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Home , Fishing bait, Fishing techniques, Surrounding net, Turtle excluder device

PAPER Techniques to Reduce the of Threatened Marine Animals

AUTHORS ABSTRACT Timothy Werner Unintended injuries and fatalities to non-target marine species—a major component of Scott Kraus “bycatch”—is one of the principal threats to the survival of many endangered marine New populations and species. This paper describes both proposed and existing fishing tech- Andrew Read niques for reducing non-target species bycatch, and reviews their focus across different Duke University and wildlife groups. The intent of this inventory was to gain a better understanding of the range of techniques available and to highlight priorities for research and develop- Erika Zollett ment. In all, 55 techniques were identified, with the majority directed at reducing bycatch in University of New Hampshire longline fisheries, and intended to benefit primarily seabirds, sea , and small mam- mals. Bycatch reduction is a dynamic field with many examples of effective techniques, though some underserved fisheries and wildlife groups should receive more attention. Introduction illions of dollars are spent each year Methodology some techniques mainly used in in the research and development of fishing We attempted to document all available operations became part of the final list. Mtechniques to reduce unintended injuries and information on that have Generally, in categorizing bycatch reduc- fatalities to non-target marine species that forms been used to reduce non-target wildlife spe- tion approaches the tendency was to be inclu- a major component of “bycatch.” The vast cies bycatch in world fisheries. Information sive. For example, Excluder Devices and majority of this investment in conservation on bycatch reduction methods is highly dif- Sea Lion Excluder Devices were combined as occurs in economically developed countries fuse and for this review we consulted various one approach, under “excluders”, because they (principally the United States, Canada, Aus- sources including journal articles, unpublished fundamentally work the same way. tralia, and Europe) although the problem is government reports, and experts in the field. Both existing and proposed bycatch miti- global in scale. Taken as a whole, bycatch is A number of reviews have examined bycatch gation techniques were considered, and orga- one of the major threats to the survival of many reduction for particular fisheries (e.g., nized according to whether they represented endangered marine populations and species. Broadhurst, 2000; Hall, 1995) or for wildlife an approach (1) intended to avert contact with This paper describes both proposed and groups within particular fisheries (e.g., Gilman a fishing operation and gear altogether, (2) existing fishing techniques for reducing non- et al., 2005), but the scope of this study is all intended to facilitate escape from temporary target species bycatch, and reviews their focus methods and multiple capture, or (3) that required release post-cap- across different fisheries and wildlife groups. wildlife groups. The decision to pursue a more ture. For each technique we identified the - The intent of this inventory was to gain a comprehensive treatment was motivated by ing method (gillnet, , trap/ better understanding of the range of tech- an interest in identifying bycatch reduction pot, trawl, dredge, and hook-and-line) in niques available and to highlight priorities for approaches that might find application in more which it was or could be used, and identified research and development. than one fishing method, and to better appre- studies undertaken to evaluate its efficacy for The bycatch reduction methods summa- ciate the potential impacts on species or wild- various wildlife groups. The studies compiled rized in this paper are all intended to accom- life groups apart from the one targeted. consisted mainly of ones that directly reported modate continued fishing of target species. Excluded from consideration were recre- on a scientific field trial as opposed to papers Other strategies that can lead to lowered ational fishing, target species bycatch (i.e., ju- summarizing general findings or synthesizing bycatch levels include fishing area closures, venile fish), and strategies for mitigating the responses from fishers. Occasionally, however, temporal closures, reductions in fishing effort, consequences of ghost fishing, a serious and reports of lab studies or third-party papers and cessation of fishing altogether. In some widespread form of bycatch in which fishing reporting on original field research were in- cases, applying one or more of these other gear can continue to catch and kill animals cluded. Wildlife group classifications were se- measures may represent a better strategy for after it has been lost, discarded, or abandoned lected somewhat arbitrarily and represent solving a particular bycatch challenge than by fishers. Depredation, or the predation of broad categories (sea birds, for example) in altering fishing methods, though they often or catch by non-target species, order to keep this review at a manageable scale. face resistance from the . was considered in this review. This meant that Certainly the number of categories could be

