Some population parameters of Scyliorhinus canicula(Linnaeus, 1758) from the northeastern Mediterranean Sea
Ebru Ifakat Ozcan, Nuri Başusta
Fisheries Faculty, Munzur University, Tunceli, TURKEY
Fisheries Faculty, Firat University, 23119, Elazig, TURKEY
A total of 1150 lesser spotted dogfish (Scyliorhinus canicula L., 1758), (562 female, 588 male) were collected by commercial trawlings in depths of 155-400 m in the Northeastern Mediterranean Sea between March 2012 and May 2014. Total length and weight of the fish were ranged from 12.0 to 51.0 cm and 4.13 to 396.0 g, respectively. It was determined that female/male ratio was 1:1.2. Monthly length frequency data of S. canicula were analyzed using FISAT II for estimating population parameters, including asymptotic length (L∞), growth coefficient (k) and recruitment pattern to assess the status of the stock. The parameters of von Bertalanffy growth equations were estimated as L∞=56.70 cm, K=0.20 year-1 and t0= -1.60 year and W∞= 622.01 g. The growth performance index (Ф’) value was calculated as 2.808. Length-weight relationships was found to be W=0.0013*L3.239 (R2=0.97), SE of b=0.016 and 95 % confidence intervals of b = 3.209-3.271. The type of growth shows positive allometric growth (b>3). Catch rates were calculated as 34.94 cm for females and 35.04 cm for males. Instantaneous mortality coefficient, natural mortality (M), fishing mortality coefficient (F) and total mortalities (Z) exploitation rate were estimated of S. canicula as Z = 1.06 year-1, M = 0.47 year-1, F = 0.59 year-1. The exploitation rates (E) was determined as 0.56 year-1. Therefore on the S. canicula distributed in Iskenderun Bay were under fishing pressure.
Keywords: Scyliorhinus canicula, growth, length-weight relationships, mortality, catch rate