Leatherback turtles are living links to an ancient past, but their continued existence is now critically threatened. As the sole surviving species of the family Dermochelyidae, the leatherback traces its evolutionary history back over 100 million years. Throughout this time, leatherbacks have perfected the navigational skills that allow them to travel the world’s oceans in search of prey, and develop cues to help adult females return to their natal beaches to produce the next generation of the world’s largest sea turtles.
While leatherbacks have survived natural limiting factors for millions of years, they are no match for the collective pressures humans have placed on them in the past half-century. Today the future of leatherback turtles hangs in a delicate balance, one that is increasingly weighted against the species. Leatherbacks are falling prey to fishing nets, hooks, entangling lines, marine debris, and garbage. They are victims of vessel strikes. Coastal development and beachfront armoring destroy critical habitat such as nesting beaches. The bright lights of beachfront resorts and other buildings disorient nesting adults and emerging hatchlings. Leatherbacks are also poached for their meat, oil, and eggs.
The actions outlined in the North American Conservation Action Plan (NACAP) are essential to advancing the conservation and recovery of leatherbacks and to preventing their extinction in the Pacific Ocean in the foreseeable future.
In North America, as elsewhere, important conservation and regulatory measures have been developed. Canada, the United States (US), and Mexico all recognize the precarious status of leatherbacks and have afforded them the highest levels of legal protection. These protections complement other declarations, such as the World Conservation Union’s (IUCN) listing of the species as “critically endangered.” Canada and the United States have both developed Pacific and Atlantic leatherback recovery plans to direct research and management actions. Mexico has implemented a program to monitor and police nesting beaches. The US National Marine Fisheries Service (NMFS) is addressing some causes of fishing related mortality (trawling and longlines) and evaluating the effectiveness of mitigation measures that have been put in place.
Community outreach and capacity-building programs are in place in all three countries, and those lessons are being shared with other nations whose waters also serve as important foraging habitat for leatherbacks throughout their life history.
Despite the positive efforts of individual governments, the number of female leatherbacks returning to nesting beaches in the Pacific continues to decline each year. Little is known about the status of other life stages. Ultimately, the conservation measures of several individual countries may not be effective enough to recover Pacific leatherback populations. A coordinated multigovernment approach is urgently needed if leatherbacks and other highly migratory species are to remain part of our shared national, North American, and international heritage.
The primary vehicle for collective action on conservation and management of leatherback sea turtles within the North American region is the Inter-American Convention for the Conservation and Protection of Sea Turtles (IAC). This Convention, to which Mexico and the United States are Party, and Canada is eligible to accede as a range state, entered into force in 2001. The Convention’s objective is to “promote the protection, conservation and recovery of sea turtle populations and of the habitats on which they depend, based on the best available scientific evidence, taking into account the environment, socio-economic and cultural characteristics of the Parties.”
Through the Commission for Environmental Cooperation (CEC) of North America, and consistent with the objectives of the IAC, the governments of Mexico, the United States and Canada have a unique opportunity to confirm their international leadership in conservation and ocean management through the implementation of integrated, trinational conservation actions and the fostering of multi-lateral management plans with other nations. This cooperative leadership will significantly enhance the effectiveness of each country’s existing conservation and recovery goals for leatherback turtles and improve the likelihood of recovery for leatherback turtles throughout the Pacific portion of their range and beyond.
Leatherback turtles are the largest of the marine turtles, frequently exceeding 150 cm in length. They have the most extensive range of any living reptile and have been reported in all the world’s oceans.
Except for the brief time leatherbacks spend on beaches as eggs, hatchlings or nesting females, these species lead a completely oceanic existence, foraging widely in temperate ocean waters. Leatherbacks have specific habitat needs at each stage of their lives. When nesting, females require high energy, sandy beaches with a deep ocean approach and few obstructions (Pritchard 1971, Ernst and Barbour 1989). Hatchlings and juveniles less than 100 centimeters in carapace length appear to prefer almost exclusively tropical waters (Eckert 2002a), while large juveniles and subadults likely share habitats with adult leatherbacks. Adults frequent cooler waters, including the continental shelves off Canada and the United States (Shoop and Kenney 1992). They follow oceanic frontal systems where productivity is high, providing high concentrations of prey (Lutcavage 1996).
Leatherbacks feed at the ocean surface (Eisenberg and Frazier 1983) as well as at depth (Hartog 1980; Eckert et al. 1989), primarily consuming cnidarians (jellyfish and siphonophores) and tunicates (pyrosomas and salps) (NMFS and US FWS 1998; Work and Balazs 2002). When diving, leatherbacks appear to spend almost the entire portion of each dive traveling to and from maximum depth, suggesting that maximum exploitation of the water column is of paramount importance to them. Maximum dive depths for post-nesting females in the Caribbean have been recorded at 475 meters and over 1,000 meters, with routine dives recorded at between 50 and 84 meters. The maximum dive length recorded for such female leatherbacks was 37.4 minutes, while routine dives ranged from 4 to 14.5 minutes (Lutcavage and Lutz 1997).
Leatherbacks are thought to mature on average between 13 and 14 years of age (9 years is a likely minimum) (Zug and Parham 1996). Every 2 to 4 nesting seasons, gravid adult females make long migrations from their feeding areas back to the tropical beach they originated from as hatchlings. There, each female lays on average 4–6 clutches of eggs per season, with approximately 65–85 eggs in each clutch (NMFS 2004).
Although a female leatherback may lay thousands of eggs over her lifetime, not all of those eggs will become adult leatherbacks; in fact, the odds of a young turtle hatching and reaching maturity are quite low (1:1,000). Leatherbacks that survive and reach the subadult and adult stages of their lives would normally have a high chance of surviving for many years. Unfortunately, the relatively recent human impacts introduced into leatherback habitats have decreased their chances of survival at all stages of their life cycles: the result is that the species is being decimated (Spotila et al. 1996; Spotila et al. 2000).
