engleski

Seasonal variation of gonado-somatic index and length-weight relationship in the horse mackerel, Trachurus trachurus (Osteichthyes: Carangidae) from the eastern Adriatic Sea

Seasonal changes in length-weight relationships (LWRs), gonadosomatic index (GSI) and condition factor in the horse mackerel Trachurus trachurus (Linnaeus, 1758) were studied. A total of 1136 specimens (580 males and 556 females) ranging from 15.7 to 37.0 cm in total length (TL) were collected in the eastern Adriatic Sea. Samples were taken at monthly intervals (January-December 2004) using bottom-trawls. The GSI reached maximum values in March and minimum in September. Including specimens collected in all seasons, the b values of length-weight relationships (W = aLb) showed that growth of both males and females was isometric i.e., equal in length and weight. Allometric parameters of b values varied during the year ; positive allometric growth was noted in winter, while in late spring (May) and summer (June and July) negative allometric growth was observed. The condition factor was lowest immediately after spawning (July) and highest at the recovery phase (September). Seasonal variation of LWRs and condition

Length-weight; gonads; Tracurus trachurus; Adriatic Sea

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