’ contribution to maintenance and, where possible, restoration of
biological integrity, diversity, and environmental health (BIDEH) at multiple landscape scales.
Sound professional judgment incorporates field experience, knowledge of refuge resources,
refuge functions within an ecosystem, applicable laws, and best available science, including
consultation with others both inside and outside the Service.
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Wilderness (602 FW 3)
Service planning policy (602 FW 3) requires the conduct of a wilderness review in association
with the development of a refuge CCP. The wilderness review process has three phases:
inventory, study, and recommendation. After first identifying lands and waters that meet the
minimum criteria for wilderness during the inventory phase, the resulting wilderness study areas
are further evaluated to determine if they merit recommendation from the Service to the
Secretary of the Interior (Secretary) for inclusion in the National Wilderness Preservation
System. A more complete discussion of wilderness inventory, study, and recommendation is
included in Appendix F.
General Guidelines for Wildlife-Dependent Recreation (605 FW1)
This set of policies (605 FW 1-7), published in July 2006, defines the System’s wildlife-dependent
recreation policy, provides guidelines used to manage wildlife-dependent recreation
on refuge lands and identifies visitor service standards.
National Wildlife Refuges in the Pacific
Nineteen individual refuges are scattered across the central and western Pacific Ocean, with
several refuges located on the main Hawaiian Islands and others found from Guam to American
Samoa (Figure 1.1). The Hawaiian and Pacific Islands NWR Complex which provides
administrative guidance and oversight for the 19 refuges, is located in Honolulu, Hawaii. This
Complex also co-manages the newly established Papahānaumokuākea Marine National
Monument with the National Oceanic and Atmospheric Administration and the State of Hawaii.
Within this administrative structure is a subset of seven refuges known as the Remotes Complex.
The Remotes Complex straddles the Equator near the center of the Pacific Ocean. They are
farther from human population centers than any other U.S. area and represent one of the last
frontiers and havens for fish and wildlife in the World. These remote refuges are the most
widespread collection of coral reef and seabird/shorebird protected areas on the planet under a
single country’s jurisdiction. Only one of these seven refuges, Palmyra Atoll NWR, has on-island
dedicated staff members. Remotes Complex staff, located within the complex office in
Honolulu, manage all the remaining refuges, including Howland. Staff, funding, and logistical
support are often shared among these remote refuges to help defray operational costs.
The Howland CCP identifies several management strategies that are dependent upon activities
and staff support from the Remotes Complex office, ship transportation support from other
Federal agencies, or the establishment of partnerships with other organizations. Because of the
great distances involved in traveling to these remote refuges, most management activities,
including the simple act of visiting a refuge, are sometimes planned to occur concurrently during
the same voyage. For this reason, cost estimates for management activities at Howland are pro-rated
amongst the seven refuges within the Remotes Complex.
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Figure 1.1 Map of National Wildlife Refuges in the Pacific.
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Refuge Establishment, Purpose, and Boundary
Refuge Establishment
Howland Island is an unincorporated territory under the sovereignty of the United States. The
Secretary of the Interior has broad authority over the territories of the United States by virtue of
the Act of March 1, 1873, (43 U.S.C. 1458) which transferred general authority “…to perform all
duties in relation to the Territories of the United States…” from the Secretary of State to the
Secretary of the Interior. In addition, President Franklin D. Roosevelt signed Executive Order
7368 on May 13, 1936, also placing control and jurisdiction of Howland Island with the
Secretary of the Interior. Further, pursuant to the provisions of the Reorganization Act of 1949,
the Secretary of the Interior is authorized under Reorganization Plan No. 3 of 1950 to re-delegate
to any officer or agency within the Department of the Interior any of the functions legally under
his jurisdiction.
Under the authority of Reorganization Plan No. 3, the Secretary of the Interior, on June 27, 1974,
designated Howland Island and its territorial sea extending to the 3 nautical mile (nmi) limit as a
unit of the National Wildlife Refuge System to be “administered under the general regulations
for the National Wildlife Refuge System published in Title 50, Code of Federal Regulations” (39
FR 27930). Section 25.21 of these regulations state that “…all areas included in the National
Wildlife Refuge System are closed to public access until and unless we open the area for a use or
uses in accordance with the National Wildlife Refuge System Administration Act of 1966 (16
U.S.C. 668dd-668ee), the Refuge Recreation Act of 1962 (16 U.S.C. 460k-460k-4) and this
subchapter C.” Howland Island National Wildlife Refuge remains closed to public access.
Refuge Purpose
Refuge purposes are often times are based upon land acquisition documents and authorities.
These statements give indications for the biological reason or justification for the acquisition or
land transfer. Purposes listed in acquisition authorities, or legislative acts, are often general in
scope. For Howland, this general purpose is:
“...for the development, advancement, management, conservation, and protection of fish and
wildlife resources...” (16 U.S.C. 742f (a)(4)), and “...for the benefit of the United States Fish
and Wildlife Service, in performing its activities and services. Such acceptance may be
subject to the terms of any restrictive or affirmative covenant, or condition of servitude...”
(16 U.S.C. 742f (b)(1)) (Fish and Wildlife Act of 1956).
Acquisition documents often contain more specific purpose statements. The specific purpose
statement for establishment of Howland identified in the biological ascertainment report at the
time of transfer to the Service is (USFWS 1973):
“…the restoration and preservation of the complete ecosystem, terrestrial and marine.
Special consideration must be given to the protection of nesting seabird populations.”
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Refuge Boundary
Howland is located in the central equatorial Pacific Ocean (Figure 1.2). The boundary for
Howland includes:
“all of said island … together with its territorial sea extending outward to the three-mile
limit” (39 Federal Register 27930).
The emergent land area for Howland encompasses 648 acres and submerged lands and waters
within the 3-mile limit encompass 33,671 acres for a total of 39,319 acres.
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1-8 Chapter 1 – Introduction
Figure 1.2 Howland Island National Wildlife Refuge: Geographic Location and
Boundary.
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Chapter 1 - Introduction 1-9
Regional and Ecosystem Conservation Plans
Regional and ecosystem conservation plans and initiatives are also important to evaluate and
incorporate into developing each CCP. These plans typically address issues or concerns that are
site specific or of regional concern, and address needs more current than when the refuge was
established.
Remote Islands Ecosystem Plan: Howland Island, Baker Island, and Jarvis Island
National Wildlife Refuge
The ecosystem plan for Howland, Baker, and Jarvis identifies Howland as having a reef that is
“…healthy and provides habitat for giant clams” (USFWS 1998b). The plan further implies that
all three islands represent models of intact ecosystem components that are either pristine in
nature, have been, or are being managed and restored to pre-human contact conditions.
Coral Reef Initiative in the Pacific: Howland Island, Baker Island, and Jarvis Island
National Wildlife Refuges
The Coral Reef Initiative for Howland, Baker, and Jarvis restates the wildlife and ecological
values identified in the ecosystem plan (USFWS 1998a). This document identifies three
important components of the three ecosystems: “They provide a breeding platform for pelagic
birds using large areas of ocean surface, offer a migratory stopover for long distance migrating
shorebirds, and furnish reef habitat for shallow water organisms.”
Recovery Plan for U.S. Pacific Populations of the Hawksbill Turtle (Eretmochelys
imbricate) (NMFS and USFWS 1998)
Although theoretically within the range for hawksbill turtle, little is known about their biology,
foraging and nesting behavior, threats, and distribution surrounding Howland Island. Both the
National Oceanic and Atmospheric Administration’s National Marine Fishery Service (NMFS),
and the U.S. Fish and Wildlife Service share responsibility at the Federal level for the research,
management, and recovery of Pacific marine turtle populations under U.S. jurisdiction.
Recovery Plan for U.S. Pacific Populations of the Green Turtle (Celonia mydas)
(NMFS and USFWS 1998)
Few green turtles are known to forage in the waters surrounding Howland Island and nesting is
not known to occur. However, data from the area is limited and use of Howland may be greater
than currently documented. Both the NMFS and the Service share responsibility at the Federal
level for the research, management, and recovery of Pacific marine turtle populations under U.S.
jurisdiction.
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U.S. Pacific Island Regional Shorebird Conservation Plan (Engilis and Naughton
2004)
This regional shorebird plan identifies Howland as being within the Central Pacific Islands
Subregion. No natural wetlands are known from this subregion; however, beaches on
uninhabited islands are important for shorebirds. Population and habitat goals for this subregion
state that determining population size and trends for bristle-thighed curlews and other shorebirds,
and their habitats is a management priority.
United States Shorebird Conservation Plan (Brown et al. 2000)
This nationwide shorebird plan identifies the U.S. Pacific Islands being of “critical importance
for two species of Holartic breeders, bristle-thighed curlew and Pacific golden-plover.” Further,
this plan notes that these islands provide wintering habitat essential to the maintenance of these
species as well as several other migratory shorebird species.
Seabird Conservation Plan, Pacific Region (USFWS 2005)
This plan provides an overarching review, discussion, and identification of conservation
priorities for seabirds in the U.S Pacific Islands; ranks seabirds for conservation priority; and
includes specific species accounts including their conservation needs.
Central Pacific World Heritage Project
The United Nations Educational, Scientific and Cultural Organization (UNESCO) organized and
convened meetings in Honolulu in June 2003, and Kiritimati Atoll in October 2004, to seek input
for a proposed multi-national World Heritage project now referred to as the Central Pacific
World Heritage Project (CPWHP) (UNESCO World Heritage Centre, 2003; 2004). Additional
meetings and evaluations in the U.S. and Republic of Kiribati resulted in a total of 29 atolls,
islands, and reefs belonging to four nations (United States, Cook Islands, Republic of Kiribati,
and French Polynesia) being proposed for the multi-site, multi-jurisdictional CPWHP. To date,
the Service has not acted on this proposal, but may do so in the future. However, in 2006 the
Republic of Kiribati established the world’s largest marine protected area to date that
encompasses all eight of the nation’s Phoenix Islands and intended for nomination as a World
Heritage site in 2009. All eight are the closest neighbors to Howland and Baker National
Wildlife Refuges, lying 200-450 km to the southeast of both islands.
Refuge Vision Statement
The refuge vision statement is a broad general statement that describes what the refuge staff
perceives as Howland’s fundamental attributes and contributions to a healthy world environment.
This statement will guide management activities for the lifespan of this plan, as well into the near
future. The vision statement for Howland is as follows.
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Howland is one of the last places in the world where the terrestrial and marine tropical
island ecosystems are still intact and relatively free of human impacts. Natural, physical
and ecological processes unfold with limited human interference and support a diverse
community of native marine organisms including seabirds, marine mammals, turtles, fish,
plants, corals, and other invertebrates. Nesting and foraging seabirds dominate the
landscape and seascape while sheer isolation and solitude help us see our place in the
natural world.
Refuge Goals
Goal statements are succinct statements of a desired future condition of refuge resources. Goals
comprise the whole of a refuge’s effort in pursuit of its vision and lay the foundation from which
all refuge activities arise. The goals for Howland are as follows, and will again be presented
along with objectives and strategies in Chapter 3.
1. Conserve, manage, and protect native terrestrial habitats that are representative of remote
tropical Pacific islands, primarily for the benefit of seabirds.
2. Conserve, manage, and protect native marine communities that are representative of
remote tropical Pacific Islands.