50 Marine Technology Society Journal expanded to include different groups (most Passive acoustic deterrents as sea lions away from a fishing operation. notably non-pelagic fin fish) as well as subsets Objects such as rubber tubes, thick poly- Deterrence may result from noise or tactile of the headings already represented. Never- ester rope, and chains attached to fishing nets annoyance. Anecdotal evidence from some theless, using broad categories of wildlife to alert a marine cetacean to their presence fishermen suggests this practice is widespread groups enables a cursory analysis of the taxo- using echolocation. though its efficacy is not backed up by a num- nomic emphasis in bycatch reduction research ber of studies, and it obviously threatens ani- and implementation of its methods. Vessel noise reductions mal survival. Structural or operational changes to fishing vessels that would decrease the intensity or sig- Quick-release metal wire Description of Techniques nature of their sound output, potentially de- A metal wire attached to an outrigger clip Fifty-five modifications to fishing gear or creasing the degree to which they attract ani- on a troll line. The quick-release mechanism of methods were identified for reducing non- mals that presumably associate these vessels with the outrigger clip causes the wire to travel down target species bycatch. Below is a brief de- a feeding opportunity. At least one study in the the bait line when a fish is captured. The metal scription of each. Those in italics indicate meth- Pacific indicated that the noise from longline wire may deter dolphin depredation (Zollett ods either not yet developed or widely used haulers attracted false killer whales from long and Read, 2006). by the fishing industry that may be undergo- distances (J. Watson, pers. comm.). ing experimental evaluation. Glow rope Animal predation sounds Rope consisting of polypropylene blended Acoustic pingers/alarms Audio recordings of an animal in distress, or with a phosphor that glows a bright yellow-green Underwater sound-emitting devices (maxi- of its predator, played to deter individuals of underwater in wavelengths large cetaceans can mum level of intensity equivalent to approxi- that species from entering into a fishing area. see. It glows for 48 hours after activation at an mately 175 dB re 1 µPa @ 1m) attached to Jefferson and Curry (1996) concluded that this intensity a human can see readily at 20 yards (18 fishing gear, principally gillnets. [Under NOAA’s technique was largely ineffective for reducing m). The design is based on the premise that with Harbor Porpoise Take Reduction Plan for the marine mammal interactions with fishing activ- increased visibility cetaceans and perhaps turtles Gulf of Maine, the sound output intensity for ity based on their review of multiple studies. would be more likely to avoid rope entangle- pingers is stipulated as 10 (±2) kHz at 132 (± ments at night or at depth. Current research is 4) dB re 1 µPa @ 1m (NMFS/NOAA, 1998)]. Metal oxide nets looking at how to maintain the glowing proper- Pingers are now mandated for use in some fish- Nylon nets infused with barium sulfate or ties under the rigors of mechanized hauling. eries in the U.S. Northwest Atlantic, California other metal compounds that have acoustical de- driftnet, and in Europe. The sound of these tection features for reducing small cetacean Bird-scaring devices devices is believed to alert an animal to the pres- bycatch. These may reduce small cetacean and A number of devices used to disturb birds ence of the net and thus decrease the probabil- bycatch by increasing the likelihood from foraging on bait. These include stream- ity of entanglement. Although some studies that these animals would “bounce” off the net- ers attached to a pole suspended above the have shown that pingers can have the unin- ting. Experimental results show that they can be area where bait is set or placed in the water, tended consequence of attracting pinnipeds to effective in reducing the bycatch of harbor por- towed buoys, and water jets. fishing operations (Bordino et al., 2002), this poise and greater shearwater (Trippel et al., 2003), may be controllable by raising the emitted fre- though it has not been ascertained if this is be- Dyed bait quency of the pingers above seal hearing (Kraus cause of their acoustic reflectivity, increased stiff- Bait dyed blue to reduce its visibility to et al., 1997). ness, or greater visibility over conventional gillnets. non-target species such as seabirds hovering around longlines as baited hooks are deployed. Acoustic harassment devices (AHDs) Echolocation disruptors Devices that emit sounds of such high Sounds produced to disrupt the normal White mesh on gillnets intensity that they cause pain or alarm in echolocation abilities of cetaceans. Preliminary White mesh panels on the upper part of a certain underwater species. The minimum research in Europe has shown some promise gillnet to make it more visible to diving sea- sound level is approximately 200 dB re 1 that these devices reduce depredation by bottle- birds. The mesh probably also increases net vis- µPa @ 1m. References for AHDs primarily nose dolphins in gillnets and trammel nets, ibility to other animals such as cetaceans, pinni- dealt with aquaculture operations. These de- although habituation may be a challenge peds, and sirenians though the effect would be vices may exclude some animals from impor- (S. Northridge, pers. comm.). reduced in water with poor visibility. tant habitat (Olesiuk et al., 2002), and pose a risk of impairing an animal’s hearing. These Pyrotechnics Flashing lightsticks drawbacks render this approach potentially The use of loud explosive devices, includ- Battery-operated lights set at different flicker harmful and dangerous. ing gunshots, to scare non-target species such rates intended to attract fish but not sea turtles.

