Pressures on the Sanctuary
Numerous human activities and natural events and processes affect the condition of natural and archaeological resources in marine environments. This section describes the nature and extent of the most prominent pressures on the monument.
Marine DebrisMany reefs in the Northwestern Hawaiian Islands and throughout the Pacific have been inundated with large amounts of debris lost by North Pacific commercial fishing operations or dispersed from other marine or terrestrial sources. These objects degrade reef health by abrading, poisoning, smothering and dislodging corals and other benthic organisms, and entangling fish, marine mammals, crustaceans and other mobile species. Marine debris containing hazardous materials such as pesticides, petroleum, toxic chemicals and phosphorus flares washes up on the beaches of the Northwestern Hawaiian Islands and is a danger to wildlife and humans. It is unknown how much of these toxic compounds are released from the debris while floating in the marine environment. Marine debris and derelict fishing gear hinder the recovery of the critically endangered Hawaiian monk seal and threatened sea turtles through entanglement, drowning and suffocation (NMSP 2005).
The North Pacific Subtropical Convergence Zone provides a mechanism for derelict fishing gear and other marine debris either lost or discarded throughout the Pacific Rim to accumulate in the Northwestern Hawaiian Islands (Figure 11). Under certain conditions, this convergence zone moves to encompass the Northwestern Hawaiian Islands and deposits tons of net and line on these shallow reef systems. Derelict gear may circulate for years in ocean gyres and currents until it snags on a shoal. The extensive shallow reefs of the Northwestern Hawaiian Islands are ideal for such debris settlement. Once derelict gear catches on organisms of the remote reefs and atolls of the Northwestern Hawaiian Islands, it begins a process of destructive activity.
Coastal and Terrestrial Pollution
Past uses of the Northwestern Hawaiian Islands have left a legacy of contamination on many of the atolls. The Northwestern Hawaiian Islands have hosted an array of polluting human activities including guano mining, fishing camps, U.S. Coast Guard LORAN stations, various Cold War military missions, and U.S. Navy airfields and bases (Figure 12). Contamination at all these sites includes onshore and offshore debris such as batteries (lead and mercury), PCB-containing transformers, capacitors, and barrels of petroleum and other chemicals. Many of the common contaminants biomagnify so that small amounts found in sediment can result in significant concentrations in upper trophic levels.
Several areas of contamination have been identified in the Northwestern Hawaiian Islands and include the following (Friedlander et al. 2005):
- Kure and French Frigate Shoals both have point sources of PCBs due to former U.S. Coast Guard LORAN stations. While the U.S. Coast Guard has mounted limited cleanup actions at both sites, contamination remains and is found in island soils and in nearshore sediments and biota.
- Tern Island, a part of the French Frigate Shoals atoll, was formed into a runway to serve as a refueling stop for planes enroute to Midway during World War II and served as the site of various Cold War missions. Leaking underground storage tanks were a source of petroleum contamination until removed by the Army Corps of Engineers.
- The U.S. Navy built a naval air facility and submarine base at Midway Atoll and during base reduction and closure identified and cleaned up numerous sites contaminated with petroleum, pesticides, PCBs and metals. While most known areas were remediated, several areas, including unlined eroding landfills, warrant continued monitoring for potential releases.
- Plutonium from the aboveground nuclear tests in the 1960s at Johnston Atoll has been detected in corals 700 miles to the north at French Frigate Shoals.
Climate Change and Coral Bleaching
Climatic events play an important role in the ecosystem productivity of the Northwestern Hawaiian Islands. Fluctuations in the abundances of monk seals, reef fishes and chlorophyll have been documented from the early 1980s to the present and may be associated with multidecadal climate oscillations. While severe tropical storms or typhoons are rare, winter storms are common, resulting in a noticeable increase in winds and high seas that impact the reef system.
