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Tackling Marine Debris in the 21st Century 4 Derelict Fishing Gear and Fish Aggregating Devices While all maritime sectors, from recreational boats to large commercial shipping vessels, contribute to the ocean-based marine debris problem, there has been growing concern about the contribution of fishing vessels to this problem. Endangered monk seals entangled in derelict nets in the Northwestern Hawaiian Islands (NWHI) and tons of fishing gear being hauled away from remote Alaskan shorelines are vivid evidence of the serious nature of this problem. Commercial fishing vessels generate a significant portion of the U.S. maritime waste stream, including waste fishing gear (Cantin et al., 1990; National Research Council, 1995a). Both derelict fishing gear (DFG) and fish aggregating devices (FADs) were specifically referenced in the Marine Debris Research, Prevention, and Reduction Act (33 U.S.C. § 1951 et seq.) as subjects for further review by this committee. While they can be marine debris, there are legal and practical considerations that differentiate them from other debris types. And in some coastal areas, a very large proportion of marine debris is often related to fishing (e.g., northern Australia [Kiessling, 2003], NWHI [Donohue et al., 2001], Aleutian Islands [Merrell, 1980, 1984, 1985]). Therefore, the committee has chosen to devote a separate chapter to exploring these types of debris. This chapter begins by examining DFG and follows with a discussion of FADs, which become DFG once they are abandoned.
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Tackling Marine Debris in the 21st Century DERELICT FISHING GEAR Arguably the single most important advancement in fisheries technology is the replacement of natural, easily degraded fiber ropes and twines with cheap, durable, and lightweight synthetic ropes and twines (Kristjonsson, 1959). Historically, hemp, cotton, jute, sisal, manila, silk, and linen were the primary natural fibers used to make fishing gear (Uchida, 1985; Brainard et al., 2000). They were treated with a wide variety of dyes, tars, and preservatives to retard their rate of degradation in the marine environment. Nevertheless, their failure, replacement, and repair rates were very high. These strength and durability limitations were major factors that limited catch sizes in many fisheries. Advances in polymer chemistry and production technology in the post–World War II period led to the manufacture of polyethylene, polypropylene, polyamide (nylon), and other synthetic fibers which have all but replaced the natural fibers used in fishing gear. Worldwide, these advances greatly contributed to the vast growth in fish and shellfish harvesting capacity and also set the stage for resource management challenges that are yet to be fully and effectively addressed by governments and industry. While achieving sustainable fisheries is still the primary challenge of management authorities, another result of this technological revolution that has largely been overlooked is the effect of the loss or discard of these persistent materials into the marine ecosystem. The same properties that make these new materials effective as fishing gear also make them particularly problematic as marine debris. Unlike their natural predecessors, the new materials can last for years or decades in the marine environment. They are largely impervious to biodegradation; they are resistant to chemicals, light, and abrasion; and because many of these synthetic fibers are buoyant, they can be transported long distances by ocean currents. With the entry into force of the International Convention for the Prevention of Pollution from Ships, 1973, as modified by the Protocol of 1978 (MARPOL) Annex V and its implementation via domestic laws in the late 1980s, the at-sea discharge of plastics and other synthetic polymers, including fishing gear, was prohibited. This change from long-standing ship disposal practices, coupled with concurrent rising public awareness of synthetic materials–based marine debris (e.g., Manheim, 1986; Adler, 1987; O’Hara et al., 1988; Toufexis, 1988), increased focus on the problems associated with fishing gear lost or discarded into the marine environment. DFG is of particular concern because the use of synthetic materials has made fishing gear more durable and because it can continue to entrap, entangle, and retain marine organisms after it has been lost or discarded. The committee defines fishing gear as any device or equipment or parts thereof, except vessels, used in the catching, attracting, gathering,
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Tackling Marine Debris in the 21st Century holding, and harvesting of marine or aquatic species. DFG is fishing gear in the marine or littoral environment that has been abandoned or is otherwise no longer under the control (in the context of the legitimate operations of the specific fishery) of its legal operator. This definition does not address the many circumstances that may result in the loss of control of fishing gear, but it recognizes that what constitutes “control” of fishing gear varies among specific fisheries and fishery management systems. The term “derelict” refers to the intentional or unintentional abandonment of the gear. In either case, the operator acknowledges that he must abandon (relinquish control of) his gear; hence, the use of the term “derelict” fishing gear is appropriate. Fishing gear is unlike most other discharges or disposals considered in MARPOL Annex V in that it is intentionally deployed into the marine environment with the intention of retrieval. Commercial fishing gear is capital equipment used in the pursuit of value associated with the trade in fisheries products. In deciding to deploy their gear, fishermen engage in an implicit balancing of the expected value of their catch and the risk of damaging or losing their gear (Pooley, 2000). The quality of these judgments varies with experience; environmental conditions (e.g., weather, currents, tides, sea state, presence of sea ice, the makeup of