Satellite tracking and genetic analyses have shown that leatherbacks originating from the far western Pacific nesting beaches (Malaysia and Indonesia) migrate into north Pacific waters. There they forage off the west coast of North America. Thus, most of the leatherbacks found foraging off British Columbia and central California originate from western Pacific nesting beaches. Female leatherbacks originating from nesting beaches in Papua New Guinea generally migrate south into the southwestern Pacific Ocean, approaching New Zealand. Leatherbacks originating from eastern Pacific beaches (Mexico and Costa Rica) tend to migrate into southeast Pacific waters and are regularly found off Chile and Peru (Dutton et al. unpublished data).
The eastern Pacific leatherback population was once considered the largest populations of the species in the world; in the early 1980s, one estimate suggested that it accounted for as much as 65 percent of the global population. The Mexican Pacific area hosted the largest proportion of this population; in 1981, the number of nesting female leatherbacks was estimated at over 70,000 (Pritchard 1982).
In addition to the widespread consumption of turtle eggs in Mexico, the indigenous Seri Indians also used leatherback sea turtles during important cultural ceremonies. The Seri Indians inhabited the coast of Sonora and the Gulf of California Islands and may have been the first of native Mexicans to utilize sea turtles. The Seri hunted sea turtles from balsas, or reed boats, using long harpoons made of ironwood. The relationship between sea turtles and the Seri people was complex and strongly spiritual, with a rich body of dance, song, and traditions associated with the animals. Nearly all parts of the turtle were eaten, either immediately or within days of capture (Nichols 2003). In recent years, the use of leatherbacks has been abandoned, because they are so rare (W.J. Nichols, Blue Ocean Institute, pers. comm. 2004). Despite the implementation of beach protection and enforcement of the primary leatherback nesting beaches in Mexico, the number of females returning to nest each year continues to decline. This downward trend is likely due to a combination of factors, including continued egg poaching, harvest of adults, and incidental take in fisheries, as discussed in later sections of this report.
In the United States, there is no evidence of the historic use of leatherbacks for cultural tradition or economic value, unlike the rich legacy of such practices using other hard-shelled sea turtles. There is no nesting by leatherbacks on beaches under present or former US Pacific jurisdiction, and at-sea sightings are largely confined to the continental west coast (NMFS and US FWS 1998). Leatherbacks forage regularly off central California in the late summer and early fall (Benson et al. 2003).
The first documented sighting of a leatherback in Pacific Canada (British Columbia) was in 1962. Leatherbacks are now known to make use of the highly productive coastal waters of British Columbia as foraging habitat (C. Sbrocchi, Vancouver Aquarium, pers. comm. 2004). There are currently no commercial uses for, or culturally related interactions with this species documented along this coast. Interactions (lethal and non-lethal) with commercial and recreational vessels have provided almost all of the sightings data for leatherbacks in British Columbia. Information on sightings in the coastal waters of British Columbia are limited and it is not currently possible to draw any conclusions on population trends, due in large part to the species’ infrequent presence.
4.1 Global status
Leatherback turtles have a very high risk of disappearing from the Pacific Ocean within the foreseeable future—one or two human generations (Spotila et al. 1996, 2002)—unless quick and effective action is taken to stop and reverse their extinction.
Global population estimates for leatherbacks are based on the numbers of nesting females recorded each year. When both Pacific and Atlantic stocks are considered, the global number of nesting female leatherbacks has declined from an estimated 115,000 in 1980 (Pritchard 1982) to between 20,000 and 34,500 by 1995 (Spotila et al. 1996). This trend is unevenly distributed, with nesting populations declining more severely along the Pacific coast.
The leatherback turtle was assessed by the World Conservation Union (IUCN) in 2000 and placed on their Red List of Threatened Species as “Critically Endangered” (Hilton-Taylor 2000). The leatherback is also listed under Appendix 1 of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), an international agreement that ensures that trade of wild animal and plant species does not threaten their survival. Lastly, the Convention on Migratory Species lists leatherbacks in Appendix 1 and 2, which identifies migratory species that are threatened with extinction and that would significantly benefit from international cooperation.
4.2 Eastern Pacific nesting populations
Eastern Pacific nesting beaches are found along the Pacific coasts of Mexico, Nicaragua, Guatemala and Costa Rica. All of the beaches have showed declined in last few years. Poaching has played a significant role in the decline of the leatherback.
4.3 Western Pacific nesting populations
The Western Pacific population of leatherbacks (the presumed source of most of the adults foraging off Pacific Canada and a large number of those foraging in continental US waters) includes populations that nest in Malaysia, Indonesia (Papua), Papua New Guinea and the Solomon Islands, with lesser contributions from beaches in Vanuatu, Fiji and Australia. Nesting population trends are not as well known as for the Eastern Pacific populations.
4.4 Legal status by CEC member country
Canada has designated the leatherback as endangered (Committee on the Status of Endangered Wildlife in Canada— COSEWIC), and the recently enacted Species at Risk Act (SARA) (Statues of Canada 2002, Chapter 29. Ottawa: PWGSC 2002) lists leatherback turtles as Endangered under Schedule I of the Act, providing legal protection and mandatory recovery requirements. Under SARA, the term “protection” prohibits killing, harming and harassing of individuals and prohibits the damaging or destroying of their residence and protection for any critical habitat. Although SARA limits its focus to those individuals of the species that occur in Canadian waters, the Pacific Recovery Strategy and its attendant action plan recognize the transient nature of the species, and provides not only for conservation measures in Canadian waters and where Canadian activities are prosecuted, but also for the participation of Canadians in international leatherback turtle conservation programs and projects.
In Mexico, leatherback turtles are currently listed as Endangered, which is the highest priority rank in NOM-059-SEMARNAT-2001. The leatherback is a protected species, and any commerce of it or its products is considered a federal offense (Art. 420, Código Penal Federal). Mexico has implemented monitoring and enforcement protection on all primary leatherback nesting beaches, and protecting the secondary beaches is a high priority for the government.
