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Please use this identifier to cite or link to this item: http://ntour.ntou.edu.tw:8080/ir/handle/987654321/47656

Title: 以臺灣鮪釣漁業資料建構大西洋雨傘旗魚資源豐度指標
Development of abundance index for sailfish based on data from the Taiwanese tuna longline fishery in the Atlantic Ocean
Authors: Tai, Ching-Hsuan
戴靖萱
Contributors: NTOU:Department of Environmental Biology and Fisheries Science
國立臺灣海洋大學:環境生物與漁業科學學系
Keywords: 雨傘旗魚;漁獲比例;泛加成模式;delta-lognormal
sailfish;catch ratio;generalized additive model;delta-lognormal
Date: 2017
Issue Date: 2018-08-08T03:25:21Z
Abstract: 雨傘旗魚與長吻旗魚廣泛分布於大西洋海域,由於非臺灣鮪釣漁業主要目標魚種,因此過去雨傘旗魚及長吻旗魚漁獲量是合併紀錄,為因應大西洋雨傘旗魚資源評估需求,須將雨傘旗魚與長吻旗魚漁獲資料分開提報,因此本研究彙整分析2009-2015年大西洋臺灣遠洋鮪釣雨傘旗魚作業日誌五度資料,包含年份、月份、經度、緯度、投放鈎數及漁獲量,估計臺灣鮪釣雨傘旗魚相對漁獲比例,並比較嘗試不同漁獲比例估計方法及CPUE(Catch per unit of effort)標準化方式,以重建1968-2015年大西洋雨傘旗魚資源豐度指標。研究結果顯示,臺灣鮪釣雨傘旗魚最佳漁獲比例估計方式為泛加成模式(Generalized Additive Model),而利用delta-lognormal模式對CPUE進行標準化,可以最適處理雨傘旗魚大量零漁獲量資料的影響,標準化CPUE結果顯示雨傘旗魚資源豐度在1960年至1970年快速下降,之後則呈現相對穩定的趨勢。由於目前大西洋雨傘旗魚資源狀況不佳且評估結果充滿高度不確定性,為瞭解資源現況與變動趨勢,應建立長期且更完整的資源豐度指標,以提供資源評估模式基礎輸入資料,並作為後續漁業管理所需之科學性建議。
Sailfish and spearfish are widely distributed in the Atlantic Ocean. Catch records of these two species were combined due to as non-target species in the Taiwanese tuna longline fishery in the Atlantic Ocean. However, there is a need to separate catch data of sailfish and spearfish into two species for assessment of Atlantic sailfish. Logbook data of the Taiwanese tuna longline fishery were collected in this study from 2009 to 2015, including year, month, attitude, longitude, fishing effort and catch of sailfish. We compared various methods to estimate catch ratios of sailfish in this fishery and different approaches to standardize CPUE (Catch per unit of effort) for the species, in order to develop an abundance index of Atlantic sailfish for 1968-2015. Results showed that GAMs (Generalized Additive Models) are the most appropriate methods used to estimate the catch ratio of sailfish in the fishery and that the delta-lognormal approach can deal well with large amount of zero catch data for sailfish. Standardized CPUE showed that sailfish abundance substantially decreased from the late 1960s to the 1970s and remained relatively stable thereafter. Given that the Atlantic sailfish might be overfished and large uncertainty in the assessment results, long-term series of abundance index should be developed to be used as basic input data for stock assessment to understand current stock status and the variation. Results from this study could be used to provide scientific-based suggestions for fishery management.
URI: http://ethesys.lib.ntou.edu.tw/cgi-bin/gs32/gsweb.cgi?o=dstdcdr&s=G0010531013.id
http://ntour.ntou.edu.tw:8080/ir/handle/987654321/47656
Appears in Collections:[環境生物與漁業科學學系] 博碩士論文

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