Search The Database

Acoustic pingers placed in the rear of a pair trawl net in the United Kingdom bass (Dicentrarchus labrax) pair trawl fishery did not reduce bycatch of common dolphins (Delphinus delphis). Multi-monofilament net, placed in the North Sea and West of Scotland gillnet fisheries, had no significant impact on harbour porpoise (Phocoena phocoena) bycatch when compared to traditional monofilament net. Thin twine monofilament nets (.4mm twine diameter, 90 mm mesh size) reduced bycatch of harbour porpoise (Phocoena phocoena) and seals in the North Sea and West of Scotland gillnet fisheries when compared to thick (.6mm twine diameter, 267 mm mesh size) monofilament nets. Barium sulphate nets had higher bycatch of harbour porpoise (Phocoena phocoena) and seals in the North Sea and West of Scotland gillnet fisheries when compared to traditional gillnets.

Acoustic pingers placed in the rear of a pair trawl net in the United Kingdom bass (Dicentrarchus labrax) pair trawl fishery did not reduce bycatch of common dolphins (Delphinus delphis). Multi-monofilament net, placed in the North Sea and West of Scotland gillnet fisheries, had no significant impact on harbour porpoise (Phocoena phocoena) bycatch when compared to traditional monofilament net. Thin twine monofilament nets (.4mm twine diameter, 90 mm mesh size) reduced bycatch of harbour porpoise (Phocoena phocoena) and seals in the North Sea and West of Scotland gillnet fisheries when compared to thick (.6mm twine diameter, 267 mm mesh size) monofilament nets. Barium sulphate nets had higher bycatch of harbour porpoise (Phocoena phocoena) and seals in the North Sea and West of Scotland gillnet fisheries when compared to traditional gillnets.

Acoustic pingers placed in the rear of a pair trawl net in the United Kingdom bass (Dicentrarchus labrax) pair trawl fishery did not reduce bycatch of common dolphins (Delphinus delphis). Multi-monofilament net, placed in the North Sea and West of Scotland gillnet fisheries, had no significant impact on harbour porpoise (Phocoena phocoena) bycatch when compared to traditional monofilament net. Thin twine monofilament nets (.4mm twine diameter, 90 mm mesh size) reduced bycatch of harbour porpoise (Phocoena phocoena) and seals in the North Sea and West of Scotland gillnet fisheries when compared to thick (.6mm twine diameter, 267 mm mesh size) monofilament nets. Barium sulphate nets had higher bycatch of harbour porpoise (Phocoena phocoena) and seals in the North Sea and West of Scotland gillnet fisheries when compared to traditional gillnets.

Acoustic pingers placed in the rear of a pair trawl net in the United Kingdom bass (Dicentrarchus labrax) pair trawl fishery did not reduce bycatch of common dolphins (Delphinus delphis). Multi-monofilament net, placed in the North Sea and West of Scotland gillnet fisheries, had no significant impact on harbour porpoise (Phocoena phocoena) bycatch when compared to traditional monofilament net. Thin twine monofilament nets (.4mm twine diameter, 90 mm mesh size) reduced bycatch of harbour porpoise (Phocoena phocoena) and seals in the North Sea and West of Scotland gillnet fisheries when compared to thick (.6mm twine diameter, 267 mm mesh size) monofilament nets. Barium sulphate nets had higher bycatch of harbour porpoise (Phocoena phocoena) and seals in the North Sea and West of Scotland gillnet fisheries when compared to traditional gillnets.

Trap guards, made of bungee cords, reduced interactions between bottlenose dolphin (Tursiops truncatus) and the Indian River Lagoon blue crab (Callinectes sapidus) pot fishery.

Pingers were tested to reduce harbor porpoise (Phocoena phocoena) bycatch in bottom-set gillnets in the Swedish Skagerrak Sea. During the experiment, no harbor porpoise were caught in control or experimental gillnets, possibly as a result of a combination of factors including displacement of porpoise, high prey availability in other areas, or pingers acting as passive reflectors. Pingers did not affect the catch of target species, including cod (Gadus morhua) and pollock (Pollachius pollachius).

This study is based on seventeen years of fishery observer data collected aboard drift gillnet vessels fishing for swordfish and sharks in the California Current (United States). Since use of acoustic pingers began in 1996 (source level ∼135 dB RMS, re: 1 Pa @ 1 m, frequency 10–12 kHz, pulse duration = 300 ms, pulse interval = 4 s), there have been no beaked whale entanglements through 2006, in comparison to 33 entanglements from 1990-1998. 260 cetaceans representing 12 other species were observed entangled in the fishery from 1996-2006. 

Underwater acoustic pingers were tested in Brazil to evaluate the behavioral responses of tucuxi (Sotalia fluviatilis). Five pingers were evenly placed on a floating 100 m line set along the dolphins' swimming parth in and out of sheltered waters. Dolphin sighting frequencies were recorded for functional and dummy pingers and control trials. Dolphin sightings were significantly lower in areas where the pinger line was set. Sighting frequency was significantly lower with active pingers than in dummy or control trials, but there wre no significant differences between the dummy and control trials. Preliminary results suggest that acoustic pingers attached to gillnets may be used to successfully prevent tucuxi bycatch.

Trials to assess the behavioral response of free-ranging bottlenose dolphins (Tursiops truncatus) to continuous and responsive pingers were conducted. In boat-based trials both types of pingers affected dolphin behavior, while in static trials, the detection of dolphin vocalizations was significantly lower in the presence of active continuous pingers.

A large scale pinger trial was conducted and results showed a 49% decrease dolphin (Tursiops truncatus) depredation rates when pingers were active. However the different pinger brands tried were not equally effective in reducing depredation. The AQUAmark 210 pingers had significant results, while Dukane Netmark 1000 and SaveWave Dolphinsaver High-impact did not have significant results. Profit per unit increased 9%.