the seafloor); the condition of the gear, equipment, and vessel; as well as a suite of economic pressures and regulatory factors. The fact is that fishing, legal or otherwise, entails risking the loss of some fishing gear. The challenge for fishermen, fishery engineers, fishery managers, and lawmakers is to find ways to incorporate the minimization of gear loss and its ultimate environmental hazards and the maximization of lost gear recovery into fishing operations, research programs, management and enforcement actions, and public policy directions. Sources, Fates, Abundance, and Impacts Prevention and reduction of DFG and its impacts requires an understanding of the sources, abundance, and impacts of this gear. While this information is also discussed in Chapter 2, some of what is known and some of the challenges in understanding DFG are highlighted here. As is true for other types of marine debris, there is little information available in the form of quantitative assessments of the sources and amounts of derelict gear generated by specific fisheries, or for linking those losses to impacts. Prevention of DFG begins at the source, but identifying the source may be difficult because ocean currents can transport DFG a long distance from the site of loss or discard and involve substantial time lags (Donohue et al., 2001; Boland and Donohue, 2003; Kubota, 1994; Donohue, 2005; Kubota et al., 2005; Pichel et al., 2007). As such, DFG encountered within
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Tackling Marine Debris in the 21st Century the U.S. Exclusive Economic Zone (EEZ) or on U.S. shorelines may be derived from current and past activities of domestic and foreign fishing fleets operating within or beyond the EEZ. There is evidence that fishing gear manufactured in Asia, particularly South Korea, Japan, and Taiwan, represents a significant component of DFG recovered in Alaska, Hawaii, and northern Australia (Kiessling, 2003; White et al., 2004; Timmers et al., 2005; Carpentaria Ghost Nets Programme, 2008; Bob King, personal communication; Michael Stone, personal communication). Much of the DFG documented in these locations is composed of materials commonly manufactured in Asia (e.g., twisted polyethylene twine); these materials are (reportedly) rarely used by manufacturers of fishing gear currently used in the United States, who instead use netting of domestic origin and from the European Union (e.g., braided polyethylene twine produced in Iceland and Portugal) (Bob King, personal communication; Michael Stone, personal communication). Complicating this situation is the existence of “legacy” gear; some derelict gear recovered in Alaska and Hawaii is very old, suggesting it may represent a relic of foreign fishing in what are now U.S. waters (Bob King, personal communication; Michael Stone, personal communication; and see Merrell, 1980). Prevention and reduction of DFG will have to take into account the transport of these materials across boundaries over long periods of time. Finding: Because DFG persists and can be transported long distances, parties that generate DFG may not be the ones that bear the effects of it. Increased awareness and participation by responsible parties is necessary to effectively address the DFG problem. Recommendation: All parties responsible for the generation of DFG should be involved in prevention and cleanup. Measures to prevent and reduce DFG will require international coordination and cooperation. The National Oceanic and Atmospheric Administration (NOAA), the U.S. Department of State, international fisheries management organizations, and other relevant organizations should engage in technology transfer and capacity building with nations from which DFG components originate to improve implementation of MARPOL Annex V in fisheries; encourage best practices to reduce gear loss, support recycling of used fishing gear, and promote retrieval of snagged or lost gear; and facilitate the participation of representatives from nations from which DFG components originate in DFG survey and removal efforts.
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Tackling Marine Debris in the 21st Century While the origin of some legacy gear is uncertain, sources are clearly identifiable in other cases; for example, the Northwest Straits Commission estimates that there are nearly 3,900 gillnets remaining in Puget Sound from domestic salmon fisheries from the 1970s and 1980s (Natural Resources Consultants, Inc., 2007). Ongoing domestic fisheries also contribute to derelict crab and lobster pots in the Atlantic and Pacific Oceans, the Gulf of Mexico, and Alaska (e.g., Hess et al., 1999; Guillory et al., 2001; National Oceanic and Atmospheric Administration, 2008b; Thomas Matthews, personal communication; Steven Vanderkooy, personal communication). In northeastern Atlantic fisheries, the amount of lost and discarded nets is unknown, but anecdotal evidence suggests that, in some fisheries, 30 km of net are lost or discarded during a typical 45-day trip, which translates into 1,254 km of lost or discarded netting per year (Hareide et al., 2005). It is also important to note that gear types and materials are constantly evolving; in considering measures to prevent and reduce DFG and its impacts, it is crucial to consider new fishing technologies and how these technologies may affect fishing behaviors. Most active fisheries are continually searching for materials more suited to fishing needs. For example, trawlers are currently exploring the use of aramid fiber–based netting, which is extremely strong, lightweight, and abrasion resistant. These new fibers sink and are less likely to tear apart when snagged or heavily loaded during fishing. This may be a positive development with respect to gear loss, but the degree to which improved materials leads to higher levels of (gear loss) risk taking by fishermen is not known. Typically, improvements in any fishing technology and techniques are aimed at catching more fish at less cost and those that may coincidentally reduce the probability of gear loss may also affect fishing behavior