Some biological aspects of penaeid shrimps inhabiting Yumurtalik Bight in Iskenderun Bay (north-eastern Mediterranean)

The species composition, size frequency distribution and length/weight relationships for each sex, size at first sexual maturity, and spawning seasons of the commercially important shrimp species inhabiting Yumurtalik Bight of the Nort-eastern Mediterranean were studied. Two penaeid shrimp species, Penaeus semisulcatus and Metapenaeus stebbingi, dominated the catches. Only a few individuals of Metapenaeus monoceros were captured during the study. The minimum size at first maturity was estimated to be 130 mm total length (TL) for P. semisulcatus and 55-60 mm TL for M. stebbingi. The size which 50% of the population is mature is 36 mm carapace length (CL) for P. semisulcatus and 15.4 mm CL for M. stebbingi. The highest proportion of mature females was encountered between the early spring and summer months when mater temperatures were relatively high. Most mature spawners were captured at a water depth of 5-10 m for M. stebbingi and 20-30 m for P. semisulcatus. The results showed that while P. semisulcatus does not spawn in the bight in winter months, M. stebbingi was not present in the bight from September through the winter months