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|Title: ||Preliminary stock assessment of swordfish (Xiphias gladius) in the Indian Ocean by the Age Structured Production Model (ASPM) (1952-2007)|
|Authors: ||Tom Nishida;Sheng-Ping Wang|
NTOU:Department of Environmental Biology and Fisheries Science
|Issue Date: ||2012-11-20T01:16:35Z
|Publisher: ||The seventh session of the IOTC Working Party on Billfish (WPB), Indian Ocean Tuna Commission (IOTC), July 6-10, 2009. Victoria, Seychelles|
|Abstract: ||abstract:We attempted the stock assessment of swordfish (SWO) in Indian Ocean by the ASPM. AI (abundance index) of TWN (1995-2007 without 2002) using the set by set data with the correction factor of targeting (NHBF), produced similar and realistic ASPM results to those of JPN, but less fitness than as for Japan (R 2 =60% for JAPAN and 35% for TWN). ASPM could not get convergence if we used AI of JPN and TWN together. Based on the best scenario using only JPN’s AI, F is 30% above MSY while SSB is just above the MSY level, which suggests that we should not increase the current F. 3 types of CPUE trends (JPN, TWN and La Reunion) in the SW IO (Indian Ocean) consistently show the rapid decreasing trends. Thus F specially in SW IO should be decreased.
We may have 3 hypothetical stocks based on ocean currents driven monsoons, 2 spawning areas and patterns of STD CPUE trends (NW, SW and E) as STD CPUE of Japan and Taiwan consistently shows heterogeneous patterns among these 3 areas. If this hypothesis were realistic, we need to concern the stock status mainly in the SW area as the STD CPUE shows the rapid decreasing trends, while we may not need to worry so much about the stock
status in other 2 areas (NW and E) as their STD CPUE show the flat or gradual decreasing trends This may be the possible reply to the questions raised in the last annual IOTC meeting held in Bali, Indonesia.
|Appears in Collections:||[環境生物與漁業科學學系] 演講及研討會|
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