so as to cancel those benefits (Coe, 1990). DFG has been recognized as a particularly hazardous form of marine debris since the earliest reports on effects of persistent waste materials in the environment. Records of the entanglement of threatened and endangered species, such as sea turtles, fur seals, Hawaiian monk seals, some large whales, and many seabird species date back to the 1970s (Gochfeld, 1973; Bourne, 1976, 1977; Balazs, 1978). Ghost fishing has been confirmed to occur with many static types of fishing gear (e.g., gillnets, traps, baited hooks), with potentially significant impacts on commercial stocks in some fisheries (Breen, 1987; Stevens et al., 2000; Sancho et al., 2003; Matsuoka et al., 2005; Brown and Macfayden, 2007). Other forms of DFG also have the potential to entangle marine organisms, disable vessels, cause physical damage to habitat, and contribute to the marine debris problem. The word “fishing” encompasses a broad range of activities pursued with a variety of equipment; therefore, solutions to prevent and reduce
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Tackling Marine Debris in the 21st Century DFG must be tailored to the different types of gear, their impacts, and the primary causes of loss. This section describes the primary types of fishing gear that can become derelict and includes a brief summary of the impacts and causes for loss by gear type.1 Trawl Nets Trawl nets (trawls) are expensive funnel-shaped nets towed by one, or sometimes two, vessels through aggregations of fish. Trawls can be designed to fish anywhere in the water column, from contact with the seafloor to the middle or upper portions of the water column. Fish that are herded into the mouth of the net are eventually concentrated in the end of the funnel, or cod end, and winched aboard the vessel. Trawl designs vary depending on the target species, vessel size, and regulatory limitations. Originally, trawl webbing was made from hemp treated with various preservatives, but these were replaced with nylon and then polypropylene and polyethylene in the 1950s and 1960s (Uchida, 1985) and more recently by next-generation polyethylene fibers such as Spectra® and Dyneema® and aramid fibers such as Kevlar® (Michael Stone, personal communication). Most of these materials float, which accounts for the fact that derelict trawl webbing and cod ends from trawl nets are found worldwide and notably in concentrations on shores up to thousands of miles from their putative origins (Merrell, 1980; Henderson et al., 1987; Donohue et al., 2001; Kiessling, 2003; White et al., 2004). Even though sections of trawl webbing may be buoyant, steel cables, doors, beams, and other materials used to maintain the vertical and horizontal profiles of the trawl may be weighted and the trawl as a whole is negatively buoyant. The increased strength of synthetic webbing reduces hydrodynamic drag and enables vessels to pull larger nets at higher speeds and greater depths. Historically, the loss of trawl gear was attributed mainly to snagging and tears while fishing near or on the bottom. In U.S. domestic trawl fisheries, fishermen have stated that this type of net loss is less common (Bob King, personal communication; Michael Stone, personal communication). Part or all of these nets can be lost in a snagging incident, and the repair process may generate waste webbing and lines that may be discarded or lost overboard. Trawl webbing has been identified in the entanglement of seals and sea lions (see Appendix C, Table V). It is widely distributed on coasts from tropical to Arctic and Antarctic regions of the world (Merrell, 1985; Uchida, 1985; Ryan, 1990; Ribic et al., 1992; Boland and Donohue, 2003). Trawl webbing has also been identified as particularly destructive 1 Additional information on fishing gear technology can be found through the Food and Agriculture Organization of the United Nations (2008a).
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Tackling Marine Debris in the 21st Century to fragile coral reef systems in the NWHI and similar habitats in Australia (Donohue et al., 2001; Kiessling, 2003; White et al., 2004). Gillnets Gillnets are vertical walls of mesh, sized such that target species in the desired size range are effectively caught about their girth after the head and gill covers (fish) have passed through the mesh. Gillnets are cheap to manufacture and are used worldwide in fisheries that vary from artisanal to industrial in scale. They are efficient size selectors for the target species, but they are also effective at ensnaring nontarget species, especially those that have heads small enough to pass through the mesh or that have prominent spines and angular carapaces (Carr et al., 1985; High, 1985; Breen, 1990). To maintain their shape, gillnets usually include a buoyant top (cork) line and a weighted bottom (lead) line, and they can be suspended at or near the surface, in midwater, or anchored (set) to the bottom. Early gillnets were made from natural fibers such as cotton. Current gillnets are woven from mono- and multifilament nylon, Dacron® twine, and Spectra®. Gillnets can vary in size from as small as a few square meters up to systems of nets as long as 60 km by 20 m deep, with mesh sizes varying from as small as 2 cm to as large as 50 cm. Primarily because of concerns over bycatch and ghost fishing, management interest in controlling these fisheries and their gear loss rates has been high (e.g., coastal state bans, high seas bans). Despite the United Nations ban on large-scale high seas drift gillnets and similar multilateral treaties, drift gillnets continue to be used (Brainard et al., 2000; Food and Agriculture Organization of the United Nations, 2008b). Gillnets in coastal waters are most often lost due to snagging or when attempts to retrieve them cause tears. Sections of gillnet are often lost or cut away when they become entangled as vessels jockey for position in derby fisheries such as the Bristol Bay sockeye fishery. Floating or drift gillnets are lost when marker buoys are lost in foul weather or are entangled or carried away by vessels that transit through them, or when the weight of their catch causes them to sink. In addition, an unintended consequence of prohibitions on the use of high seas drift gillnets is that vessels that deploy drift gillnets will abandon them at sea in an effort to evade enforcement vessels (National Oceanic and Atmospheric Administration, 2008a). Derelict gillnets are found worldwide on beaches, reefs, and adrift at sea. Ghost gillnets entangle fish, cephalopods, crustaceans, birds, turtles, marine mammals, vessels, and unwary humans (divers). The ghost fishing potential of gillnets varies considerably, depending primarily on the rigidity or permanence of the supporting mechanism(s). For example,
