Spatial-temporal variations in population structure, abundance and catch rates of parapenaeus longirostris (Lucas, 1846) in the sea of Marmara

In this study, temporal and spatial changes of catch per unit effort (CPUE-kg/h), stock amount (biomass-kg/km2), population structure of Parapenaeus longirostris, and current situation of the stocks, effects of beam trawl were determined in the Sea of Marmara. Samples were obtained by beam trawls monthly between October 2011-July 2014 and population parameters; size distributions, length-weight relationships, condition factor, growth-mortality parameters and sex rates were determined. The catch per unit effort value (CPUE) and abundance index of deep water pink shrimp were found 8,5 kg/h and 1545 N/h in the Sea of Marmara. The highest CPUE values were estimated region 2 (10,1 kg/h) and region 6 (15,1 kg/h). The lowest value was in region 5 (3,4 kg/h). According to depth contours, catch per unit effort values were determined as 8.8 kg/h in 50-100 m, 7 kg/h in ≥100 m. Biomass of the species was found 354 kg/km2 in the Sea of Marmara. The maximum value of biomass were in Tekirdag and Silivri and the lowest value was in the Yalova.36288 individuals were measured, total length (TL), carapace length (CL) and weight (g) values were found as 34-175 mm (107 mm), 8-41 mm (22.6 mm), 0,2-28,9g (6,1g), respectively. Carapace length-weight relationship was calculated as W=0.0022*CL2.52. Growth parameters were determined as L∞=199,5 mm, k=0,47, t0=-0,5 in total length, L∞=36,8 mm, k=0,37, t0=-0.69 y in carapace length. Total mortality, natural mortality, fishing mortality and exploitation rates were found 1,60, 0,61, 0,99 and 0,62, respectively. Male-female ratio was found as 1:1,3.