3. Contribute to the recovery, protection, and management efforts for all native species with
special consideration for seabirds, migratory shorebirds, federally listed threatened and
endangered species, and species of management concern.
4. Protect, maintain, enhance, and preserve the wilderness character of Howland’s terrestrial
and marine communities.
5. Howland’s biological, cultural and historic resources are preserved.
6. An informed, interested, and educated public appreciates remote Pacific Island NWRs
wilderness values, cultural and historical resources, and their ecosystems, with special
emphasis on seabirds.
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Howland Island National Wildlife Refuge Comprehensive Conservation Plan
Chapter 2 – Planning, Purpose and Need, and Issues 2-1
Chapter 2: PLANNING, PURPOSE, NEED, AND ISSUES
Planning Process
The CCP development process follows applicable policies contained within the Service’s Fish
and Wildlife Manual (Part 602 FW2.1, November 1996; Part 601 FW1, Part 603 FW1, and Part
605 FW1, June 2006), and the Wilderness Act of 1964 with respect to wilderness study and
review. This CCP was completed in association with an EA and is intended to meet the dual
requirements of compliance with the NWRS Administration Act and the National Environmental
Policy Act (NEPA). Both the NWRS Administration Act and NEPA require the Service to
actively seek public involvement in the preparation and adoption of environmental and
conservation documents and policies. Furthermore, NEPA also requires the Service to consider
a reasonable range of alternatives including its Preferred Alternative and the “No Action”
alternative; the latter defined as continuation of current management practices.
Purpose and Need
Overall, all refuges must comply with the System mission, goals, and policies, as described in or
promulgated by the National Wildlife Refuge System Administration Act of 1966 (NWRS
Administration Act), as amended (16 U.S.C. 668dd-668ee). The National Wildlife Refuge
System Improvement Act of 1997 amended the NWRS Administration Act. According to the
NWRS Administration Act, a CCP is required to identify and describe refuge purpose(s),
habitats and wildlife, archaeological and cultural values, administrative and visitor facilities,
management challenges and their solutions, and opportunities for compatible wildlife-dependent
recreation. The recreational activities referenced in the NWRS Administration Act as receiving
special consideration during planning efforts include hunting, recreational fishing, wildlife
observation, interpretation, environmental education, and photography.
The purpose of this CCP is to develop a vision, goals, and objectives for Howland, which in turn
provide guidance to identify and implement management activities, or strategies, during the next
15 years. Specifically, the CCP:
• sets a long term vision;
• establishes wildlife and habitat management goals and objectives;
• establishes goals and objectives for compatible wildlife-dependent recreational and
educational uses;
• identifies strategies for habitat enhancement and restoration projects;
• describes the highest monitoring and research priorities; and
• describes and evaluates wilderness values.
Howland and its management and administrative activities are managed as part of the NWRS or
System within a framework provided by legal and policy guidelines. The refuge is guided by the
mission and goals of the NWRS, the purpose of the refuge as described in its acquisition
authority, Service policy, Federal laws and executive orders, and international treaties.
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2-2 Chapter 2 – Planning, Purpose and Need, and Issues
Supplemental guidance documents (e.g., resource plans) are also included in making
management decisions but cannot replace or be in conflict with the purposes for which the refuge
was established or the mission of the System
Planning Issues and Opportunities
Issues, concerns, and opportunities were identified through discussions with key contacts, core
team members, other refuge staff, and through the public scoping process. The following section
summarizes issues, concerns, and opportunities from all public input received throughout the
planning efforts. Six issues were identified and are described below.
Issue 1: Operational Limitations
Howland is located approximately 1,815 nmi from the management staff located in Honolulu,
Hawaii. On average, it takes 8 days to reach Howland by ship, the only method of visiting the
island. The key issues and concerns affecting planning and management implementation are:
• distance from refuge headquarters;
• lack of affordable and reliable transportation;
• lack of infrastructure to support field operations;
• extreme environmental conditions; and
• safety concerns and logistical capacity to land people and equipment on-island from
small boats during limited time windows associated with low surf conditions.
Issue 2: Biological and Ecological Resources
Biological and ecological information sufficient for management or conservation purposes is
lacking. Due to the infrequency and limited staff time spent on Howland, biological and
ecological information does not allow for a detailed assessment of resources. The collection of
baseline and long-term monitoring information should be a primary concern and the focus of
management objectives.
Issue 3: External Forces
The threat of the introduction of invasive species from unauthorized visits, marine debris
washing ashore and onto coral reefs, and vessel groundings are beyond current management
control. Distance, lack of funds and staff, and the inability to have a more consistent presence on
this island opens the opportunity for invasive species introductions, limits the ability to remove
marine debris, and delays response to vessel groundings.
Global climate change (see Chapter 4) may also affect refuge resources, but is beyond control of
refuge management staff. It is anticipated that changes in the chemical composition of the
atmosphere and oceans; surface temperatures of air, land, and sea; intensity and frequency of
rainfall and storm waves; and changes in sea level would have impacts on refuge resources.
Howland Island National Wildlife Refuge Comprehensive Conservation Plan
Chapter 2 – Planning, Purpose and Need, and Issues 2-3
However, the extent and nature of these impacts, if any, is unclear and the subject of
considerable academic debate.
Issue 4: Public Use Resources
The key issues related to public use are:
• adverse ecological impacts (invasive species introductions, sewage pollution, fuel spills,
trash disposal, harassment of wildlife, damage to sensitive habitats such as coral reefs);
• whether any on-site public use should be allowed;
• to what extent the use should occur; and
• how the use should be managed.
Howland has never been formally opened to public access and use. In the past, several
recreational user groups such as amateur radio operators, bird watchers, history enthusiasts,
destination tourists, and commercial cruise vessels have expressed interest in visiting various
remote Pacific island refuges. Public access to Howland would be managed through use of
refuge-issued Special Use Permits (SUP). However, before a SUP could be issued, a request for
public access would need to be evaluated for appropriateness and compatibility.
Issue 5: Education and Outreach
In general, Pacific Island refuges are poorly recognized by the public and our partner agencies.
There are few entrance signs, no boundary signs, and little published information in popular
literature. Refuge boundaries are rarely portrayed on nautical charts and other maps.
The remote location and isolation of Howland and other Pacific island refuges make it difficult
to conduct on-site visits for educational or interpretative purposes. Thus, most educational and
interpretative opportunities are necessarily delivered remotely through various media.
In addition, general interest by the public and requests to visit remote Pacific Island refuges by a
growing recreational yachting community has increased recently. This interest requires the
public to be better informed regarding sensitive refuge habitats, species, and regulations.
Issue 6: Communication and Cooperation
Howland’s remoteness compels a growing list of partners and cooperators to be kept informed of
and included in planning and management activities at Howland. Activities that staff and partner
agencies/organizations share include:
• expedition planning;
• collaborative research projects; and
• jurisdictions of trust resources.
Most access for refuge staff to Howland has only been possible through the cooperation and
participation with partner agencies such as NOAA and the U.S. Coast Guard. Many research
interests are shared between Service and NOAA scientists, and collaborative research projects
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have been conducted in the past. Additionally, NOAA and the Service share trust resource
responsibilities for marine turtles.
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Chapter 3: MANAGEMENT DIRECTION
Overview
The Service reviewed and considered a variety of resource, logistic, social, and economic aspects
important for managing the refuge when developing this long-term management plan. As is
appropriate for a National Wildlife Refuge, resource conditions were fundamental in designing
the CCP. Marine and terrestrial resources are equally important to the management of Howland,
and are described more fully in Chapter 4. However, the logistics of reaching the island and
associated coral reefs is the primary constraint on increasing or modifying the level of
management and monitoring activity that has or currently occurs. To more fully understand this
constraint, a description of the logistical requirements and refuge management activities follows.
Marine vessels capable of traveling the open ocean for extended periods are the only opportunity
for transportation to Howland. In the recent years, NOAA, the U.S. Coast Guard, and private
charter vessels have all provided transportation. A typical voyage originating from Honolulu,
Hawaii will take approximately 8 days to arrive at Howland excluding intermediate stops at
Palmyra Atoll or Johnston Atoll NWRs. Once on-site, if wind and wave conditions warrant the
launch of a landing vessel (typically a small outboard type inflatable boat), the marine vessel will
anchor or remain stationary during the deployment of the field camp, only venturing away from
the island to complete marine surveys. The field camp itself generally consists of two
individuals, typically biologists to carry out biological surveys and other duties, and camping
gear consisting of tents, sleeping equipment, food, water, and needed survey equipment.
Cooking gear is rarely deployed since staff is only on-island for 1 to 2 days with most of that
time being engaged in work activities.
While on-island, the biologists document all bird species present, count individuals, determine
the stage of any nesting efforts, qualitatively describe vegetation, and record species presence or
absence, noting in particular the presence of any invasive species. Observations regarding the
condition of cultural sites such as the Amelia Earhart day beacon are also made. The only active
management that occurs during these site visits is the collection and on-island stockpile of
marine debris that washes ashore and poses a threat to seabirds and other wildlife that use
Howland. Any evidence of illegal activity such as unauthorized access is documented.
Photographs record general habitat conditions; however, further habitat assessment does not
occur. Although no specific activities occur with respect to wilderness values, the simple fact
that a 1 to 2 day field camp consisting of temporary lodging arrangements and minimal activity
is consistent with maintaining the wilderness values of the area.
During the period that the biologists are on Howland, marine scientists from NOAA, the Service,
and other partner organizations such as the University of Hawaii conduct surveys and monitoring
activities of the marine environment. Some monitoring activities occur on-board the vessel,
while others require the use of SCUBA equipment. All of the marine scientists, however, deploy
from the vessel conducting independent marine surveys using other skiffs and thus do not come
ashore. Marine scientists typically collect information on currents, weather, temperature,
chemical composition of the water, and the abundance and distribution of coral, algae, and other
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invertebrate and fish species. Specific marine-based surveys known as Rapid Ecological
Assessments (REA) are conducted and collect ecological data such as fish species, abundance,
and predator prey relationships. Data are also collected at permanently marked coral transects
established in 2000-2002 that document changes in coral species, age, size, numbers, and percent
cover over time. These data are collected over a 2-day period (six 1-hour dives). Following the
voyage, data from marine scientists are provided to the Service that includes a full range of
oceanographic, bathymetric, and marine biological information.
Specific details of the management program are categorized below:
• Baseline Monitoring of Wildlife Populations and Habitats. Staff visits to Howland
provide baseline and temporal monitoring efforts, documenting species presence or
absence, abundance, habitat condition, presence of invasive species and various other
physical variables such as temperature, precipitation, wind, etc.
• Voyage Preparation. The logistics of providing adequate field camp supplies such as
water, food, first aid, and communications occurs for each voyage.
• Use of extraneous unnatural lighting. Limiting and shading the lighting on vessels,
camp, and nighttime operations minimizes the threat of collision and disorientation of
wildlife that can be caused by light hazards.
• Quarantine protocols and use of Integrated Pest Management (IPM). Visitors to
Howland are required to wear new and frozen clothing and other quarantine precautions
as outlined in quarantine protocols (Appendix E). Manual pulling of weeds occurs as
time becomes available. Selective hand spray application of herbicides or pesticides,
where appropriate, may occur.
