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The Patagonian toothfish longline fishery has high levels of depredation by killer and sperm whales, which puts the whales at risk of being bycatch. Observations from 2003 to 2008 revealed significant variations of interaction rates with killer whales between vessels, suggesting the influence of operational factors on vessel interaction and depredation. When killer whales were absent at the beginning of the line hauling process, short lines (<5,000 m) provided higher yield and were significantly less impacted by depredation than longer lines. The authors also recommend that when facing depredation, vessels should leave the fishing area and travel distances > 40 n miles to prevent killer whales from finding them within a few hours. 

A Double-FAD design was tested for it's ability to mitigate the incidental capture of bigeye tuna in purse fisheries of the Western and Central Pacific Ocean.  The design consisted of two separate FADs with underwater light stimuli attached.  The number of animals caught was not large enough to conduct statistical analyses, but based on the weight of fish, the size proportion of skipjack, yellowfin and bigeye was bigger using the Double-FAD design comapared to the normal design.  The bycatch rate (proportion of total catch) of bigeye tuna was 6.1% and 7.2% on Double-FADs and 8.9% and 14.2% on normal FADs for numbers and weight respectively.  The proportion of skipjack tuna caught on the Double-FADs was 58.6% (number) and 29.1% (weight) compared to 72.4% (number) and 39% (weight) with the normal FAD.  The proportion of yellowfin tuna on the Double-FADs was 35.4% (number) and 63.7% (weight), while on normal FADs the proportion was 18.7% (number) and 46.8% (weight).  It appears this design has some effect on reducing bigeye tuna bycatch, despite the low sample size.

Acoustic pingers, Fumunda F3 (2.7 kHz) for humpback whales and F10 (10 kHz) for dolphins, were used on sharks nets within the Queensland Shark Control Program.  Sound from the acoustic pingers was present for around 1.5 km beyond the nets. Humpback whales and dugons were able to hear the F3 pinger 90 m from the net and its two harmonic overtones (5.4 and 8.1 kHz) 10 and 210 m from the net respectively. The F10 pinger was audible to both species up to 130 m from the net. Dolphins could hear the F3 pinger 45 m from the net and it's two overtones 10 and 110 m from the net.  The F10 pinger could be detected by dolphins up to 40 m from the net. Shark nets are currently fitted with 3 to 4 pingers per 200 m length of net and therefore appear to be adequate for detection by marine mammals swimming straight at the net and at a top speed.

Acoustic pingers, Fumunda F3 (2.7 kHz) for humpback whales and F10 (10 kHz) for dolphins, were used on sharks nets within the Queensland Shark Control Program.  Sound from the acoustic pingers was present for around 1.5 km beyond the nets. Humpback whales and dugons were able to hear the F3 pinger 90 m from the net and its two harmonic overtones (5.4 and 8.1 kHz) 10 and 210 m from the net respectively. The F10 pinger was audible to both species up to 130 m from the net. Dolphins could hear the F3 pinger 45 m from the net and it's two overtones 10 and 110 m from the net.  The F10 pinger could be detected by dolphins up to 40 m from the net. Shark nets are currently fitted with 3 to 4 pingers per 200 m length of net and therefore appear to be adequate for detection by marine mammals swimming straight at the net and at a top speed.

Acoustic pingers, Fumunda F3 (2.7 kHz) for humpback whales and F10 (10 kHz) for dolphins, were used on sharks nets within the Queensland Shark Control Program.  Sound from the acoustic pingers was present for around 1.5 km beyond the nets. Humpback whales and dugons were able to hear the F3 pinger 90 m from the net and its two harmonic overtones (5.4 and 8.1 kHz) 10 and 210 m from the net respectively. The F10 pinger was audible to both species up to 130 m from the net. Dolphins could hear the F3 pinger 45 m from the net and it's two overtones 10 and 110 m from the net.  The F10 pinger could be detected by dolphins up to 40 m from the net. Shark nets are currently fitted with 3 to 4 pingers per 200 m length of net and therefore appear to be adequate for detection by marine mammals swimming straight at the net and at a top speed.

A study was conduceted to test the effect of SaveWave acoustic deterrent devices on target fish catch and bottlenose dolphins in the North Carolina Spanish mackerel gillnet fishery. Observations were carried out on commercial vessels and focal visual and acoustic follows of dolphins were conducted. Fish catches were significantly lower when dolphins were observed interacting with gillnets. The SaveWave device did not affect fish catch. Dolphins were less likely to interact with gillnets and more likely to echolocate when SaveWaves were present. However, SaveWave devices were not sufficiently durable to be deployed in this fishery.

Gear modifications to the Loligo squid trawl net were developed to reduce scup bycatch.  Two extension modifications, vee and ring excluders, were developed to aid in reducing scup bycatch when large schools are encountered.  These extensions were based on the grid/gate design but made flexible enough to be wound up. The extensions work as an obstruction device and are flanked by fisheyes, which allow the fish to escape.  Previous trawl net modifications were unable to reduce scup bycatch when large schools entered the gear.  The two extensions were able to remove scup at mean rates of 86-100% compared to standard trawl gear, although small (<10 cm FL) scup were not excluded.  There were no real differences in removal rates between the two extensions.  However, the vee excluder did also remove more squid (53-69%) from the net compared to the ring excluder (7-58%).   

Experiments were conducted aboard pelagic longline vessels in the western North Pacific to determine the effectivness of paired tori lines in reducing seabird bycatch.  Paired tori lines (PT) were compared against single tori lines (ST) during these tests.  The most abundant species of bird attacking longlines was the Laysan albatross (90.2%).  There was a significant difference in the mean number of albatross and shearwater birds between ST and PT deployments, with the mean number of birds being lower with PT deployments.  PT deployments reduced attacks by albatross's by 47.8% and few attacks occurred within 75 m of the stern.  However when ST were deployed, albatross attacked from 25 to 200 m of the stern.  The number of secondary attacks was significantly lower when PT were used compared to ST, with PT deployments reducing secondary attacks by 43.4%.  In addition, no statistically significant difference in the distribution of secondary attacks between port and stern were found when ST were used but statistical differences were found during PT deployments.

Experiments were conducted at sea to determine the ability of a "topless" shrimp trawl to reduce bycatch of Atlantic herring.  The "topless" effect was created by removing the square and the top part of the section after the square on the trawl.  At-sea trials resulted in a reduction of Atlantic herring bycatch by an average of 86.6% and produced an increase of 13.5% in pink shrimp catch.  The bycatch of several species of flounder did increase with this new design, albeit less than 3%, which could have been a factor of the wider wingend spread and slight difference in the footgear between the experimental and traditional gear.  There were no differences in catches for other bycatch species (blueback herring and silver hake) between the two gears. In addition, the "topless" trawl was easier to sort and clean and therefore required less labor.

Two types of longline sets, night and day, were evaluated for differences in catch composition in Seychelles waters.  Night sets were set at dusk and retrieved at dawn and used shallow baskets targeting swordfish, while day sets were set at dawn and retrieved at dusk and used shallow and deep baskets to target tuna.  The majority (75%) of species, both bycatch and market, were caught during day sets. The proportion of bycatch to target species decreased with depth.  Lancetfish were the main bycatch species during day sets and sharks were the primary bycatch species during night sets.