Fall 2006 Volume 40, Number 3 51 Reflective/colored buoys Buoy line messenger system Underwater sets Buoys coated with a material to make them Underwater traps or nets linked to a sur- Methods that reduce bycatch by eliminat- reflect or blend into the natural environment face buoy by a weak line. To haul the gear, a ing gear sets at the surface. These include so that they are a less conspicuous signal to sea messenger device would be sent down the devices such as setting chutes that place sets turtles, which are thought to be attracted to weak line along with a stronger hauling line. below the ocean surface in longline operations buoys used in fishing operations. The messenger device would attach the haul- where they are less prone to seabird predation, ing line to the bottom gear for retrieving the and setting gillnets below the sea surface to Scent deterrents gear. The premise is that a large whale would reduce entanglement rates of small cetaceans. The application of substances that pro- easily break free from a weak line suspended duce odors to deter non-target species from in the , and the stronger line Line shooter entering into a fishing area. needed for hauling could be located out of A device used on longline vessels to in- harm’s way. crease the speed at which baited lines get be- Noxious bait low the water’s surface where seabird preda- Bait that is treated with compounds in- Acoustic releases tion mainly occurs. tended to make it unpalatable to non-target Devices that use an acoustic trigger for re- species. leasing a buoy attached to submerged pots that Raised footropes would then float to the surface for retrieval. An alteration to the lower edge of a trawl Artificial bait This would eliminate vertical (and potentially net in which the “mouth” is raised high enough Bait manufactured from non-natural sub- entangling) lines in the water column. in the water column to prevent it from drag- stances as a substitute to natural bait that may ging across the . Raised footropes are render it less appealing to non-target animals. Bait machines obligatory during certain periods of the year Devices that toss the bait beyond the tur- in bottom in Massachusetts to re- Novel bait species bulence of longline boat propellers that tend duce the bycatch of non-target demersal spe- Changing the type of bait, such as switch- to keep bait buoyant longer where it is more cies such as flounder. ing from to , to deter non-tar- prone to seabird predation. get animals (such as sea turtles) that prefer one Decreased soak time type of bait versus another. Thawed bait Soak time is the length of time that fish- Frozen bait is thawed before it is set in the ing gear is submerged between hauls; reduc- Animal prodding water to increase the rate at which it sinks in ing it appears to change bycatch probabilities. The physical prodding of non-target longline fisheries. (The sinking rate can also species using a pole or other implement to be increased by puncturing the swim bladder Sinking/weighted lines deter them from interacting with a fishing of fish bait). Changing the property of fishing lines so operation. that they are less likely to catch or ensnare ani- Alternative offal discharge mals feeding at the surface or in the mid-water Electromagnetic deterrents Discarding waste away from where bait column. They include low profile line, a kind Electromagnetic fields created in the vi- enters the water to lure non-target species of rope linking pots that might be sus- cinity of a fishing activity to deter interac- (seabirds) away from baited hooks in longline pended deep enough to avoid whale entangle- tion of non-target species with fishing gear, fisheries. ments but with enough floatation to lie above bait, or target species. The main prize of the rocky bottoms that tend to abrade them. 2006 Smart Gear competition run by the Side sets Weighted mainlines may also increase the sink- World Wildlife Fund was for a magnetic The placement of fishing gear over the ing rate of pelagic longline gear, making it less shark deterrent to be tested on pelagic side of a longline vessel rather than the stern. likely to capture surface-feeding seabirds. longlines. Polet et al. (2005) describe evalu- Studies have shown that seabirds avoid going ations of an “electro-trawl” in which electric after baited hooks near the vessel hull, and by Decoy deterrents charges stimulated into moving the time the stern passes the hooks they are Approaches that include setting longlines upward from the sea floor into the path of deeper in the water than they would be in in novel patterns (such as in a sinusoidal shape) the trawl mouth. In this approach, the space stern sets (Brothers and Gilman, 2006). or using “dummy” sets to mask the presence of between the groundrope and the benthos a fishing operation. might be increased without reducing target Night sets catch levels but decreasing the contact the The setting of fishing gear at night so that Vessel chasing (hazing) trawl might have with some non-target seabirds are less likely to see sets. Lights may The use of boats to chase non-target ma- benthic and groundfish. also be dimmed to enhance the effect. rine animals from a fishing area.

