Karadeniz'de 2013-2014 Av Sezonunda Avlanan Hamsinin (Engraulis encrasicolus) Büyümesinin ve Ölüm Oranlarının Farklı Modellerle Belirlenmesi

Determination of Growth and Mortality Rates of Anchovy (Engraulis encrasicolus) Caught in the Black Sea in 2013- 2014 Fishing Season with Different Models

Özet

Bu çalışma, Eylül 2013 ve Nisan 2014 tarihleri arasında Doğu Karadeniz sahillerinde avcılık yapan ticari gırgırteknelerinden örneklenen hamsi balığının yaşa dayalı altı farklı büyüme modeline göre (von Bertalanffy, Gompertz, Lojistikya da Richards, Üssel, Morgan Mercer Flodin ve Weibull) büyümesi ve dört ölüm oranı modelline göre (Pauly, 1980; Djabalivd., 1993; Alagaraja, 1984 ve Srinath, 1998) ölüm oranının belirlenmesi amacıyla yürütülmüştür. Toplamda 5486 balıkörneklenmiş ve 1265 balığın yaş tayini yapılmıştır. Dişilerin ortalama boyu erkeklerden daha büyük hesaplanmıştır (P

Abstract

This study was conducted to describe age-based growth by six different growth models (von Bertalanffy, Gompertz, Logistic or Richards, Exponential, Morgan Mercer Flodin, Weibull) and mortality by four different empirical mortality models (Pauly, 1980; Djabali et al., 1993; Alagaraja, 1984; Srinath, 1998) of the anchovy obtained from commercial purse seine between September 2013 and April 2014 on the coast of the Eastern Black Sea. Of the 5486 sampled fish, the age of 1265 (824 females, 441 males) was determined. The mean total length (TL) of females was significantly greater than the mean total length of males (P < 0.05). The Weibull (AIC = 2593.5; L∞ = 19.6 cm and K = 0,031 year-1 ) and Morgan Mercer Flodin (AIC = 2593.8; L∞ = 17.0 cm and K = 0.108 year-1 ) models for males, the von Bertalanffy (AIC = 5725.4; L∞ = 11.1 cm and K = 2.064 year-1 ) and Exponential (AIC = 5725.4; L∞ = 11.1 cm and K = 2.065 year-1 ) models for females considered as the most suitable growth models. The total instantaneous mortality rate calculated by the catch curve method, Z, was estimated higher for females (3.5 year-1 ) than males (3.3 year-1 ). Instantaneous natural mortality ratio, M, was estimated lower in Djabali et al. (1993) model and highest in Srinat (1998) model for both sexes. Natural mortality rates calculated using different growth model parameters and exploitation rate (E) values calculated using M data showed that the anchovy stock was exploitation at a higher degree than the optimum exploitation (E = 0.5) criterion, which is indicative of overfishing in the anchovy population in the 2014-2015 fishing season.