Investigation of Length-Weight Relationships for 10 commercial fish species as a possible trophic state index of Coastal Lagoons

Abstract

          Length-weight (L-W) relationships were estimated and compared for 10 commercially important fish species caught during September-December 2004 from two lagoons in the Ionian Sea based on similar length ranges. The median value of the exponent b of the L-W relationships was 3.091 and ranged from 2.444 to 3.536. The larger specimens of the mid-trophic level species (i.e. Sparus aurata, Diplodus annularis and D. sargus) were heavier at the same length in the less eutrophic lagoon. In contrast, most of the low-trophic level species (i.e. Mugilidae) did not show significant (P>0.05) differences of the L-W parameters between the studied lagoons. The estimated parameters of the L-W relationships for each species between the two lagoons in relation to their trophic state are also discussed. Our findings indicated that the L-W relationships of the mid-trophic level species may be possibly used as an index of the trophic state in lagoons.