2026-03-14T09:16:53Z https://kochi.repo.nii.ac.jp/oai

oai:kochi.repo.nii.ac.jp:00006498 2023-08-22T02:38:46Z 100:576:584

Overfishing of Three Siganid Species (Family: Siganidae) in　Lagonoy Gulf, Philippines Soliman, Victor S. 24545 Bobiles, Renan U. 24546 Yamaoka, Kosaku 24547 overfishing stock assessment siganid settlement new moon application/pdf Juvenile and older Siganus canaliculatus, S. spinus and S. argenteus were assessed in Lagonoy Gulf from　analysis of total　juvenile catch trend obtained in commercial fishing operations and using length-basedfishery methods to generate evidences of overfishing of the resource. Estimates of annual instantaneous　total, fishing and natural mortalities were high which corresponded to their high exploitation. Exploitation　rates of the three species were higher by 34-64% beyond the level that would be sustainable. Capture　lengths were generally lower than their reported　maturity size which means the fishes were caught before　they would have contributed to recruitment in the fishery. Total　juvenile catches and catch-per-unit-effortin 2001-2004 were continuously declining, which registered 50% decline in 2003-2004. The highest volumes　of juvenile catch were obtained consistently in April and May new moons although the appearance　of juveniles is apparently year-round. At about the same period in summer (April and May), the　larger,　gravid siganids, were fished intensively although the fishery has been practiced throughout the year. The　high exploitation of juveniles and larger siganids in the gulf could not be expected to decrease in coming　years but rather it would intensify given the historical uptrend of fishery exploitation in the gulf If leftunregulated within sustainable level for the older fish and not rationalized until completely stopped for the　juveniles, this will lead to significant stock depletion that will be disadvantageous to the fishery as a whole. departmental bulletin paper Graduate School of Kuroshio Science, Kochi University 2009-02-28 VoR application/pdf 黒潮圏科学 = Kuroshio Science 2 2 145 150 1882823X AA12321175 https://kochi.repo.nii.ac.jp/record/6498/files/Soliman.pdf http://hdl.handle.net/10126/1215 https://kochi.repo.nii.ac.jp/records/6498 eng