Comparison of weight-length relationships and relative growth between intertidal and offshore populations of Hexaplex trunculus (Gastropoda: Muricidae) from the Gulf of Gabès (southern Tunisia)

Abstract

The present study reports weight-length (W-L) relationships and discusses the relative growth of the banded murex (Hexaplex trunculus) from intertidal and offshore areas of the Gulf of Gabes (southern Tunisia). Overall, 9634 H. trunculus were sampled (6608 from intertidal and 3026 from offshore), with both populations comprising broad ranges in shell length (intertidal: 13.6–78.5 mm; offshore: 22.9–91.1 mm) and total weight (intertidal: 0.2–63.8 g; offshore: 0.6–92.5 g). In both populations, W-L relationships were highly significant and the morphometric parameters were highly correlated (intertidal: r = 0.967; offshore: r = 0.973). Relative growth was significantly different between populations, with intertidal H. trunculus displaying a negative allometry (b = 2.962) and offshore H. trunculus exhibiting isometric growth (b = 3.013). Factors influencing total weight (soft-body weight and shell weight) and potentially responsible for differences in W-L relationships and relative growth between populations were discussed. In addition, a useful comparative analysis for fisheries biology, assessment and management purposes was performed with analogous information from other populations of H. trunculus from the Mediterranean Sea and the Atlantic Ocean.