Co-variation of gonadosomatic index, condition factor and length-weight relationships of poor cod, Trisopterus minutus (Gadidae), in the Eastern Adriatic Sea
Monthly changes in length-weight relationships (LWRs), gonadosomatic index (GSI) and condition factor in the poor cod Trisopterus minutus (Linnaeus, 1858) were studied. A total of 1263 specimens (463 males and 800 females) ranging from 8.9 to 25.5 cm in total length (TL) were collected in the eastern Adriatic Sea. Samples were taken at monthly intervals (January-December 2007) using bottom-trawls. In total sample, the b values of LWRs showed that growth of both males and females was isometric. Allometric parameters of b values varied during the year; positive allometric growth was noted in winter (February and March), while in summer (July and August) negative allometric growth was observed. The GSI reached the highest values in February and the lowest values in September. The condition factor was low immediately after spawning (May and July) and high at the recovery phase (August). Seasonal variation of LWRs and condition factor of poor cod were connected with gonadal change as well as feeding activity and energy distribution. During summer and autumn, food energy is spent in somatic growth, while in winter it is converted in gonad development.