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Tackling Marine Debris in the 21st Century pelagic drift gillnets typically hang between a cork line and a lead line and are set more or less in a line without fixed endpoints. Thus, they are subject to significant deformation by waves and currents. These nets have been shown to collapse over periods of days (Gerrodette et al., 1985), greatly reducing their long-term ghost fishing potential. Set gillnets, by virtue of their fixed, anchored framing, may remain fully deployed and fishing long after they are lost or abandoned (Carr et al., 1985). Ghost gillnets in the shallow temperate waters of Puget Sound and in the Columbia River have been observed to self bait such that predators and scavengers attracted to entangled animals are themselves entangled, thereby perpetuating the cycle of destruction (Kappenman and Parker, 2007; Natural Resources Consultants, Inc., 2007). For example, a derelict net off Lopez Island in Puget Sound that had been in place for 15 years is estimated to have caught over 16,500 invertebrates, 2,340 fish, and 1,260 seabirds (Natural Resources Consultants, Inc., 2008). Additionally, one derelict gillnet, whose location was known for several years before a joint NOAA/ U.S. Coast Guard (USCG)-led multiagency effort was able to recover it in 1999, weighed over 2,000 kg (Donohue et al., 2001). As nets become fouled, they become more visible and lose their vertical profile, and their fishing capacity declines. Traps, Cages, and Pots Traps and pots are cages with wire, webbing, or other mesh, on a rigid or collapsible frame made of metal, wood, and other materials. They can range in size from small and light to quite large and heavy. Trap fisheries for crustaceans and finfish are carried out in relatively shallow, productive coastal and shelf areas worldwide. Fishing traps are typically weighted to sink and stay on the bottom with an attached marker float to allow relocation and hauling back to the surface. Traps can be fished singly or connected together in strings. Traps are fitted with entry doors designed to prevent escape of the catch once inside. They are usually baited to attract the target species and retrieved and rebaited on a schedule suited to the catch rates, weather, and regulations of specific fisheries. Trap fisheries have also benefited from the replacement of natural fiber webbing and lines with more durable synthetic materials. Trap loss has many causes, but includes weather-related movement and damage and loss due to conflicts with other user groups. Fishing vessels snag and move trap gear, floats are snagged on passing vessels or in towed fishing gear, competitors are reported to vandalize each other’s gear in some fisheries (Acheson, 1977), and fishery closures and economic circumstances prevent or inhibit gear retrieval. Several trap fisheries in the United States are reported to have left tens or even hundreds of thou-
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Tackling Marine Debris in the 21st Century sands of derelict traps in their fishing areas (Stevens et al., 2000; Guillory et al., 2001). In the Gulf of Mexico’s spiny lobster and stone crab fisheries, traps are lost continually through the fishing season at a rate of 1–2 percent each month or 20–50 percent annually (Thomas Matthews, personal communication). Traps catch legal and undersized target species as well as many other species that are attracted to the bait and are small enough to pass through the trap doors (Smolowitz, 1978; High, 1985; Breen, 1990). Traps often include holes sized to permit the escape of undersized target and nontarget species; bycatch unable to escape is typically released each time the trap is retrieved, but the loss of a trap means that animals that are unable to escape from the trap will starve or be preyed upon by their fellow captives. This catching and self-baiting cycle can continue for days to years until the trap is disabled, usually by being buried in sediments, general disintegration and biofouling, disintegration of degradable escape panels, if required and present, or by retrieval. Although most U.S. trap, cage, and pot fisheries require that they be equipped with rot cord (i.e., sections of twine that compromise the integrity of the pot once they biodegrade), Stevens et al. (2000) reports that one such equipped ghost pot alone held 125 crabs. An alternative to rot cord, galvanic releases—often used in pop-up oceanographic devices—offer greater consistency in the time to failure but have not yet won widespread application as release devices for fishing traps. The loss of commercial species in derelict traps can be substantial. For example, derelict traps are estimated to account for about 7 percent of total mortality in the Dungeness crab fishery off the Fraser River delta in British Columbia (Breen, 1987). Matsuoka et al. (2005) shows that the take of octopus by derelict traps in a bay in Japan was equal to or twice that landed annually by the commercial fishery. Depending on the time of year, trap type, and location, annual ghost fishing mortality in the blue crab fishery ranges from 7.7 to 60 crabs per trap (Guillory et al., 2001). Marine mammals—in particular right whales, humpback whales, and dolphins—and sea turtles have been observed entangled in traps or buoy lines or groundlines (i.e., the line between traps) (National Oceanic and Atmospheric Administration, 2007a). While these entanglements are most likely to occur in active gear rather than in derelict gear, the extent to which derelict gear poses a threat to these marine mammals is unknown and indeed these entanglements are one vector for turning active gear into DFG. Hook-and-Line A wide variety of hook-and-line fisheries operates worldwide, including commercial longline, troll, jig, and dinglebar fishing, and recreational