4.4.3 United States
The leatherback turtle is listed as endangered under the Endangered Species Act (ESA) (16 U.S.C. § 1531 et seq.) throughout its global range. No areas in the Pacific Ocean are currently designated as critical habitat for leatherbacks. As discussed in section 6.3, the United States has implemented regulations to establish a leatherback conservation area off central and northern California from August 15 through November 15, 2004. During this period and in this area, no person may fish with drift gillnet gear (50 CFR 223.206).
Because all female sea turtles spend a portion of their life nesting on land and the remainder at sea, two separate federal agencies, the US Fish and Wildlife Service (US FWS) and NOAA’s National Marine Fisheries Service (NMFS) share responsibilities for the conservation of sea turtles. Pursuant to the ESA, both Services must also encourage: (a) foreign countries to provide for the conservation of ESA-listed species; (b) the entering into bilateral or multilateral agreements with foreign countries to provide for such conservation; and (c) foreign persons who directly or indirectly take listed species in foreign countries or on the high seas for importation into the United States for commercial or other purposes to develop and carry out conservation practices designed to enhance such listed species and their habitat.
5.1 Fisheries bycatch
In the Pacific Ocean, fishing activities and gear represent the single greatest threat to leatherback populations. Leatherbacks are adversely affected by a variety of fishing gear, including longlines, pots, traps and weirs, gillnets (both set and drift), trawls, purse seines and other gear types.
Leatherbacks are incidentally captured in commercial and recreational fisheries throughout their Pacific range, including areas adjacent to their nesting beaches and along migratory pathways. Because of their massive front flippers, leatherbacks are especially vulnerable to entanglement in fishing gear (James 2001). They are vulnerable to both gear in use (especially un-monitored gear with long soak times) and abandoned gear. Entangled turtles will drown if unable to free themselves, but may also lose limbs or become more vulnerable to predation while attempting to break free. Turtles that do break free may still be encumbered by trailing gear (NMFS 2001). Excess line can wrap around limbs or other body parts and cause constriction, infection or amputation. These lines can also be ingested. The encumbrance of hauling gear such as single or multiple pots can prevent normal foraging and swimming activities. Leatherbacks that are released from longline gear with or without hooks and lines may also experience post interaction injury and mortality.
Very few fisheries in the Pacific Ocean are observed or monitored for sea turtle bycatch; however, the following sections summarize known effects of various fisheries on leatherbacks based on observations, research, and anecdotal reports.
5.1.1 Longline gear
Leatherbacks are incidentally captured as bycatch in longline fisheries throughout the Pacific Ocean. Lewison et al. (2004) estimated that in one year (2000), 20,000 leatherbacks were caught by pelagic longliners throughout the Pacific. These researchers calculated that on average, an individual leatherback in the Pacific Ocean might be incidentally captured every two years. The most significant hazard of longline fisheries for leatherbacks results from potential entanglement in or hooking by gear used in the fishery, which can injure or kill sea turtles. Because leatherbacks are generally not attracted to the bait used to attract pelagic fish species (e.g., squid and mackerel), they are primarily entangled in the gear, or hooked in the shoulder, flipper, or back. Leatherbacks have been documented interacting with Pacific longline fisheries originating in many countries, including the United States (primarily Hawaii and California), American Samoa, Japan, Chile, and Costa Rica. A proportion of these interactions included mortalities (NMFS 2004). Currently, there are over 5,000 longliners fishing in the central and western Pacific Ocean (includes non-artisanal-coastal, distant water, and offshore), and over 1,100 largescale longline vessels fishing in the eastern tropical Pacific Ocean (ETP). Lewison et al. (2004) estimate pelagic longline effort in the Pacific in 2000 to be approximately 728 million hooks, equaling on average, 2 million hooks set per day. Recent estimates from the eastern Pacific show that well over 30,000 artisanal longline vessels operate off of the Pacific coast of Central and South American ports (NMFS 2004).
Leatherbacks are also entangled in gillnets. Drift gillnets set in habitats that overlap with foraging or migrating leatherbacks increases the likelihood for interactions. Similarly, set gillnets may interact with leatherbacks during their internesting period, particularly if they are set close to the nesting beaches.
Prior to the early 1990s, high seas driftnet fisheries freely operated in the Pacific Ocean and interacted with thousands of sea turtles. Researchers estimated that over 1,000 leatherbacks were taken by the combined fleets of Japan, Korea, and Taiwan during a one-year period (Wetherall 1997).
Since high seas driftnet fisheries were banned through a United Nations moratorium in 1992, leatherbacks have been documented entangled in drift gillnet gear in fisheries operating out of California and Oregon ports, coastal gillnet and setnet gear out of Taiwan, and by artisanal drift gillnet fisheries operating from Chile. Based on strandings, observed injuries and co-location of species and gear, leatherbacks are also suspected to be entangled in gillnet gear operating out of Mexico, Costa Rica, Nicaragua and Peru (NMFS 2004).
As with longline fisheries, it is very difficult to estimate the number of gillnetters operating in the Pacific Ocean and the associated effort, especially for artisanal fisheries. Gillnet vessels have been documented operating out of most of the North, Central and South American countries. In addition, because of the demand for leatherback meat in some countries, leatherbacks incidentally taken in a gillnet will more often be killed and eaten, regardless of whether the turtle was found alive in the net (Kelez et al. 2003). Little is known about gillnet fishing effort out of the western Pacific and south Pacific nations and territories.
Since the 1992 ban, active North and South Pacific large-scale high seas driftnet fisheries no longer pose a significant threat to leatherbacks; however, the large numbers of drift nets still at large in the Pacific continue to “ghost fish” for a variety of marine species, including leatherback turtles.
5.1.3 Other fisheries
Leatherback turtles are also threatened by other fisheries in the Pacific Ocean, although likely to a lesser degree than gillnets and longlines simply due to the nature of the fisheries and the areas fished.
