Present status of the commercial sea cucumber fishery off the north-west and east coasts of Sri Lanka

Abstract

The sea cucumber fishery has been providing an important means of livelihood to the coastal fishing communities in Sri Lanka for centuries. Stock status, level of exploitation and mortality parameters of eleven commercial sea cucumber species were studied off the north-west and the east coasts of Sri Lanka using data collected from an underwater visual census and fishery-dependent surveys carried out in 2008 and 2009. The total abundance of sea cucumbers was higher in the north-west than the east (P < 0.01). However, the total abundance of all the species declined between 2008 and 2009. The commercial fishery predominantly relies on two nocturnal species:Holothuria spiniferaandThelenota anax. Holothuria spiniferahad the highest contribution (73.2%) to the total landings in the north-west while this was provided byT. anax(93%) in the east. Both catch per unit effort and total landings declined in 2009 compared to 2008 having three exceptions (H. spinifera, Holothuria atraandStichopus chloronotus) in the north-west. Further, the collection of immature individuals, reduced landings of high-value species and temporal shifting of fishing activities were observed in both areas. Two approaches (simple linear regression and random effects models) were used to estimate the natural mortality of sea cucumbers and the estimated values were 0.50 yr−1and 0.45 yr−1, respectively. Apart from the management of local sea cucumber resources, this information is important to update the regional and global sea cucumber statistics as well as for launching regional management programmes.