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Tackling Marine Debris in the 21st Century fishing using rod-and-reel or hand lines. These fisheries contribute to the DFG problem through the loss and discard of primarily monofilament fishing lines, although many other synthetic materials are used in braided fishing lines that may be equally persistent when derelict (e.g., Dacron®, Spectra®, and aramid polymers such as Kevlar®). Loss of these lines is commonly caused by snagging and breakage during retrieval attempts, and by discard of snarled and damaged line. Longlines may be fished as drift or set (anchored) gear and can be lost due to weather, currents, damage by conflicting fishing activities (e.g., trawling) and other vessel traffic, as well as by vessel and equipment failures. Intense derby fisheries may result in longlines being set across each other, rendering the whole irretrievable (National Research Council, 1999). The impact of derelict fishing lines is most obvious and dramatic when it entangles sea turtles, sea birds, and marine mammals; however, virtually all marine animals are susceptible to this entanglement (e.g., Shomura and Godfrey, 1990). Fishing line entanglement ordinarily results in traumatic amputation; strangulation; or other disablement leading to infection, starvation, heightened risk of predation, or death for the victim. Coral damage and death from entanglement in derelict monofilament fishing line (and associated sinkers and steel hooks) has been documented in South Africa (Schleyer and Tomalin, 2000), in the Mediterranean in northeastern Italy (Bavestrello et al., 1997), and in Hawaii (Asoh et al., 2004; Yoshikawa and Asoh, 2004). Other Gear Types Other major types of fishing gear include purse seines, shellfish dredges, FADs, shore-based fish traps and weirs, and net pens, cages, mesh bags, and lines used for aquaculture (coastal and offshore). These activities lose gear but, with the possible exception of FADs in the tropical tuna fisheries (see below), they are not yet documented as contributing to the overall impacts of DFG in the same magnitude as trawls, gillnets, traps, and line fisheries. Likewise, trammel nets, which are replacing gillnets in some fisheries, and lobster nets, which are replacing traps especially in coral reef habitats, while not yet documented, may also contribute to DFG. The growth of coastal and offshore aquaculture in Asia, Latin America, and Europe suggests that materials used in aquaculture are likely to become a more prominent component of DFG. Legal and Regulatory Issues There is some confusion among international and U.S. agencies over who is supposed to prevent, by regulation or otherwise, the generation
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Tackling Marine Debris in the 21st Century of marine debris by fisheries, especially DFG because it is both a marine debris and a fishery management problem. The various international and domestic laws and regulations that govern activities that generate DFG and other marine debris from fisheries are summarized here. While it is generally recognized that fishing is one of the freedoms of the seas, the discharge of unwanted fishing gear or the careless loss of useful or waste gear is not. Under the United Nations Convention on the Law of the Sea, “all states have the right of their nationals to engage in fishing on the high seas subject to their treaty obligations … [and to] the rights … and the interests of coastal states” (Article 116). Treaty obligations that are relevant to the DFG problem and its impacts on marine life include the environmental protection provisions of the Law of the Sea Convention (summarized in Chapter 3), the United Nations Fish Stocks Agreement of 1995, regional international fisheries agreements, and the provisions of MARPOL and its annexes. The conservation qualification of the high seas right of fishing is detailed in the United Nations Fish Stocks Agreement of 1995, which states that nations that fish for straddling and highly migratory fish species (which include tunas) have “a duty to adopt measures to minimize … catch by lost or abandoned gear” of both target and nontarget species through the development of environmentally safe fishing gear and techniques (Article 5[f]). Nations that are parties to both MARPOL Annex V and one or more international fishing agreements are summarized in Appendix D. Under international law, both coastal states and flag states (nations that register fishing vessels) bear responsibility to prevent marine debris, including DFG, by providing adequate reception facilities at fishing ports and enforcing regulations requiring proper disposal of waste fishing gear. MARPOL Annex V MARPOL Annex V addresses waste fishing gear in its ban on the discharge of plastics in all areas of the sea. Regulation 3 prohibits the disposal of “all plastics, including but not limited to synthetic ropes, synthetic fishing nets, [and] plastic garbage bags” (International Maritime Organization, 2006c), and a similar ban applies to special areas (Regulation 5). Regulation 6, however, exempts these discharges from the prohibition if they involve an “accidental loss of synthetic fishing nets, provided that all reasonable precautions have been taken to prevent such loss” (International Maritime Organization, 2006c). Therefore, it is not a violation if plastic or other synthetic fishing gear falls overboard due to damage to the fishing vessel or its equipment, provided that all reasonable precautions were taken to prevent such loss, or if the gear is intentionally put overboard in order to secure the safety of the vessel, its crew, or lives at sea.
