Seasonal Variation in the Length-Weight Relationships and Condition Factor of Four Commercially Important Sea Cucumbers Species from Karachi Coast- Northern Arabian Sea

Abstract

Length-weight relationships and condition assessment are a common practice in fisheries analyses; however, such information is unknown for most sea cucumber species. The present study investigated length-weight relationships and relative condition indices of four commercially important sea cucumbers: Holothuria arenicola, Holothuria atra, Holothuria pardalis and Holothuria verrucosa. Additionally, the seasonal variations obtained between three climatic seasons (pre-monsoon, monsoon and post-monsoon) were analyzed. The results showed that the four species grow allometrically, with negative allometric b values ranging from 0.84 to 1.74. There were significant differences of length-weight relationships between climatic seasons for H. arenicola and H. atra. The lower b values were observed during post-monsoon and the higher b values during monsoon in three of the four species. During the post-monsoon, the condition of the bigger individuals of H. arenicola and H. atra was lower than that of the small individuals. The differences in length-weight relationships of H. pardalis and H. verrucosa were not significant between climatic events. The higher temperatures occurred during monsoon and the lower during post-monsoon, but these data only showed a significant correlation with the relative condition factor of H. arenicola. Best condition of the individuals of H. arenicola occurred at temperatures between 22 to 31°C. Studies about environmental variables and characteristics of the substratum type are necessary in order to complement the understanding of the length-weight relationships and condition of these species.