Modelling habitat associations of 14 species of holothurians from an unfished coral atoll: Implications for fisheries management

Abstract

Currently there is no commercial or subsistence fishing for holothurians on the Cocos (Keeling) Islands and, despite a prominent government presence, no reported cases of poaching or illegal fishing. However, because of recent interest in developing a commercial fishery for holothurians there, a survey was initiated to provide baseline data on the previously unfished local holothurian populations. Fourteen species of holothurians were recorded during the survey, with the most abundant species being Holothuria atra; only 4 other species had relatively high abundances. A total of 20 556 holothurians were counted; however, 97% of these were considered to be of low commercial value. The high- and medium-value species found in this survey were all in extremely low abundances, with restricted distributions. The distribution and abundance of holothurians was closely linked with benthic habitats, with 48% of the variation in holothurian populations explained by 13 habitat variables. Several species displayed distinct habitat preferences: H. atra was associated with sand-dominated habitats, Actinopyga mauritiana was associated with relic reefs and soft corals, while Holothuria fuscopunctata and Stichopus herrmanni were both associated with reef flats. The densities recorded in the present study represent the natural abundance and distribution of holothurian populations at this atoll. Given the low numbers of commercially important species, it is highly unlikely that a commercial fishery would be economically viable at the Cocos (Keeling) Islands and it would be more beneficial to maintain the natural holothurian population.