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A review of recently published articles dealing with the effects of magnetic fields on elasmobranchs and potential use in bycatch avoidance was conducted. The authors suggest these papers ignore that teleosts may also demonstrate magnetite based magnetoreception and that electroreception is present in many teleosts. Based on this, the possibility of induction based indirect magenetoreception in telosts should also be considered. The authors suggest that experiments showing teleosts are insensitive to magnetic deterrents is likely a result of flawed design and sample sizes. The authors therefore recommend independent studies be conducted to test the hypothesis of magnetic force detection in teleosts.

A laboratory study was conducted to determine the impact of an electrical field on mortality rates and histological changes on model marine organisms. The tests were carried out to provide more information on the impact of electrotrawling om marine species. Two species of invertebrates, brown shrimp (Crangon crangon L.0) and king ragworm (Alita virens S.) were used as model species for crustaceans and polycheates, respectively. Specimens were expose to a homogeneously distributed electrical field varied by frequency (5-200 Hz), electrical field strength (150-200 Vm-1), pulse polarity, pulse shape, pulse duration (0.25-1 ms), and exposure time (1-5 s). Shrimp tended to do a tail flip in response to some electric pulses and ragworm showed a squirming response independent of the frequency. There were no increases in mortality or injuries for either species with any of the pulse parameters tests. Shrimp exposed to 200 Vm-1 showed significantly higher severity of intranuclear baculoform virus infection. 

Alternative trap designs were tested to determine their ability to reduce bycatch of ecologically important herbivore species such as parrotfish and surgeonfish. Catches from traditional Antillean chevron traps were compared to catches from traps with 1) short escape gaps (20X2.5 cm), 2) traps with tall escape gaps (40X2.5 cm) and 3) traps with a panel of large aperture mesh. The mean number of fish caught in the various traps were: 11.84 (control), 4.88 (short gap trap), 4.43 (tall gap traps) and 0.34 (large mesh traps). Short gap traps caught 74% fewer bycatch fish species, 58% fewer key herbivores and 90% fewer butterflyfish. Large gap traps caught 80% fewer bycatch fish species, 50% fewer key herbivores and 98% fewer butterflyfish. Juveniles were able to escape via the gaps and so the mean length of captured fish was significantly higher in the gap traps compared to the control trap. Catches of high-value fish were not affected by the use of gap traps.

Experiments were conducted aboard longline vessels operating in the Seychelles targeting swordfish and tuna. Experimental longlines fitted with hook timers and temperature depth recorders were used to identify differences in species composition, quantity and depth of catch between night sets using a shallow basket (swordfish target) and day sets using both shallow and deep baskets (tuna target). The majority of species were caught during day sets (75%). Lancetfish was the main bycatch species during daytime sets. Sharks were the most common nightime bycatch species, with blue and shortfin mako sharks being the predominant shark species. All marketable species were caught in the 150 m layer, marlins were never caught below 100 m. Sharks were caught below 150 m during both night and day sets. For other bycatch species, all were caught in depths less than 150 m during night sets. Daytime depth captures varied.

Integrated weight longlines (IW) were tested for their ability to reduce sea bird bycatch in demersal longline fisheries. The target fishery for testing was the Pacific cod fishery operating in the Bering Sea, Alaska, USA. Three experimental mitigation techniques were tested: 1) IW line alone, 2) IW paired with streamer lines (IWPS) and 3) unweighted longlines with paired streamer (UWPS) against a control (UW). Information on catch rates, seabird abundance and attack rate, and gear sink rate and performance were collected. Seabird bycatch was dramatically reduced with all three experimental longlines. Surface foraging seabirds had higher reduction in mortality rates (91-100%) compared to diving seabirds (80-97%). The IWPS mitigation technique performed best because it allowed the gear to sink within the protection of the streamer, completely eliminated surface foraging and reduced shearwater catch by 97%. UWPS and IW reduced surface foraging catches rates by 98% and 91%, respectively. Shearwater catch rates were reduced by 87% with UWPS and 80% with IW. Catch rates of Pacific cod did not vary across mitigation techniques and the control.