• Scientific Information Exchange. Refuge staff currently attends various professional
meetings and conferences related to Pacific island and marine resources. Additionally, a
limited amount of staff time is devoted to the development of peer reviewed journal
articles and contributing to NOAA and Service-sponsored Web sites and status reports.
• Preservation of Wilderness Values. Since its establishment, Howland has been managed
to preserve its wilderness values and characteristics even though it has never been
proposed for wilderness designation. These values are intrinsic at this remote,
uninhabited island and coral reef ecosystem. Management activities do not impinge on
these values.
• Public Access. Since establishment, Howland has never been formally opened to public
access and use. Access and public use remains closed. All individual opportunities for
compatible use such as specific research projects are administered using individual SUPs.
• Interpretation, Education, and Outreach. Current opportunities for off-site education
exist at the Maritime Museum, Honolulu, Hawaii. A hands-on exhibit representing a
Pacific island refuge is maintained to educate school-aged students about seabirds,
invasive species, marine debris, and the National Wildlife Refuge System (System).
Interpretative displays are also used periodically at conventions and professional
meetings.
• Protection and Preservation of Cultural Resources. Cultural resources remain intact and
in situ. Field camps are situated to avoid impacts to cultural resource sites.
Archaeological reconnaissance to avoid impacts to cultural resources is required prior to
management activity that would potentially disturb surface or subsurface resources.
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Chapter 3 – Management Direction 3-3
• Waste Disposal at Sea. Disposal of waste in refuge waters is prohibited.
• Waste Disposal on Island. All waste from food products, equipment, and containers that
is brought onto the island is removed during demobilization. Depending upon the
duration of the site visit, human excrement will be either bagged, stored in a chemical
toilet, or decomposed using portable biodegradable toilets, all of which are subsequently
removed during field camp demobilization.
• Refuge Boundary. There are no changes to the refuge boundary.
• Cultural Resources Inventory. Presence and condition of cultural resources on Howland
is re-evaluated.
• Wilderness Study Area. A recommendation for Wilderness Study Area (WSA)
designation is postponed until a Legislative Environmental Impact Statement (LEIS) and
wilderness proposal are developed for all other remote Pacific island national wildlife
refuges (NWRs) as part of their CCP processes.
• Marine ecosystem monitoring. Funding requests are required for additional exploration
of deep slope resources by a ship equipped with a remotely operated vehicle (ROV) or
submersible to operate at depths between 150 and 300 feet.
• Seabird Nesting Restoration. Electronic calls are deployed and used as seabird nesting
attraction devices designed to attract Phoenix petrels (Pterodroma alba) and Polynesian
storm petrels (Nesofregetta fuliginosa). These electronic call devices consist of solar
powered speakers broadcasting calls of both species in suitable areas of the island. Both
of these small ground-nesting Procellariforms are severely depleted or extirpated
throughout much of their range. The mammal-free status of Howland Island makes it an
ideal site within the species’ original range to restore a breeding population of each
species.
Once field operations are complete, or the weather becomes increasingly inclement, the field
camp is demobilized and all equipment and personnel are transported back to the research vessel.
Typically, the other two other equatorial island refuges (Baker and Jarvis) are also visited in this
same manner. Travel time between Howland and Baker is 5 hours, and between Baker and
Jarvis is 5 days. Once the three surveys are completed, or at least attempted, the voyage
continues with approximately 6 to 7 days to travel back to Honolulu, again with intermediate
stops at Palmyra Atoll or Johnston Atoll NWRs, or continuing on for 4 days to Rose Atoll NWR
in American Samoa where voyage scientists and biologists can be exchanged and then fly back
to Honolulu. In total, it is expected that in order to visit Howland, Baker, and Jarvis for 1 to 2
days per refuge, a biologist or marine scientist needs to devote 20 to 26 days total travel. Trip
reports are completed, distributed, and filed once field staff returns to the Honolulu office.
The only difference between the management condition prior to the completion of the CCP, and
the actions described in this CCP is an increase in the frequency of staff visits from once every
two years to once every year. In order to meet the increase in the number of site visits, refuge
staff in Honolulu is administratively burdened to seek additional funding sources and develop
partnerships for additional visits. This may take the form of producing internal project proposals
(RONS), or seeking funding support through grants or partnerships with other agencies, research
institutions, and non-government organizations. Overall, wildlife and habitat management
activities remain consistent. The only additional terrestrial management activity is promoting
nesting use by two seabird species with the use of solar powered electronic calling devices.
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Phoenix petrel calls would be placed near the kou (Cordia subcordata) grove, and the Polynesian
storm-petrels calls would be placed near the coral slab habitat on the north beach crest.
Increased monitoring in the marine environment depends upon partnership opportunities
developed with NOAA, the University of Hawaii, or other partners. At a minimum, marine
scientists would resurvey REA and other transect sites. Transportation to and from the island
would still relies upon NOAA or other partners. Public use and access remains closed.
The ability of the Service to meet the mission of the System, “…to administer a national network
of lands and waters for the conservation, management, and where appropriate, restoration of the
fish, wildlife, and plant resources and their habitats within the United States for the benefit of
present and future generations of Americans” and the refuge purpose of “…the restoration and
preservation of the complete ecosystem, terrestrial and marine. Special consideration must be
given to the protection of nesting seabird populations” is limited. A one to two day visit to the
island once every year does not provide the opportunity for refuge staff to complete anything
other than basic biological surveys of species presence or absence. Restoration, preservation, or
protection of terrestrial and marine ecosystems, or nesting seabirds is not possible. However,
lack of projected budget and staffing preclude management staff from increasing management
activity beyond what is described in this CCP. If, during the lifetime of this plan, budget and
staffing become available to pursue an increased level of management activity then the CCP will
be reevaluated.
Goals, Objectives, Strategies, and Rationale
Goals and objectives are the unifying elements of successful refuge management. They identify
and focus management priorities, resolve issues, and link to refuge purposes, Service policy, and
the Refuge System Mission.
A CCP describes management actions that help bring a refuge closer to its vision. A vision
broadly reflects the refuge purposes, the Refuge System mission and goals, other statutory
requirements, and larger-scale plans as appropriate. Goals then define general targets in support
of the vision, followed by objectives that direct effort into incremental and measurable steps
toward achieving those goals. Finally, strategies identify specific tools and actions to
accomplish objectives.
The goals for Howland over the next fifteen years under the CCP are presented on the following
pages. Each goal is followed by the objectives that pertain to that goal. The goal order does not
imply any priority in this CCP. Some objectives pertain to multiple goals and have simply been
placed in the most reasonable spot. Similarly, some strategies pertain to multiple objectives.
Following the goals, objectives, and strategies is a brief rationale intended to provide further
background information pertaining to importance of an objective relative to legal mandates for
managing units of the NWRS including refuge purpose, trust resource responsibilities (federally
listed Threatened and Endangered species and migratory birds), and maintaining/restoring
biological integrity, diversity, and environmental health.
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Chapter 3 – Management Direction 3-5
Goal 1: Conserve, manage, and protect native terrestrial habitats that are
representative of remote tropical Pacific islands, primarily for the benefit of
seabirds.
Objective 1a: Conserve, manage, and protect habitat for nesting seabirds.
Upon CCP approval and throughout the life of the CCP, conserve, manage, and protect a mosaic
of approximately 648 acres of terrestrial habitat consisting of 30 acres of beach and beach
strand, 500 acres as short grass and forbs, 6 acres as scrub shrub, and 112 acres as bare ground
on Howland Island as nesting habitat for ≥ 11 seabird species.
Strategies Applied to Achieve Objective
Conduct and record incidental observations of invasive terrestrial species.
Adhere to strict quarantine protocols for all island visitors (see Appendix D).
Collect and stockpile marine and other human debris not considered to be historically important.
Rationale:
The 11 nesting seabird species on Howland use all island habitats (see Chapter 3.9.1 and
Appendix B). Masked and brown boobies prefer to nest on bare open ground. Gray-backed,
sooty, and white tern, and brown and blue grey noddy also nest on the surface, but are tolerant of
vegetated areas. Lesser frigatebirds, typically known as a shrub nesting species, are found
exclusively on the ground at Howland. Red-tailed tropicbirds prefer shaded areas and can be
found nesting on the surface, under coral slabs, or in shrubs. Red-footed booby and great
frigatebird are the only two exclusive shrub nesting species.
The Seabird Conservation Plan (2005) recognizes remote Pacific islands as providing important
and varied breeding habitat, specifically Howland as being important for ground nesting species.
Additionally, the plan recognizes that near-shore waters provide areas of upwelling currents with
important food resources for seabirds.
Maintaining the island free of mammalian predators, invasive insects, and invasive plants is
critical for seabird survival (USFWS 2005). Strict quarantine protocols have been previously
established for all island visitors in order to eliminate the threat of introducing invasive plants,
insects, and animals (see Appendix D).
Marine and other human generated debris poses an entanglement threat for multiple wildlife
species. Stockpiling debris can reduce the overall area impacted, thereby reducing the
entanglement threat.
Objective 1b: Increase baseline information on terrestrial habitat.
Within 15 years of the CCP approval, conduct monitoring to determine vegetation species
presence/absence and distribution on Howland Island.
Strategies Applied to Achieve Objective
Document presence/absence of island vegetation.
Coordinate with Regional Office GIS staff to assess and/or develop remote sensing capability to
map and monitor island habitats.
Rationale:
In general, insufficient time has been spent on Howland to adequately quantify habitat on
Howland, and how this habitat relates to seabird biology. Collection of baseline biological
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information is essential to adequately understand and manage the refuge. Although it is known
that the 11 nesting seabird species use all habitats on Howland, this information has only been
obtained from the short duration, infrequent visits (1 to 2 days every 2 years) to the island.
There has been no quantitative assessment of breeding species habitat associations. The
distribution and delineation of habitats itself has been estimated, but never been quantified.
Remotely collected data may provide an option for data collection in the absence of being
capable of visiting Howland.
Goal 2: Conserve, manage, and protect native marine communities that are
representative of remote tropical Pacific islands.
Objective 2a: Conserve, manage, and protect marine habitat.
Upon CCP approval, conserve, manage, and protect approximately 33,671 acres of submerged
lands consisting of an estimated 3,000 acres coral reef and 30,671 acres of deep water/pelagic
habitat on Howland.
Strategy Applied to Achieve Objective
Continue and expand partnership with NOAA and others to manage coral reef ecosystems.
Rationale:
The conservation and protection of the Nation’s coral reefs is becoming increasingly important
for agencies with responsibility to manage and conserve those (Executive Orders 13089 and
13158). Because the refuge boundary for Howland extends to 3 nmi from the island shoreline,
all shallow water coral reefs are contained within the refuge boundary. Threats to the coral reef
system include predatory species such as crown-of-thorns starfish, invasive species such as the
corallimorph Rhodactis howesii, and marine debris (e.g. abandoned fishing gear) that collects on
corals, smothering or breaking them. The responsibility for protecting, managing, and
conserving coral reef ecosystems is shared with NOAA. The Service and NOAA often
participate in joint management activities throughout the Pacific; however, no active
management activities have occurred at Howland.
Objective 2b: Increase baseline information on marine community.
