Information on the deep-water giant red shrimp Aristaeomorpha foliacea (Risso, 1827) (Crustacea, Decapoda, Aristeidae) population in Antalya Bay (Eastern Mediterranean Sea, South of Turkey) based on the MEDITS protocol

Abstract

The main aim of this study was to contribute to the current knowledge on the population of Aristaeomorpha foliacea in Antalya Bay located on the southern coast of Turkey in the Mediterranean Sea. Monthly samples were collected between July 2016 and July 2017 from experimental trawl surveys in accordance with the International Bottom Trawl Survey in the Mediterranean (MEDITS) protocol. The abundance index was calculated as 4308.6 N/km 2 and the biomass index as 66.8 kg/km 2. The relationship between total weight (TW) and carapace length (CL) was estimated to be TW = 0.00078⋅CL2.76 for females and TW=0.00049⋅CL2.92 for males. The seasonalized von Bertalanffy growth parameter estimates were CL∞=66.12mm, K=0.43 years −1, tanchor=0.36 years, C=0.63 and ts=0.21 years for females, and CL∞=44.02mmK=0.39 year −1, tanchor=0.30 years, C=0.77 and ts=0.87 years for males. Female shrimps grew slightly faster and reached a larger asymptotic size hence exhibiting a greater growth performance than males. The spawning season was determined as the summer. Recruitment took place in spring, and the sex ratios were found to be 1.29:1 in favor of males. The median size at first maturity was estimated as 37.7 mm CL for females and 30.1 mm CL for males. The annual total mortality rate was 1.66 and 1.41, the annual natural mortality rate 0.57 and 0.72, and the exploitation rate 0.66 and 0.49 for females and males, respectively. The fishing ground for A. foliacea in Antalya Bay is situated within 12 nautical miles off the shore within the territorial waters, thus closed to commercial trawl fisheries between 15 April and 15 September in accordance with the Turkish fishery regulations. The closing period, which coincides with the spawning season and also provides a reduction in the fishing pressure, is clearly of great importance for the sustainability of this species in Antalya Bay.