Interactions between vertical lines under increased tension with a physical model of a North Atlantic right whale flipper was investigated. This was an updated experiment. The original flipper model was based on data (flipper outlines and bone measurements) collected from three different whales. The physical flipper was computer generated from these data and covered with 1/2 in neoprene rubber, which was overlayed with 1/8 in thick vinyl rubber sheeting. The flipper was made from fiberglass, was free flooding and covered with 1/2 in neoprene and then with 1/8 in vinyl-rubber. The flipper angle was adjustable forward and aft, relative to the 'whale body'. The flipper and frame was attached to a fishing boat, and deployed 12 feet below the surface. A taut vertical line was created using a large mooring block, which was fitted with a pulley and a swivel. A 5/8 in line was attached to a 28 in float and attached to a sinking line that ran across the bottom. Cameras were used to observe the flipper-line interactions. Scenarios were run using both forward and aft flipper positions, and at different contact points along the flipper's leading edge. There were three zones (relative to the whale body panel) on the leading edge: A) acute, N) normal and O) oblique. During the first 11 trials, six events were glancing interactions in zone C (outer edge) and five interactions occurred at zones A and B. The flipper moved vertically down, with a slight angle towards the back edge of the flipper, in the water column during these interactions. The second 11 trials occurred in zones A and B with one glancing event in zone C. The interactions (except for the glancing) resulted in the float moving downward. Interactions that occurred in zone A and B lead to significant damage to the leading edge of the flipper. The results from these trials suggest that for entanglements involving a whale flipper as the initial point of contact with vertical fishing ropes, increased line tension will likely produce more severe lacerations than ropes under lower tension. Any potential benefit of using ropes with increased tension may be offset by the potential for more severe injury.

This study investigated whether North Atlantic right whale behavior changes, in terms of response distance, to changing visual characteristics of rope mimics in their path. 20 ft rope mimics were made from two 10 ft sections of rigid PVC pipe, with an approximate diameter of 1 inch. The rope mimics were weighted and attached to a lobster buoy to simulate a vertical line in the water column. A 30.5 cm disk was placed around the rope for reference use in video footage. The following color ropes were used: black, green, two types of white (white and glow in the dark), orange and red. Experiments were conducted in Cape Cod Bay using surface feeding whales. A significant difference in the distance of first change in behavior occurred between black and green ropes vs red and orange ropes. The response time was earlier with the latter colors. No significant difference was found between frontlit and backlit ropes.

Low-powered sound sources were tested for their ability to deter gray whales from potentially harmful areas. An acoustic device (1-s frequency modulated 1-3 kHz warble deterrent signal) was moored to the seafloor in the gray whales migration path off central Oregon. Observers (land based) tracked whales with a theodolite to locate whales as they passed the headland. Tracklines were compared between times when the acoustic deterrent was on and off. Statistical analysis did not show a significant difference between the hypothesized zone of influence (within 500 m of the deterrent) and areas out to 3 km. Poor weather and equipment issues prevented acquiring an adequate sample size, so the results were considered inconclusive. 

A desk-based study was conducted to evaluate 'conservation-relevant elements' of local governments involved in coastal and aquatic resource management, particularly bycatch mitigation. Four sites were looked at: 1) Trat, Thailand, 2) Mahakam River, Indonesia, 3) Malampaya Sound Philippines and 4) Guimaras and Iloilo Straits, Philippines. The species of interest was Irrawaddy dolphin (Orcaella brevirostris) caught in small-scale fisheries. Several attributes were looked at including; extent to which conservation-relevant governance elements are active and effective, contribute to enforcement, coordinate across institutions and engage communities. These attributes appeared to vary across sites with noticeable differences between Malampaya Sound and Trat. Malampaya Sound has mostly low ratings for the assessed attributes, compared to high ratings for Trat. Involvement of local communities and support from external institutions were determined as being necessary. Bridging organizations were some of the most active, effective and engaged institutions at all of the sites.

Two models of high field strength neodymium magnets (N35-Ni and N35-NdFeB types) were tested to determine their ability to deter sharks incidentally captured in Spanish and  Portuguese longline fisheries operating in the Northeast Atlantic Ocean. The main shark species tested was blue shark (Prionace glauca). The larger magnet was 26 mm X 11 mm X 12 mm, 0.885 T and the smaller magnet was 20 mm X 13 mm X 15 mm, 0.464 t. Field test results indicated the magnets do not reduce blue shark catch rates and may instead have an attractive effect. The attractive effect was significantly higher for the larger magnets.