Report of Japan's Scientific Observer Program for Tuna Longline Fishery in the Atlantic Ocean in the Fishing years of 2005 and 2006

This document reports the outline of the Japanese scientific observer program for longline fishery in the Atlantic Ocean conducted from August 2005 to March 2007.It also summarizes the data collected by this program. In 2005 fishing year (FY, thereafter, fishing year starts from August to next July), 504 operations and 1,343,789 hooks were observed. In 2006 FY, 378 operations and 981,021 hooks were observed. Majority of observation was conducted in the North Atlantic in both years. Number of observed species and individual number were 43 and 7,175 in 2005 FY. In fiscal 2006, 46 species and 10,621 individuals were observed. In the central and eastern North Atlantic, albacore and blue shark were dominant, while bluefin tuna were dominant in western North Atlantic. In general, most species examined were alive when they were brought up on the deck except for longbill spearfish. Regional difference in sex ratio was observed for many species. Especially, marked difference was observed for sharks (blue shark, porbeagle and shortfin mako shark). Length -frequency distribution showed regional difference in their modes and the size range for bluefin tuna, bigeye tuna, yellowfin tuna, longbill spearfish, blue shark and porbeagle. In general, large individuals occurred in tropical region except for bluefin tuna and porbeagle, for which difference between east and west was rather prominent.