Maturation, reproduction and recruitment of the sand smelt, Atherina boyeri Risso, 1810 (Pisces:Atherinidae) in the estuary of Mala Neretva River (southeastern Adriatic, Croatia)

Abstract

          Characteristics of maturation and recruitment of the sand smelt, Atherina boyeri, from the Mala Neretva River estuary in the southeastern Adriatic, Croatia in 2001/2, are presented. The average gonadosomatic index (GSI) during a 12-month period was 1.59% for females and 2.1% for males. The highest value was in April, 5.4% for females and 4.7% for males. The smallest mature female was 5.2 cm total length. Fifty percent of the females were mature at 7.75 cm total length. New juveniles began to recruit in June and July and later appeared in fewer numbers. In general, the GSI was lower than in other sand smelt populations. The reasons are difficult to determine but might be partly explained by the high and unpredictable temperature and salinity variations in the researched area that have led to previously described disturbances of the sand smelt life cycle, as in feeding and a high incidence of spinal deformities.