Age, growth and mortality of a semi-isolated lagoon population of sand smelt, Atherina boyeri (Risso, 1810) (Pisces: Atherinidae) in an estuarine system of northern Greece

Age, growth and mortality of the sand smelt, Atherina boyeri (Risso, 1810), were studied in the Vistonis estuarine system in northern Greece from February 1989 to August 1990. Overall male : female sex ratio was 1 : 2.5, statistically different from unity. Total lengths ranged between 13 and 105 mm. Age determination based on scale readings showed that the population comprised five age‐groups. Sand smelt grew allometrically (b = 3.22) and rapidly during the first year, achieving 60% of their growth. Growth parameters of the population were: L_∞ = 116.97 mm, K = 0.35 year⁻¹ and t_o = −0.99 years. Growth index ϕ′ was 3.69 of all individuals studied. The mean growth index was significantly lower for the Mediterranean lagoon (ϕ′ = 3.73, SD = 0.1) than for Atlantic populations (ϕ′ = 3.92, SD = 0.06). Total mortality rate was Z = 1.29 year⁻¹ and natural mortality M = 0.95 year⁻¹. Males had a lower life span than females, the latter dominating length classes >60 mm. Exploitation rate of the studied population was E = 0.26, suggesting that stock size might increase and generate improved possibilities for exploitation.