Title: Assessment of the sustainability status of Stichopus naso (Family: Stichopodidae) in the northern coastal waters of Sri Lanka
Abstract
Kasun Dalpathadu's final project will be published in due time. Until then we share the abstract and a link to a poster.
The sea cucumber fishery in Sri Lanka has expanded due to international demand, generating significant income through Bêche-de-mer exports. However, increased fishing pressure has led to local depletion and fishery collapse in several areas. Harvesting of Stichopus naso using SCUBA diving in Jaffna began in 2019. This study conducted a preliminary stock assessment of S. naso in the Jaffna fishing ground to inform sustainable management strategies. Catch and effort data from logbook records (2019–2021) were analysed using the DeLury Depletion Model via the CEDA 3.0 software package to assess the stock and project future population trends. Sensitivity analyses were conducted to evaluate the model's responsiveness to natural mortality (M) and data aggregation intervals. Results indicated that the 2021 harvest rate was unsustainable, contributing to stock depletion. Projections show a continued population decline if fishing pressure remains at the 2021 level. Due to data limitations, the model's output carries uncertainty, warranting a ‘precautionary management approach’ for the S. naso resource in the Jaffna fishing ground. An annual total allowable catch (TAC) of 3,821,110 individuals, equivalent to 2020 catches, is recommended for the next three years. Individual quotas should be allocated to fishers active between 2019 and 2024, and existing effort-control measures should be maintained. To improve future assessments, an underwater resource survey is urgently needed to refine estimates of M and gather biological data. Enhanced monitoring will support more robust stock assessments and allow for the refinement of management strategies. Alternative assessment methods should be explored as data quality improves. These recommendations aim to guide the S. naso fishery toward recovery and long-term sustainability.