In the United States, the shrimp trawl fishery has been a significant source of sea turtle bycatch. The operation of nets being dragged through the water column results in the incidental capture of leatherbacks foraging or swimming in the path of trawl gear. Turtle excluder devices (TEDs) can reduce the number of turtles that drown when captured in shrimp trawl nets by providing an opening that allows turtles to escape from the trawl gear. Shrimp trawlers who export their product to the United States are required to use TEDs. TED regulations were amended in 2003 to increase the size of the escape opening, a change that will benefit leatherbacks and large hard-shelled turtles
Trawl fisheries in the eastern Pacific primarily target shrimp. The extent of the impact on leatherbacks of the hundreds of trawlers that operate in the Pacific Ocean is currently unknown; however, shrimp trawl fisheries have been documented interacting with leatherbacks in the Atlantic Ocean. Limited observer data from Costa Rican Pacific shrimp trawls in recent years have yielded no leatherback captures, although all observations have occurred in the past 10 years, after the documented leatherback decline at Costa Rican nesting sites (R. Arauz, PRETOMA, pers. comm. 2004).
Purse seiners capture their target species by encirclement. A turtle may become entangled in the webbing at any time during the set, including along the outside perimeter. Turtles captured by purse seines may suffer injuries from net entanglement or from being dropped on deck or run through the power block as the net is hauled aboard. In addition, sea turtles have been documented entangled in fish aggregating devices, which are used by purse seine fishermen to attract tuna. Leatherbacks have been observed captured by tuna purse seiners in the eastern tropical Pacific. However, interactions are very rare, and survival rates are extremely high since animals can be released alive (NMFS 2004).
Leatherbacks have also been documented entangled in pot or trap gear. The turtles typically get their flippers or other parts of their body entangled in the floatline or other fixed gear. Wrapped gear can restrict the turtle’s movement or cut into the skin. If the gear is discarded, the turtle might be capable of swimming away with the gear trailing, or may drown due to the weight of the gear or not being able to reach the surface to breathe. On the east coast of North America, where there are thousands of lobster and crab traps and pots, many leatherbacks have been found entangled. The extent of the impacts of this fishery on leatherbacks in the Pacific are currently unknown, although stranding records from California have documented leatherback entanglement in crab pot gear (J. Cordaro, NMFS, personal communication 2004).
Troll fisheries occur off the west coast of North America, and the target species is most often albacore tuna and salmon. Troll fisheries may interact with sea turtles when the hook and line dragged through the water column snags or entangles an animal. There have been anecdotal reports of sea turtles being snagged by troll lines off California (NMFS 2004). The main period of troll fisheries interception in Pacific Canada is probably between July and September, when the salmon troll fisheries coincide with leatherback appearance in British Columbian waters. The severity of all accidental capture-related threats from these fisheries in British Columbian waters is presently impossible to quantify due to limited data.
5.2 Human impacts on nesting habitat (beaches and adjacent areas)
Leatherback nesting beaches are threatened by human encroachment. Increased human presence tends to bring artificial lighting to these areas and may result in an increase in poaching, noise, and pollution. Human activities on nesting beaches can disturb nesting females and their eggs. Females may abort nesting attempts, shift nesting beaches, delay egg-laying and select poor sites. Compaction of sand from people walking and driving over nests can impair hatchling emergence. Artificial light sources can disorient hatchlings and deter nesting females. Vehicles driving on the beaches compact sand and nests, unearth nests, and create ruts that hatchlings can get trapped in on their seaward migration (NMFS 1998).
Removal of trees and vegetation increases the potential for erosion and reduces shading, which may increase the temperature of the sand. Increasing sand temperatures may impair development of the young turtle in the egg, reduce hatchling success, or affect the sex of the hatchlings. For example, in the western Pacific, the main leatherback nesting beach of Jamursba-Medi is threatened by logging activities, including lumber harvest and transportation and the construction of a log pond and base camp. Such activities remove vegetation, change drainage patterns, and increase human presence, which may also increase poaching of eggs. Logs washed up on the beach may hinder females coming ashore to nest and hatchlings from reaching the ocean (Hitipeuw 2003).
Coastal construction adjacent to nesting beaches often results in the need to provide protection for upland structures in the form of beach armoring. Sea walls, rock revetments, riprap, sandbags, and groins alter shoreline sand transport, leading to the degradation or elimination of suitable nesting beach habitat. Armoring can also prevent nesting females from reaching a suitable nesting site and can trap or delay hatchlings and females on their journey back to sea, increasing exposure to predators. The subsequent removal of these structures can also negatively impact nesting habitat (NMFS 1998).
Sand and coral rubble removal and other beach mining activities can also severely impact nesting beach habitat. Attempts to replace sand lost to erosion—a process known as beach nourishment—can cause problems for leatherback nesting. The machinery used to haul and distribute sand can compact the beach, destroy nests, and create a beach profile that is unsuitable for emerging adult females. Sand of reduced quality or different composition can result in an altered or poor nesting habitat for nesting females and can hamper the development and successful emergence of healthy hatchlings (NMFS 1998).
Introduced exotic plants can displace natural vegetation and proliferate on nesting beaches. Increased shade from introduced plants can result in cooler temperatures within nests and may alter sex ratios of hatchlings. Roots may entangle eggs and hatchlings. Nesting females can also become tangled in vegetation, slowing or preventing their return to the sea (NMFS 1998).
Beaches also tend to concentrate some of the same kinds of debris and pollution that are hazardous to leatherbacks at sea. Examples include plastics, abandoned netting, and oil.
5.3 Direct killing of nesting females
In Mexico, in spite of legislation, female leatherbacks are still documented being killed on nesting beaches, primarily for eggs, but also for their oil, which can fetch a high price. In January 2004, Reuters reported that two female leatherbacks had been killed on the beach of San Valentin, on Mexico’s Pacific coast in Guerrero. Aerial surveys over Piedra de Tlacoyunque, Guerrero documented more than 20 females slaughtered on a single beach Sarti et al. (1996b).
5.4 Egg removal by humans
Leatherback nests are threatened by poaching in both the eastern and western Pacific. Eggs, which are consumed as a protein source, serve as an economic resource for poachers. Poaching of eggs places additional, long-term pressure on the reproductive viability of nesting populations.