52 Marine Technology Society Journal Remote attractor devices through without becoming entangled this is a panel of fine mesh attached to the Devices used for attracting non-target ani- (DeAlteris et al., 2005). part of the purse seine farthest from the mals away from fishing activity where they boat when the net is “pursed.” The mesh is might become captured or entangled in gear. Circle hooks fine enough so that dolphins are unlikely to A circular hook design in which the point of be entangled, and allows dolphins to es- Deep-water sets the hook is perpendicular to the hook shank. cape over the top of the net. These panels Baited hooks in longline fisheries set be- Circle hooks are used widely in many recreational are used in conjunction with a “back down” low 100 meters of water to avoid the principal and commercial fisheries and recently have been procedure in which the purse seine is towed feeding zones of sea turtles and other epipe- shown to reduce both the hooking rate and the backwards, lowering the cork line to facili- lagic species. Increasing the depth at which mortality of turtles that are hooked on pelagic tate the escape of dolphins. pelagic drift nets are set may also reduce bycatch longline gear. As a result of several successful field rates of air-breathing vertebrates. trials (Bolten and Bjorndal, 2005; Watson et al., Alternative net filaments 2005), these hooks are becoming increasingly Varying the diameter of gillnet filaments or Fence or net barriers used in longline fisheries. their weaves (e.g., multi-monofilament) to re- Barriers erected in aquaculture and corral- duce mortality of small cetaceans and other ani- type fishing gear to exclude non-target spe- Break-away lines mals in gillnets by making the nets stronger and cies. Barrier nets can create a separate bycatch Ropes that use weak links or are designed stiffer. Stronger nets may result in larger non- problem based on reports of fatal entangle- to break at strengths substantially lower than target animals being less prone to entanglement. ments that have occurred with California sea usual for hauling ropes. The intent is for ropes lions and humpback whales (Petras, 2003). to function normally for fishing but allow a Galvanic releases large whale to break free if entangled. Links on fishing gear (such as pots or Trap guards (T-bars, otter guards) lines) designed to eventually dissolve thereby Welded bars or netting placed in some pot Time tension line cutter releasing any entrapped or entangled animal. traps to prevent pinnipeds or otters from enter- A link connecting the bottom gear and Galvanic releases have been proposed to reduce ing them and preying on the target catch (such vertical line in a pot that would break the number of vertical lines in the water by as eels). Bungee trap guards have also shown under any pressure sustained longer than securing hauling lines in a coil at the ocean floor success at reducing bottlenose dolphin interac- the time it takes to haul in the gear when until the release dissolves, freeing a buoy that tions with crab pots (Noke and Odell, 2002). fishing. This device was designed to reduce brings the hauling line to the surface. large whale entanglements in pot fishery Fleet communication endlines. The line cutter can be reset before Weak hooks The dissemination of real time informa- it is redeployed. Hooks that are strong enough to hold the tion between fishing vessels on the presence target catch but straighten out under the pull of non-target animals to avoid fishing in areas Buoy line trigger release of larger, non-target animals. in which they are congregating. A line-cutting device that will detach a surface buoy from vertical line when pres- Baiting techniques Excluder devices sure—such as that from a whale’s baleen—is Applying alternative methods of securing A grid of metal bars or mesh placed usu- exerted against a plate that is attached to the bait to a hook or other fishing gear. A singly ally within the neck of a trawl that has an buoy. It was designed in order to prevent ropes threaded baiting technique is being evaluated opening for escape at either the top or bot- becoming entangled in whale baleen. as an approach for reducing loggerhead sea tom. Large animals that strike the bar exit turtle bycatch in longline fisheries (Eric through the opening, while the smaller tar- Stiff rope Gilman, pers. comm.). get species pass through the bars and are cap- A kind of rope that would be stiff in the tured in the net. Examples of excluder de- water column but loose on the deck of a boat. Long gangions vices in trawls are the Nordmore grid, the Various prototypes are in research and devel- Longer gangions (leader lines attached to (TED), and the Sea opment. The theory behind these ropes is that the main floating line of a longline) are used to Lion Excluder Device (SLED). A sea turtle their rigidity will prevent them from entan- reduce sea turtle bycatch mortality by allow- excluder chain mat is used in the Northwest gling large whales while fishers will find them ing turtles to swim to the water’s surface to Atlantic dredge fishery. A new modi- at least as practical as regular rope. breathe if hooked. NOAA Fisheries prohibits fication to pound nets may reduce sea turtle longliners from setting gangions within two bycatch by replacing the upper two-thirds Medina Panel gangion lengths of the floatline, and requires of the leader netting with vertical ropes spaced Used in the purse seine fishery for yel- that “the length of the gangion [be] at least 10 wide enough apart to let sea turtles swim lowfin in the Eastern Tropical Pacific, percent greater than the length of the floatline