Problems associated with increased sea surface temperatures have been reported in the Northwestern Hawaiian Islands. Sea surface temperature information obtained from NOAA demonstrated that water temperatures at Midway rose nearly two degrees centigrade over the usual summer maxima in August of 2002. Corresponding with this warm water event, substantial coral bleaching was observed-a process whereby coral colonies lose their color due to the expulsion of symbiotic microscopic algae (zooxanthellae) from most coral tissues-on reefs at the three northwestern most atolls: Kure, Midway, and Pearl and Hermes (Figure 13). At the three northern atolls, bleaching was most severe on the backreef, moderate in the lagoon, and low on the deeper forereef (Kenyon et al. 2006). No significant bleaching was found the following year during surveys conducted in July 2003. Substantial coral bleaching at several reef systems was confirmed in the Northwestern Hawaiian Islands during surveys conducted in September and October 2004 (Kenyon and Brainard 2006). Military construction, including the dredging of a ship channel and filling for the airfields, dramatically changed water levels and circulation in the Midway lagoon, and may have exacerbated the effects of 2002 and 2004 lagoon coral bleaching. At Pearl and Hermes Atoll and Midway Atoll, bleaching was most pronounced in the shallow backreef habitat. The incidence of bleaching in the shallow backreef habitat at Kure, the northernmost atoll in the Hawaiian Archipelago, was less than that at Pearl and Hermes and at Midway (NMSP 2005, Friedlander et al. 2005, Hoeke et al. 2006)
Climate models predict that global average sea level may rise considerably this century, potentially affecting species that rely on coastal habitat. Most of the Northwestern Hawaiian Islands are low lying and therefore potentially vulnerable to increases in global average sea level. The effects of habitat loss on Northwestern Hawaiian Islands biota are difficult to predict, but may be greatest for endangered Hawaiian monk seals and threatened Hawaiian green sea turtles at Pearl and Hermes Reef (Baker et al. 2006).
There has been a worldwide increase in the reports of diseases affecting marine organisms. However, the factors contributing to disease outbreaks are poorly understood due to lack of information on normal disease levels in the ocean. The Northwestern Hawaiian Islands are considered to be one of the last relatively pristine large coral reef ecosystems remaining in the world. As such, it provides the unique opportunity to document what may be the normal levels of disease in a coral reef system exposed to limited human influence (Friedlander et al. 2005, Harvell et al. 1999).
Recent studies in the Northwestern Hawaiian Islands have begun to document baseline levels of coral and fish disease (Work et al. 2004, Aeby 2006) (Figure 14). Tumors, as well as lesions associated with parasites, ciliates, bacteria and fungi, have been found on a number of coral species. During a 2003 survey of 73 sites throughout the Northwestern Hawaiian Islands, evidence of coral disease was found at very low levels at 68.5 percent of the sites across all regions. The overall average prevalence of disease (number of diseased colonies/total number of colonies) was estimated at 0.5 percent (range 0-7.1 percent) compared to the average prevalence of disease of 0.95 percent in the main Hawaiian Islands. The prevalence of disease varies among different genera of coral with the highest prevalence in species of the genera Porites and Acropora. Recent disease observed on giant table corals at French Frigate Shoals may have spread from Johnston Atoll about 520 miles to the south (Friedlander et al. 2005).
In the Hawaiian Archipelago, more than 50 percent of endangered Hawaiian green sea turtles nest at East Island, French Frigate Shoals in the Northwestern Hawaiian Islands. Green sea turtles are affected by fibropapillomatosis, a disease that causes tumors in turtles. Although most cases of the disease in the Hawaiian Islands have been observed in the main Hawaiian Islands, green sea turtles are highly migratory. The prevalence of fibropapillomatosis in the Hawaiian green turtle population was estimated at 40 to 60 percent, with the majority of cases found among juvenile turtles. The majority of recent turtle strandings are by juvenile turtles with the disease (Work et al. 2004). As such, fibropapillomatosis may pose a significant threat to the long-term survival of the species (Quackenbush et al. 2001,NMFS and USFWS 1998).
Alien species can be defined as organisms that are not native to a particular ecosystem and have been accidentally or deliberately introduced to an area outside of their historic geographic range. An invasive species is one that demonstrates rapid growth and spread, invades habitats, and displaces native organisms. A total of 11 introduced invertebrate, fish and algal species have been recorded in the Northwestern Hawaiian Islands and are generally low in number and impact. One potential exception to this is the coral disease observed on table coral which has an unknown source and may possibly be caused by an alien (introduced) species. Alien species may be introduced unintentionally by vessels, marine debris or aquaculture, or intentionally, as in the case of some species of groupers, snappers and algae. Eleven species of shallow-water snappers and groupers were purposely introduced to one or more of the main Hawaiian Islands in the late 1950s (Randall 1987). Presently, two of these introduced fish, the ta'ape (Lutajanus kasmira) and the roi (Cephalopholis argus) are now established in the Northwestern Hawaiian Islands.
