Recovery and escape sizes of Croakers ( Family; Sciaenidae) caught by modified shrimp beam trawl codend with excluder device in the Nigerian nearshore sea

Abstract

Fishing activities were done in nearshore sea (<20m depth <2 nautical miles) to determine the size and quantity of croaker, Pseudotolithus Spp by-catch caught by a modified shrimp beam trawl with excluder device. Data from 30 replicate landings indicated that the quantity of croakers recovered increased inversely with the quantity escaping for all size ranges. Croakers having size ranges of 1 to 15cm were highly released, while 16 to 30cm were retained in the codend. By-catch of P.elongatus with size range of 26 to 30cm did not occur in the fishery.At size ranges of 21 to 25cm and 26 to 30cm, P.senegalensis have 100% selectivity. P.typus size range of 1 to 5cm did not occur in the fishery, at size ranges of 21 to 25 cm and 26 to 30cm, its selectivity was 100%. Size range at first capture for the three-croaker by-catch species is 11 to 15cm. The results are discussed in terms of the effects that the size range of croaker by-catch exploited in the fishery have on other Nigerian fisheries targeting mature stock of croaker.

Key words: Size selectivity, Croaker, Recovery, Escape, Shrimp trawl, excluder device