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研究報告

更新日期: 2015-02-09
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三大洋混獲物種資源調查研究

年度 2013
計劃名稱 三大洋混獲物種資源調查研究
中文摘要 「三大洋混獲物種資源調查研究」之中文摘要: 一、「三大洋主要鯊魚漁獲魚種歷史漁獲量推估及CPUE標準化之研究」        本研究利用觀察員在太平洋所得的鯊魚混獲資料來進行單位努力漁獲量之標準化,以修正歷史漁獲資料,並回推鋸峰齒鮫(blue shark)及灰鯖鮫(shortfin mako shark)的混獲數量。根據2012年ISC鯊魚工作小組會議之建議,將北太平洋水域區分為A、B二個區域,其中A區域係30度N以北的水域,B區域是0度N-30度N的水域;而南太平洋則依據觀察員回報之鯊魚努力量分布,劃分為0度-20度S的低緯度水域(C區)及20度S以南的水域(D區)。由於鯊魚在鮪延繩釣的作業中是屬於混獲性魚種,常常會有零漁獲(Zero Catch)的情形產生,因此本研究利用Delta-lognormal GLM進行CPUE之標準化,避免過多無漁獲資料可能產生的標準化問題。結果顯示北太平洋大釣船歷年鋸峰齒鮫之總漁獲量約在0 – 1,151噸間變動,南太平洋則在100-3,600噸之間。小釣船則約在8,847 – 16,081噸間。北太平洋大釣船歷年灰鯖鮫之總漁獲量約在0 – 120噸間變動,南太平洋則在40-1,300噸左右。本研究進行了太平洋水域主要混獲鯊魚歷年CPUE變動情形的分析,結果顯示鋸峰齒鮫CPUE仍能維持一定水平,並未發現有明顯下降的趨勢,再加上該種類漁獲體長資料顯示,所漁獲的個體多為成熟的較大個體,因此目前針對該種類資源狀態的判斷仍持較樂觀的看法。灰鯖鮫則由於資料不足所限,導致CPUE無法估計的情形產生,本研究將嘗試其它方法來估算太平洋灰鯖鮫之歷年CPUE。此部份為本研究初步之結果,未來仍需持續進行分析。 二、「遠洋鮪釣漁業混獲生態相關物種研究」       本計畫為科技保密計畫,故不引入相關資訊,請另參照細部計畫期末報告紙本。 三、「更新我國減少延繩釣漁業意外捕獲海鳥之行動計畫」             聯合國糧農組織(FAO)於1999年通過避免延繩釣漁業意外捕獲海鳥之國際行動計畫,希望加強海鳥保育。在FAO國際行動計畫中,要求各國應該檢視其漁業混獲海鳥情況,酌情制定國家行動計畫(National Plan of Action),藉由評估(assessment)、引進保育措施(mitigation measures)、研究開發(research and development)、教育宣導(education, training and publicity),並持續蒐集資料(data collection)。台灣於2005年通過國家行動計畫,就當時情況說明台灣鮪延繩釣漁業現況、可能意外捕獲海鳥概況、國際組織保育規範、台灣對減少意外捕獲海鳥之努力以及未來將採行之措施以及相關附錄。之後,各國際區域性漁業管理組織紛紛通過相關決議,台灣方面也經由觀察員計畫,蒐集分析海鳥混獲資訊並提供國際漁業組織。 有鑑於台灣通過該NPOA已近七年,本計畫旨在檢視我國第一版海鳥國家行動計畫內涵,更新國際區域性漁業管理以及海鳥保育組織之規範,以及我國延繩釣漁業混獲海鳥相關研究之成果。實施方法將納入國際及國內近期研究成果,以及國際區域性漁業組織通過且台灣正在執行的相關海鳥保育措施,以更新我國避免延繩釣漁業混獲海鳥國家行動計畫,以更新並呈現我國遠洋鮪釣漁業配合保育管理規範。 四、「我國在三大洋混獲鯊魚資源風險評估」        生態風險評估(Ecological risk assessment) 在生物學數據不足的情況下,是一種有效用以評估物種所承受之風險程度的方法。此方法主要是依據生產力及敏感性兩項參數;生產力即物種在捕撈所能夠承受之恢復能力,利用族群內部增加率法進行估算;敏感性為物種可能受到漁業的影響程度,利用可得性、遭遇性、選擇性和捕獲後死亡率估算。生態風險評估風險最高為平滑白眼鮫,最低為鋸峰齒鮫。本研究使用整合性生態風險評估探討漁業對大西洋常見之8種大型鯊魚資源的影響,其中包含生態風險評估(ERA)、鯊魚物種瀕危狀態(C)以及漁獲體型變化趨勢指標(S)等三項指標,以群集分析(CA)及多元尺度分析(MDS)進行整合性生態風險評估的結果,可將8種鯊魚區分為四群,承受風險最高的平滑白眼鮫為第一群;紅肉丫髻鮫承受的風險次之為第二群;第三群為丫髻鮫、深海狐鮫、灰鯖鮫、污班白眼鮫及高鰭白眼鮫;而承受風險最低的鋸峰齒鮫為第四群。建議風險最高的兩群應實施較嚴格之管理措施;其次者應減少漁獲壓力;風險最低者應持續監控以確保鯊魚資源永續利用。  
英文摘要 Abstract of \"The relation between bycatch species in the three oceans\": 1. \"Estimation of historical catches and standardization of CPUEs for dominant sharks in three oceans\" :       The catch and CPUE of the blue shark and shortfin mako shark were estimated based on the observers’ records of Taiwanese tuna longline fishing vessels operating in the Pacific Ocean from 1971-2012. Based on the suggestion of the ISC shark working group in 2012, two areas namely, A (north of 30ºN), and B (0º-30ºN), were categorized in the North Pacific Ocean. According to the distribution of observed shark catch and effort, the South Pacific was divided into C (0º-20ºS) and B (south of 20ºS) areas in this study. The shark catch data reported by observers were used for CPUE standardization to adjust the historical shark catch in Task I and to estimate blue shark and mako shark catches for Taiwanese large scale longline fishery in the Pacific Ocean. Due to high zero catch records for both of blue and mako sharks, the CPUE was standardized using the delta-lognormal approach where one model is used to estimate the proportion of positive catches and a separate model the positive catch rate. All main effects tested were significant and included in the final model. Blue shark bycatch in weight were estimated about 0-1,151 tons in North Pacific Ocean and 100-3,600 tons in South Pacific Ocean between 1971 and 2012. The estimated shortfin mako shark catch in weight were 0-120 tons in North Pacific and 40-1,300 tons in South Pacific. Estimated annual catch of blue sharks by Taiwanese small-scale longline fisheries ranged from 8,847 to 16,081 tons in 2001-2011. Standardized CPUE series of the blue sharks caught by Taiwanese longline fishery showed a stable trend. The stable trend suggested that the blue shark stock in the North Pacific Ocean seems at the level of optimum utilization. However, the shortfin mako shark CPUE could not be estimated due to data limitations. The different methods will be tried to estimate the shortfin mako CPUE in Pacific Ocean. The results in present study are preliminary and further investigation is needed. 