Within 15 years of CCP approval, continue monitoring coral species to determine size, cover,
density, diversity, and distribution; fish species presence/absence and habitat associations; sea
turtle species presence or absence; and marine mammal species presence or absence;
oceanographic conditions in relation to climate change effects.
Strategies Applied to Achieve Objective
Conduct and record incidental observations of corals, fish, turtles, marine mammals, and their
habitats.
Accompany NOAA or other scientific partners on marine surveys.
Conduct REA (Rapid Ecological Assessments) on at all existing survey sites to document coral,
fish and turtle density, diversity, distribution, and habitat associations.
Develop proposals and conduct deep slope marine surveys by ROV (remotely operated vessel)
or submersible to document presence or absence of deep slope coral and fish species.
Rationale:
Responsibility for managing marine resources is shared with NOAA, and has led to many
cooperative studies. Unlike the logistic constraints of completing terrestrial surveys, marine
surveys are conducted throughout the entire time that the marine transport vessel is at Howland.
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Additionally, since most site visits to Howland are aboard NOAA research vessels, the purpose
of these voyages is to conduct marine surveys and studies. Consequently, a full compliment of
up to 20 marine researchers and another 20 support staff contribute to conducting marine
surveys across all alternatives. As a result, marine surveys are more comprehensive than
terrestrial surveys on Howland, although individual dives are limited to one hour and depths less
than 20 m.
REAs constitute baseline monitoring of the marine ecosystem, and are one component of all
alternative strategies. Further expansion of REA’s could be accomplished only as a component
of Alternative D.
Additional surveys (marine mammals, deep slope), as described beginning with Alternative B
can be achieved as components of cooperative efforts with other agencies or research
organizations. As an example, little is known of marine mammal use surrounding Howland, or
the history of sea turtle use and nesting, although it is known that some species are found in the
vicinity.
The Marine Mammal Commission has encouraged the Service to generate partnerships with
NOAA to help document baseline information. Developing additional partnerships with NOAA
or other organizations may also assist in meeting terrestrial objectives by providing the
opportunity for additional trips to Howland.
Goal 3: Contribute to the recovery, protection, and management efforts for all
native species with special consideration for seabirds, migratory shorebirds,
federally listed threatened and endangered species, and species of management
concern.
Objective 3a: Develop baseline migratory bird and other species information.
Within 10 years of CCP approval, conduct monitoring (in rank order) to determine: seabird
species presence or absence, relative abundance, breeding chronology, distribution, and habitat
use; counts of shorebirds; presence or absence and distribution of sea turtles; and presence or
absence of terrestrial invertebrates on Howland Island. The desired conditions by which this
will be met is understanding of the complete annual chronology for 5 of 11 seabird species;
population trend data over the 10-year period for all 11 seabird species; and the numbers and
distribution of shorebirds, turtles and other terrestrial invertebrates.
Strategy Applied to Achieve Objective
Record incidental observations of all species’ presence or absence, relative abundance, and
distribution.
Rationale:
The Seabird Conservation Plan (2005) repeatedly recognizes the importance of the U.S. Pacific
Islands in providing predator-free seabird nesting and roosting environments. Their protected
status, in concert with nearby marine forage resources contribute to their importance. The
Seabird Plan further identifies infrequent inventories as insufficient to accurately detect or
monitor populations, suggesting instead that a rigorous collection of population data is needed.
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In addition to Howland being recognized as important habitat for seabirds, the U.S. Pacific
Islands Regional Shorebird Conservation Plan (2004) lists determining baseline information for
bristle-thighed curlews, and other species, as the goal of the Central Pacific Islands Subregion.
The endangered species recovery plans for both species of turtles indicate that little is known
about their biology in the central Pacific. Data on other terrestrial wildlife species found on
Howland Island is lacking.
Objective 3b: Restore breeding populations for 2 seabird species.
Within 10 years of CCP approval, establish up to 5 nesting pairs each of Phoenix petrel
(Pterodroma alba) and Polynesian storm-petrel (Nesofregetta fuliginosa) during a minimum of
three consecutive years on Howland Island.
Strategies Applied to Achieve Objective
Implement and maintain electronic calling devices to promote nesting.
Coordinate with RO and develop capabilities for remote surveillance equipment.
Rationale:
The Seabird Conservation Plan (2005) recognizes the Polynesian storm-petrel may flourish on
Howland, as well as Baker and Jarvis, due to the removal of predators from the islands. The
Phoenix petrel is known from the Phoenix Islands, but does not currently inhabit Howland,
though it is thought that they did historically. A recommendation of the Seabird Conservation
Plan (2005) is expand efforts to assess habitat suitability and restore populations through
translocation to predator-free U.S. islands such as Howland. While the physical translocation of
species to Howland is not being suggested, electronic calling devices are designed, and have
been successful, in attracting and establishing nesting seabird colonies to other islands.
Objective 3c: Develop baseline data and understand turtle use of Howland.
Upon CCP approval, monitor hawksbill and green turtles to document any nesting sites, all
adjacent coral reef and nearshore water foraging sites, and overall population density and
distributions, and review literature to determine previous records of, and use of sea turtles during
the guano mining and WWII eras.
Strategies Applied to Achieve Objective
Record incidental observations of nearshore turtle use.
Develop partnership with NOAA for study of turtles at Howland.
Rationale:
There is currently little information related to use of Howland resources by sea turtles, though it
is known that they do use refuge habitats. Sea turtles may have been collected or harvested
during the guano and WWII eras. Sea turtles have been photographed in the water during joint
Service/NOAA expeditions since 2000. Data collected over the life of this plan would help to
establish a baseline understanding of sea turtle populations in the central Pacific.
Objective 3d: Expand baseline information on marine community.
Upon CCP approval, monitor populations of globally depleted marine species such as giant
clams (Tridacna sp.), bumphead parrotfish (Bolbometapon muricatum), Napoleon wrasses
(Cheilinus undulatus), large groupers (Cephalopholis sp., Epinephelus spp., Variola spp., etc.),
sharks (Carcharhinus spp., Triaenodon spp., Negaprion spp., Galeocerdo spp., etc.), pearl
oysters (Pinctada margaritifera), the invasive corallimorph (Rhodactis howesii) and corals
(Anthozoa, Hydrozoa) to document their presence or absence and relative abundance on
Howland.
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Chapter 3 – Management Direction 3-9
Strategies Applied to Achieve Objective
Conduct marine surveys such as REA.
Maintain the monitoring of permanent coral and macro-invertebrate transects established in
2000-2002.
Solicit partnership for survey of deep slope habitat.
Rationale:
Many marine species of commercial importance have been globally depleted. Protected areas
such as Howland still provide sanctuary areas. However, illegal fishing activity, including
evidence thereof, has been noted surrounding several Remotes refuges. Howland, as well as
other remote island refuges provide the opportunity to study and protect the marine ecosystem.
Objective 3e: Develop baseline scientific information on marine mammal use of Howland.
Within 10 years of CCP approval, increase scientific understanding of marine mammal presence
and use of Howland marine waters. The desired conditions by which this will be met will be to
document all marine mammal use of nearshore waters.
Strategies Applied to Achieve Objective
Incidental observations of marine mammals.
Solicit partnership for study of marine mammals at Howland.
Rationale:
NOAA, the Service, Oceanic Institute, University of Hawaii, and Bishop Museum marine
biologists have collected data on marine species of concern since 2000. Only anecdotal
information exists on marine mammal use of the waters surrounding Howland Island. However,
studies elsewhere in the Pacific indicate that waters surrounding small islands may support
distinct local populations of marine mammals. It is also important to understand the threats
human activity may pose to this important resource (Marine Mammal Commission. pers.
comm.), including unauthorized fishing.
Goal 4: Protect, maintain, enhance, and preserve the wilderness character of
Howland’s terrestrial and marine communities.
Objective 4a: Protect and maintain wilderness values.
Upon CCP approval, continue to preserve the wilderness values (e.g. size, naturalness, solitude,
supplemental values) of Howland. Achievement of this objective will be evaluated by assessing
loss or degradation of values that qualified it for potential designation (see Appendix F).
Strategies Applied to Achieve Objective
Use minimum tools necessary to manage refuge resources.
Continue to manage Howland as wilderness.
Monitor values of naturalness and solitude.
Rationale:
Howland has been and is managed as a wild, natural area due to its remote location, historic lack
of human impact, and limited human presence. Areas of Howland have been identified as
meeting the criteria for a Wilderness Study Area (Appendix F). Completion of the wilderness
review process and as appropriate development of a Legislative EIS will be pursued for all
Pacific Remote Island Refuges once their CCP’s have been completed.
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Some human generated debris remains from past occupations. Additionally, debris such as
discarded fishing nets continuously washes ashore. This debris impinges upon wilderness
values.
In the interim, all areas identified as suitable WSAs would continue to be managed as
wilderness. All management activities would be conducted in such a manner as not to detract
from the wilderness values identified in the Wilderness Inventory.
Goal 5: Howland’s biological, cultural and historic resources are preserved.
Objective 5a: Protect cultural resources.
Upon CCP approval, continue to protect existing cultural resources. The desired conditions by
which this will be met will be to document any change in condition of Amelia Earhart day
beacon memorial, or other recognized cultural/historical resource.
Strategy Applied to Achieve Objective
Record incidental observations of condition of cultural resources.
Rationale:
Restricting human use of Howland would maintain cultural resources by limiting the opportunity
for invasive species establishment, and reducing the opportunity for unauthorized collection or
disturbance. In order to keep cultural resource sites protected, the locations and descriptions of
fragile cultural resources would not be made available to the public.
Objective 5b: Enhance Law Enforcement Capabilities
Upon CCP approval, seek to improve partnerships with the NOAA Office of Law Enforcement
to increase enforcement capacity. The desired conditions by which this will be met will be to
formalize interagency agreements and develop remote surveillance techniques to document
unauthorized access to the refuge.
Strategies Applied to Achieve Objective
Establish joint enforcement operational protocols with NOAA Office of Law enforcement.
Evaluate the effectiveness of deploying acoustical devices to detect ship traffic in the vicinity of
the refuge.
Rationale:
Enhancing law enforcement capability to detect and prosecute unauthorized access would
preserve biological and cultural resources by limiting the opportunity for invasive species
establishment and deterring unauthorized collection or disturbance.
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Goal 6: An informed, interested, and educated public appreciates remote Pacific
Island NWR wilderness values, cultural and historical resources, and their
ecosystems, with special emphasis on seabirds.
Objective 6a: Provide off-site education and interpretation opportunities.
Within three years of CCP approval, develop an off-site educational opportunity for the public to
learn about Pacific Island refuge wilderness values, cultural and historical resources, tropical
island ecosystems, seabirds, and coral reef. The desired conditions by which this will be met
will be through publications, educational programs, displays, or other media.
Strategy Applied to Achieve Objective
Develop, with External Affairs office, Honolulu, an interpretative brochure, display, or
educational program for all remote Pacific Island refuges.
Rationale:
While it is important for the public to understand and appreciate the resource values associated
with remote island refuges, it is logistically difficult to do this on-site at Howland and still
protect the island’s wildlife, habitats, wilderness values, cultural and historical resources, and
visitor’s safety. For these reasons, interpretative or educational opportunities for the public to
learn and appreciate the values of remote Pacific Island refuges and resources will be provided
primarily as off-site programs and interpretative brochures.