While anti-poaching regulations are enforced in Mexico and the primary nesting beaches are generally protected by enforcement personnel, the beaches are very long and in some case remote, making it difficult to provide protection over an entire nesting season. Funding to support enforcement activities is also a limiting factor (NMFS 1998).
5.5 Predation of eggs by animals
Natural predators, such as raccoons, rats, mongoose, birds, monitor lizards, snakes, crabs, and other invertebrates eat turtle eggs. Beach insects such as fly larvae and crickets also eat leatherback eggs, as do domesticated species such as cats, dogs, and pigs. In Florida’s Hobe Sound National Wildlife Refuge (HSNWR), introduced armadillos (Dasypus novemcinctus) and native raccoons (Procyon lotor) have preyed on leatherback eggs (Engeman et al. 2003). In fact, managers developed control methods to remove the armadillos and raccoons in order to reduce hatchling loss (Engeman et al. 2003).
5.6 Traditional harvest of leatherbacks
The CEC does not have a mandate to work outside of North America. The CEC Parties recognize that some threats to leatherback turtles originate outside North America and thus the NACAP highlights some of these threats so that the CEC Parties can work outside the CEC to help address them. For example, in the Kai Islands, located approximately 1,000 kilometers southwest of the Papua, Indonesian nesting beaches, adult leatherback turtles are traditionally hunted and captured at sea by local people. Villagers hunt leatherbacks only for ritual and subsistence purposes and according to their traditional beliefs, they are forbidden from selling or trading the meat. During the 1990s, it was estimated that approximately 200 leatherbacks were taken annually by the villagers, while currently approximately 20 leatherbacks are taken annually. Villagers are reportedly too involved in promoting their local economy to engage in the harvest of leatherbacks. In addition, a specialist from a local nongovernmental organization is currently working with the eight villages to explore the potential for monitoring a community-based harvest and exploring alternative substitutes for traditional harvest (Hitipeuw 2003b).
5.7 Waste at sea and along the coast
Leatherbacks consume debris such as plastic bags and balloons, objects that resemble jellyfish, their preferred prey (Mrosovsky 1981). The effects of plastic bag ingestion on leatherback physiology and behavior, including impaction and death, are reviewed by Fritts (1982). Dead leatherbacks have been found choked on plastic bags, and phthalates derived from plastics have been found in the leatherback egg yolk (Juárez-Cerón 1998).
Leatherbacks are exposed to the same pollutants as other forms of marine life. In populated areas, these include sewage and agricultural and industrial chemical runoff. Bioconcentration of chemical pollutants in the prey of leatherbacks has not been studied and their impact is not known. Accumulation of heavy metals and PCBs has been demonstrated (Davenport et al. 1990).
5.8 Other threats
5.8.1 Boat strikes
Turtles have been documented injured or killed after being struck by boats and propellers. Due to their habit of basking at the surface of the water or swimming just beneath the surface, leatherbacks may be at particular risk for vessel strikes and propeller wounds (NMFS 1998).
5.8.2 Diseases and parasites
Little is known about diseases and parasites in leatherbacks. Fibropapilloma tumors have recently been observed in leatherbacks in Mexico (Huerta et al. 2002; Murakawa and Balazs 2002).
Sharks and killer whales have been reported to attack adult leatherbacks (Sarti et al. 1994; Caldwell and Caldwell 1969).
5.8.4 Oil exploration and extraction
Oil extraction from the seabed carries risks of spills, blowouts, and increased marine traffic. Oil exploration may also pose indirect threats to foraging habitat, through associated actions involving drilling, anchoring, explosives, and pollution. Oil spills from tankers, ships, or through extraction poses a risk to leatherbacks as well. While increased safety standards have minimized this threat through implementation of double-hull requirements, blow-out prevention, and improved response and cleanup, the risk still exists. Direct mortality due to oiling and negative impacts to the skin, blood, digestive and immune systems, and salt glands may occur if spilled oil makes contact with a sea turtle (Milton et al. 2003).
The Canadian Recovery Plan for leatherbacks lists at-sea aquaculture operations as potential environmental threats due to noise from predator-scaring devices, fecal pollution, potential entanglement in anchoring systems and the possibility of parasite transmission (Department of Fisheries and Oceans 2003).
In order to obtain information on leatherback turtle distribution, abundance and potential threats in Pacific Canadian waters, Fisheries and Oceans Canada and the Vancouver Aquarium Marine Science Centre have developed a sightings reporting network for Pacific leatherback turtles. Information about such sightings will be linked with the British Columbia Cetacean Sightings Network. In 2002, the project began compiling historical sightings and developing a database to store both historical and new sightings.
As leatherback turtles in Pacific Canadian waters are likely from the same genetic stocks as those in Pacific US waters, Canada may consider making its measurable recovery objectives consistent with the Recovery Criteria outlined in the Recovery Plan for US Pacific Populations of the Leatherback Turtle (NMFS and US FWS 1998).
Conservation programs aimed at protecting nesting leatherbacks in Mexico have been in place since the early 1980s, and there is little information on the degree of poaching prior to the establishment of these programs. Since protective measures have been in place, particularly emergency measures recommended by a joint United States/Mexico leatherback working group meeting in 1999, there has been greater nest protection and nest success, but egg poaching has not been entirely eradicated on any of the beaches (A. Barragán, KUTZARI, pers. comm. 2004).
On 17 September 2003, the state of Michoacán invited the states of Guerrero and Oaxaca, as well as the federal government, to sign an agreement to recover the nesting leatherback population. An action plan was quickly put in place under the leadership of Semarnat (Secretaría de Medio Ambiente y Recursos Naturales). Although conservation of this species is primarily a federal mandate, state and municipal governments have developed socio-economic plans in the areas where leatherbacks nest. These plans aim to create alternative economic activities (e.g., tourism as an alternative to egg harvesting) that will reduce the pressure on leatherbacks. The state and municipal governments also participate in security and enforcement. Community networking is also a feature of this plan, and local communities are working to develop new conservation efforts to address potential threats to leatherback populations, such as coastal fisheries.