2. \"Research on Incidental Catch of Ecological Related Species by Taiwanese Distant Water Tuna Longline Fisheries\" :      本計畫為科技保密計畫,故不引入相關資訊,請另參照細部計畫期末報告紙本。 3. \"Update the National Plan of Action of reducing incidental catch of seabirds by longline fisheries\" :            Food and Agriculture Organization adopted International Plan of Action of Avoiding incidental catch of seabirds of longline fisheries in 1999(IPOA-seabirds).The IPOA requested related countries shall review its situation of seabirds incidental catch of longline fisheries and adopt National Plan of Action if necessary. For achieveing the goal, the countries shall assessment, introduce mitigation measures, conduct research and development, promote education, training and publicity, and continuing data collection. Taiwan adopted its NPOA-seabirds in 2005, which is explored the seabirds bycatch status of Taiwanese tuna longline fisheries, the International organizations conservation measures, Taiwan's effort on reducing seabirds bycatch and future plan. After that, lost resolutions and recommendations are adopted by Regional Fisheries Managenet Organizations. Taiwan also collected related information from observer program and provide analysis to RFMOs. Considering the NPOA-seabirds has adopted for seven years, the objectives of this program is to review the progressing for conduct the NPOA-seabirds, review the update status and research on Taiwanese tuna longline fisheries.  A updated NPOA-seabirds of Taiwan would be final for demostration the status and effort has been done by Taiwan tuna longline fleets for reducing the bycatch of seabirds.   4. \"Ecological risk assessment of bycatch sharks by Taiwanese fisheries caught in three oceans\" :       Ecological risk assessment is an efficient method which can be used to evaluate the risk of fish species when its biological information is insufficient. This method is based on two parameters: productivity and susceptibility. The intrinsic population growth ratewas used to culculate the productivity. The susceptibility was calculated by the availability, encounterability, selectivity and post-capture mortality. The Silky shark had the highest ecological risk while the blue shark had the lowest. This study used an integrated risk assessment including three indices: ecological risk assessment, CITES endanger status, and the trend of body weight change to evaluate the risk of overexploitation for 8 pelagic shark species in the Atlantic Ocean. The results of cluster analysis and multi-dimensional scaling analysis indicated that the Silky shark (Carcharhinus falciformis) has the highest risk (group I), followed by the Scalloped hammerhead (Sphyrna lewini) (group II); while the Smooth hammerhead (S. zygaena), Bigeye thresher shark (Alopias superciliosus), Shortfin mako (Isurus oxyrinchus), Oceanic whitetip shark( C. longimanus), Sandbar shark( C. plumbeus) had moderate risk (group III); the blue shark(Prionace glauca) had the least risk of overexploitation (group IV). A rigorous management measure was recommended for the two highest risk groups; setting total allowable catch quota was proposed for the median risk group; a consistent monitoring was suggested for the least risk species.
計畫編號 102農科-11.1.1-漁-F6(Z)
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