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Howland Island National Wildlife Refuge Comprehensive Conservation Plan
Chapter 4 – Refuge and Resource Description 4-1
Chapter 4: REFUGE AND RESOURCE DESCRIPTION
Geographic/Ecosystem Setting
Howland Island, located at approximately lat. 0º49’ N. and long. 176º38’ W is a northwestern
outlier of the Phoenix Archipelago and is included in the Central Pacific subregion of the
Polynesian Region of the Pacific Basin. This subregion, the largest of four in the Polynesian
Region, is the most remote part of the tropical Pacific and includes only low-lying reef islands,
atolls, and submerged reefs. Vegetation patterns are determined by the highly variable but
normally low rainfall levels found along the Equator in the central Pacific. In turn, the arid
weather and ocean circulation patterns impose limits on floating seed plant dispersal strategies.
Howland falls in the central Pacific dry zone with rainfall less than 40 inches per year, and thus
"cannot support any forest or closed woody vegetation" (Mueller-Dombois and Fosberg 1998).
The nearest landmasses are Baker Island 32 nmi to the south, and McKean Island 352 nmi to the
south southeast. Both islands are also in the Phoenix Islands. The remaining 8 Phoenix Islands
under the jurisdiction of the Republic of Kiribati are the next closest neighbors to Howland
Island, up to 480 nmi to the southeast. The next closest landmasses outside the Phoenix Islands
are the Gilbert Islands, with Beru Island closest to Howland Island at 420 nmi to the southwest.
Tarawa Atoll, the capitol of the Republic of Kiribati, is 600 nmi to the west in the central Gilbert
Archipelago.
Climate
General Climate and Related Oceanographic Conditions in the Central Equatorial
Pacific
The climate associated with Howland Island can be generalized as being arid, warm, and tropical
with moderate breezes and light to moderate rainfall. Although differences in climate exist
among the islands, climate monitoring stations are not readily available in the equatorial Pacific.
Consequently, site-specific data is lacking for most central Pacific locations, or have only been
collected for a short period. In order to describe the weather conditions on Howland Island,
weather monitoring data are taken from historic onsite weather data, or from the closest weather
monitoring station, located on Kanton Island.
There are several climatic factors that influence weather on Howland: trade winds, rainfall, and
oceanic currents. Trade winds are surface winds that typically dominate airflow in tropical
regions and predominate from the southeast at Howland between 12-17 miles per hour.
Atmospheric pressure gradients range from high pressure areas located near lat. 30º N. and lat.
30º S., to the low pressure band located near lat. 5º N., driving both the northeast and southeast
trade winds. This area of low pressure located just north of the Equator is referred to as the
‘doldrums’ or the Intertropical Convergence Zone (ITCZ) and lacks these prevailing trade winds
because they converge and rise upward.
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Solar heating also allows the moist air mass of the ITCZ to rise, thus cooling the air mass and
producing a band of heavy precipitation several degrees to either side of the ITCZ (Wallace and
Hobbs 1977). Howland’s position near the Equator places it outside this band of heavy
precipitation. Changes in these typical patterns occur seasonally and during periodic events
known as the El Niño Southern Oscillation (ENSO). During an ENSO event, the ITCZ shifts
south and east toward unusually warmer waters. At Howland, this shift typically leads to lighter
wind speeds and more rainfall (USFWS 2001, USFWS 1998a, Vitousek et al. 1980).
Prevailing ocean currents surrounding Howland Island also influence weather patterns on the
island by moderating the surrounding surface air temperatures. These surface currents roughly
mimic the direction of the trade winds. Howland is almost always within the flow regime of the
westward flowing South Equatorial Current.
Howland Island also lies in the path of the subsurface easterly flowing Equatorial Undercurrent
(EUC) also referred to as the Cromwell Current. As the EUC strikes the submerged western
slopes of Howland Island, nutrient rich waters are deflected upward, enriching the primary
productivity of the surface waters surrounding Howland. These upwelling waters from the EUC
are slightly cooler than adjacent sea surface waters and may moderate the effects of localized and
periodic sea surface warming events.
Howland Island Climate Data
There is very little weather data available from Howland Island. Weather observations were
made during the military occupation of Baker and Howland Islands from 1935-1945 (AEC
1963). However, these military records could not be located within refuge files in Honolulu. A
single reconnaissance trip to Howland and Baker Islands by the Logistics Planning Group of
Holmes & Narver INC, for the U.S. Atomic Energy Commission (AEC) in October 1963
recorded sea water temperatures between 86ºF and 87ºF (AEC 1963). Air temperatures during
that time period ranged from 80ºF to 94ºF with an average of 85ºF. Wind speeds during this visit
averaged 13 miles per hour with a range of 6-23 miles per hour. In winter, the average daily
range of air temperature is reported as 78-88ºF, and during summer the average daily range is 78-
90ºF (NOAA 1991).
The nearest weather station to Howland is at Kanton Atoll, located in the Phoenix Islands at lat.
02º46’ S., long. 171º43’ W., or roughly 378 nmi southeast of Howland (USFWS 1998a). This
station reports total annual rainfall is approximately 30 inches with precipitation consistent
throughout the year (NOAA 1991). Weather data at Kanton support the conclusions of arid
conditions in the northern Phoenix Islands.
Global Climate Change
A continuously growing body of unequivocal scientific evidence has emerged supporting the
anthropogenic nature of current global climate change. During the 20th century, the global
environment experienced variations in average worldwide temperatures, sea levels, and chemical
concentrations. Global air temperatures on the earth’s surface have increased by 1.3°F since the
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mid-19th century (IPCC. 2007a). Eleven of 12 years from 1995 to 2006 are the warmest on
record since 1850 (IPCC 2007b). Global water temperatures have increased by 0.31º on average
in the upper 300 m during the past 60 years since 1948 and changes in ocean heat content have
penetrated as deep as 3000 meters (Levitus et al. 2005). Subsequently, sea levels rose
approximately 1.7 mm (0.07 in) ± 0.5 mm/yr during the 20th century (IPCC. 2007a); this rate
rose dramatically to 3.1 mm (0.122 in) ± 0.7mm/yr since 1993 (IPCC 2007b).
While the concept of climate change is now widely accepted, the extent and impact of future
changes as well as the exact source (natural or human induced) remains a debate (OPIC 2000).
Emerging consensus contends that increasing quantities of greenhouse gases (GHGs) in the
atmosphere, especially carbon dioxide (CO2), are beginning to affect climate and may be the
dominant force driving recent warming trends. The amount of GHGs globally has grown due to
human activities since pre-industrial times, with an increase of 70% between 1970 and 2004
(IPCC 2007b). Carbon dioxide has increased by about 80% in the same time period. The
atmospheric concentrations of CO2 and methane in 2005 were 379 ppm³ and 1774 ppb,
respectively. These amounts greatly exceed concentrations recorded in the global environment
over the last 650,000 years (IPCC, 2007a). Other emissions and GHGs from human activity
have enhanced the heat trapping capability of the earth’s atmosphere, causing warmer
temperatures. Although the increase in carbon dioxide is largely attributed to fossil fuel use,
land use changes have also increased the amount of cleared land surfaces, thereby reflecting
more solar radiation (IPCC 2001, IPCC 2007a, IPCC, 2007b).
Global forecasting models offer a variety of predictions based on different emission scenarios.
OPIC (2000) suggests that a further increase in GHG emissions could double atmospheric
concentrations of CO2 by 2060 and subsequently increase temperatures by as much as 2 to 6.5°F
over the next century. Recent model experiments by the IPCC (2007a) show that if GHGs and
other emissions remain at 2000 levels, a further global average temperature warming of about
0.18°F per decade is expected. Sea-level rise is expected to accelerate by two to five times the
current rates due to both ocean thermal expansion and the melting of glaciers and polar ice caps.
Consequently, patterns of precipitation and evaporation may be altered. These changes may lead
to more severe weather, shifts in ocean circulation (currents, upwelling), as well as adverse
impacts to economies and human health (OPIC 2000, IPCC 2001, Buddemeier et al. 2004, IPCC
2007a). Hansen, et al. (2008) propose that current models may underestimate the slower
feedback processes such as ice sheet disintegration, vegetation migration, and greenhouse gas
release from soils and that these factors may come into play in this century. These changes will
have a significant effect on the national wildlife refuges in the tropical Pacific. The changing
global environment and the implications this may have for ecological and geological processes in
the Central Tropical Pacific are important considerations for future management of trust
resources there. The four areas of impact linked to global climate change that may have the
greatest potential effect on Howland Island NWR and its wildlife are sea level rise, weather and
ocean circulation changes, ecological disruptions and coral bleaching due to increased ocean
temperature, and oceanic chemical composition change.
Vitousek (1994) reported, “Changes in both climate and biological diversity are known with less
certainty than are changes in C02 concentrations, global biogeochemistry or land use.” Because
temperature is more variable both spatially and temporally than C02 concentration, it is difficult
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to separate human-caused vs. natural background variation. However, it is certain that increasing
concentrations of C02 and other greenhouse gasses will cause increasing climate change
(Vitousek, 1994).
The equatorial locale for Howland places it near the path of anomalous water current and surface
wind conditions during ENSO events, but the paucity of weather and oceanographic data at
Howland renders it difficult to assess the impacts and trends of global climate change at the
island. The upward deflection of cool subsurface waters into shallow water by the upwelling
effects of the EUC further complicates an assessment of climate change effects, because this
phenomenon has been rarely reported outside of the three equatorial refuges (Howland, Baker,
Jarvis).
The insular nature of both the terrestrial and coral reef habitats of Howland will result in the
same high vulnerability of resident organisms that is seen in range restricted or mountaintop
species elsewhere (Parmesan 2006).
Sea Level Rise
While global temperature is projected to rise by 3.6 to 9ºF and sea level to rise by more than 31.5
inches during the next two centuries, sea levels have fluctuated by an order of 328 feet over the
past 18,000 years as natural background variation and thawing out from the last ice age
(Michener et al. 1997). Contributions to sea level rise by climate change are ice-sheet melting,
alpine glacier melting and thermal expansion of the sea. Sea levels have risen by 4-8 inches
during the past century (Michener et al. 1997). The Intergovernmental Panel on Climate Change
(IPCC 2001) predicted a sea level rise of 3.5 inches to 34.6 inches by the year 2100 unless
greenhouse gas emissions were reduced substantially. They also suggested that continuing
greenhouse gas emissions could trigger polar ice-cap melting after 2100 accompanied by sea
level rise greater than 16 feet. More recent modeling indicates that melting could occur faster
than the IPCC predicted (Overpeck et al. 2006).
Evidence also suggests that the world’s oceans are regionally divisible with regard to historic
fluctuations in sea level. Localized variations in subsidence and emergence of the sea floor and
plate-tectonics activity prevent extrapolations in sea level fluctuations and trends between
different regions. While researchers in IPCC (2007a) state that water levels in the equatorial
Pacific are rising at a rate of 1.2 to 2 mm per year, it may not be possible to discuss uniform
changes in sea level on a global scale, or the magnitude of greenhouse gas-forced changes, as
these changes may vary regionally (Michener et al. 1997). As an example, tide gauge records on
the Atlantic coast indicate a sea level rise of 0.06 to 0.16 in/year over the past century, whereas,
they have indicated a 0.35 to 0.39 in/year increase along the Gulf Coast of the United States
(Michener et al. 1997).
