Bottom trawl discards in the northeastern Mediterranean Sea

Discard practices of trawlers in three main areas of the Aegean and western Ionian Seas were examined. Data collected on board commercial vessels during 3 years (1995–1998) of seasonal (Autumn, Winter, Spring) monitoring were used to estimate discarded quantities. About 44% (range 39–49%) of the total catch was discarded at sea (13 500–22 000 t annually); the main component of the discards was fish. Hauls were classified into two main clusters using the discard quantities of fish, crustaceans, and cephalopods. The two clusters were discriminated by depth. Two sets of equations that classify new hauls in the clusters, using depths and duration of the hauls or marketable yield, were applied. The discarded yield of fish showed more precise relationships with their marketable yield in each season than did crustaceans and cephalopods. The latter were strongly affected by the specific characteristic of the different areas and clusters.