6.3 United States
6.3.1 Domestic management and action
Under the Endangered Species Act, any federal agency shall insure that any federal action authorized, funded, or carried out is not likely to jeopardize the continued existence of any endangered or threatened species or result in the destruction or adverse modification of their critical habitat. Under Section 7 of the Act, “formal consultations” are conducted to determine whether an action is “expected to reduce the species’ likelihood of surviving and recovering in the wild.” If the resultant “biological opinion” concludes that the action is jeopardizing the continued existence of a listed species, the agency conducting the consultation (for sea turtles: NOAA Fisheries in the marine environment and the US Fish and Wildlife Service for nesting habitat on land) will identify reasonable and prudent alternatives to the action. Because NOAA’s NMFS manages several fisheries that operate off the Pacific Ocean, the agency is required to consider the effects of these fisheries on listed species, including sea turtles, which may be adversely affected by the operation of the fisheries. The following sections describe several consultations that have taken place to address the threat of US fisheries on leatherbacks, including management and conservation actions that have resulted from Section 7 consultation.
California/Oregon drift gillnet fishery
Off the coasts of California and Oregon, a drift gillnet fishery operates and targets both swordfish and thresher shark. In 2000, NMFS conducted a Section 7 consultation to determine the effects of this fishery on sea turtles. The biological opinion determined that the operation of the fishery was expected to reduce the leatherbacks’ likelihood of surviving and recovering in the wild. In order to protect leatherbacks during a period when they are often found in large numbers foraging off Monterey Bay before heading back across the Pacific to the nesting beaches of Indonesia, NMFS implemented a time/area closure for the fishery. This time/area closure has been in place since 2001, and since then, observers have reported zero takes of leatherbacks.
Hawaii-based longline fishery
In 2001, NMFS conducted a Section 7 consultation on the longline fishery operating out of Hawaii. Analysis of the data showed that the shallow set swordfish fishery, which generally fished in the northern Pacific north of Hawaii, was interacting with a large number of leatherbacks and loggerheads. Because there were few discernable seasonal or environmental patterns to help stratify the bycatch, NMFS closed the shallow-set longline fishery operating out of Hawaii to protect loggerhead and leatherback turtles. Tuna fishing was also restricted to protect sea turtles through time-area closures.
In May 2004, the swordfish fishery was reopened but continues to operate under strict controls which includes: a maximum number of sets per year; a maximum number of leatherbacks take per year; 100 percent observer coverage; and mandatory use of a circle hook and mackerel bait combination. Once the maximum turtle take and/or maximum number of sets is reached, the fishery will close for the year.
California-based longline fishery
In response to a shift of the Pacific longline fleet to the US West Coast and fishing out of California ports, a similar analysis was conducted on the California-based longline fishery. Based on an analysis of the impacts of this fishery on leatherbacks (and primarily loggerheads), NMFS banned shallow-set longlining based out of west coast ports to protect those species.
6.3.2 Circle hook experiments in North Atlantic
Most recently, experiments conducted in the North Atlantic by the United States have determined that the combined use of larger offset circle hooks and mackerel bait has the potential to reduce the interaction rate and mortality of leatherbacks and loggerheads significantly. Based on the results of two years of experiments, in the fall of 2003, the Western Pacific Fisheries Management Council proposed that NMFS allow the operation of a shallow-set longline fishery based out of Hawaiian ports. Strict controls would be imposed on the fishery in order to reduce sea turtle interaction and mortality rates, as described above. Following a Section 7 consultation on this proposal, NMFS accepted the modifications to the fishery, and the fishery re-opened (see above).
Implementation of gear modifications in US fisheries, such as those demonstrated in gear experiments in the Atlantic may have broader implications for sea turtles around the world. If modified longline fisheries can demonstrate that target species (e.g. swordfish and tuna) can be caught sustainably and with similar catch-per-unit-effort as before, yet reduce or avoid the take of turtles, the international community will be more likely to accept the results and change their style of fishing accordingly.
IOSEA MOU– Indian Ocean and South-east Asia Memorandum of Understanding on the Conservation and Management of Marine Turtles and their Habitats: The IOSEA was formed under the auspices of the Convention on the Conservation of Migratory Species. Under the Memorandum of Understanding (MOU), the signatory states have developed a comprehensive Conservation and Management Plan and have an established Secretariat financed through voluntary funding. Currently there are sixteen signatory states, including the United States. The Plan has six objectives, including: reduction of direct and indirect causes of sea turtle mortality; improvement of sea turtle habitat; collaborative research; exchange of information; increased public exchange; and enhancement of national, regional and international cooperation. Each objective contains various programs and activities for each country to undertake.
FAO–COFI - Food and Agriculture Organization, Committee on Fisheries: The FAO has been in existence since 1945 and offers direct developmental assistance to needy countries, collects, analyzes and disseminates information, provides policy and planning advice to governments and acts as an international forum for debate on food and agricultural issues. The Committee on Fisheries (COFI) was established in 1965 and is essentially the only global inter-governmental forum where major international fisheries problems and issues are examined and recommendations made to governments, nongovernmental organizations, and regional fisheries organizations, for example. COFI has also been used as a forum for the negotiation of global agreements and non-binding instruments.
At the last session of COFI, held in February of 2003, the United States supported a proposal submitted by Japan to conduct an FAO Technical Consultation on the issue of sea turtle interactions with fishing gear. Experts met in March 2004, in Rome, to prepare for the consultation, which occurred in November 2004 in Bangkok. The key objectives of the consultation are to: (1) review the status of sea turtle species and the overall impact fisheries have had on their populations; (2) review development of new fishing gears and techniques to reduce sea turtle bycatch and mortality; (3) produce, if appropriate, guidelines to reduce sea turtle mortality in fisheries; and (4) consider assistance to members from developing States for the conservation of sea turtles. The United States will likely promote the use of large circle hooks and seek standardized data collection and the establishment of observer programs in fisheries that pose high levels of threat to the recovery of sea turtles.
