CONVERSION ON SAMPLED-CAS INTO CAA OF THE NORTH ATLANTIC TAIWANESE ALBACORE CATCH, DATING FROM 1981 TO 2008, USING KNIFE CUTTING ALGORITHM

SUMMARY Catch at age (CAA) data has always been very important, even indispensable, piece of information required for modern fisheries stock assessment modeling exercises. Although quite a few models already to include conversion algorithms of catch at size (CAS) into CAA, to set aside such conversion as separate procedure will be much beneficial mainly due to the complexity of type of fisheries with specification of circumstances. As one of the major fishing fleets targeting on North Atlantic albacore resource, Taiwan Fisheries Agency has long been endeavouring on collecting North Atlantic albacore’s catch at size data from its operating vessels. Monthly random sampled CAS, which was summed up from those reported Taiwanese North Atlantic operating longliners, of Taiwanese albacore catch by area 31 and area 32 were firstly compiled. A conversion on CAS into CAA was then applied at this point by using knife cutting algorithm accompanied with its derived mean weight per fish, based on obtained age distribution and official age-weight growth equation. Yearly Taiwanese CAA, based on reported sampled vessels, by areas 31 and 32 were then summed up with its corresponding total estimated weight were also provided. The area-time table of Taiwanese CAA provided in this document has to be raised to match with its Task 1 catch reports. The standard procedure of size measuring only the first 30 fishes of catch is a very good random sampling setup, it is noticed that the level (monthly/seasonally/yearly) of compilation procedure, however, may result in different figures. RESUME