Population dynamics of the garfish,Belone euxini(Belonidae: Belone) from the south-east Black Sea

Abstract

To describe the age, growth, mortality and distribution of the garfish, Belone euxini and differences in these parameters from other populations, monthly samplings were conducted between December 2011 and July 2013 in the south-east Black Sea. Garfish catch decreased to its lowest levels in spring months, especially after May, and it was completely finished by the summer months. The mean total length (TL) of the female was significantly greater than the mean TL of the male (P < 0.05). The sex-ratio of female:male with size was skewed towards males up to 38 cm length-class, and skewed towards females above the 38 cm class (P < 0.05). The growth pattern of garfish was described by goodness of fit of the data and biological interpretation of growth parameters. The exponential (females: L∞ = 88.3 cm TL, K = 0.108 yr−1, males: L∞ = 71.9 cm TL, K = 0.151 yr−1) and von Bertalanffy (females: L∞ = 81.6 cm TL, K = 0.125 yr−1, t0 = −2.25 year, males: L∞ = 81.6 cm TL, K = 0.125 yr−1, t0 = −2.13 year) models were considered the most suitable growth models. Total instantaneous mortality rate, Z, was estimated as 1.04 yr−1 for females and 1.24 yr−1 for males. Instantaneous natural mortality ratio, M, was estimated higher for males than for females. The exploitation rate of both sexes was also higher than the optimum exploitation (E = 0.5) criterion, which is indicative of overfishing of the garfish population.

Comparison of four nonlinear growth models for effective exploration of growth characteristics of turbot Scophthalmus maximus fish strain

“…Using this criterion, the best model is the one with the lowest AIC results. AIC was calculated as (Bilgin et al, 2014):…”

“…The nonlinear growth models which have been extensively used in fish are Chapman-Richards (Richards, 1959), Gompertz (Gompertz, 1825), Logistic (Richards, 1959) and von Bertalanffy (Bertalanffy, 1938) models. The characteristics of these models have been studied in detail by Fitzhugh (1976), Deniel (1990), Tsangridis and Filippousis (1994), Imai et al (2002), Tsoularis and Wallace (2002), Katsanevakis and Maravelias (2008), Lin and Tzeng (2009), Helidoniotis et al (2011), Baer et al (2011), Bilgin et al (2014, Figueiredo et al (2014), Ansah and Frimpong (2015); Drew et al (2015), and Lugert et al (2016). Moreover, some relevant mathematical formulas reflecting biological growth characteristics, such as time to inflection point, weight at inflection point, instantaneous growth rate and relative growth rate were reported by various authors (Fitzhugh, 1976;France et al, 1996;Tsoularis and Wallace, 2001;Koya and Goshu, 2013).…”

“…Various nonlinear growth models have been proposed to explain the growth pattern of individuals for a particular species (Bilgin et al, 2014). Growth pattern of turbot or other flatfish species are mainly described by von Bertalanffy model (Deniel, 1990), von Bertalanffy, Schnute, and Gompertz model (Baer et al, 2011) and logistic, Gompertz, von Bertalanffy, Kanis, and Schnute models (Lugert et al, 2016), due to goodness of fit of the data.…”

Histology of the digestive system of the garfishBelone belone(Teleostei: Belonidae)

“…The garfish, Belone belone, is a pelagic fish widely spread in the north-eastern Atlantic, Mediterranean (Collette & Parin 1970;Zorica et al 2011;Zorica & Čikeš Keč 2012). In the Black Sea, the Sea of Azov and the Sea of Marmara, Belone euxini (Günther, 1866) was reported (Bilgin et al 2014). This fish species is usually found in offshore areas, except during spawning period when it migrates into coastal regions (Zorica et al 2011;Zorica & Čikeš Keč 2012).…”

Untitled

“…Data concerning population dynamics details such as length and age structure, sex ratio, growth and mortality rate of B. euxini have been published (Bilgin et al, 2014), while data describing this species' reproduction biology such as fecundity and egg size, fist maturity size, spawning time and annual number of spawning are presented here.…”