Title : New approaches to assessing and managing the multispecies fishery in the Gulf of Thailand
Abstract:
Marine fisheries in Thailand are multispecies/multi-gear fisheries. The Multispecies Maximum Sustainable Yield (MMSY) has been used as the reference point for fisheries management, with an equilibrium surplus production model used to estimate MMSY of three groups: demersal species, pelagic fish and anchovy. Additionally, single species assessments are conducted for 17 economically important species using length frequency data to monitor the status of individual species. Thailand is attempting to increasingly apply ecosystem-based management concepts that considers the broader ecosystem rather than focusing solely on individual species. Unlike traditional fisheries management, which often emphasizes maximizing the yield of specific target species or species groups, ecosystem-based approaches better account for complex interactions within marine ecosystems, including predator-prey relationships, habitat requirements, and the effects of environmental changes on marine life. This presentation introduces a project on the use of tools for ecosystem-based fisheries management to fisheries in the Thai waters of the Gulf of Thailand. A new draft harvest strategy that highlights how single species, multispecies and ecosystem considerations can be combined in a single strategy is being developed. This uses multiple data sources, including statistical catch and fishing effort, species composition and catch per unit effort (CPUE) from research vessels, and port sampling data for major fishing gears covering both artisanal and commercial vessels. The project has resulted in the MMSY re-estimated using dynamic models, with results presented by using Kobe Plots that describe changes in biomass and fishing effort over time. Recent single species assessment results have also been updated. Principle component analysis (PCA) and heatmaps are used to describe changes in catch composition over time, with implications for MMSY. Finally, the presentation outlines ecosystem indicators of topology, resiliency, and distortive pressures, which are combined into an Ecosystem Traits Index (ETI) score that describes the trajectory of the Gulf of Thailand ecosystem’s health. All of this information will be integrated and used to further develop and deliver harvest strategies that enhance the sustainability of Thai fisheries and support ecosystem health.
