Size-distribution and length-weight relationship of a deep-water population of Holothuria scabra (Jaeger, 1833) in Zanzibar, Tanzania

Abstract

A study was carried out on the size distribution, length-weight relationship and condition factor of a deep-water population of the commercially important tropical sea cucumber Holothuria scabra in Zanzibar, Tanzania. Samples were collected from fishers and supplementary information gathered. The deep water (15-20 m) population of H. scabra is dominated by large sized individuals that have already attained maturity. There was no significant difference in size between male and female individuals (p>0.05). The sex ratio in this population significantly differed from 1:1 in favour of male individuals (p=0.01). The results showed significant correlation between length and weight for male, female, indeterminate individuals, and pooled data, with r values of 0.681, 0.794, 0.821 and 0.680, respectively. Moreover, the b-value for male, female, indeterminate individuals and pooled data was 1.288, 1.439, 1.686 and 1.407 respectively, which revealed that individuals of deep-water H. scabra exhibit negative allometric growth. The mean condition factor (K) value when all data were pooled together was 4.213±0.106 indicating that individuals were in good condition and came from a healthy environment. This study fills a key information gap that is relevant to the management of the H. scabra fishery in the country.