Population dynamics of the freshwater clam Galatea paradoxa from the Volta River, Ghana

Abstract

Population parameters such as asymptotic (L∞), growth coefficient (K), mortality rates (Z,F and M), exploitation level (E) and recruitment pattern of the freshwater clam Galatea paradoxa were estimated using length-frequency data from the Volta River estuary, Ghana. The L∞ for G. paradoxa at the Volta estuary was 105.7 mm, the growth coefficient (K) and the growth performance index (Ǿ) ranged between 0.14–0.18 year-1 and 3.108–3.192, respectively. Total mortality (Z) was 0.65–0.82 year-1, while natural mortality (M) and fishing mortality (F) were 0.35–0.44 year-1 and 0.21–0.47 year-1, respectively, with an exploitation level of 0.32–0.57. The recruitment pattern suggested that G. paradoxa has year-round recruitment with a single pulse over an extended period (October–March) in the Volta River. The Volta River stock of G. paradoxa is overfished and requires immediate action to conserve it. This can be achieved by implementing a minimum landing size restriction and intensifying the culture of smaller clams which is a traditional activity at the estuary.

Keywords

• recruitment
• mortality
• growth parameters
• Volta River
• Bivalvia