Abstract Biomass of the coastal fish fauna of Gokgeada Island was seasonally investigated at different stations between August I 995 and June 1996. Fish species were collected by means of trammel net and gill net from 6 stations around the island. Biomasses of the 59 species were calculated (260.647 g). Seasonal productivity index (P') among the stations was determined by means of Shannon-Weaver Index. Productivity index was the highest in the spring at the stations I (P'; 3.995) and III (P': 3.673).