Populations of alien marine species that have already colonized areas of the main Hawaiian Islands represent the most likely source of invasive species in the Northwestern Hawaiian Islands. Most can be found from littoral zones to deep water coral beds. The few alien species known from the Northwestern Hawaiian Islands are mostly restricted to areas of higher human activity at Midway Atoll and French Frigate Shoals (Godwin et al. 2005). Though not all introduced species will become invasive, those that do could have some of the following potential environmental impacts to the Northwestern Hawaiian Islands (State of Hawaii 2003):
- loss of native biodiversity;
- functional changes of freshwater, other inland waters, and nearshore marine ecosystems;
- alterations in nutrient cycling pathways; and
- decreased water quality.
Between 1750 and the 1920s, western explorers harvested monk seals, whales, fish, seabirds and guano from various parts of the Northwestern Hawaiian Islands. More recently, the history of fishing and other resource extractive uses included the overexploitation of the indigenous black-lipped pearl oyster (1928 to 1930), the beginning of a commercial fishing fleet (1930s to 1940s), a cessation of commercial uses during World War II, a resumption of commercial fishing (1945 to 1960) during which Tern Island was used as a transshipment point for fresh fish flown to Honolulu, and a proliferation of foreign fishing vessels from Japan to Russia (1965 to 1977). Currently fishery management plans exist for precious corals, bottomfish, pelagics, crustaceans and coral reef fisheries, however, the only active fishery is for bottomfish.
The recent Presidential Proclamation that established the monument determined that commercial fishing for bottomfish and associated pelagic species may continue within the monument until June 15, 2011. The proclamation established caps for total landings for each fishing year at 350,000 pounds for bottomfish species and 180,000 pounds for pelagic species. After June 15, 2011, commercial fishing for bottomfish and associated pelagic species will be prohibited in the monument.
The federally permitted Northwestern Hawaiian Islands commercial bottomfishfishery has been regulated under the current management regime since 1986 (Figure 15). The fishery targets deepwater (generally > 75-100 fm) snappers, and one endemic species of grouper (WPRFMC 2004). The allowable gear and fishing requirements were designed to minimize habitat impacts and maintain by-catch levels of approximately 25 percent (WPRFMC 1986, NMSP 2004b).
Fishing effort in the main Hawaiian Islands is the major stress on the bottomfish fishery in the Hawaiian archipelago. However, in 2002, data suggested that fishing effort had exceeded acceptable levels in the Mau zone, one of two fishing zones established in the Northwestern Hawaiian Islands. Data from the following year indicated that overfishing was no longer occurring in the Mau zone, and currently there is no reason to believe that the fishing mortality metrics for either of the Northwestern Hawaiian Islands' zones (Mau or Ho'omalu) will change significantly in the future. Nonetheless, it has been recognized that the assessment methods rely heavily on fishery-dependent data sets that lack information on important segments of the population. As such, a Bottomfish Stock Assessment Panel was convened by the Western Pacific Regional Fishery Management Council in January 2004 to develop a plan to improve data collection and assessment methodologies
Commercial Pelagic Fisheries
A very small number of commercial pelagic trolling fishermen have recently operated in the Northwestern Hawaiian Islands. These fishermen do not have federal fishing permits, as the fishery management plan for pelagic species does not regulate this small fleet. The fishermen operated under a State of Hawaii commercial marine license that enabled them to sell their catch legally.
Hawaii's commercial pelagic fishery is divided into four distinct types of fisheries: pole and line (aku) boats, handline (ika shibi and palu ahi) boats, pelagic trolling boats, and pelagic longline (swordfish and tuna) boats. Of these, pelagic trolling is the most popular statewide, with 90 percent of the participants and 50 percent of the small boat landings (WPRFMC 2003). The Hawaii Department of Land and Natural Resources, Division of Aquatic Resources has records for nine commercial pelagic trolling vessels fishing in the Northwestern Hawaiian Islands between 1991 and 2000. The current fishing gear and methods have little to no impact on the habitat and have very low levels of bycatch. However, activities associated with fishing vessels, such as anchoring, could damage submerged historic shipwreck and aircraft sites (NMSP 2004b).
LongliningCommercial pelagic longlining was prohibited within 50 nautical miles of the Northwestern Hawaiian Islands in 1991 because of interactions with endangered and threatened species within the Protected Species Zone.
Commercial Lobster Fishery
The now-closed, commercial lobster fishery began in 1976 (Figure 16). Advances in trap design and processing techniques led to a steady increase in total landings. Catch per unit effort (lobsters per trap) declined dramatically between 1983 and 1987. In 1991, NOAA Fisheries issued an emergency closure of the fishery. Reasons for closure included: (1) a decrease in catch per unit effort below acceptable levels; (2) indications of sporadic or poor recruitment events; and (3) an indication that the spawning stock biomass was at 22 percent of pre-exploitation levels, which was close to the 20 percent definition of overfishing (NMSP 2004b).
