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|Title: ||CPUE standardization with targeting analysis for swordfish ( Xiphias gladius ) caught by Taiwanese longline fishery in the Indian Ocean.|
|Authors: ||Sheng-Ping Wang;Tom Nishida|
|Issue Date: ||2017-03-09T01:52:17Z
|Publisher: ||The Twelfth Session of the IOTC Working Party on Billfish, Indian Ocean Tuna Commission (IOTC)|
|Abstract: ||ABSTRACT:In this study, cluster analysis was used to classify the data sets in relation to the
species composition of catches. Based on the results of cluster analysis, data sets were
grouped into nine clusters and assigned to specific fishing types. The CPUE
standardization of swordfish of Taiwanese longline fishery in the Indian Ocean for
1980-2012 using generalized linear model (GLM). Including the effect of cluster
related to fishing types substantially improved the performance of GLM. The effect of
cluster was the most effective variable for explaining the variance of nominal CPUE.
Generally, the trends of standardized CPUE obtained from GLMs with cluster effect
were relatively smoother than those obtained from GLMs without cluster effect. In
addition, the trends of standardized CPUE were somewhat different when using all
data sets or data sets extracted from cluster with higher catch proportions of swordfish,
especially for areas SW and SE. Because few data sets were available from swordfish
clusters for area SW and SE in early and recent years, the estimates may be highly
uncertain. Therefore, we would suggest that the standardized CPUE series obtained
from GLM with cluster effect based on all data sets might be more appropriate to be
applied to stock assessment as relative abundance indices.
|Appears in Collections:||[環境生物與漁業科學學系] 演講及研討會|
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