Increases in sea level and associated increases in storm surges and storm intensity will affect
Howland Island. Shoreline erosion and salt water intrusion into subsurface freshwater aquifers
have been noted throughout the Pacific (Shea et al. 2001). Due to the deep marine slopes
directly adjacent to Howland Island, increases in sea level could significantly erode shorelines
and overall island surface area since opportunities for accretion of lands do not exist. Loss of
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breeding habitat for seabirds, wintering grounds for migratory shorebirds, and habitat for native
plants, and land crabs are predicted at current rates of sea level rise.
Ocean Temperature Increases
Most climate projections suggest that more intense wind speeds and precipitation amounts will
accompany more frequent tropical typhoon/cyclones and increased tropical-sea surface
temperatures in the next 50 years (Walther et al. 2002, IPCC, 2007). The third IPCC (2001) has
concluded, with “moderate confidence” that the intensity of tropical cyclones is likely to increase
by 10-20 percent in the Pacific region when atmospheric levels of CO2 reach double pre-industrial
levels (IPCC 2001). One model projects a doubling of the frequency of 4-inch-per-day
rainfall events and a 15–18 percent increase in rainfall intensity over large areas of the Pacific
(IPCC 2001). The IPCCl (2007) states that it is “more likely than not” that the rise in intense
tropical cyclones is due to anthropogenic activity.
Above normal mean sea surface temperatures have been shown to cause bleaching and mortality
in corals both in nature and in the laboratory with bleaching generally occurring in shallower
waters (Floros et al. 2004). Coral bleaching, the expulsion of symbiotic zooxanthellae from
coral polyps and subsequent loss of photosynthetic pigments is the result of both natural and
anthropogenic stresses. Although corals may pale in response to seasonal increases in sea
surface temperature, there has been a higher frequency of large scale bleaching events since the
1980s (Nicholls et al. 2007). The most severe global bleaching event ever recorded occurred in
1997-98 when over 50 countries showed signs of bleaching (Grimsditch and Salm 2005). Many
species of coral currently exist in the upper limits of their specific temperature range; thus, an
increase in average sea surface temperatures (even by 1.8 or 3.6ºF) over a sustained period has
been shown to cause mass bleaching, especially in shallow waters habitats (Grimsditch and Salm
2005). Other variables have also been implicated in bleaching and mortality events, including,
extended periods of high temperatures, low wind velocity, clear skies, calm seas, low rainfall,
high rainfall, salinity changes, high turbidity or acute pollution. Floros et al. (2004) goes on to
note “The causes of coral bleaching are debatable, but widely thought to be the result of a variety
of stresses, both natural and human-induced, that cause the degeneration and the loss of the
colored zooxanthellae from the coral tissues.”
Bleaching episodes in equatorial islands appear to be linked to the El Niño-Southern Oscillation
(ENSO). Widespread bleaching events occurred during the El Niños of 1982-83, 1987-88, and
1997-98 (Buddemeier et al. 2004). During the warm phase of ENSO, or El Niño, sea-surface
temperatures are usually warm, trade winds weak, and sea level decreases in the western Pacific
(IPCC 2001, Buddemeier et al. 2004). These combined factors result in a dramatic increase in
coral bleaching (Buddemeier et al. 2004). While El Niño events have increased in intensity and
frequency over the past decades, some longer-term records have not found a direct link to global
warming (Cobb et al. 2003) and do not predict significant changes in El Niño; however, they do
suggest an evolution toward more “El Niño-like” patterns (Buddemeier et al. 2004). Most
climate projections reveal that this trend is likely to increase rapidly in the next 50 years
(Walther et al. 2002).
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Most climate projections suggest that more intense wind speeds and precipitation amounts will
accompany more frequent tropical typhoon/cyclones and increased tropical-sea surface
temperatures in the next 50 years (Walther et al. 2002, IPCC. 2007a). The third IPCC (2001)
has concluded, with “moderate confidence” that the intensity of tropical cyclones is likely to
increase by 10 to 20 percent in the Pacific region when atmospheric levels of CO2 reach double
pre-industrial levels (IPCC 2001). One model projects a doubling of the frequency of 4 inches
per day rainfall events and a 15-18 percent increase in rainfall intensity over large areas of the
Pacific (IPCC 2001). The IPCC (2007a) states that it is “more likely than not” that the rise in
intense tropical cyclones is due to anthropogenic activity.
If coral reef ecosystems do not acclimate to projected thermal stresses, more frequent bleaching
events and widespread mortality will occur. The ability of coral reef ecosystems to withstand
these impacts will depend on the extent of degradation from other anthropogenic pressures and
the frequency of future bleaching events (Nicholls et al. 2007).
Field observation of corals at Baker, Howland, and Jarvis during five separate expeditions from
2000-2006 indicate that corals may be recovering from a bleaching event that took place during
the previous few years (1997-1998). Corals continued to increase in cover and size based upon
observations during all subsequent (post 2000) visits, including those at permanent transect sites
(Maragos 2008; Maragos et al. 2008a & 2008b, Miller et al. 2008). Although coral bleaching
was predicted to occur at Jarvis in 2003 based upon NOAA satellite based temperature and wind
data, no evidence of bleaching was reported there during the early 2004 and 2006 visits
(Maragos 2000-2006, unpublished data). One possible explanation is that the cool upwelling
waters of the EUC are buffering the effects of the otherwise warmer seawater temperatures at the
island.
Tudhope (2000) sampled 6 cores obtained from 2 large, 3-4 meter Porites coral heads at Jarvis in
1999 to track sea surface temperature and coral growth rates over several or more decades using
stable oxygen isotope as a measure of Sea Surface Temperature. He found a good correlation
between this measure and the NINO3.4 Index, which is one of the most widely used and reliable
indicators of the status of ENSO. The results of their work at Jarvis and at four other tropical
sites in the Line and Cook Islands contributed to demonstrating linkages between the tropics and
the North Pacific over hundreds of years (D’arrigo et al 2005). Hawaii Undersea Research
Laboratory (HURL) submersible dives at Jarvis in July 2005 revealed many deep-water corals,
and samples of some were taken for climate change and paleo-climate analyses. The results of
these analyses are not yet available.
Oceanic Acidification and Atmospheric Chemistry
Glacial and interglacial periods in the Earth’s history, as measured from deep Antarctic ice cores,
reveal cyclical fluctuations in the concentration of global CO2. However, recent increases fall
outside the range of peak prehistoric CO2 levels. Current atmospheric CO2 concentrations are at
their highest levels in more than 160,000 years, with humans emitting 25 billion tons of CO2
annually (Buddemeier et al. 2004). The rate of increase is also five to ten times more rapid than
any of the sustained changes in the ice-core record (Vitousek 1994). The higher the
concentration of CO2 in the atmosphere, the greater the amount of CO2 dissolved in the surface
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ocean. When CO2 dissolves in seawater it forms carbonic acid (H2CO3), a weak acid that
releases additional hydrogen ions and increases the acidity of the ocean. In order to buffer this
acidity, the hydrogen ions react with carbonate (CO3
2-) ions and convert them to bicarbonate ions
(HCO3
-). However, this buffering ability has diminished due to the rapid rising CO2
concentrations and the global seawater pH has decreased by 0.1 units since 1750, with regional
variations (Royal Society 2005, IPCC 2007). Models predict that over the 21st century, average
surface ocean pH will continue to fall between 0.14 and 0.35 units (IPCC 2007a).
Increased atmospheric CO2 and ocean acidification affect marine organisms. As the
concentration of carbonic acid and bicarbonate ions rises, the concentration of carbonate ions
decreases. Many corals and marine organisms use calcium (Ca2+) and carbonate ions from
seawater to secrete CaCO3 skeletons (Buddemeier et al. 2004, IPCC 2007). Change in CO2
levels will increase the partial pressure of CO2 in seawater, thus reducing the over-saturation of
aragonite, a form of calcium carbonate that is the major building block for coral reefs (Vitousek,
1994). On a transect in the Pacific Ocean that ran very near Jarvis, Feeley et al. (2004) show that
the aragonite saturation horizon is shallow and is shoaling compared to the pre-industrial
aragonite saturation horizon. This reduces the width of the zone in which marine organisms have
optimum aragonite concentrations for shell-building. The result of this is uncertain but is
thought to reduce the rate at which corals can deposit calcium carbonate, thus reducing the rate at
which coral reefs will be able to keep up with any increases in sea level. A lowered calcification
rate means calcifying organisms (corals) may grow skeletons at a slower rate, lower density,
and/or decreasing strength. Thus, changes in global seawater chemistry reduce the ability of
corals to successfully compete for space and increase susceptibility to breakage (Grimsditch and
Salm 2005). In addition to changes in the carbonate system, changes in ocean chemistry may
affect the availability of nutrients and toxins to marine organisms.
It should also be noted that chemical composition changes in the atmosphere may also affect
terrestrial ecosystems. For instance, the quantity of nitrogen available to organisms affects
species composition and productivity. Increase in nitrogen can alter species composition by
favoring those plant species that respond to nitrogen increases (Vitousek, 1994). Increased
carbon dioxide can also affect photosynthetic rates in plants, change levels and characteristics of
secondary compounds in plant tissues, change plant species composition, lower nutrient levels,
and lower weight gain by herbivores.
Geology and Soils
Howland Island is a low-lying, nearly level island with a slightly depressed central area
surrounded by a narrow shallow fringing reef. The submarine slopes descend steeply to great
depths beyond the fringing reefs (Maragos et al. 2008a). Surface deposits on the island consist
of calcareous sands and coral rock. Soil texture is coarse and not easily compacted. The central
depression is likely the result of the combined effects of guano mining more than a century ago
and wave action depositing sand rocks and boulders around the island’s fringe. The island was
likely formed as a result of submarine volcanic activity and changes in the earth’s crust caused
by continental tectonic plate movement, including emergence of a high volcanic island, its later
subsidence, reef accretion, and its gradual northwesterly drift away from the East Pacific Rise
over the past 50 to 80 million years. Although scientists since Darwin (1842) have been
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pondering seamount, island, and atoll formation in the Pacific, the specifics of how Howland
Island was formed have not been investigated, although they would likely follow the general
sequence first postulated by Darwin.
The dominant theory of atoll formation states that islands form in deep tropical oceans as a result
of underwater volcanoes that grow to the surface to form high volcanic islands, giving coral
polyps a foundation to grow upon and form reefs fringing the island. In the Pacific most of these
volcanoes originated at the East Pacific Rise or at hotspots (Maragos et al. 2008a). In time, the
volcano becomes dormant, and its mass pushes down on the earth’s crust causing it and its island
to subside and shrink in size, while its fringing reefs continue to grow upward and maintain
proximity to the sea surface. Coral reefs, originally fringing the edges of a large island, may
become barrier reefs around larger islands outlining the contour of the original coastline, with a
lagoon occupying the space vacated by the shrinking island. Eventually, further subsidence
causes the island to disappear completely from the lagoon leaving behind an atoll. However, for
small islands such as Howland, lagoons may not have formed at latter stages, and continued
subsidence has left only a small low reef island in its wake. Based upon deep drilling through
the atolls in the Marshall Islands in the 1940s and 1950s, it is believed that these processes
occurred well before the beginning of the last ice age (approximately 115,000 years ago) and
encompassed more than 50 to 60 million years and up to several thousand feet of reef growth
equal to the degree of subsidence over that time span. In addition, it is hypothesized that
changes in sea level associated with the end of the last ice age and the deposition of highly
permeable coralline limestone (calcium carbonate) derived from the remains of marine
organisms likely contributed to the carbonate platform that characterizes the contemporary
geologic structure of Howland Island.
