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The Eel Fishery in Tributaries Along Lagonoy Gulf: Implications for Management and Conservation

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The Eel Fishery in Tributaries Along Lagonoy Gulf: Implications for Management and Conservation BU R&D Journal 24 (1): 67-81, July 2021 | ISSN (Print): 0016-4139 journal.bicol-u.edu.ph | ISSN (Online): 2719-082X doi: 10.47789/burdj.mbtcbbgs.20212401.11 The Eel Fishery in Tributaries Along Lagonoy Gulf: Implications for Management and Conservation Plutomeo M. Nieves1,*, Antonino B. Mendoza Jr.1, Raul G. Bradecina2, John Christopher C. Nolial1, Niño C. Celestial1, Satoshi Kubota3, and Katrina L. Canon3 1Bicol University Tabaco Campus, Tabaco City, Albay, Philippines 2Partido State University, Goa, Camarines Sur, Philippines 3Laboratory of Molecular and Cellular Biology, Kochi University, Kochi Japan *Corresponding author: [email protected] Abstract This study provides a discussion of the eel fishery in the tributaries and rivers along Lagonoy Gulf primarily to formulate management and conservation strategies supportive of the economic potentials and sustainability of the resources. Data collection employed key informant interview and focus group discussion to collect fishery-based data together with the collection of 300 samples per month. Caudal cutaneous pigmentation method was used in species identification. GIS map was prepared to identify the potential eel habitats. The species composition across the study area include: Anguilla marmorata (89.80%), A. bicolor pacifica (10.10%) and A. japonica (0.10%). The wide-distribution of A. marmorata could be explained by the fastness of leptocephalus metamorphosis. Two gears type were identified: modified fyke net was mainly used in glass eel collection while the remaining gears for adult eel. Post-harvest practices are similar to milkfish. Finding showed no clear indication of the status and trend of the fishery. Supply and value chain is limited to 30 collectors, 93 fishers and 5 traders, their number increases proportionately in-line with increasing catch. Estimated annual production for glass eel is 4,626 kg - 1,386 kg valued at ₱9.4M to ₱12.67M and about 325MT to 81.3 MT adult eel annually valued at ₱23.3M to ₱6.6M. Policies and strategies supportive of economic potential of eel resources are recommended alongside the development of sustainable management interventions to sustain the fishery. Further study on species identification using a combination of morphological and molecular technique is recommended. Keywords: modified fyke net, ichthyotoxic plant, caudal cutaneous pigmentation, and glass eel Introduction markets are Japan, South Korea and China, where eels are perceived as delicacies and a source of stamina. The Philippines is one of the few areas in the world Unfortunately, the country’s shipments of live eels in where high-value species of eels such as Anguillids (true 2014 valued at $34.87 million declined (5,142. MT) from eels) and Monopterus (paddy eels) thrive. The Philippines about $38.29 million (5,455.26 MT) worth of live eels is also home to five of the only 16 eel species in the exported in 2013 (Business Mirror, February 24, 2015). world, namely, Anguilla marmorata (Giant Mottled Eel), Despite this, the BFAR expects demand for Philippine live Anguilla bicolor pacifica (Indian Short-finned Eel), Anguilla eels to remain high. luzonensis (Luzon Mottled Eel), Anguilla celebesensis Watanabe and Miller (2012) comprehensively (Celebes Long-finned Eel) and the Anguilla japonica describe the species, geographic distribution, habitat, (Japanese eel) (Ame et al.., 2013). and conservation of freshwater eels. Freshwater eels of From an economic standpoint, eels have a huge the genus Anguilla are widely distributed throughout global market with a good export price of $15,000 in the many parts of the world and consist of 16 species. European market in 2010 (Crook, 2014). For this reason, Three of the species are divided into separate subspecies many people and entrepreneurs are into catching and that have different morphological characteristics and trading Anguilla along major tributaries in the Cagayan geographic ranges. The morphology of all anguillids is River from Lal-lo to Gonzaga in Cagayan. The major generally similar, but is divided into four groups based BU R&D Journal, Vol. 24, July 2021 ISSN (Print): 0016-4139 | ISSN (Online): 2719-082X Nieves et al.: The Eel Fishery in Tributaries Along Lagonoy Gulf: Implications for Management and Conservation journal.bicol-u.edu.ph on taxonomic differences in terms of body markings, anguillid species, particularly larval transport and glass maxillary bands of teeth, the position of the dorsal fin, eel recruitment. The major threat facing all freshwater and the number of vertebrae. Five are temperate and eel species in the Philippines is the growing exploitation 11 tropical but all are