Weight-length relationships and condition factor trends for thirty-eight fish species in trawled and untrawled areas off the coast of northern Sicily (central Mediterranean Sea)

Abstract

Summary This paper reports the weight-length relationship (WLR) for thirty-eight fish species from the Gulf of Castellammare (NW Sicily, Mediterranean Sea). A total of 59 870 fish were collected and measured during four seasonal trawl surveys carried out in 2005 at 10 to 200 m depth. The b parameter of the WLRs ranged from 1.79 (Cepola macrophthalma) to 3.56 (Conger conger). Significant differences in both a and b values among seasons were detected for eight species. Moreover, the condition factors (as weight-at-length) of Merluccius merluccius and Mullus barbatus were compared in different area/year combinations characterized by the presence or absence of trawling impact. While M. barbatus showed a higher condition factor in trawled areas/years, possibly due to density-dependent factors linked to the increased biomass in the no-trawl area, no such link was detected in M. merluccius.