Stock assessment of bigeye tuna in the Western and Central Pacific Ocean, including an analysis of management options [SA WP1] Adam Langley, et al.

By: Contributor(s): Material type: ArticleArticleLanguage: ENG Publication details: [Pohnpei, Federated States of Micronesia] Western and Central Pacific Fisheries Commission (WCPFC) 2008Description: 134 p. ill., graphs 30 cmSubject(s): DDC classification:
  • 639.27783
Online resources: Summary: "This paper presents the 2008 assessment of bigeye tuna in the western and central Pacific Ocean. The assessment uses the stock assessment model and computer software known as MULTIFAN-CL. The bigeye tuna model is age (40 age-classes) and spatially structured (6 regions) and the catch, effort, size composition and tagging data used in the model are classified by 25 fisheries and quarterly time periods from 1952 through 2007. The catch, size and tagging data used in the assessment were updated from the 2006 assessment. It should be noted that, at the time the assessment was conducted, 2007 data were not complete for some fisheries, most notably the distant-water longline fisheries. The estimation of standardised effort for the main longline fisheries used the GLM approach as per the 2006 assessment. The current assessment included a number of additional fisheries (Japanese coastal pole-and-line and purse-seine and equatorial purse-seine) and reconfigured several main fisheries (Indonesia and Philippines domestic fisheries and the longline fishery within region 3). The revised fisheries structure was equivalent to the 2007 yellowfin assessment. The sensitivity of the assessment model to a wide range of assumptions was examined, including the natural mortality-at-age schedule, steepness of the spawning stock-recruitment relationship, historical and current catch levels from the Philippines and Indonesian domestic fisheries, alternative catch history for the equatorial purse-seine fishery, the assumption of constant (versus increasing) catchability of the Japanese longline fleet, and structural assumptions related to recruitment distribution and movement. Of the sensitivity analyses, it was decided to focus on the results of the analyses which were considered more plausible, while still deviating significantly from the base-case analysis. Four sensitivities were selected for detailed examination."
Item type: Meeting Paper
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Holdings
Current library Call number Status Date due Barcode
SPC Special Collections SPC 639.277 83 WES 2008 Available

"WCPFC-SC4-2008/SA-WP-1 Rev.1"

Includes bibliographical references (p. 31-33)

"This paper presents the 2008 assessment of bigeye tuna in the western and central Pacific Ocean. The assessment uses the stock assessment model and computer software known as MULTIFAN-CL. The bigeye tuna model is age (40 age-classes) and spatially structured (6 regions) and the catch, effort, size composition and tagging data used in the model are classified by 25 fisheries and quarterly time periods from 1952 through 2007. The catch, size and tagging data used in the assessment were updated from the 2006 assessment. It should be noted that, at the time the assessment was conducted, 2007 data were not complete for some fisheries, most notably the distant-water longline fisheries. The estimation of standardised effort for the main longline fisheries used the GLM approach as per the 2006 assessment. The current assessment included a number of additional fisheries (Japanese coastal pole-and-line and purse-seine and equatorial purse-seine) and reconfigured several main fisheries (Indonesia and Philippines domestic fisheries and the longline fishery within region 3). The revised fisheries structure was equivalent to the 2007 yellowfin assessment. The sensitivity of the assessment model to a wide range of assumptions was examined, including the natural mortality-at-age schedule, steepness of the spawning stock-recruitment relationship, historical and current catch levels from the Philippines and Indonesian domestic fisheries, alternative catch history for the equatorial purse-seine fishery, the assumption of constant (versus increasing) catchability of the Japanese longline fleet, and structural assumptions related to recruitment distribution and movement. Of the sensitivity analyses, it was decided to focus on the results of the analyses which were considered more plausible, while still deviating significantly from the base-case analysis. Four sensitivities were selected for detailed examination."