Length-frequency distribution, growth and sex ratio of sand smelt, Atherina boyeri Risso, 1810 (Pisces: Atherinidae) in four Mediterranean lagoon systems

The sand smelt, Atherina boyeri (Risso, 1810), is a small, short-lived euryhaline teleost fish, common in the Mediterranean coastal lagoon. Sand smelt is a resident species which completes the entire life cycle within these systems. The populations of this species are intensive exploited by artisanal fisheries in the lagoons of central-southern Italy. The aim of study has been to obtain information about the population structure of sand smelt in four Italian lagoon systems. Fogliano and Caprolace lakes are very small and hypersaline environments belonged to Circeo National Park lagoon systems. Lesina and Varano lagoons are more extensive but with lower salinity values belonged to Gargano National Park. Lesina Lagoon is shallow, while Varano Lagoon is deeper than the four systems. Samples of sand smelt were collected using fike-nets. In the laboratory, specimen total lengths were measured to the closest 0.1 mm. Total body weight was measured to the closest 0.01 g. Sex and gonad maturation were macroscopically identified in the samples. Sex ratio was determined and the chi-squared test was used to determine whether the sex ratio varied from 1:1. Length-frequency distribution of each population was represented and length-weight relationships were calculated using the logarithmic form of the formula: W = a x TLb. Some differences between the population structures of sand smelt in the four lagoon systems were found.