catadromous with their offshore and associated illegal trade of glass eels for aquaculture spawning areas located at tropical latitudes. programs in East Asian farms. Fishing for glass eels has been driven by market value resulting in relatively high Anguillid species vary in maximum body size and in levels of exploitation. Without hard evidence on the the sizes of their species ranges, with A. marmorata being population dynamics of eel, it is difficult to quantify the one of the largest species with the widest geographic influence of these threats to the species as a whole. distribution, while species such as A. borneensis and A. dieffenbachii have restricted geographic distributions. The rivers and tributaries along Lagonoy Gulf (LG) Some species have single spawning areas and panmictic in Eastern Philippines is a potential freshwater settlement spawning populations, but others have multiple area for migrating eels because its location receives water populations, such as A. marmorata, which is present from the Pacific Ocean through the North Equatorial in three different ocean basins. Anguilla japonica is a Current (NEC) and Kuroshio Current that transport temperate catadromous species mainly distributed in larvae from the major spawning grounds of tropical eels Taiwan, China, Korea and Japan; mature males spawn in the western waters of the Mariana Islands. This project in the western waters of the West Mariana Ridge explored the fishery for catadromous freshwater eel (Tsukamoto, 1992; Han et al., 2012). After hatching, the resources along tributaries and rivers in LG with the hope larvae passively drift from the spawning ground by way of managing the stock and enhancing the livelihood of the of the North Equatorial Current (NEC) and the Kuroshio people depending on the fishery. Without science-based at depths typically between 50 and 150 m from 4-6 information, the threat of overexploitation, illegal trade, months before reaching the East Asian coast (Han et al., recruitment and migration, and climate change cannot be 2012). The larvae then metamorphose to glass eel and adequately addressed. It also provides a comprehensive adopt sheltering behavior to escape from oceanic current, account of the eel fishery in LG. This consists of the and actively swim toward the nearby estuaries and rivers potential migration and settlement areas of the eels, the for growth (Tesch, 2003). All anguillid species enter species composition of eels found, the collection gears freshwater for their juvenile growth period, but many used, the post-harvest practices, including the marketing remain in estuaries, brackishwater lakes or lagoons and and trade. The general aim was to describe the full range some may not enter freshwater. In freshwater, anguillids of activities of the eel fishery and to explore the economic live in rivers, streams and lakes, but the degree of use of benefits within sustainable levels. different habitats ranging from small streams far inland to the estuary appears to vary among species. Some eels The project’s primary goal was to generate even switch between habitats, moving back downstream science-based information as input in the formulation to the estuary to complete their juvenile growth period. management and conservation strategies supportive Their unique catadromous life history has made them to the economic potentials and sustainability of the eel vulnerable to the effects of dams that block their fishery in the tributaries and rivers along Lagonoy Gulf. migrations, pollutants, parasites, viruses and overfishing. Specifically, it sought to: (1) identify eel fishing grounds in Changes in conditions in the ocean also influence their tributaries along LG; (2) determine species composition recruitment success in terms of their larval feeding or and abundance of eel caught; (3) determine eel catching transport success. Glass eels are best observed in areas gears and efficiency; (4) determine post-harvest handling closer to the spawning site and from offshore waters practices and (5) determine supply and value chain for which are less disturbed by environmental factors. eels from the study sites in LG. According to Han and colleagues (2016), glass eels hide in the seabed during the day and rise up to the surface at night. The arrival peaks occurred during all lunar periods Materials and Methods except the full moon period as in the case of A. marmorata or other eel species occurring in the Philippines due to Sampling Area. The study covers the provinces the influence of Kuroshio Current. bordering LG which include the provinces of Albay, Camarines Sur and Catanduanes (Figure 1). The As with many anguillid eels, there are threats during identification of sampling sites within the sampling the transitional phases of their life histories. Climate area was accomplished using snowballing technique in change plays a vital role in
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