DISCARDS FROM BEAM TRAWL FISHERIES IN THE GERMAN BIGHT (NORTH-SEA)

Discards from beam trawl fishery were estimated for 1990 and 1991 usin g data from surveys with FRV ''Solea''. These catches were carried out by simulating commercial conditions. AU fish species, starfish and sw imming crabs were artificially split into discards and marketable frac tions. For 1 kg of sole (Solea solen), the main target species in this fishery, there were G. I kg of flatfish discards (both years), 0.5 kg of roundfish discards (both years), 4.3 kg (1990) or 10.7 kg (1991) o f starfish discards, 0.5 kg (1990) and 0.1 kg (1991) of swimming crab discards and 1.1 kg (1990) or 1.3 kg (1991) of marketable plaice (Pleu ronectes platessa). Plaice, dab (Limanda limanda) and flounder (Platic hthys flesus) dominated the discards fraction. The total mass of disca rds in the German Bight in 1991 was estimated at 36 000 t fish, 58 000 t starfish and 800 t swimming crabs; the number of individuals to 420 million fish, 5800 million starfish and 120 million swimming crabs. T he reliability of catches by fishery research vessels for estimating d iscards in commercial fisheries is discussed.