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Age and growth of Venus verrucosa L. (Bivalvia: Veneridae) in the northern Adriatic, Pula

Age and growth of the warty venus Venus verrucosa (LINNAEUS, 1758) was investigated on specimens collected from a commercial catch near Pula (northern Adriatic) in the February 2006. Shells were aged based on internal annual growth lines revealed by shell sectioning of the right valve. On every specimen, distances between each growth line and umbo were measured. In addition, age and growth were estimated from growth increments using Gulland-Holt method. Length of analysed V. verrucosa ranged from 37.1 to 52.0 mm (x±sd = 43.8±4.22 mm), while estimated age ranged from 4.5 to 11.5 years (x±sd = 7.5±1.63 years). The age structure of the catch was dominated by the sixth-age-class (28%) with the average length of 42.6 mm. Older specimens (age class ten and eleven) represented a small proportion of the catch (~5%). Results of this study indicate that V. verucossa reaches the minimal landing size of 25 mm in its second year. With respect to the methods applied, obtained von Bertalanffy equations for length were: according to direct analysis of growth lines equation Lt=48.85 (1-e-0.329(t+0.283)) and according to Gulland-Holt method equation Lt=49.14 (1-e-0.313(t-to)). These equations did not significantly differ from each other, ф’1= 6.67 and ф’2= 6.63.

bivalve ; Venus verrucosa ; age ; growth ; northern Adriatic

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