Gillnet Bycatch Research Articles

Bycatches of common guillemot (Uria aalge) in the Baltic Sea gillnet fishery

Bycatch of common guillemots (Uria aalge) appears to be the single most serious threat to the population, and the proportion of recoveries of ringed birds in fishing gear, compared with other finding circumstances, has significantly increased during a 28 year period (P<0.01). Out of 1952 ringed common guillemots reported found between 1972 and 1999 in the Baltic Sea, 980 (50.2%) were caught in fishing gear. The bycatch in set gillnets for cod (Gadus morhua) constituted 22.3%, drift gillnets for salmon (Salmo salar) 65.5%, and other fishing gear 12.2%. The proportion of recoveries in cod gillnets has significantly increased during the study period (P<0.05), while no clear trend was observed in the recoveries in salmon gillnets. The Swedish fishing effort follows a similar pattern for cod but has decreased for salmon. The observed increased use of cod gillnets in the Baltic Sea may have contributed to the observed decrease in adult survival rate, and we provide two different estimates suggesting that significant proportions of the guillemot population are caught annually in the Baltic Sea gillnet fishery. We suggest several available techniques to reduce bycatch in the Baltic Sea fishery.

Harbour porpoise (Phocoena phocoenaL.) by-catch in set gillnets in the Celtic Sea

A programme to assess the cetacean by-catch in the Irish and UK set gillnet fisheries in the Celtic Sea was conducted from August 1992 to March 1994 using volunteer observers. Observers were present for the hauling of over 2500 km of net which caught 43 harbour porpoises and four common dolphins, with one of each alive. The by-catch rate was 7.7 porpoises per 10 000 km · h of net immersion. A negative relationship was found between porpoise by-catch and tidal speed but no other relationships were found with operational or environmental variables. Spatial and temporal stratification of the by-catch rate and eVort data had a small eVect on estimated total by-catch, which was therefore estimated from pooled data. The estimated total annual by-catch of 2200 porpoises (95% C.I. 900‐3500) is 6.2% of the estimated number of porpoises in the Celtic Sea and there is serious cause for concern about the ability of the population to which they belong to sustain this level of by-catch. ? 1997 International Council for the Exploration of the Sea