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Tackling Marine Debris in the 21st Century FIGURE 4.3 The western and central Pacific Ocean, the eastern Pacific Ocean, and the Western and Central Pacific Fisheries Commission Convention Area (reprinted with permission from the Western and Central Pacific Fisheries Commission). ing on drifting FAD sets (69 percent in 2006 according to available log-sheet data) (Williams and Reid, 2006). Overall, information on how many FADs are deployed and the rate of FAD loss, appropriation, and recovery is unknown for the WCPFC fleet. While WCPFC does not have any regulations specific to the use of FADs, the Convention on the Conservation and Management of Highly Migratory Fish Stocks in the Western and Central Pacific Ocean contains language that specifically requires measures to minimize “catch by lost or abandoned gear” and could also be applied to derelict FADs: adopt measures to minimize waste; discards; catch by lost or abandoned gear; pollution originating from fishing vessels; catch of non-target species, both fish and non-fish species;…and impacts on associated or dependent species, in particular endangered species and promote the development and use of selective, environmentally safe, and cost-effective fishing gear and techniques (Article 5(e)).
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Tackling Marine Debris in the 21st Century International Commission for the Conservation of Atlantic Tunas A study published by Ménard et al. (2000) estimates that the total number of FADs with radio or satellite buoys used by the 45 purse seiners landing in Abidjan (Côte d’Ivoire) in 1998 might exceed 3,000. The FAD seeding area ranges from 0 to 20ºW and generally does not exceed 2ºS as a southern limit, corresponding to the westward South Equatorial Current (Ménard et al., 2000). Within the International Commission for the Conservation of Atlantic Tunas (ICCAT), information is completely lacking on the number of FADs deployed, the number of sets on any given FAD, and the number of FADs retrieved, lost, or appropriated each year. Within ICCAT, control of FADs rests with two provisions. First, ICCAT requires that all fishing vessels and fishing gear have identifiable markings in accordance with generally accepted standards (International Commission for the Conservation of Atlantic Tunas, 2003). The second is a moratorium on FAD fishing in given areas, which was intended to reduce fishing mortality on bigeye tuna, particularly juvenile bigeye, but may have a collateral benefit in reducing the number of FADs (and therefore the number that could become debris). The “Agreement of the Community Producers of Frozen Tuna for the Protection of Tunas in the Atlantic Ocean” established a voluntary regulation prohibiting anchoring or fishing under floating objects in a wide area of the Atlantic Ocean, between the African coast and 20ºW and 5ºN and 4ºS, from November 1997 to January 1998. The agreement was continued during the same months of 1998 and 1999 (International Commission for the Conservation of Atlantic Tunas, 2001). In 2004, the Commission adopted a substitute time–area closure, which entered into force in mid-2005 (International Commission for the Conservation of Atlantic Tunas, 2004). This measure closes fishing by purse seiners and bait boats during the month of November inside the “Piccolo” area, a small subregion (less than 25 percent) of the original moratorium area. The Piccolo area is defined as 10º–20ºW and 0º–5ºN (Figure 4.4). Indian Ocean Tuna Commission Since the 1990s, FAD usage by European Union purse seine fleets has increased significantly in the Indian Ocean (Morón et al., 2001), particularly in the Somalia gyre and around the Seychelles plateau, where FADs are the dominant fishing mode (Itano, 2007b). Here, drifting FADs lack surface rafts or floatation, aside from some purse seine corks and the radio or satellite buoy, and are instead carefully ballasted plastic oil drums suspended below the surface with nylon netting hanging beneath the drums. This style of FAD is popular as it reduces
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Tackling Marine Debris in the 21st Century FIGURE 4.4 Area of the current FAD moratorium (hatched area) and the proposed time–area closure (i.e., “Piccolo”) (International Commission for the Conservation of Atlantic Tunas, 2001; reprinted with permission from the International Commission for the Conservation of Atlantic Tunas). the surface visibility of the FAD and therefore its rate of appropriation by other vessels. The Spanish purse seine fleet operating in the western Indian Ocean is assisted by supply (or tender) vessels; these vessels, in addition to other duties, may search for FADs and logs, build or repair FADs, assess tuna abundance on other floating objects it encounters, and appropriate productive FADs belonging to other vessels (Arrizabalaga et al., 2001). Tender vessels clearly improve the ability of fishing associations to utilize FADs. Consequently, the added efficiency has led to the banning of their use in the Pacific and the Atlantic tuna fisheries; therefore, the Indian Ocean Tuna Commission (IOTC) is the only fleet with tender vessels that service FADs (Itano, 2007a). Skipper surveys from French and Spanish purse seine vessels operating in the western Indian Ocean estimated the total number of actively monitored FADs at approximately 2,100 at any given time (Moreno et al., 2007). IOTC views this number as a highly dynamic estimate, as FADs can sink or be appropriated by other purse seiners and have a lifetime between a few days to several months. In order for IOTC to better under-
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Tackling Marine Debris in the 21st Century stand the fishing effort within the Indian Ocean, more information is needed on the activities of supply vessels and the use of FADs. Therefore, IOTC is now requesting that its members provide the number and characteristics of supply vessels operating under or assisting purse seine vessels operating under each nation’s flag, or licensed to operate in a nation’s exclusive economic zones; the level of activity of supply vessels, including number of days at sea by 1º grid area and on a monthly basis; and data on the total number and type of FADs operated by a nation’s fleet by 5º grid area and on a monthly basis (Indian Ocean Tuna Commission, 2007). Despite this requirement, within the IOTC fleet, information is completely lacking on the number of FADs deployed or carried by each vessel; the number of sets on any given FAD; and the number of FADs retrieved, appropriated, or lost each year. Given the information collected on FAD use in the Pacific, Atlantic, and Indian Oceans, it is clear that FADs could contribute a substantial amount of marine debris. However, much more information is needed to fully understand the extent of this problem. Other Impacts While the committee’s charge was to evaluate the role