Population Index and Growth Estimation Based On SLW Index of the Sea Cucumber (Holothuria arguinensis Koehler & Vaney, 1906) in the Moroccan Waters of the Atlantic Coast

The population structure and growth parameters of the commercially important species of sea cucumber Holothuria arguinensis in Moroccan waters was studied, being the first study reported along these waters. We collected 455 individuals of H. arguinensis at Skhirat, and 209 at Souiria K’dima, Northern and center Atlantic of Morocco. To avoid deviation from the accurate measurements in sea cucumber related to statistical estimation because of the elasticity of the body wall, we used a compound index which merged length and width to give the SLW index (square root of length multiplied by width) and its related modifications such as Le (recalculated length) were assessed and different morphometric relationships were also explored, the results indicate that recalculated length appears to be more valuable and helpful in obtaining an accurate length of sea cucumber. The student’s t-test revealed that H. arguinensis has allometric growth (b ≠ 1 or b ≠ 3, P < 0.05). The von Bertalanffy growth function including L∞, K and t0 were estimated to be L∞ = 25.96 cm, K = 0.17 yr.−1, t0 = –1.55 year at Skhirat, and L∞ = 25.44 cm, K = 0.29 yr−1, t0 = –1.02 year at Souiria K’dima. The longevity in H. arguinensis was high (8.51 years at Skhirat and 6.81 years at Souiria k’dima) and the estimated natural mortality of H. arguinensis was low (0.47 year−1 at Skhirat and 0.67 year−1 at Souiria k’dima) when analyzed against other sea cucumber species, which indicated that this organism might be resistant to predation. Similarly, these findings will be used to establish a sustainable management strategy to exploit this marine resource and support the fishery development plans and aquaculture.