WIESŁAW Blady, Jan Netzel and Janusz Zaucha
Sea Fisheries Institute, Kołłątaja 1, 81-332 Gdynia, Poland

Key words: cod gillnets, cod selectivity, set gillnets, cod catches

Abstract.
This paper presents the results of investigations which were carried out in the Baltic Sea in 1994 - 1995. The results show that cod length in catch depends on mesh sizes rather than on the type of gillnet material. With mesh sizes of 45 mm (bar length) the average cod length in the catch was 41 cm, while with a mesh size of 65 mm, the average cod length was about 53 cm. The results of the investigation show that gillnets are characterized by very good selectivity; this is confirmed by the selectivity coefficients that range from 3.9 - 4.5. The by-catch of undersized cod specimens was usually low for all analyzed gillnets. Most important, fishermen accept the present allowable mesh size of 105 mm (mesh opening) in the cod gillnets and this mesh size is sufficient to protect the cod of a total length of over 35 cm.