The entire western or leeward beach of the island is sandy and low, while the eastern side,
constantly pounded by waves generated by the trade winds, is higher, more abrupt, and covered
with coral rubble and sandstone slabs. There is no pronounced beach crest or central basin (dry
lagoon) typically found on some larger low-lying reef islands. Soils of low-lying atolls in the
Pacific frequently consist of accumulations organic matter, guano, pumice, or other transported
material on top of a calcareous sand or limestone substratum (Morrison 1990). The soil of
Howland Island is composed of coral fragments and light brown coral sand with a low
percentage of organic matter.
Hutchinson (1950) concluded that phosphates accumulate preferentially on islands, such as
Howland, Baker, and Jarvis, that are situated in climatic dry belts used by large populations of
seabirds. Deposits of phosphate-rich soils have formed over time from guano deposited on the
island by fish-eating seabirds. Mild acids formed from the decomposition of organic matter
carry the guano downward in the soil to limestone soil layers where acids are neutralized and
calcium phosphate is accumulating from the chemical changes. In addition, when guano-beds
are exposed to rain their soluble constituents are removed and the insoluble matter is left behind.
The soluble phosphates washed out of the guano may also become fixed to the coral sand and
limestone by the process described above. The calcium phosphate rocks and soil occur among
the sedimentary strata and were the principal sources of phosphate targeted for commercial
fertilizer use during the guano mining period between 1861 and 1891 (see Chapter 3.15). Even
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after the guano mining era, the soil profile still contained heavy guano deposits (Christophersen
1927).
Hydrology
No information is available on the subsurface hydrology of Howland Island. However, its small
size and prevailing arid rainfall conditions would not likely result in the formation of a drinkable
groundwater lens. During staff visits to Howland, potable water is carried in containers to the
island for short staff visits, and could be produced on site via reverse osmosis technology for
prolonged staff visits, just as it is now produced for permanent field stations at other remote
Pacific Island NWRs.
Air and Water Quality
Due to the lack of human presence, oceanic and air quality are expected to be good and lacking
in pollutants. Vapors from abandoned spilled fuel storage drums left behind during the World
War II era are likely to be confined to the immediate vicinity of the drums and have probably all
volatized. The acoustic environment at Howland is completely natural without any
anthropogenic noise except during periodic staff visits. On the island, dominant natural sounds
include the wind, calls of seabird and shorebirds, and seawater lapping on the shoreline with
wave action crashing further offshore on the outer reef margin. Underwater the dominant sounds
are wave action and surge striking the reef slopes and the sounds of thousands of feeding and
moving invertebrates and fish.
Environmental Contaminants
Fuel storage drums left behind by the U.S. military during the World War II era contained
residual aviation and motor fuel. In 1987, the U.S. Army Corps of Engineers, sponsored by
funds from the Defense Environmental Restoration Program, organized an expedition to
Howland and Baker to dispose of the fuel by burning it on-site while in the drums (H. Takemoto,
per. comm.). However, the Corps efforts did not completely consume the fuel, and the burning
left toxic residues in many of the drums and surrounding soils (Lee Ann Woodward, USFWS,
per. comm.). At Howland Island, there were only a handful of these drums. The total area
affected by the drums and contaminated soil is estimated at 26 yd2. The main source of
contamination is rusting steel and iron from various machine parts and drums.
Terrestrial Vegetation and Habitats
Howland Island is vegetated with grasses, herbaceous plants, and shrubs. Areas devoid of
vegetation occur along exposed beach and shoreline areas. Only strand species able to survive
long periods of drought and irregular opportunities to reproduce during the infrequent wet years
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of the ENSO persist here. By 1924 when Christophersen (1927) did the first thorough survey of
Howland Island’s vegetation, there had already been approximately a century of visits by
Europeans and guano miners. Despite this traffic and the potential for introductions,
Christophersen found a very depauperate flora consisting of five native species (Lepturus repens,
Boerhavia sp., Portulaca lutea, Tribulus cistoides, and Cordia subcordata) and one that had
probably been accidentally introduced (Portulaca oleracea). Since then at least 4 more species
were intentionally introduced (Cocos nucifera, Casuarina sp., Pandanus sp., and Coccoloba
uvifera) and at least 7 as wave carried adventives or additional accidental introductions by
humans (Digitaria pacifica, Sophora tomentosa, Sida fallax, Scaevola taccada, Suriana
maritima, and Tournefortia argentea) for a contemporary total of only 16 species (see Appendix
B). On a short visit in 2004, only nine species of plants were located (Flint and Eggleston 2004).
It is likely that seeds of additional species are regularly washing up on the beach and then dying
back as conditions become too dry or high surf washes the plants away. Table B-3, Appendix B,
lists all the plant species of Howland Island, collections or first observations, and most recent
information about current presence or absence.
The structure of the plant community is grassland and low forbs cover. A single grove of kou
(Cordia subcordata) in shrub growth form reaching 15 feet high grows in the interior. The kou
along with tree heliotrope (Tournefortia) and naupaka (Scaevola) bordering the beach serve as
important nesting and roosting habitat for the red-footed booby and cover for wintering bristle-thighed
curlews. Great frigatebirds and white terns also prefer to nest above the ground on the
few shrubs available, but all the other species nest directly on the ground. Shrubs and rock piles
also provide shade and daytime cover for the numerous land hermit crabs, Coenobita perlatus
that inhabit Howland Island.
Terrestrial Wildlife
Seabirds, shorebirds, lizards, vegetation, insects, crabs, and invasive rats and feral cats have been
observed and studied at Howland Island during the current century. The Service subsequently
eradicated all rats and cats from the island to allow repopulation by several nesting seabird
species and greater use by all remaining indigenous terrestrial species.
Seabirds and Land Mammals
There are no native land mammals at Howland Island. Numerically dominant vertebrates are
migratory seabirds and shorebirds. Howland Island falls into the North American Bird
Conservation Region (BCR) 68 along with all the other island territories of the United States.
Earliest ornithological surveys at Howland Island took place long after the introduction of the
Polynesian rat (Rattus exulans) so the composition of the avian community prior to human
contact can only be surmised by looking at other islands in the Phoenix Archipelago that did not
suffer the invasion of rats. The findings of the ornithologist on the Whippoorwill Expedition of
1924 are the only comprehensive ornithological records prior to 1963, when scientists from the
Smithsonian Institution visited eight times between 1963 and 1965. Table B-4 in Appendix B
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Chapter 4 – Refuge and Resource Description 4-11
lists species and estimates of numbers for seabird species on all staff visits since 1973. Munro
(1924) found 11 species of seabirds breeding in 1924.
Several avian species are listed by various authorities as species of concern. Of note, seabird
species listed by IUCN as Vulnerable include Phoenix petrel (Pterodroma alba) and the
Polynesian storm-petrel (Nesofregetta fuliginosa), both of which probably occurred at Howland
Island prior to the introduction of rats. The Phoenix petrel is also considered a bird of National
Conservation Concern by the Service and the Phoenix petrel and Polynesian storm-petrel are
classified as highly imperiled in the Pacific Region Seabird Conservation plan. The blue noddy
(Procelsterna cerulean) and lesser frigatebird (Fregata ariel) are included in the category of
High concern in that document (USFWS 2005).
Cats were introduced during 1935 to 1942 resulting in decreased abundance and diversity of
seabirds species breeding at Howland by 1963 (Sibley et al., 1965). After feral cats were
removed in 1986, 11 seabird species are again breeding and 2 Procellariform species (Wedge-tailed
Shearwaters Puffinus pacificus and an unidentified storm-petrel) that likely bred there prior
to rat introduction have been seen on the ground in the colony presaging re-colonization. The
three most numerous breeding species at Howland are the lesser frigatebird (Fregata ariel) [a
BCC or bird of conservation concern in BCR (Bird Conservation Region) 68 and listed as a bird
of High concern at the Regional level], masked booby, (Sula dactylatra), and sooty tern
(Onychoprion fuscatus). Table B-4 also provides the breeding seabird species at Howland.
Shorebirds
Species occurrence and counts of the eight migratory shorebird species recorded from Howland
Island are displayed in Table B-4, Appendix B. The four most common migrants wintering at
Howland are ruddy turnstone (Arenaria interpres), Pacific golden plover (Pluvialis fulva),
bristle-thighed curlew (Numenius tahitiensis), and wandering tattler (Heteroscelus incanus). Of
these, the bristle-thighed curlew and the Pacific golden plover are considered species of High
Concern in the national conservation priority scheme for shorebirds (Engilis and Naughton
2004). All of the species mentioned above except wandering tattler are labeled as high concern
in the Regional shorebird plan and Bristle–thighed Curlews and Pacific Golden Plovers are Birds
of Conservation Concern in BCR 68. These islands provide crucial wintering habitat and may
serve as rest-stops for arctic-breeding shorebirds wintering farther south in the Pacific Islands.
Reptiles
Only two species of terrestrial reptiles have been reported from Howland Island: snake-eyed
skink (Cryptoblepharus peocidopleurus) and mourning gecko (Lipidodactylus lugubris). Both
species were first reported by Hague in 1862, and served as alternate prey for cats when they
were present on Howland Island. Only the snake-eyed skink has been observed during recent
visits to Howland.
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4-12 Chapter 4 – Refuge and Resource Description
Invertebrates (crabs and insects)
Howland Island is home to a large number of the land crab, Coenobita perlata. Their large
biomass plays a dominant role in terrestrial food webs on the island where they consume a wide
variety of organic matter of all types. Other terrestrial arthropods and mollusks are very poorly
known. The entomologist Edward L. Caum visited Howland Island in 1924 and a number of
other naturalists collected insects on subsequent trips but there are no published accounts or lists
until Ashley Browne of the University of Hawaii visited in 1939 and published a short note
listing 3 species of insects that were collected (Browne 1940). Recent observations, but not
collections, during staff visits by Service biologists include house flies, small ants, moths,
millers, butterflies, and spiders.
Kirkpatric and Rauzon (1986) compared food habits of feral cats at Howland and Jarvis Islands.
Although there were crickets, cockroaches and tenebrionid beetles in the stomach of Jarvis cats
(n=73), no insect remains were found in a smaller sample (n=5) of Howland Island cats.
Marine Habitats, Fish, and Wildlife
Previous Surveys
Before regular marine assessment and monitoring efforts began in 2000, marine scientists visited
Howland to collect fish, corals, and perhaps other reef life, but there were no systematic surveys
of the reefs in the literature. Extensive collections of reef fishes were accomplished by Fowler
(1927), anon. (1950), Helfrich (1962), and Wass (1966). More recently, the Smithsonian
Institution Pacific Ocean Biological Survey (SIPOBS), and others in Mundy et al (2002)
continued this work. The dominant reef life studied during post-1997 expeditions include:
benthic algae (Peter Vroom, Kim Paige per. comm.), corals and anemones (John Schmerfeld, Jim
Maragos, Greta Aeby and Jean Kenyon per. comm.), other reef invertebrates (Scott Godwin,
Dwayne Minton, and Robin Newbold per. comm.), and reef fishes (Ed DeMartini, Bruce Mundy,
Brian Zgliczynski, Brian Green, Richard Wass, Alan Friedlander, Stephanie Holzwarth, and
others per. comm.).