6.4.1 Regional Fisheries Management Organizations
There are several regional fisheries management organizations that have recently begun to take great interest in facilitating the advancement of effective programs to reduce fisheries-related sea turtle bycatch and mortality.
ATTC - Inter-American Tropical Tuna Commission: The Inter-American Tropical Tuna Commission (IATTC), established by international convention in 1950, is responsible for the conservation and management of fisheries for tunas and other species taken by tuna-fishing vessels in the eastern Pacific Ocean. Currently, there are 14 members of the Commission, including the United States and Mexico.
Recently the Commission has begun to address sea turtle bycatch issues through resolutions and the formation of a Bycatch Working Group. Because there has not been a systematic collection of data on longline fisheries under the IATTC’s jurisdiction, the impact of these fisheries is unknown. However, the Bycatch Working Group met in Kobe, Japan in January 2004 and drafted resolutions that addressed proper release and handling of sea turtles incidentally taken in both purse seine gear and longline gear. Japan proposed a resolution requiring the use of circle hooks by all longline boats fishing shallow sets (less than 100 meters) in the eastern tropical Pacific, but not all members could agree to the resolution.
WCPFC - the Western and Central Pacific Fisheries Commission: When the Western and Central Pacific Fisheries Commission (WCPFC) enters into force, it will have fisheries conservation and management responsibility for a large portion of the western and south Pacific. Ideally, the WCPFC will follow the IATTC’s lead and address sea turtle bycatch management and mitigation issues in their fisheries as soon as practicable.
ISC - North Pacific Interim Scientific Committee for Tuna and Tunalike Species: The Interim Scientific Committee (ISC) was formed in 1995 as a first step towards creating a fishery management and conservation organization for the pelagic fish stocks of the North Pacific. The purpose of the ISC is generally to enhance scientific research and cooperation for conservation and utilization of pelagic fish stocks. Membership is open to all coastal states of the region as well as States whose vessels fish in the region. Canada, the United States and Mexico, as well as several regional organizations have all participated in past meetings.
In 2004, a Bycatch Working Group was formed to address issues of bycatch of sea turtles, sharks and seabirds, including collection of data, sharing of information, etc. The Bycatch Working Group is likely to be an important source for scientific advice and recommendations to the WCPFC and possibly to the IATTC for any of their swordfish fisheries.
ICCAT - International Commission for the Conservation of Atlantic Tunas: The International Commission for the Conservation of Atlantic Tunas (ICCAT) is similar to the IATTC but operates in the Atlantic and comprises associated interested countries. The ICCAT has also begun to address sea turtle bycatch through resolutions. The US proposed a resolution that was adopted that would (1) collect data on sea turtle interactions; (2) require release of incidentally caught sea turtles and safe handling protocols and (3) support the FAO technical consultation on sea turtles.
6.4.2 Smaller Scale International Contracts/Collaborations
United States and Canada: Both the United States and Canada meet annually to informally consult on bilateral, multilateral and global fisheries conservation and management issues. The purpose of these meetings is not to negotiate agreements but more to provide broad coordination on issues of concern. Such issues in the past few years have included sea turtle conservation, as both countries share mutual concern for the species.
United States and Mexico: The United States and Mexico share a Fisheries Cooperation Program, which has been in effect since 1983. Through this program, both countries agreed to have their respective fisheries agencies (NMFS and PESCA) meet annually to review a broad range of issues involved in their bilateral fisheries relationship. The last bilateral meeting between the two agencies took place in Los Cabos, Mexico, on 9–10 March 2004. Conservation and management issues are generally the major topics discussed at these meetings, including the protection of sea turtles.
Three MOUs have resulted from these meetings, which have served to formalize different aspects of the relationship between Mexico and the United States. One MOU relevant to sea turtle conservation is the MEXUS-PACIFICO research program. Through this, a “turtle working group” has been established between the two countries. A “leatherback working group” meets informally and discusses priorities for protection and monitoring of the nesting beaches. In the beginning, NMFS provided much of the funding for leatherback conservation activities on Mexican nesting beaches, filtered through a nongovernmental organization, but now Mexico provides about 50 percent of the funding for efforts.
6.4.3 Domestic Legislation
Marine Turtle Conservation Act of 2003: Recently, the US Congress has recognized that more effort needs to be put forward to protect and conserve sea turtles in the world, particularly given such drastic declines in some populations, for example, the eastern Pacific populations of leatherbacks. After passing through both Houses of Congress, the Marine Turtle Conservation Act was signed, on 2 July 2004. The Act provides a funding mechanism to qualified marine turtle conservation projects in foreign countries to conserve nesting habitats, protect sea turtles in nesting habitats and prevent illegal trade of sea turtles. The Act provides urgently needed financial assistance to foreign countries in the amount of $5.0 million in a Marine Turtle Conservation Fund for the next five years (2005 through 2009).
6.4.4 Inter-American Conventions and Agreements
Inter-American Convention for the Protection and Conservation of Sea Turtles (IAC): The IAC is the first regional agreement among participating states of North, Central, and South America and the Caribbean Sea and gives broad coverage for protecting sea turtles and their habitats in the Western Hemisphere. The IAC sets the standards for conservation of these species. The Convention came into force in May 2001 and currently there are eleven contracting parties, including Mexico and the United States. Canada has not yet actively engaged in the process to become a party to the Convention.
In general, the IAC sets out measures that each Party should adhere to in order to protect, conserve, and recover sea turtles, including prohibition of take or trade of turtles or their eggs. Exceptions are made for traditional communities that depend on turtles to satisfy economic or subsistence needs—in those cases, a management program will be put in place that includes limits on take.
The Parties have committed at the national level:
- to protect and conserve sea turtle populations and their habitats;
- to reduce the incidental capture, injury and mortality of sea turtles associated with commercial fisheries;
- to prohibit the intentional take of, and domestic and international trade in, sea turtles, their eggs, parts, and products;
- foster international cooperation in the research and management of sea turtles; and
- implement any other measures necessary for their protection.