of drifting FADs in the generation of marine debris, the concern over FADs is primarily focused on their ecological impact, both on target fisheries species and on pelagic species overall. These broader concerns do not go away after FADs have been lost or otherwise abandoned—FADs as DFG can be expected to exercise an ecological impact on target and nontarget species and on benthic and littoral ecosystems when they sink or wash ashore. Therefore, it is useful to briefly discuss these other impacts of FADs. The widespread use of FADs has shifted the pattern of fishery exploitation of tunas over the past 20 years. In the Atlantic and Indian Oceans, approximately 75 percent of skipjack tuna (Katsuwonus pelamis), 35 percent of yellowfin tuna (Thunnus albacares), and 85 percent of bigeye tuna (T. obesus) catches reported by purse seine fisheries are made in the vicinity of FADs (Fonteneau et al., 2000). In all oceans, the majority of yellowfin and bigeye tuna caught in association with FADs are juveniles. Therefore, fishing on FADs may alter the age structure of some pelagic tuna populations by removing juveniles over mature adults (Gates and Gysel, 1978; Fonteneau et al., 2000; Schlaepfer et al., 2002; Hallier and Gaertner, 2008).
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Tackling Marine Debris in the 21st Century Some scientists are concerned that FADs may function as an ecological trap: a situation where population growth is reduced as a result of individuals choosing a maladaptive habitat (Gates and Gysel, 1978; Schlaepfer et al., 2002). It is hypothesized that this situation could arise if individuals are misled by environmental cues that lead them to settle in habitats that are substandard for reproduction and survival (Battin, 2004; Robertson and Hutto, 2006). Association with FADs may alter the natural movements of fractions of tuna stocks and thereby artificially increase the natural mortality rate or reduce the intrinsic growth rate, reducing the productivity of tuna populations (Hallier and Gaertner, 2008). For example, studies in the Atlantic and Indian Oceans indicate that tuna associated with drifting FADs were less healthy, have slower growth rates, and are in poorer condition than those in free schools (Hallier and Gaertner, 2008). Also, tuna associated with FADs have significant changes in migratory direction and displacement rates relative to tuna in free schools (Hallier and Gaertner, 2008). Studies in recent years, especially within the ETP tuna fishery, indicate that FAD fishing bycatch (i.e., discards of small tuna and nontarget species) can be up to 50 percent of the total catch (Inter-American Tropical Tuna Commission, 2007b). One study reported that almost 20 percent of the tuna caught under FADs are discarded because they are below the market minimum requirement for size or condition (Inter-American Tropical Tuna Commission, 2007b). Bycatch of small tuna and other species contributes to discarded, unreported, or underreported catch and may represent a significant source of undocumented fishing mortality. In addition to undersized tuna, FAD-associated bycatch includes large pelagic fishes (e.g., mahi-mahi, rainbow runner, yellowtail) and undersized billfishes (Fam. Istiophoridae), anchovies (Fam. Engraulidae), herrings and sardines (Fam. Clupeidae), and grunts (Fam. Haemulidae). Entanglement of sea turtles in drifting FADs has been noted as an area of special concern by scientists and the purse seine industry (Delgado de Molina et al., 2006). Likewise, the bycatch of several species of sharks in association with FADs is an increasing concern due to declines in their populations (Hall, 1994). Improving the Understanding and Management of Fish Aggregating Devices To date, very little is known about the total number of FADs in the world’s oceans, the number of vessels that fish on or use FADs, the number of FADs deployed by fishing vessels, whether and with what frequency FADs are recovered, the frequency with which individual FADs are set upon, the total number of sets on FADs, and the expropriation and loss
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Tackling Marine Debris in the 21st Century rate of FADs. RFMOs have a role in collecting and a need for improved data on FADs to achieve their goals of sustainable international fisheries with minimal environmental impact. Currently, at-sea observer programs are the best means to collect specific data on FADs and their use. However, tracking and identifying drifting FADs can be difficult, with FADs taken onboard, modified, and in some cases appropriated from other vessels and provided with a different radio or satellite buoy. Greater control and documentation of FADs is needed if FAD deployment, usage, and loss are ever to be understood. The IATTC observer program has the most complete record of FAD use through its Flotsam Information Record (FIR) program (Figure 4.5). FIR contains the key points to consider when describing and tracking floating objects. The form includes parameters such as time and location, description and dimension of the FAD and its components (including vertical appendages and associated electronics), how the FAD was located, and information on the origin or ownership of the FAD. FIR also describes whether the FAD is left in the water and any significant alterations or enhancements that may have been made. The FIR program could serve as a model system for collecting data on FADs for other regional fishery management organizations. Similarly, RFMOs have a role in improving regulations and management of FADs. In December 2007, WCPFC considered, but has yet to implement, the most comprehensive resolution on FAD use. The resolution would prohibit FAD fishing between either July through September or October through December in the EEZs and the areas beyond national jurisdiction within the area bounded by 20ºN and 20ºS. The resolution has an exemption for purse seiners home ported in the Philippines and operating on the high seas off the coast of the Philippines, which are entirely dependent on FAD sets, but requires the Philippines to implement its national tuna plan, which limits the number of FADs to 25 FADs per purse seine vessel and to provide the national tuna plan for review and endorsement in 2008 by WCPFC. Even more notable was the requirement that parties submit to WCPFC management plans for the use of FADs within their jurisdictional waters and by their vessels on the high seas containing the following elements: limits on the number of licensed FADs; design, operation, and maintenance of FADs; application process for deployment of FADs; location of FADs and reporting; marking of FADs; location in relation to navigational routes and shipping; closed areas;
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Tackling Marine Debris in the 21st Century FIGURE 4.5 IATTC Flotsam Information Record (FIR) card (reprinted with permission from the Inter-American Tropical Tuna Commission).
