Size at sexual maturity in the queen conch Strombus gigas from Colombia

Abstract

Size at sexual maturity was investigated in 346 queen conch, Strombus gigas, collected from the Archipelago of San Andres, Providencia and Santa Catalina (SAI), Colombia. Size at sexual maturity is defined as the size (based on total shell length and lip thickness) at which 50 % of the population of queen conch sampled had mature and emission gonad developmental stages, based on microscopic examination (samples of gonads were processed by standardized histological methods). Only 12.14% of whole samples had mature and emission gonad developmental stages. The size at sexual maturity based on total shell length (STmat) was estimated to be STmat=249 mm for females (n=14), STmat=234 mm for males (n=28) and STmat=241 mm for both sexes (n=42). Lip thickness (LTmat) at sexual maturity was estimated to be LTmat=17.5 mm for females, LTmat=13 mm for males and LTmat=13.5 mm for both sexes. STmat and LTmat for females were greater than those estimated for males, according to plot of the cumulative size frequencies. The maximum sizes that had mature gonad stage were 285 mm ST and 24 mm LT for males (n=2) and 280 mm ST and 30 mm LT for females (n=2). The present size restrictions adopted by some countries with queen conch fisheries is 5 mm LT and/or 180-250 mm ST, which is not adequate to protect conch stocks. A lip thickness of 13.5 mm or greater appears from this study as to be a better maturity criterion. Therefore, this criterion should be adopted by Caribbean countries as a fisheries management tool in order to protect the queen conch fishery and ensure sustainability of the fishery.