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Simulation and analysis of the pelagic ecosystem of the Northwest Pacific based on Ecopath with Ecosim
|Authors: ||Chien-Bang Jin|
|Contributors: ||NTOU:Institute of Marine Affairs and Managemen|
Ecopath;Ecosim;Ecoranger;Northwest Pacific;pelagic ecosystem;large sharks;longline-fishery;fishery management strategy
|Issue Date: ||2011-06-30T08:11:15Z
|Abstract: ||本研究利用水生生態系統模擬軟體Ecopath with Ecosim (EwE)建構西北太平洋表層海洋生態系模式(120°E ~ 140°E, 20°N ~ 30°N)，並從前人之研究中蒐集此海洋生態系內延繩釣漁業主要目標魚種與其餌料生物共17個物種(群)的生物學資料，胃內容物與漁獲量資料做為模式輸入之參數。且利用Ecoranger模擬參數估計之不確定性，再以Ecosim模擬延繩釣漁業和漁業管理政策對此海洋生態系可能造成之影響。鼠鮫目和白眼鮫目之生態位階為4.16，是西北太平洋表層海洋生態系內最頂端的捕食者，鋸峰齒鮫為本海洋生態系中資源量最豐富之物種，其生態位階為3.99較鼠鮫目和白眼鮫目低，根據Ecosim模擬之結果顯示西北太平洋表層海洋生態系之鼠鮫目與白眼鮫目資源可能過漁，若大型鮫類完全從本海洋生態系中消失，會對此海洋生態系的生態平衡造成很大之影響，建議應以F35%之生物參考點進行管理。鬼頭刀和鯖鰺類為西北太平洋海洋生態系中關鍵度指數最高之物種，這可能是因為延繩釣漁業在本海洋生態系內大量捕撈大型鮫類，鮪魚類與旗魚類，因而減弱這些物種對其餌料生物的Top-down control。延繩釣漁業會因移除鬼頭刀和海洋哺乳類之餌料競爭者和捕食者而使這兩個物種的生物量增加，但對其他目標魚種皆產生負面影響，減少延繩釣漁業之努力量可使大型鮫類，鮪魚類與旗魚類之資源量得以恢復。|
An aquatic ecosystems simulated software named Ecopath with Ecosim (EwE) was used to construct a model to represent the pelagic ecosystem in the northwest Pacific. The input of parameters including biological imformation, diet compositions and yields of 17 functional groups, which are the main target species of longline-fishery and their preys, were collected from literatures. The Ecoranger was used to estimate the effects of uncertainties of input parameters. The impacts of longline-fishery and fishery management strategies on this marine ecosystem were simulated with Ecosim function. In the northwest Pacific pelagic ecosystem, Lamniforms and Carcharhiniforms whose trophic level equal 4.16 are the top predators. The blue shark which has lower trophic level than Lamniforms and Carcharhiniforms is the most abundant large sharks species. The results of Ecosim simulations indicated that Lamniforms and Carcharhiniforms are overfishing. Furthermore, a series of strong and unforeseen changes in the abundances of many species may occur, due to the removal of large sharks from this marine ecosystem. Therefore, a biological reference point of F35% for Lamniforms species was proposed. The scombrids and dolphinfish have the strongest keystone effects because the decrease of Top-down control from top predators, such as large sharks, tuna and swordfish species were heavly removed from the northwest Pacific pelagic ecosystem by longline-fishery. Longline-fishery has positive effects on dolphinfish and marine mammals by removal of both their predators and competitor for preys. But longline-fishery makes negative effects on other target species. Therefore, a decrease of longline-fishery efforts may result in a recovery of large sharks, tuna and swordfish species.
|Appears in Collections:||[海洋事務與資源管理研究所] 博碩士論文|
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