Over time, noxious bait, consisting of dead steelhead containing lithium chloride, did not prevent California sea lion (Zalophus californianus) predation of Washington steelhead trout (Salmo gairdneri). Acoustic harassment devices worked only for a short time in reducing California sea lion depredation before sea lions began to habituate to sounds.
December 2025
Reducing seabird bycatch in longline fisheries using a natural olfactory deterrent
School shark (Galeorhinus galeus) liver oil dripped behind fishing vessels in the northern New Zealand snapper (Pagrus auratus) longline fishery reduced seabird numbers and dives on baits when compared to canola oil and seawater control treatments. The shark liver oil did not affect the number of target snapper, gurnard (Chelidonicthys kumu), kaha-wai (Arripis trutta), or […]
Study on the methods to mitigate the bycatch of juvenile bigeye tuna by introducing Double-FADs with light stimulus for tuna purse seine fishery in the Western and Central Pacific Ocean
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 […]
Assessment of modified gillnets as a means to reduce bycatch in southeastern North Carolina coastal waters
Gillnets with three difference mesh sizes (2 7/8″, 3″ and 4″) were modified to use 200 lbs/200 yard lead line and 11 oz buoyancy floats (versus 50lbs/200 yard lead line and 3 oz floats) to increase the tension in the net. Catch rates of Atlantic sharpnose and bonnethead sharks were significantly lower in the 4″ […]
Bycatch in drift gillnet fisheries: A sink for Indian Ocean cetaceans
In the Indian Ocean tuna gillnet fisheries, cetacean bycatch is very high, but it is understudied and poorly understood. This paper investigates the issue and makes specific recommendations to strengthen knowledge and management: improve catch and bycatch reporting, increase research and analyses of cetaceans in the region in order to assess bycatch, revise the conservation […]
Do by-catch reduction devices in longline fisheries reduce capture of sharks and rays? A global meta-analysis
A meta-analysis of online publications revealed only one technique to be effective as a bycatch reduction device in longline fisheries, which involves raising demersal longlines off the seafloor using flotation. Other techniques as BRDs include monofilament leaders which, like floating demersal longlines, are suggested as promising approaches for further evaluation. Although not effective as a […]
Behavioral responses of minke whales (Balaenoptera acutorostrata) to experimental fishing gear in a coastal environment
Field experiments were conducted to determine behavioral responses of minke whales to experimental ropes and buoys made up of different colors, simulating those used in crab and whelk fishing gear. Trials were conducted with yellow, orange, green, blue, white and black ropes. Visual and acoustic monitoring was used to assess behavioral responses of whales to […]
Case Studies in North Atlantic Right Whale Fishing Gear Entanglements
Entanglement in commercial fishing ropes threatens the recovery of the North Atlantic right whale (Eubalaena glacialis), a species largely restricted to waters off of eastern North America. In recent years, serious entanglements have been increasing, and mortality from conflicts with fishing operations exceeds US legal mandates, with 83% of the population showing incidence of scarring […]
Pelagic gillnet modification trials in northern Australian seas
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 […]
Comparison of three seabird bycatch avoidance methods in Hawaii pelagic longline fisheries
Side-setting in combination with a bird curtain resulted in the lowest seabird– Black-footed albatross (Phoebastria nigripes) and Laysan albatross (Phoebastria immutabilis)–capture rate when placed on pelagic longline gear for tuna and swordfish in Hawaiian waters when compared to underwater setting chutes and blue-dyed bait.
Trial setting of deep longline techniques to reduce bycatch and increase targeting of deep-swimming tunas
Pelagic longlines were weighted with lead weights, enabling them to fish deeper in the water column than traditional pelagic longlines. Weighted longlines caught 31 target species with a slightly higher catch per unit effort (CPUE) of 1.3 fish/100 hooks (49 kg/100 hooks) compared to traditional gear (38 target species and a CPUE of 1.08 fish/100 […]
Incidental catch of marine turtles by Spanish bottom trawlers in the western Mediterranean
A questionaire administered to the bottom trawling fleet in the western Mediterranean (northeastern Spain) reported 238 bycacth events involving loggerhead sea turtles (Caretta caretta), calculated as a monthly CPUE of .09. The authors dicuss this figure relative to nearby coastal regions and suggest some possible mitigation measures.
Performance in 2005 of an alternative leader design on the bycatch of sea turtles and the catch of finfish in Chesapeake Bay pound nets, offshore Kiptopeake, VA: Data and results of preliminary analyses
An alternative leader design reduced loggerhead (Caretta caretta) sea turtle interactions in a Chesapeake Bay pound net fishery for finfish. There was no change in catch of weakfish (Cynoscion regalis), croaker (Micropogonias undulates), and harvestfish (Peprilus alepidotus).
International Marine Mammal – Gillnet Bycatch Mitigation Workshop
Fisheries bycatch is the principal threat to many marine mammals. In some cases, bycatch reduction devices have been shown to mitigate the bycatch of non-target species, but the scale of the problem outpaces progress in finding solutions. In particular, bycatch in coastal gillnet fisheries is one of the most immediate threats facing many marine mammal […]