Age, growth and population structure of Acanthocardia tuberculata (Bivalvia: Cardiidae) in the eastern Adriatic Sea

A study of the age, growth and population structure of Acanthocardia tuberculata from the eastern Adriatic Sea was carried out. The condition index analysis identified one reproductive peak, which occurred between April and May, for a population of A. tuberculata in the Cetina River estuary with uni-modal recruitment. Annual growth rings on the external shell surface consisted of a dark ring deposited during the summer-autumn period and a light ring deposited during winter-spring. This was validated by acetate peels of shell sections and marginal increment analysis. Shell lengths of aged specimens ranged from 19.7 to 62.9 min (mean = 41.21+/-8.96 mm). Estimated ages ranged from 5 months to 11 years, with mean values of 2.1, 2.4 and 3.1 years for Rab Island, Pag Bay and the Cetina River estuary respectively. Shell deposition is fastest during the first two years of life and significantly decreases after the 4th year. The growth parameters L-infinity and k were estimated using the Gulland-Holt method and by fitting length at age data to a von Bertalanffy growth curve. Values of L-infinity, ranged from 52.6 mm (Rab Island) to 59.7 mm (Pag Bay). The growth constant k showed greater variations (0.49 to 0.77 year(-1)), while growth performance index values (empty set') ranged from 3.13 to 3.36.