Five sets of recent surveys through early 2006, have been accomplished in cooperation with the
NOAA Pacific Islands Fisheries Science Center (PIFSC) and their research vessels (Townsend
Cromwell, Oscar Elton Sette, and Hi‛ialakai), primarily through the sponsorship of the Center’s
Coral Reef Ecosystem Division (CRED) (R. Brainard, per. comm.). The surveys since 2000, are
of several types including oceanographic data collection, towed diver surveys, rapid ecological
assessments (REA) at stationary sites, and collections of marine animals and plants for
identification and description in the lab. The Service, with assistance from CRED established
three permanently marked transects to document trends in corals and some macro-invertebrates
over time since 2000.
Despite these intense efforts, several important habitats at Howland have not been adequately
surveyed. Shallow reef terraces off both the southern and northern horns of the island are bathed
Howland Island National Wildlife Refuge Comprehensive Conservation Plan
Chapter 4 – Refuge and Resource Description 4-13
in strong, turbulent and at times unpredictable currents, preventing REAs at both ends. In
addition, the windward reefs were inaccessible during most staff visits because of heavy
tradewind generated waves close to the reef and onshore winds that would push the dive skiffs
too close to the reefs. Moreover, due to safety concerns, dives have generally been limited to
depths of 65 feet and one hour duration. Because of these limitations, some important habitats
are still poorly sampled and deep slope habitats (164 to 3,281 ft) within the refuge remain mostly
unexplored, except for early 2006 acquisition of high resolution bathymetry of Howland from
Multi-Beam™ surveys (S. Ferguson, per. comm.) and substantial oceanographic data (R.
Brainard, per. comm.).
At the time of this CCP, data from coral, other marine invertebrates, algae, and fish surveys were
available for review and compilation, and Maragos et al. (2008a) and Miller et al. (2008) provide
updated compilations based upon site visits through 2006.
Submergent Habitats
Howland’s shallow marine benthic habitats consist of fringing reef crests, shallow back reefs,
steep fore reefs, spurs-and-grooves, and small reef terraces. The last two habitats are restricted
to the windward (east side) of the island. In addition, a shallow short channel was blasted
through the narrow fringing reef during the pre-World War II era to facilitate small boat access
between the shoreline and ocean. The deep slope habitats below depths of 65-98 feet have not
been surveyed by divers, although remotely operated vehicles (ROVs) have been launched to
collect video- and camera-based data. Pelagic habitats occur further offshore beyond the
influence of upwelling and nearshore oceanographic processes. Nearshore habitats include
distinct upwelling zones off the west side of the island; oligotrophic waters off the windward
reefs; and turbulent rip currents and possibly mesoscale eddies off the north and south ends of
the island. The PIFSC has conducted oceanographic research off the island to contrast the
differences between nutrient rich upwelling zones and the ambient nutrient-poor ocean
conditions outside areas of upwelling currents.
Reef Life
The marine ecosystem of Howland remains mostly undisturbed and pristine. Multitudes of
marine species inhabit and visit the shallow water habitats that surround Howland Island, several
of which are listed or ranked by various authorities as being imperiled. Of note, the giant clam
(Tridacna maxima) is abundant at Howland Island and is listed under the Convention on
International Trade in Endangered Species of Wild Fauna and Flora (CITES). The humphead
wrasse (Cheilinus undulatus) is also listed under CITES and designated as Endangered by the
International Union for the Conservation of Nature (IUCN) and occurs in the nearshore waters of
Howland. Nearshore waters are also home to two endangered species of sea turtles and sea
mammals that have yet to be studied. Taken collectively with the terrestrial habitat, the coral
reefs are an integral component of the overall health of the Howland Island ecosystem.
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4-14 Chapter 4 – Refuge and Resource Description
Corals
To date (January 2006), 97 species and 30 genera of corals and a few other large anthozoans
have been reported from Howland reefs (Table B-1, Appendix B). Additional range extension
records from collections and photographs may also exist. This compares to 92 species and 38
genera reported at neighboring Baker, only 32 nmi to the south. These totals are in the range of
other atolls in the Phoenix Islands (Kanton in Maragos and Jokiel 1978); lower than, or
comparable to similarly sized islands further to the west (Marshalls, Samoa); and higher than, or
comparable to similarly sized islands to the east (Hawaii, Line Islands). There is no credible
explanation for the higher genera totals at Baker compared to Howland, except that geographic
isolation may be causing differential recruitment success. Supportive of this hypothesis is that 3
of the genera reported at Howland were missing at Baker, and 11 of the genera at Baker were
missing from Howland. All sides of Baker have been surveyed compared to just the west and
southeast side of Howland, and this may also be contributing to the higher generic diversity at
Baker and discrepancies between the two reefs (Maragos per. comm.).
Corals are generally in healthy condition at Howland, with the eight most abundant genera there
also the same as the eight most abundant found throughout the Line, Phoenix, and eastern
Samoan Islands: Acropora, Favia, Fungia, Leptoseris, Montipora, Pavona, Pocillopora, and
Porites. Coral disease prevalence and predation on corals are also low (G. Aeby and B. Vargas
per. comm.). Although dead standing corals reported during the summer of 2000 were likely
indicative of a coral bleaching event a few years earlier, no major bleaching event has been
reported during the 2000-2006 surveys, and corals are presumably recovering rapidly during the
period. Of future possible concern is the rapid expansion of the corallomorpharian Rhodactis
howesii at Howland between the 2004 and 2006 staff visits near the historic boat anchorage.
This species has increased to “invasive” proportions at Baker and Palmyra Atoll NWR where it
appears to be stimulated by dissolved iron from corroding anchors or shipwrecks. Thus, it raises
the possibility of corroding steel or iron being present at Howland Island which was observed in
the form of chains and anchors at the western boat anchorage
Nearshore Fish
Approximately 324 species of reef fish are known from Howland reefs (Mundy et al. 2002;
Table B-2, Appendix B). This compares with 247 species from nearby Baker. Moreover, ten
families of fish reported at Howland have not been reported from Baker, and six minor families
from Baker have not been reported from Howland. Of interest is the presence of several species
of goby and scorpion fish families at Howland and the lack of these families at Baker. Possible
explanations for these differences may be that sampling and survey intensities may be
insufficient and different between the two islands, or that geographic isolation may result in
differential recruitment rates between the two islands. As noted earlier, not all habitats at
Howland have been surveyed to the same degree as those at Baker.
Reef fish populations appeared healthy and diverse with little indication of unauthorized harvest
(Maragos, USFWS, per. comm.). However, during 2000 surveys Maragos noted many small
sharks and no larger sharks at both Howland and Baker. In contrast, numerous small and some
Howland Island National Wildlife Refuge Comprehensive Conservation Plan
Chapter 4 – Refuge and Resource Description 4-15
large sharks were at both locales by 2004 and 2006. Because “shark finning” (the catching of
sharks only to remove their fins for sale) is a growing concern in the Pacific and other oceans, it
is possible that a pre-2000 harvest of sharks at Howland resulted in the absence of larger adult
sharks in 2000. Larger sharks and additional recruitment by 2004 and lack of subsequent shark
fin harvest in the area may explain the more normal size distribution in sharks observed in 2004
and 2006 (Maragos et. al 2008b).
The fact that the disparities for the coral genera did not track in the same direction as for the fish
families (more coral genera at Baker versus more fish families at Howland), reinforces the
hypothesis of geographic isolation may lead to biodiversity heterogeneity based on chance and
differential recruitment success. Geographic isolation would require both corals and reef fish to
rely more on local recruitment vis-à-vis external recruitment. The latter would likely play a
much larger role where reefs and islands are larger and closer together and result in similar
biodiversity characteristics.
Marine Mammals
On most staff visits to Howland Island, a group of ~approximately 40 bottle-nosed dolphins
(Tursiops truncatus) appear as the ship approaches the island. In 1993, individuals from this
group were observed preying on rainbow runners (Elagatis bipinnulatus) that were sheltering
under the vessel. Formal quantitative surveys of marine mammal distribution and abundance
have not been undertaken at the refuge. Historically, sperm whales (Physeter macrocephalus)
were caught near Howland in the nineteenth century (Townsend, 1935, cited in Sibley and
Clapp, 1965).
Pelagic Wildlife
Oceanic pelagic fish including skipjack, yellowfin tuna, and blue marlin prefer warm surface
layers, where the water is well mixed by surface winds and is relatively uniform in temperature
and salinity. Other pelagic species, such as albacore, bigeye tuna, striped marlin, and swordfish,
prefer cooler, more temperate waters, often meaning higher latitudes or greater depths. In fact,
the largest proportion of the tuna catch in the Pacific Ocean originates from the warm pool, even
though paradoxically this is a region of low primary productivity. Tuna movement to upwelling
zones at the fringe of the warm pool may be key in resolving this apparent discrepancy between
algal and tuna production. Preferred water temperature often varies with the size and maturity of
pelagic fish, and adults usually have a wider temperature tolerance than subadults. Thus, during
spawning, adults of many pelagic species usually move to warmer waters, the preferred habitat
of their larval and juvenile stages.
Large-scale oceanographic events (such as El Niño) change the characteristics of water
temperature and productivity across the Pacific, and these events have a significant effect on the
habitat range and movements of pelagic species. Tuna are commonly most concentrated near
islands and seamounts that create divergences and convergences, which concentrate forage
species, and also near upwelling zones along ocean current boundaries and along gradients in
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temperature, oxygen, and salinity. Swordfish and numerous other pelagic species tend to
concentrate along food-rich temperature fronts between cold upwelled water and warmer oceanic
water masses (NMFS 2001). These frontal zones also function as migratory pathways across the
Pacific for loggerhead turtles (Polovina et al. 2000). Loggerhead turtles are opportunistic
omnivores that feed on floating prey such as the pelagic cnidarian, Vellela vellela (“by the wind
sailor”) and the pelagic gastropod Janthina spp., both of which are likely to be concentrated by
the weak downwelling associated with frontal zones (Polovina et al. 2000).
The estimated hundreds of thousands of seabirds breeding at national wildlife refuges in the
Central Pacific Ocean are primarily pelagic feeders that obtain the fish and squid they consume
by associating with schools of large predatory fish such as tuna and billfish (Fefer et al. 1984, Au
and Pitman 1986). These fish―yellowfin tuna (Thunnus albacares), skipjack tuna (Katsuwonus
pelamis), mahimahi (Coryphaena hippurus), wahoo (Acanthocybium solandri), rainbow runner
(Elagatis bipinnulatus), broadbilled swordfish (Xiphias gladius), and blue marlin (Makaira
indica)―are apex predators of a food web existing primarily in the epipelagic zone. While both
the predatory fish and the birds are capable of foraging throughout their pelagic ranges (which
encompass the tropical Pacific Ocean), the birds are most successful at feedin