As described in sections 6.2 and 6.3, Mexico and the United States have been addressing each of these commitments through federal and state regulations, through cooperative agreements with other countries, and with other regional fishery management organizations. With these commitments, Mexico is actively endorsing and implementing the IAC management program into their laws.
Relevant to leatherback conservation, and data collection, the United States also has several MOUs with other countries. An MOU between NMFS and the Ministry of Energy and the Environment (MINAE) of Costa Rica was signed in February 2004, addressing issues of concern regarding sea turtles, cetaceans, and sharks of the Pacific Ocean. In this MOU, there is particular emphasis on the research and protection of leatherback turtles nesting in the Las Baulas National Park. The MOU is in effect for five years. In addition, currently there is a draft Letter of Agreement between Instituto del Mar del Perú and NMFS regarding Pacific sea turtles. As per the draft Agreement, special attention will be given to leatherback sea turtles and emphasis will be placed on the development of fisheries experiment and sea turtle bycatch reduction technologies in the Peruvian commercial and artisanal fisheries of the Pacific. Lastly, there is an existing MOU between NMFS and Chile’s Servicio Nacional de Pesca. The two agencies have agreed to work collaboratively on sea turtle research and conservation needs, specifically studying the migratory behavior and impact of fishing activity on leatherback turtles.
Turtles are a popular and iconic group of animals that hold much appeal to various community sectors, particularly to those North Americans who identify themselves as being predisposed to conservation attitudes and behaviors. However, as the vast majority of the North American public will never encounter a leatherback turtle, opportunities to benefit leatherbacks directly are extremely limited. As is the case for most other marine species, leatherbacks are likely to be perceived by the public as being more abundant than research would suggest, regardless of statements or evidence to the contrary. This is due in large measure to the inherent difficulties associated with humans’ abilities to construct personally meaningful time-space conceptual models of phenomena as vast as the Pacific Ocean (Bill Mott, The Ocean Project, pers. comm. 2003).
The commercial fishing industry recognizes the fact that leatherbacks are threatened by their industry, particularly the longline and gillnet fisheries. In the United States, the longline industry has been instrumental in working closely with researchers to develop gear experiments and de-hooking devices to reduce interactions and mortalities with sea turtles captured on a longline. US fishermen are also helping to fund a project in Baja California to protect and monitor one of the secondary leatherback nesting beaches, Agua Blanca (C. Fahy, NMFS, pers. comm. 2004).
An Overview of the North American Conservation Action Plans
As mandated by the 1994 North American Agreement for Environmental Cooperation (NAAEC), the Commission for Environmental Cooperation (CEC) encourages Canada, Mexico and the United States to adopt a continental approach to the conservation of wild flora and fauna. In 2003, this mandate was strengthened as the three North American countries launched the Strategic Plan for North American Cooperation in the Conservation of Biodiversity.
The North American Conservation Action Plan (NACAP) initiative began as an effort promoted by Canada, Mexico, and the United States, through the Commission for Environmental Cooperation (CEC), to facilitate the conservation of marine and terrestrial species of common concern.
The main assumption supporting this initiative is the need and opportunity to enhance—through coordination—the effectiveness of conservation measures undertaken by diverse countries sharing migratory or transboundary species.
Building Partnerships to Conserve Species of Common Concern
The implementation of the Strategic Plan for North American Cooperation in the Conservation of Biodiversity calls for identifying an initial set of North American regions and species for which the benefits of cooperation could be more effective and best illustrated. Two regions, one marine and one terrestrial, stood out that spanned the three countries: the Baja California to Bering Sea region and the central grasslands. Current activities developed in these regions include the identification of priority conservation areas within them as a basis for establishing an institutional conservation network.
Similarly, the countries, through the CEC, agreed upon an initial set of marine and terrestrial species of common conservation concern for which North American Conservation Action Plans would be developed. The initial six species (three marine and three terrestrial) were selected for these conservation action plans because of their ecological significance, their level of threat and the opportunities they present for joint action.
The goal of a NACAP is to facilitate a long-term cooperative agenda for the conservation of these species of common concern throughout their ranges of distribution in North America. Through each NACAP, the CEC provides a valuable planning tool to help focus limited resources and ensure that cooperative actions taken for the conservation of species of common concern are based upon sound science, and are targeted at priority actions. The implementation of these actions, however, is incumbent on the diverse players of each country.
The expected users of a NACAP are principally those organizations and individuals engaged in the conservation of shared North American species, including governments at the various federal, state/provincial, local and indigenous, tribal/first nations levels, and civil society.
The Pacific Leatherback Sea Turtle North American Conservation Action Plan
This NACAP, developed for the Pacific leatherback sea turtle (Dermochelys coriacea, hereafter “leatherback turtle”), resulted from a trinational workshop hosted by the CEC in San Francisco, California, in March 2004 and benefited from the in-depth review of an extensive list of wildlife experts from diverse backgrounds from Canada, Mexico and the United States. Furthermore, the content of this NACAP has been shared with diverse government agencies found within each country related to the well-being of the species.
The leatherback turtle action plan is divided in eight sections, providing a trinational outlook related to the species. The initial four sections provide an updated account of the species and its current situation. The fifth section identifies the main causes of loss or decline and puts in perspective the ensuing sections related to current management and actions taken in each country, as well as public and commercial perception of the species and the threats it faces. Against this background, the last section offers a list of key trinational collaborative conservation actions. The identified actions address the following main objectives:
- Protection and management of nesting beaches and females
- Reducing mortalities from bycatch throughout the Pacific Basin
- Waste management, control of pollution and disposal of debris at sea
We hope that over time efforts such as the NACAPs will indeed provide an effective basis for cooperation and networking among diverse sectors of society working on the well-being of these species and their habitats across North America.
Hans Herrmann and Jürgen Hoth
Biodiversity Conservation Program
Commission for Environmental Cooperation