Standardized CPUE for blue sharks caught by the Japanese longline fishery in the Atlantic Ocean
Standardized CPUE for blue sharks caught by the Japanese longline fishery in the Atlantic Ocean.
Hiraoka, Y. and Yokawa, K.
The standardized CPUEs of blue shark in the North and South Atlantic are updated to 2009 by the new models in the short- and long-term, respectively. The trends of standardized CPUEs given by the two analyses were compared with the result by the same method as the previous study by Matsunaga (2008). The long-term CPUE trend (1971-2009) is estimated by the modified previous model, and the short-term CPUE trend is obtained using blue shark data only (1994-2009). In all cases, the general trends of CPUEs were similar among different models and data sets, except for the short-term result in the North Atlantic in the mid-1990s. The result of this study at least indicates the status of the stocks of blue shark has not changed remarkably in recent years in both the North and South Atlantic, and also it suggests the need for additional studies of the filtering method to select the data for CPUE analysis in order to increase the increase the reliability of the estimated annual CPUE trend of blue shark.
Collect. Vol. Sci. Pap. ICCAT, 68(5): 1893-1907 (2012)