engleski

Age, growth, and population structure of the smooth clam Callista chione in the eastern Adriatic Sea

The age, growth, and population structure of the smooth clam Callista chione were determined from samples collected by hydraulic dredge and SCUBA at four locations in the eastern Adriatic during 2007 and 2008. The age of 436 clam shells was determined from internal growth lines present in shell sections and the timing of growth line formation was ascertained from the monthly collections of clams to occur between August and September during the period when sea water temperatures were maximal. In addition, age of 30 older individuals was verified with acetate peels of polished and etched shell sections. Differences were apparent in the age structure and growth rates of clams collected from the four locations. Von Bertalanffy growth (VBG) curves obtained for clams from these locations were Lt = 72.4 (1–e–0.25 (t-2.68)) (Rab Island), Lt = 74.5 (1–e–0.15 (t+0.57)) (Pag Bay), Lt = 79.3 (1–e–0.34(t-0.97)) (Cetina estuary), and Lt = 82.5 (1–e–0.11 (t+2.88)) (Kaštela Bay). The age of the smooth clams ranged between 3 and 44 years whilst median clam ages were similar at three of the four locations i.e. 14, 12, 4 and 12 years respectively. The VBG growth constants recorded from clams in this study are within the range of values obtained by previous authors for the species. The observed differences in population structure between locations indicate different levels of exploitation and illustrate the need for establishing long term strategies for the sustainable exploitation of smooth clams in the Croatian Adriatic.

Adriatic Sea; bivalve age; Callista chione; growth; population structure

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