Publication Abstract

The annual pattern of condition andmaturity in bass, Dicentrarchus labrax, in waters around England and Wales

M.G. Pawson and G.D. Pickett

Morphometric data onbass, Dicentrarchus labrax L. (Pisces: Percoidei), sampled around the coasts ofEngland and Wales between 1982 and 1990, have been analysed to elucidate seasonal patternsof feeding, body condition and gonad maturity. The somatic condition and fat reserves ofbass in the Irish Sea and southern North Sea improved more rapidly during the spring andsummer than in bass further to the south. In winter, however, fat reserves were higher andthere was more food in the stomachs of bass caught in the western English Channel. Theonset of maturity was related to fish length. Male bass became mature for the first timeat 32-36 cm total length, but though many females showed signs of gonad growth at thissize, no female <42 cm was found with mature (ripe or spent) gonads. Gonad developmentin adult bass of both sexes began in October and, from January until June, most males>36 cm had ripe testes. The period during which ripe eggs could be expressed from theovaries of female bass was briefer, with spawning apparently peaking in April. It isconcluded that the migration of adult bass to the north in spring and southwards andwestwards in autumn has both growth and reproductive benefits related to sea temperature,and that the more limited movements of bass <42 cm, which remain in relatively cold,inshore waters in winter, results in an inhibition of gonad maturity in females.

Reference:

M.G. Pawson and G.D. Pickett, 1996. The annual pattern of condition and maturity in bass,Dicentrarchus labrax, in waters around England and Wales. Journal of the Marine BiologicalAssociation of the UK, 76: 107-126.