The fecundity of common cuttlefish (Sepia officinalis) in the offshore area of Mauritania

Abstract:

The common cuttlefish, Sepia officinalis Linnaeus 1758, is mostly found in the eastern Atlantic and in the Mediterranean Sea, and constitutes an important fishery resource in the world cephalopod fisheries by attaining high market value in the Mediterranean and Asian markets. Herein,the individual fecundity of S.officinalis was studied based on the samples collected from the pelagic fisheries outside Mauritania during the fishing season of July to August in 2015. In addition, the relationship between individual fecundity and the biological indices of each individual, including mantle length, mantle width, fin length, fin width, head width, body weight, eviscerated weight, and head weight, was analyzed by using mathematic regression equations. The results showed that the frequency distribution of mantle length, mantle width, fin length, fin width, head width, body weight, eviscerated weight, and head weight was unimodal respectively. The potential fecundity (PF) was 13 06~3 375 oocytes, with an average of 2 466±545 oocytes, and increased significantly with sexual maturation (P<0.05); the relative fecundity by mantle length (PF_ML) was 8.70~18.56 oocytes/mm, with an average of 14.17±2.12 oocytes/mm; while the relative fecundity by body weight PF_BW was 2.72~7.81 oocytes/g, with an average of 5.18±1.23 oocytes/g. Based on the comparison of variance, PF_BW was more stable than PF_ML (δ_PFBW²< δ_{PFM L}²).There was a significant relationship between F and PF_BW and the biological indices(P<0.05), while PF_ML showed little evidence to correlate with the biological indices due to the low value of correlation coefficient (P>0.05). Furthermore, a multiple regression analysis revealed that the potential fecundity was significantly correlated with fin length, while relative fecundity by body weight was significantly correlated with body weight.This finding showed that fin length was the reliable index to estimate the potential fecundity, while body weight was appropriate to estimate the relative fecundity by body weight for S. officinalis.