Fall 2006 Volume 40, Number 3 53 for longline sets in which the combined length greater injury to the animal (Bolten and bycatch events are rare in space and time even of the floatline and the gangion is 100 meters Bjorndal, 2004; Watson et al., 2005). Pyro- though the consequences may be critical for spe- or less” (NMFS/NOAA, 2002). technics also were listed twice, once as an acous- cies survival. The entanglements of North At- tic deterrent and again as a tactile deterrent lantic right whales in lobster pot and gillnet lines Lipid soluble rope because the effect on an animal may be sensed represent a perfect example of this point. This A that would dissolve once both ways. One more device, the quick- species occurs exclusively in the Northwest At- embedded in the blubber of a large whale. release metal wire, occurs twice in Table 1 lantic and its total population is an estimated because it may be sensed by dolphins using 350 individuals. Its small population size means Sea turtle-friendly bridles eyesight or echolocation. that even infrequent entanglement events may A bridle design used in trap fishing for More techniques have been applied to hook- be catastrophic for the population. Very high lev- minimizing sea turtle entanglement. and-line fisheries (longlines, specifically) than for els of fishing effort, even when offset by a low all other fishing methods combined. This is due encounter rate, mean that a large proportion (15%) De-hookers to the large number (nearly half of the total of this remnant population interacts with fishing Devices designed to safely remove hooks longline techniques) of bycatch mitigation ap- gear each year (Knowlton et al., 2005). The low from sea turtles and other byatch species cap- proaches developed exclusively to deter sea bird encounter rate and critical status of this popula- tured by hook-and-line fisheries. Dipnets may bycatch that results from predation on baited tion rule out any field evaluation of potential be used for small turtles or other non-target longline hooks as they are being set. In contrast, bycatch mitigation measures, so alternative meth- animals to haul them on to the deck more only one bycatch reduction method was identi- ods for testing gear must be devised. Several scien- safely for hook removal. fied for dredges (although see Smolowitz, this tists in the United States and Canada are working issue of MTSJ). Similarly lacking were studies with the fishing industry to experiment with al- evaluating bycatch reduction methods for a num- ternative gear types to see whether or not they are Summary of Results ber of wildlife groups suspected or known to viable fishing techniques. But the best methods Table 1 lists these techniques together perish following conflicts with fishing operations, for testing “whale-safe” gear may be in tank tests with an indication of the commercial fishing including sirenians (manatees and dugong), sea with models, and monitoring whale entangle- method in which they are or could be used, snakes, and non-commercial pelagic (Read ment records to determine progress as new gear and a reference to studies evaluating their et al., 2006; Milton, 2001; Goodyear, 1999). types are implemented. efficacy for various groups of wildlife. An The list also highlights the absence of mitigation The development and use of bycatch re- estimated 33 of the methods are presently techniques for two other non-target groups com- duction methods (particularly gear modifica- used with the remainder proposed for po- monly occurring as bycatch: elasmobranchs and tions) almost always targets one population, tential development and application. By far, invertebrates. The former includes many species species, or animal group. Based on the 52 stud- most of the techniques in use take an ap- vulnerable to extinction from fishing and the ies identified that reviewed the efficacy of these proach of avoiding contact with fishing gear latter represents diverse and threatened commu- methods (Table 1), all but 7 evaluated bycatch (81%) as opposed to facilitating escape or nities such as deep-sea reefs (Fowler et al., levels for just one species or wildlife group; typi- release once an animal has come into contact 2005; Probert et al., 1997). Table 2 shows the cally the results apply to only a subset of that with it. Considering only those approaches taxonomic coverage of the studies compiled as population. Though not surprising, an obvi- geared towards avoiding conflicts, 61% (or part of this review. ous concern in altering fishing methods is the 16/26) operate under the principle of physi- The number of available approaches, impact that the change might have not only on cally excluding animals from fishing areas, however, is not necessarily a proxy for the suc- one population but also on different groups gear or bait. The other 10 can be divided cess of bycatch mitigation. A single effective and ecosystems. An undesirable consequence according to the type of sensory detection approach, such as excluder devices for sea of using new fishing methods would be to in- the animal would use in averting conflict: turtles in prawn trawl fisheries, may be suffi- crease the total mortality of endangered marine auditory, visual, olfactory, gustatory, tactile, cient for achieving the reductions desired. species or populations even though bycatch is or electromagnetic. Of these, the visual and Nearly all of the techniques used by the fish- reduced for the species of initial concern. For auditory approaches predominate with sea- ing industry have been subjected to some degree example, many studies indicate that circle hooks birds being the principal target group based of scientific field evaluation as shown in Table 1. can reduce sea turtle byatch in longline fisheries on the number of available techniques. It is important that modifications to fishing gear but in at least one study they were shown to Circle hooks were listed as both a device and methods undergo this scrutiny to ensure increase the catch of blue sharks (Bolten and for escaping contact with gear and for facili- that they are likely to have the desired impact on Bjorndahl, 2003). In that particular study, blue tating release upon capture. This is because bycatch rates and that the industry has adequate sharks made up the target catch and so the circle hooks have been shown to reduce the justification before making costly changes. Some- study results represented an optimal outcome capture rate of sea turtles over J-hooks as well times, however, researchers need to adopt cre- for fisheries bycatch research in which a low- as result in fewer deep hookings that cause ative approaches, particularly in cases in which cost modification produces not only a reduc-

