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National Committee on Marine Sciences (NCMS)

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AGROVOC Keyword: search.filters.agrovoc.aquacultureOcean Decade Challenge: search.filters.odc.Challenge 10: Change humanity’s relationship with the ocean

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    Complex patterns of genetic structure in the sea cucumber Holothuria (Metriatyla) scabra from the Philippines: implications for aquaculture and fishery management
    Lal, Monal M.; Macahig, Deo A. S.; Juinio-Meñez, Marie A.; Altamirano, Jon P.; Noran-Baylon, Roselyn; de la Torre-de la Cruz, Margarita; Villamor, Janine L.; Gacura, Jonh Rey L.; Uy, Wilfredo H.; Mira-Honghong, Hanzel; Southgate, Paul C.; Ravago-Gotanco, Rachel (Frontiers Media SA, 2024-06-04)
    The sandfish Holothuria (Metriatyla) scabra, is a high-value tropical sea cucumber harvested from wild stocks for over four centuries in multi-species fisheries across its Indo-Pacific distribution, for the global bêche-de-mer (BDM) trade. Within Southeast Asia, the Philippines is an important centre of the BDM trade, however overharvesting and largely open fishery management have resulted in declining catch volumes. Sandfish mariculture has been developed to supplement BDM supply and assist restocking efforts; however, it is heavily reliant on wild populations for broodstock supply. Consequently, to inform fishery, mariculture, germplasm and translocation management policies for both wild and captive resources, a high-resolution genomic audit of 16 wild sandfish populations was conducted, employing a proven genotyping-by-sequencing approach for this species (DArTseq). Genomic data (8,266 selectively-neutral and 117 putatively-adaptive SNPs) were used to assess fine-scale genetic structure, diversity, relatedness, population connectivity and local adaptation at both broad (biogeographic region) and local (within-biogeographic region) scales. An independent hydrodynamic particle dispersal model was also used to assess population connectivity. The overall pattern of population differentiation at the country level for H. scabra in the Philippines is complex, with nine genetic stocks and respective management units delineated across 5 biogeographic regions: (1) Celebes Sea, (2) North and (3) South Philippine Seas, (4) South China and Internal Seas and (5) Sulu Sea. Genetic connectivity is highest within proximate marine biogeographic regions (mean Fst=0.016), with greater separation evident between geographically distant sites (Fst range=0.041–0.045). Signatures of local adaptation were detected among six biogeographic regions, with genetic bottlenecks at 5 sites, particularly within historically heavily-exploited locations in the western and central Philippines. Genetic structure is influenced by geographic distance, larval dispersal capacity, species-specific larval development and settlement attributes, variable ocean current-mediated gene flow, source and sink location geography and habitat heterogeneity across the archipelago. Data reported here will inform accurate and sustainable fishery regulation, conservation of genetic diversity, direct broodstock sourcing for mariculture and guide restocking interventions across the Philippines.
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    Evolving governance structures in community-based sandfish mariculture and their interactions with livelihood outcomes: Evidence from the Philippines
    Fabinyi, Michael; Gorospe, Jay R; McClean, Nicholas; Juinio–Meñez, Marie Antonette (Frontiers Media SA, 2022-11-02)
    Sea cucumber mariculture is an important emerging field of practice and applied research in the coastal tropics. This is due to the existing importance of tropical sea cucumber fisheries for wealth generation and poverty reduction, and the potential for mariculture to contribute to the longer term sustainability of these fisheries while generating benefits additional to those from wild caught sea cucumber. Understanding the optimal institutional arrangements for sea cucumber mariculture is an important area of focus in this field, with a variety of arrangements currently in place. This paper documents the establishment of a communal form of sea ranching in the Philippines, as a case study of community level institutional processes. It describes the background to establishment of the sea ranch in the community of Victory, challenges encountered and how these were managed, and the evolution of governance arrangements. In charting this process, we assess the impacts on livelihood outcomes, highlighting this as a crucial aspect influencing this evolution and the nature of community involvement in the sea ranch. While the sea ranching project generated a range of benefits for livelihoods, including possible spillover effects for the surrounding fishery, substantial economic returns from harvests did not occur. Thus, the system of governing the sea ranch evolved from a communal model to a more exclusive household model primarily to improve operational efficiency. In order for possible benefits of the sea ranch to be sustained and enhanced, greater integration with fisheries management and government support will be needed.
    We are grateful to the Samahan ng Maliliit na Mangingisda ng Barangay Victory, Inc., the local government unit of Barangay Victory and Bolinao for their support to the Sea cucumber Research Program. We are also thankful to Tirso Catbagan, Josh Caasi, Rona Cabanayan-Soy, and Garry Bucol for their invaluable assistance during the field monitoring of sandfish in the sea ranch.