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Tackling Marine Debris in the 21st Century
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Tackling Marine Debris in the 21st Century deployment of FADs in archipelagic waters; effect of FAD fishing by purse seine vessels on tuna longline fishing; monitoring of the FAD fishery; effect of FAD fishing on sizes of tuna taken; effect of FAD fishing on bycatch species; reporting requirements for FAD fishing; reporting of species mix in FAD fishing; reporting of bycatch in FAD fishing; reporting of utilization of bycatch; conflict resolution in relation to FADs; license status of vessels in relation to areas of FAD deployment; replacing of lost FADs; access to FAD areas; confidentiality of FAD position information; and number of tender vessels per catcher vessel. Implementation of this resolution would be an important step toward greater control and understanding of FADs. Information collected from FAD management plans could be used to more effectively evaluate the role of FADs in the generation of marine debris. In 1999, IATTC considered (but failed to adopt) the following measures to reduce bycatch and adverse impacts of FADs on the tuna resource: limits on the depth of FADs; limits on the number of sets on FADs and floating objects; limits on the number of FADs that a vessel can carry; analysis of the effects of the use of bait with FADs; seasonal or area bans or closures on the use of FADs; and modification of the FAD design (Inter-American Tropical Tuna Commission, 1999). These measures, if adopted by IATTC, could provide a framework for greater control over FAD fishing in ETP. Finding: Currently, there is very little control or data on FADs in international fisheries. Recommendation: The United States should take a leadership role by requiring that its own purse seine fleet submit a FAD management plan incorporating the plan elements proposed by WCPFC;
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Tackling Marine Debris in the 21st Century encouraging RFMOs to adopt requirements for FAD management plans; and using port state jurisdiction in its territories to limit access to vessels flying the flag of countries that fail to require their vessels have a FAD management plan. Recommendation: RFMOs should adopt measures and manage FADs in such a way that the ownership of those FADs is clear. RFMOs should control the number of FADs through chips, marking, tags, or other means to limit the number of FADs that can be carried and deployed by a vessel; acquire more information to characterize FAD usage in each of the agreement areas; adopt resolutions requiring parties to provide information on FAD use by vessel, including the number of sets on FADs, the number of FADs carried and deployed, and FAD retrieval, loss, and appropriation rates; and establish mechanisms to gather information on FADs including reports from parties, vessel logbooks, and observer programs. At a minimum, RFMOs need to collect and report annual data on the number of FADs deployed, the number returned to shore, the number lost, and an annual estimate of the number currently being fished. Finding: Replacement of plastic components and synthetic ropes and webbing used to construct FADs with readily degradable materials such as natural fibers would lessen the adverse impacts of FADs that become marine debris. Recommendation: RFMOs should support the development of FAD designs that do not incorporate persistent synthetic or scrap materials but instead include materials that will self-destruct, readily biodegrade, mitigate entanglement, and provide an incentive for FADs to be maintained and regularly retrieved. RFMOs should also prevent the use of synthetic and scrap material in FADs through regulation. CONCLUSION The following finding and recommendation express overarching concepts discussed in the previous findings and recommendations in Chapter 4.
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Tackling Marine Debris in the 21st Century Overarching Finding: DFG and abandoned or lost FADs fall under both MARPOL Annex V (and corresponding domestic laws) and fisheries management treaties and regulations. This overlap has complicated implementation of measures to prevent and reduce these sources of debris. Current regulations do not include accountability measures for gear loss, and fishermen and fisheries management organizations have few incentives and several disincentives to take responsibility for the impacts and for cleanup. Inadequate port facilities and high disposal costs are an impediment to disposal of waste and DFG. Overarching Recommendation: MARPOL Annex V (and corresponding domestic law) and international and domestic fisheries treaties and regulations should be revised to clearly identify and prohibit preventable losses of fishing gear, including FADs. IMO, FMCs and fishery management organizations, and other relevant entities should incorporate gear accountability measures and facilitate proper disposal of fishing gear, including FADs.