Population structure and dynamics of the cut trough shell Spisula subtruncata (da Costa) in the Sea of Marmara, Turkey

Growth, mortality rates, reproduction and recruitment pattern of an unexploited population of the cut trough shell Spisula subtruncata from the northern part of the Sea of Marmara were studied using the length frequency samples of 12 consecutive months from December 2005 to November 2006 and FISAT II software which incorporates both Bhattacharya and ELEFAN I methods. The growth parameters obtained were: (i) Bhattacharya: L∞ = 24.14 mm shell length, K = 1.03 year−1, t0 = − 0.181, C = 0.78 and WP = 0.77 of year (i.e. September); (ii) ELEFAN I: L∞ = 27.3 mm, K = 0.82 year−1, C = 0.85 and WP = 0.92 of year (i.e. November), and an Rn value of 0.394. The growth confirmed to a negative allometric pattern. The longevity estimated was 3.66 years. Natural mortality and total mortality (Z would be equal to M, being F = 0) were estimated 1.255 and 1.177 year−1, respectively. The reproductive period, estimated from the condition index, is from the second half of the spring to early autumn with a peak between May and June. The recruitment pattern occurred as unimodal with a peak between June and August.