Beyond Allowable Catch Limits: Assessing Spatial Population Structure of Sea Cucumber Stocks Based on Fishing Effort, Habitats, and Refugia

Sea cucumbers targeted for “beche de mer” are currently being overfished throughout the world counting for 20,000 - 40,000 tons per year in Asia and Pacific alone. Its ease in harvesting coupled with recent increases in demand has led many local stocks to become commercially extinct. The demand has grew to the point that it has not only depleted the traditional fishing grounds close to Asia but also protected areas such as Galapagos where it experienced a fishery collapse. To meet the ever increasing demand have lead the fishery to expand to new non-traditional fishing grounds such as the Republic of Seychelles. 

Sea cucumber fisheries in the Seychelles provide a unique opportunity to measure fishery impact on stock density and distribution because the fishery tracks its spatial fishing effort. The fishery is SCUBA operated to depths of 30 m, which in turn could be hypothesized that depths greater than 40m could act as a natural refugia. Additionally, Seychelles has at least 14 marine protected areas (MPAs), most designated as no-take zones, that include potential sea cucumber habitats. The study looked at these refugia for their stock contribution. This study combines fishery log data, habitat data, and fishery independent survey data to analyze sea cucumber size structure and density among various habitats and areas subject to different fishing pressures. This study is an on going process and a population dynamic model accounting for fishing effort, habitat, and refugia will be created after additional survey years.