The Northwestern Hawaiian Islands lobster fishery was closed in 2000 by both federal court order related to the National Environmental Policy Act and protected species issues, and by NOAA Fisheries to protect lobster stocks because of: (1) shortcomings in understanding the dynamics of the Northwestern Hawaiian Islands lobster populations; (2) uncertainty in population model parameter estimates; and (3) the lack of appreciable rebuilding of the lobster population despite significant reductions in fishing effort throughout the Northwestern Hawaiian Islands. Additionally, there was some concern at the time that the lobster fishery could impact juvenile monk seal foraging success. However, dietary studies of monk seals have been inconclusive because they were initiated too late to assess the extent to which adult seals or pups forage for lobsters. The Presidential Proclamation of the Northwestern Hawaiian Islands as a marine national monument has determined that any commercial lobster fishing permit shall be subject to a zero annual harvest, which effectively closes the lobster fishery in perpetuity
Recreational and Sport Fishing ActivitiesRecreational catch and keep fishing is prohibited in the monument. Recreational fishing had previously taken place in the vicinity of Nihoa Island, based on reports of pelagic spearfishing and recreational trolling by fishermen from the main Hawaiian Islands. Catch and effort data is unavailable for this fishing activity.
Historical Trade in Coral and Reef SpeciesThe harvest of live rock and live coral is currently prohibited throughout the Hawaiian Archipelago by both state and federal regulations (WPRFMC 2001). The harvest of other coral reef species has been prohibited in federal waters of the Northwestern Hawaiian Islands since the establishment of the Northwestern Hawaiian Islands Coral Reef Ecosystem Reserve in 2000 by Executive Order.
No domestic or commercial precious coral fishery has ever operated in the Northwestern Hawaiian Islands, although a fishery management plan was issued in 1981. One permit was issued to harvest coral under an experimental fishing permit, but the venture was unsuccessful. Although harvest of coral reef species such as black-lipped pearl oysters (Figure 17), turtles and reef fish occurred in the early and mid-1900s, coral reef species are no longer commercially harvested in the Northwestern Hawaiian Islands (NMSP 2004b).
Other Fishing ActivitiesA short-lived commercial fishing operation involving a single vessel using bottom longlines to catch sharks was conducted at French Frigate Shoals and nearby banks in the year 2000. During one 21-day fishing trip, this vessel caught 990 sharks in the Northwestern Hawaiian Islands consisting mainly of sand-bar sharks at 69 percent, Galapagos sharks at 18 percent, and tiger sharks at 10 percent (Vatter 2003).
Recreational fishing and Native Hawaiian sustenance fishing previously had been at low levels. Sustenance fishing included fishing for pelagic reef and bottomfish species using trolling, handline, and pole and line fishing techniques. Sustenance fishing has taken place aboard research, U.S. Coast Guard and military vessels. This type of fishing is also believed to occur from transiting vessels, including sailboats, although no data exists to confirm this assumption. Fishing effort and landings are currently undocumented, but efforts have been made to collect this information from NOAA ships. NOAA conducted a pilot sustenance fishing survey on all NOAA permitted vessels in 2005-2006. Voluntary reporting indicated that very few fish were caught during the time surveyed. The Presidential Proclamation allows for sustenance fishing and defines it as fishing for bottomfish or pelagic species in which all catch is consumed within the monument, and that is incidental to an activity permitted by the monument. Some illegal foreign fishing activities have also been known to occur around the Northwestern Hawaiian Islands. Regulations are enforced primarily by the U.S. Coast Guard, but enforcement is difficult primarily due to the size of the monument.
Vessel Hazards and Groundings
Hazards to shipping and other forms of maritime traffic are inherent in the Northwestern Hawaiian Islands’ 1,200 miles of islands, islets, shallow submerged reefs and shoals. The region is exposed to open ocean weather and sea conditions all year, punctuated by severe winter storm and wave events. Vessel groundings and the release of fuel, cargo, rats and other items pose real threats to the Northwestern Hawaiian Islands. The region contains 127 known potential maritime resource sites. Some represent environmental threats, while others consist chiefly of marine debris and are of little specific value. Wrecks of historic sailing vessels in high energy environments are considered artifact “scatter sites,” and do not pose an immediate or critical threat to their surroundings. More modern shipwrecks, such as the fishing vessels Hoei Maru #5 and Paradise Queen II at Kure, or the tanker Mission San Miguel at Maro Reef, are greater threats to reef ecosystems. Mechanical damage from the initial grounding, subsequent redeposition of wreck material by storm surge, fishing gear damage to reef and species, and fuel, oil or hazardous contents are all issues to be considered. In some cases it may be more detrimental to remove the grounded vessel than to leave it where it is, and this option must be weighed when deciding how to respond to these threats.
