The study tested the use of a horizontally divided codend with small square mesh (40mm) and a simple frame to stimulate fish to swim into the upper compartment of a separator trawl. The majority of fish were separated successfully from Nephrops norvegicus, but fish preference for both trawl compartments was uniform. Additionally, separation efficiency was lower for small roundfish and flatfish.
This study investigated the efficiency of a sieve‐panel to separate bycatch species from Norway lobster (Nephrops norvegicus) in trawl gear via mechanical and behavioral means. Four different designs of varying panel mesh size or inclination were tested. The sieving efficiency for Nephrops increased from ~17% to ~71% as mesh size increased, and decreased with increasing carapace length, but did so less as panel inclination and mesh size increased. The sieving efficiency for roundfish was low, while the efficiency for flatfish decreased with fish size.
The experiment aimed to determine what size of cull ring would reduce the catch of pre-recruit stone crab (Menippe mercenaria) and other bycatch while maintaining legal-sized catch. Catch compositions of crabs from unmodified plastic commercial stone crab traps and traps fitted with three sizes of cull rings were compared in the stone crab fishery across Florida’s west coast. Traps outfitted with cull rings retained bigger crabs, had less bycatch, and fewer pre-recruit crabs, while yielding the same number of legal-sized crabs as traps without cull rings.
Data was collected on the relative performance of single and multiple round, rectangular, and square escape gaps across three fishing operations. Compared to control traps, those with escape gaps maintained catches of legal-sized P. pelagicus, but caught 51–100% fewer undersized individuals. Generally, rectangular escape gaps and especially multiple configurations were the most effective. Escape gaps represent a low-cost option for minimizing interactions with unwanted catches throughout the fishery.
The individual and cumulative effects of increasing mesh size and installing three escape gaps (36 × 120 mm) in collapsible‐netted round traps were assessed to address concerns associated with excessive discarding in an Australian portunid fishery. Compared to conventional traps of 56‐mm mesh throughout, those with the same mesh size and escape gaps caught significantly fewer (by 54%) undersized blue swimmer crabs, Portunus armatus, and yellowfin bream, Acanthopagrus australis (by 64%).
The study compared the efficiency of five models of pots designed to catch Atlantic cod (Gadus morhua) for use in Newfoundland and Labrador‘s cod fishery. Catch per unit effort (CPUE), total lengths of cod, and bycatch rates were compared across each pot type. All pot types were successful at catching cod, but two models (a modified Newfoundland-style pot, which used 58mm clear monofilament entrance funnels, a mesh separator panel, and two bait bags; and a four-entrance pot) had the highest CPUE.
The study assessed the efficacy of applying bird scaring line regulations from the demersal longline fishery in Alaska to a similar fishery along the U.S. West Coast. However, unlike in the Alaskan sablefish fishery, some U.S. West Coast sablefish vessels utilize floated longlines. Results from the study confirmed that bird scaring regulations from Alaska were sufficient to protect baits from bird attacks on longlines without floats, but not baits with floats.
A meta-analysis of 15 papers examined the general impact of seabird BRD technology upon commercial longline fishing operations. Since there were relatively few papers with data suitable for meta-analysis, the researchers pooled studies with BRD-and fishery-related metrics included as covariates. The analysis found a small (9%) increase in target catch with BRD use in longline fisheries, while seabird bycatch was reduced by 89%.
The ability of little penguins (Eudyptula minor) to distinguish differently colored netting materials was tested under controlled conditions to test gillnet color as a potential bycatch mitigation technique. Clear, green, and orange colored monofilament were tested in the form of a gillnet mimic in an enclosed tank containing 25 penguins. Orange colored monofilament line resulted in lower collision rates with the gillnet mimic (5.5%) in comparison with clear (35.9%) and green (30.8%) monofilament lines.
A computer model was produced to provide insight into how the Critically Endangered North Atlantic right whale (NARW) becomes entangled. It allows an anatomically accurate model of a NARW Population estimates of the critically endangered North Atlantic right whale to "swim" into fishing pot ropes, that incorporate realistic physical properties and can generate measures of physical forces (such as rope tension).
Please enter your article summary here
This study examined spatial interactions between false killer whales (Pseudorca crassidens) and the Hawaii-based deep-set longline fishery. False killer whales occur as bycatch in this fishery that exceed allowable levels. Five satellite tagged whales (occurring within three groups) in combination with logbook entries showed that only two groups of whales approximated gear at a distance closer than 50km. On two occasions whales from one group came close enough to interact with gear, and one of six sets involved had no catch which may be explained by depredation.
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.
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 deterrent, circle hooks may increase survivaility post-hooking.
This study combines government reports, published journal articles, and data from a questinnaire administered to the fishing industry to assess marine mammal bycatch in Chile.
A fish selector reduced bycatch by 60% in the Seattle salmon gillnet fishery.
A fish selector reduced bycatch by 60% in the Seattle salmon gillnet fishery.
Illuminated nets were tested to evaluate their effect on catch and bycatch in set nets, principally green and loggerhead sea turtles, in northern Cyprus. Reductions in the catch of sea turtle and non-target sharks and rays were recorded with no effect on target catch. Data were collected from 130 field sets thst occurred over a two-year period. Experimental effort should be expanded to better ascertain the relationship between the illuminated devices used and sea turtle bycatch reduction.