54 Marine Technology Society Journal A list of techniques for reducing non-target species bycatch. The ones in bold presently exist; the remainder are proposed for possible use or further development. An "X" under Fishing Method indicates where a technique is known to be used, and an asterix denotes where it potentially could be used (excluding any assumption of its efficacy). Large whales and large elasmobranchs (e.g., whale sharks) were combined in one column due to shared large body size. Checkmarks in Wildlife Group columns refer to field studies that showed the efficacy of a method; an "X" in these columns represents studies that showed no effect. The numbers used are identified in the References, and the Appendix summarizes details from these studies. aThe types of circle hooks used did not reduce sea turtle hookings, but there were fewer throat hookings which is though to increase post-hooking survivability; balso reduced some non-target finfish bycatch; cunclear if the potential benefits extend beyond the entrapment section of the gear; dsummary of other studies; esimulation in flume tank using dummy animals; fin this case, blue shark was a target species; gresults contrasted between trial periods.

Fall 2006 Volume 40, Number 3 55 TABLE 2 ods is a dynamic field that has produced many effective strategies for some endangered popu- The focal species of studies that evaluated bycatch reduction techniques for non-target animals based lations of marine wildlife. In commercial fisher- on this review. (Note: some occurrences may reflect multiple references from one long-term study). ies, most available techniques are directed at reducing the bycatch of small marine mam- Species Number of occurrences mals, seabirds, and sea turtles. Although this (Caretta caretta)11 taxonomic emphasis is justifiable given the high Harbor porpoise (Phocoena phocoena)7 degree of endangerment from fishing encoun- Black-footed albatross (Phoebastria nigripes)6 ters, it is certainly the case that other non-target Laysan albatross (P. immutabilis)6 species are as or more seriously endangered by (Dermocheles coriacea)5conflicts with fishing operations but to date California sea lion (Zalophus californianus)3have received little bycatch mitigation attention. Common dolphin (Delphinus delphis)3With respect to gear type, hook-and-line fisher- Bottlenose dolphin (Tursiops truncatus)3ies appear to have more bycatch mitigation tech- (Chelonia mydas)3niques available than exist in other fishing meth- Harbor seal (Phoca vitulina)2ods. This is encouraging given the concerns about Common murre (Uria aalge)2the consequences of longline fisheries to non- Rhinoceros auklet (Cerorhinca monocerata)2target species bycatch, but at the same time it Killer whale (Orcinus orca)2amplifies the contrast with other fishing meth- Kemp’s ridley sea turtle (Lepidochelys kempii)2ods in which there are relatively fewer techniques Franciscana (Pontoporia blainvillei)1for reducing bycatch. In other fisheries such as Short-beaked common dolphin (Delphinus delphis)1 coastal gillnets, individual nets may cause lower Humpback whale (Megaptera novaeangliae)1levels of bycatch than trawls and longlines, but Hector’s dolphin (Cephalorhynchus hectori)1because of their widespread use worldwide they New Zealand fur seal (Arctocephalus forsteri)1may have a major contribution to non-target Pan-tropical spotted dolphin (Stenella attenuata)1species bycatch. These are areas of research wor- Gray whale (Eschrichtius robustus)1thy of attention. To suggest that this review was exhaustive Beluga whale (Delphinapterus leucas)1 would be misleading. Fisheries bycatch reduc- Dall’s porpoise (Phocoenoides dalli)1 tion is a very active area of research with many Shearwater (Puffinus gravis)1 ongoing studies and the frequent development (Lepidochelys olivacea)1 of novel initiatives. Among these are initiatives Long-snouted spinner dolphin (Stenella longirostris)1 to address mammal bycatch in trawls, the re- Hawksbill sea turtle (Eretmochelys imbricata)1search and development of innovative ground Hooker’s sea lion (Phocarctos hookeri)1and endlines for trap and gillnet fisheries by the Consortium for Wildlife Bycatch Reduction (administered by the New England Aquarium), tion in non-target species bycatch but an in- increase their interactions with fishing opera- and several prospective techniques supported crease in target catch. However, this finding tions with prolonged use (Geiger and Jeffries, through World Widlife Fund’s Smart Gear com- raises the question of what impact circle hooks 1987; Stewardson and Cawthorn, 2004). In petition. Nevertheless, we hope that the infor- may have on pelagic sharks generally. another example, TEDs reduced non-target mation contained in this article will contribute On the other hand, many bycatch reduc- finfish bycatch in addition to that of sea turtles to the evolving global knowledge base of tion methods showed benefits across multiple (Christian and Harrington, 1997). In general, bycatch reduction approaches. We intend to non-target groups of wildlife. Acoustic pingers excluder devices in trawl gear appear to work publish this content on the Worldwide Web provide a good example; multiple studies have well for many different wildlife groups which where it will be available for use and applica- shown that their use can reduce the bycatch of in part explains why they have received so tion by the fishing industry, fisheries research- cetaceans, pinnipeds, and seabirds (Barlow and much research attention around the world. ers, marine biologists, and managers of living Cameron, 2003; Bordino et al., 2002; Gearin marine resources. Over time, such a Web-based et al., 2000; Culik et al., 2001; Koschinski and database could invite ongoing contributions Culik, 1997; Kraus et al., 1997; Lien et al., Conclusion and updates by international experts and thus 1992; Melvin et al., 1999; Stone et al. 1997), Mitigating bycatch in non-target species more efficiently capture the state of the art of although pinnipeds may habituate to and even through modifications to fishing gear and meth- bycatch reduction.

