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Summary:

Passive acoustic deterrents in the form of chains of metallic beads and air-filled plastic tubing attached to gillnets in Australia did not reduce bycatch of two small cetaceans: the Atlantic bottlenose dolphin (Tursiops truncatus) and Spinner dolphin (Stenella longiristris). A sub-surface set gillnet (set 4.5 m below the surface) in Australia reduced cetacean catch rate [Atlantic bottlenose dolphin (Tursiops truncatus) and Spinner dolphin (Stenella longiristris)] when compared to a standard surface set net. The sub-surface net decreased total fish (teleost species: tuna, mackerel, billfish) and shark catch approximately 25%.

Summary:

Passive acoustic deterrents in the form of chains of metallic beads and air-filled plastic tubing attached to gillnets in Australia did not reduce bycatch of two small cetaceans: the Atlantic bottlenose dolphin (Tursiops truncatus) and Spinner dolphin (Stenella longiristris). A sub-surface set gillnet (set 4.5 m below the surface) in Australia reduced cetacean catch rate [Atlantic bottlenose dolphin (Tursiops truncatus) and Spinner dolphin (Stenella longiristris)] when compared to a standard surface set net. The sub-surface net decreased total fish (teleost species: tuna, mackerel, billfish) and shark catch approximately 25%.

Summary:

Acoustic Harassment Devices (AHDs) were shown to exclude harbor porpoise (Phocoena phocoena) from bays in British Columbia.

Summary:

Pingers reduce bycatch of California sea lions (Zalophus californianus) and short-beaked common dolphins (Delphinus delphis) in the California drift gillnet fishery for swordfish and sharks. Catch of target fish species (broadbill swordfish (Xiphias gladius), common thresher shark (Alopias vulpinus), and shortfin mako shark (Isurus oxyrinchus)) and non-target species were not affected by pinger use.

Summary:

Pingers are effective in reducing the bycatch of Franciscana dolphins (Pontoporia blainvillei) but increase interactions between fishing gear and South American sea lions (Otaria byronia) in an Argentinian bottom gillnet fishery.

Summary: Harbor porpoise (Phocoena phocoena) avoided an area around a non-lethal, experimental gillnet equipped with a pinger in British Columbia, Canada. In a separate experiment with gillnets in the Baltic Sea, pingers did not affect the catch of targeted herring (Clupea harengus).

Summary:

Acoustic pingers were tested for their effectiveness to reduce entanglement of Hector's dolphins in New Zealand gillnets. A remote control device was used to raise either active or passive acoustic pingers near Hector's dolphins. The dolphins' movement and distribution was observed from shore.Dolphins avoided the immediate area when pingers were active, but did not leave the larger harbor area. Dolphin sightings made during active pinger trials were distributed significantly farther from the source than during passive trials. 

Summary:

Three different device types were mounted on floatline to test their potential for reducing harbor porpoise bycatch. The devices were two passive reflectors (target strength ranging from -38 dB to -24 dB) and a 2.9 kHz pinger. Behavioral responses of 355 harbor porpoise groups were monitored. 92.4% of the groups avoided the pinger equipped floatline, while only half the groups avoided the reflectors and control, empty, floatline.  

Summary:

Acoustic alarms reduce bycatch of harbor porpoises (Phocoena phocoena) in the Gulf of Maine sink gillnet fishery. Gillnets with and without acoustic alarms caught similar quantities of target species, cod and pollock. Acoustic alarms did not affect catch of bycaught silver hake, but Atlantic herring was caught less frequently in experimental nets with alarms. Harbour seals depredated fish caught in both nets with and without acoustic alarms.

Summary: Gillnets equipped with acoustic pingers caught only one harbor porpoise (Phocoena phocoena) compared to 42 caught in control nets off of New Hampshire, USA. Alarms sounds are above groundfish hearing and are not expected to affect fish catch.