In 1998, the Paradise Queen II ran aground at Kure Atoll, spilling 11,000 gallons of diesel fuel and 500 gallons of hydraulic fluids and oil. The vessel also lost 3,000 pounds of frozen lobster tails, 4,000 pounds of bait, 11 miles of lobster pot mainline, and 1,040 lead-weighted plastic lobster traps. Traps rolling around in the surf broke coral and coralline algal structures. In 2000, researchers found broken coral, 600 lobster traps, and the bodies of two monk seals among piles of nets surrounding the decaying wheelhouse (USFWS 2000). Also in 2000, the 85-foot longliner Swordman I,carrying more than 6,000 gallons of diesel fuel and hydraulic oil, ran aground at Pearl and Hermes Reef in 2000. Vessel Monitoring System technology allowed agents to track the disaster and quickly send out equipment for a clean-up, costs for which the government had to sue to recover. Since 1976, at least 15 vessels have run aground in the Northwestern Hawaiian Islands. Among these are two recent incidences: the M/V Casitas (Figure 18) was engaged in marine debris removal when it ran aground at Pearl and Hermes Reef, and the S/V Grendel is thought to have been adrift without a pilot when it landed on the reef at Kure atoll (NMSP 2005, Friedlander et al. 2005).
Tourism and Recreation
Due to the Northwestern Hawaiian Islands' isolation, tourism and recreational activities have historically been extremely limited. Midway Atoll has served as a base for an ecotourism operation conducted under the auspices of the U.S. Fish and Wildlife Service since 1996. Midway Atoll National Wildlife Refuge accommodates visitor use such as historic preservation service projects, guided tours, diving and snorkeling trips, and fishing operations (extraction and non-extraction). In addition, Midway Atoll has been a destination for a limited number of cruise ships. For the past three years, one cruise ship per year has visited Midway (Barry Christenson [Manager, Midway Atoll National Wildlife Refuge], pers. comm.) However, visitor use in recent years has been minimal due to the lack of routine, affordable air charter service to and from Midway Atoll National Wildlife Refuge. With plans for future tourist activities around Midway Atoll, historic shipwreck sites in the vicinity may become more vulnerable to impacts from divers and snorkelers. Impacts include artifact removal and damage from improper diving techniques. Many of these impacts can be mitigated with education and outreach efforts that inform visitors of site preservation protocols
(Friedlander et al. 2005).
Possible impacts from tourism at Midway include disturbance to nesting seabirds, Hawaiian monk seals, green sea turtles, spinner dolphins, fish and marine invertebrates. Visitor programs will be provided with orientation materials and will be subject to restrictions (e.g. 150 ft. approach distance for seals) intended to minimize impacts to wildlife (USFWS 2006).
Coastal development in the Northwestern Hawaiian Islands has consisted of infrastructure to support a guano mining operation at Laysan Island a century ago, naval base construction at Midway and French Frigate Shoals during the first half of the 20th century, and U.S. Coast Guard LORAN station construction and operations at Kure and French Frigate Shoals for several decades following World War II. The Midway Naval Air Station supported several hundred to several thousand soldiers and dependents during pre- to post-World War II. Navigation channels for the naval bases at Midway and were dredged during the middle of the 20th century. These types of coastal development activities alter current flow and shoreline configuration and, as a result, may significantly alter coastal erosion patterns. Operation of housing and other facilities in the past has contributed to point and nonpoint sources of pollution to the marine environment.
Since the closure of Navy and U.S. Coast Guard facilities, coastal development activities have been limited to small-scale conversion of abandoned U.S. Coast Guard buildings on Tern Island at French Frigate Shoals and Green Island at Kure to wildlife research stations (Figure 19). The only recent coastal construction has been the repair of the seawall protecting Tern Island's small runway and buildings and construction of a small boat ramp at French Frigate Shoals in 2004. Current human population levels are limited to a few workers and volunteers at wildlife stations operated at Laysan, French Frigate Shoals and Midway year round and at Kure, Lisianski, and Pearl and Hermes atolls seasonally.