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of the experimental design).

Studies evaluating the efficacy of bycatch reduction methods for non-target species. (NR = not reported or recorded as part

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visibility of

It was not ascertained if the results obtained were due to the increased acoustic reflectivity, physical stiffness, or greater acoustic reflectivity, due to the increased obtained were was not ascertained if the results It the nets, though last characteristic likely caused reduction in shearwater bycatch. 1

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Appendix

64 Marine Technology Society Journal Acknowledgments References 42Bolten, A. and Bjorndal, K. 2004. Experiment Individuals that reviewed the preliminary (Those preceded by numbers are referenced in to Evaluate Gear Modification on Rates of Sea list of bycatch reduction techniques partici- Table 1) Turtle Bycatch in the Longline pated at the 2005 Annual Meeting of the Fishery in the Azores—Phase 3. Final Project 44Barham, E., Taguchi, W.K. and Reilly, S.B. Consortium for Wildlife Bycatch Reduction and Report submitted to the U.S. National Marine 1977. Porpoise reduction methods in the included Ken Baldwin (University of New Fisheries Service. Archie Carr Center for Sea yellowfin purse seine fishery and the importance Hampshire), Nelson Beideman (Blue Water Turtle Research, University of Florida, Gainesville. of Medina panel mesh size. Mar Fish Rev. Fishermen’s Association), Nigel Brothers 39(5):1-10. 43Bolten, A. and Bjorndal, K. 2005. Experiment (Consultant), Glenn Delaney (Consultant), to Evaluate Gear Modification on Rates of Sea 2 Marianne Farrington (New England Barlow, J. and Cameron, G.A. 2003. Field Turtle Bycatch in the Swordfish Longline Aquarium), Doug Forsell (U.S. Fish and Experiments Show That Acoustic Pingers Fishery in the Azores—Phase 4. Final Project Wildlife Service), Martin Hall (Inter-Ameri- Reduce Marine Mammal Bycatch in the Report submitted to the U.S. National Marine can Tropical Tuna Commission), Norm Holy California Drift Gill Net Fishery. Mar Fisheries Service. Archie Carr Center for Sea (Better Gear), Scott Kraus (New England Mammal Sci. 19:265–83. Turtle Research, University of Florida, Gainesville. Aquarium), Ed Lyman (Massachusetts Divi- 23 Boggs, C.H. 2001. Deterring albatrosses sion of Marine Resources), Patrice McCarron 3Bordino, P., Kraus, S., Albareda, D., Fazio, A., from contacting baits during swordfish longline (Maine Lobstermen’s Association), Alice Palmerio, A., Mendez, M. and Botta, S. 2002. sets. In: Edward F. Melvin and Julia K. Parrish, Mackay (University of St. Andrews), Larry Reducing incidental mortality of Franciscana eds. Seabid Bycatch: Trends, Roadblocks and Madin (Woods Hole Oceanographic Insti- dolphin Pontoporia blainvillei with acoustic Solutions. pp. 79-94. Fairbanks, Alaska: tution), Bill Montevecchi (Memorial Uni- warning devices attached to fishing nets. University of Alaska Sea Grant College Program. versity), Andrew Read (Duke University), Mar Mammal Sci. 18:833–42. Glen Salvador (U.S. National Marine Fish- 30 Boggs, C.H. 2003. Annual Report on the Broadhurst, M.K. 2000. Modifications to eries Service), Carolyn Stewardson (Austra- Hawaii Experiments to reduce bycatch in prawn trawls: a review and lian Department of Agriculture, Fisheries and Reduce Sea Turtle Bycatch under ESA Section framework for development. Rev Fish Biol Forestry), Ed Trippel (Canadian Department 10 Permit 1303. U.S. National Marine Fisher. 10:27-60. of Fisheries and Ocean), John Watson (U.S. Fisheries Service Honolulu Laboratory, National Marine Fisheries Service), Tim Honolulu. 42 pp. [Results cited by: Gilman, Brothers, N. and Gilman, E. 2006. Technical Werner (New England Aquarium), and Pat E., N. Brothers and D.R. Kobayashi. 2005. Assistance for Hawaii Pelagic Longline Vessels White (Maine Lobstermen’s Association). Principles and approaches to abate seabird to Change Deck Design and Fishing Practices Valuable contributions were subsequently by-catch in longline fisheries. Fish and to Side Set (Executive Summary). Report received from Jack Ames (California Depart- Fisheries 6:35-49.] prepared for the Hawaii Longline Associtation, ment of Fish and Game), Karin Forney U.S NOAA Fisheries, and Western Pacific 37 Bolten, A. and Bjorndal, K. 2002. (NOAA), Eric Gilman (Blue Ocean Insti- Regional Fishery Management Council. Experiment to Evaluate Gear Modification on tute), Amy Knowlton (New England (Accessed September 27, 2006: http:// Rates of Sea Turtle Bycatch in the Swordfish Aquarium) and Erika Zollett (University of www.wpcouncil.org/pelagic/Documents/ Longline Fishery in the Azores. Final Project New Hampshire). Exec_sum_Side_set_tech_assist_HI.pdf#search= Report submitted to the U.S. National Marine %22side%20sets%20bird%20bycatch%22). Fisheries Service. Archie Carr Center for Sea Turtle Research, University of Florida, Gainesville. 35Christian, P. and Harrington, D. 1987. Loggerhead turtle, finfish and shrimp retention 33 Bolten, A. and Bjorndal, K. 2003. Experiment studies on four excluder devices (TEDs). In: to Evaluate Gear Modification on Rates of Sea Proceedings of the Nongame and Endangered Turtle Bycatch in the Swordfish Longline Wildlife Symposium, 8-10 September, 1987. Fishery in the Azores—Phase 2. Final Project pp. 114-127 Georgia DENR, Social Circle, Report submitted to the U.S. National Marine GA. [Publication cited in Broadhurst, M.K. Fisheries Service. Archie Carr Center for Sea 2000. Modifications to reduce bycatch in Turtle Research, University of Florida, Gainesville. prawn trawls: a review and framework for development. Rev Fish Biol Fisher.10:27-60.]

