Search The Database

Large escape openings located at the sorting grid panel, which could be a beneficial tool to reduce marine megafauna bycatch, such as Greenland shark, did not impact northern shrimp catch rates in comparison to traditional gear. 

A mobuilid sorting grid placed over the hopper used to sort bycatch on tuna purse seine vessels aided in the release of larger mobuilid rays without increasing handling time.  

Seal exclusion devices (SEDs) are effective in reducing pinniped bycatch in the Patagonian squid fishery, however, drowning may still occur during trawl hauling. 

Use of ferrite magnets did not act as a deterrent for blue shark (Prionace glauca) bait strikes. Time to strike, number of prior interactions, number of sharks present, and number of people in the water also did not influence bait strikes. 

An analysis of records of static net bycatch sampling in the United Kingdom from 1996-2023 found that use of acoustic deterrent devices (ADDs) reduced harbor porpoises bycatch per haul (BpH) to 0.23 of the background rate. BpH increased for harbor seals and grey seals (Phoca vitulina and Halichoerus gryphus) when ADDs were used. Current efforts to reduce harbor porpoise bycatch may be increasing seal mortality in the same fisheries. 

Turtle excluder device (TEDs) with reduced bar spacing may help to reduce bycatch of small sea turtles that can pass through the deflector bars of standard TEDs. A bent bar top opening TED installed at 55°, a bent bar, bottom opening TED installed at 45°, and straight bar, top opening TED installed at 55° were evaluated. None of the TEDs significantly reduced total catch or bycatch. However, the bent bar, bottom opening TED and straight bar, top opening TED both significantly reduced invertebrate (largely jellyfish) catch. 

Solar powered LED lights flashing at a 10% duty cycle (5Hz, 20 min on, 180 mins off) attached to gillnets resulted in a 63% reduction in predicted mean sea turtle bycatch rates. This falls within the range found in previous studies that looked at static lights (40-90% reduction in bycatch), suggesting sea turtle bycatch can be reduced with less power consumption.  

The study tested the effect of Lumo Leads on seabird bycatch and catch rates in the Korean tuna longline fleet. Lumo Leads (previously called "safe leads") add weight to longlines by threading the line through a channel, rather than crimping to the line. This can reduce flyback speed and improve crew safety. Lumo Leads also provide protection from exposure to lead weights, and contain optional fluorescent dye to provide an alternative to single-use glow sticks or electric lights.  Unweighted branch lines caught more than twice the number of seabirds compared to weighted branch lines, although branch weighting alone was not able to completely reduce bycatch. Adding more weight and placing weights closer to the hook increased branch weighting effectiveness as a bycatch mitigation technique. However, catch rate for albacore tuna on weighted lines was significantly lower than on unweighted lines. Catch rate also decreased as weight of the leads increased. There was no effect of branch weighting on catch rates for southern bluefin tuna or yellowfin tuna.