Fall 2006 Volume 40, Number 3 65 5Culik, B.M., Koschinski, S., Tregenza, N. 28Gearin, P.J., Pfeifer, R., Jeffries, S.J., DeLong, Goodyear, C.P. 1999. An analysis of the and Ellis, G.M. 2001. Reactions of harbor R.L. and Johnson, M.A. 1988. Results of the possible utility of time-area closures to porpoises Phocoena phocoena and herring 1986-87 California sea lion-steelhead minimize billfish bycatch by U.S. pelagic Clupea harengus to acoustic alarms. Mar predation control program at the Hiram M. longlines. Fish Bull. 97(2):243-255. Ecol-Prog Ser. 211:255–60. Chittenden Locks. NWAFC Processed Report Hall, M.A. 1995. Bycatches in purse-seine 88-30, Alaska Center, 16Cummings, W.C. and Thompson, P.O. fisheries. In: T.J. Pitcher and R. Chuenpagdee, NMFS, NOAA, Seattle, Washington. 111 pp. 1971. Gray whales, Eschrichtius robustus, avoid eds. By-catches in Fisheries and their Impact the underwater sounds of killer whales, 11Geiger, A.C. and Jeffries, S.J. 1987. on the Ecosystem. 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Fall 2006 Volume 40, Number 3 67 27Watson, J., Foster, D., Epperly, S. and Shah, A. 2002. Experiments in the Western Atlantic Northeast Distant Waters to Evaluate Sea Turtle Mitigation Measures in the Pelagic Longline Fishery. Report on Experiments Conducted in 2001. NOAA Fisheries, Southeast Fisheries Science Center Report, Mississippi Laboratories, Pascagoula, MS.

31Watson, J.W., Foster, D., Epperly, S. and Shah, A. 2004. Experiments in the Western Atlantic Northeast Distant Waters to Evaluate Sea Turtle Mitigation Measures in the Pelagic Longline Fishery. Report on Experiments Conducted in 2001-2003. U.S. National Marine Fisheries Service, Pascagoula, MS.

29Watson, J.W., Epperly, S.P., Shah, A.K. and Foster, D.G. 2005. Fishing methods to reduce sea turtle mortality associated with pelagic longlines. Can J Fish Aquat Sci. 62:965-981.

34Yokota, K. and Kiyota, M. 2006. Preliminary report of side-setting experiments in a large sized longline vessel. National Research Institute of Far Seas Fisheries, Fisheries Research Agency, Japan.

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68 Marine Technology Society Journal