216 



Fishery Bulletin 101(2) 



Buoy 1 



OTHER 



Inshore FADs 



Buoy 3 



Cross Seamour\t 



Buoy 2 





OTHER 



163W 



161W 



159W 



157W 



155W 



Figure 1 



The study area around the Hawaiian archipelago showing the boundaries of 

 the sites used in the model. Individual crosses indicate the geographic loca- 

 tion of the FADs. 



allocation and sustainability issues that are increasingly 

 frequent in all oceans. 



Conventional tagging of bigeye and yellowfin tuna was 

 initiated in 1995 in order to advance understanding of the 

 dynamics of tuna aggregations in the Hawaiian fishery 

 and to provide management guidance. Although initially 

 concentrating on the Cross Seamount, the Hawaii Tuna 

 Tagging Project (HTTP) expanded its scope to tag fish 

 throughout the archipelago and has tagged and released 

 more than 17,000 bigeye and yellowfin tuna of roughly 

 equal numbers during a five-and-half year period. 



Previous analyses of the data suggested that recruitment 

 (transfer) rates from the Cross Seamount to the inshore ar- 

 eas were low and concluded that fishing effort on the Cross 

 Seamount was not having an adverse impact on other com- 

 ponents (inshore trolling and handlining, offshore longlin- 

 ing) of the local tuna fisheries (Sibert et al., 2000). It was 

 also suggested that bigeye tuna on the Cross Seamount had 

 a higher mean residence time than yellowfin tuna (Holland 

 et al., 1999; Sibert et al., 2000). 



However, those previous analyses were made while tag- 

 ging was still in progress, using a small set of recapture 

 data. Since that time, many more tag releases and recover- 

 ies have been made which permit a more complete view 

 of movement and residence times. The work presented 



here includes releases and recoveries up to June 2001. A 

 size and site-specific tag attrition model was developed to 

 analyze the data and provides information on transfer and 

 exploitation rates that are important for management of 

 the resource and for subsequent fishery assessments. The 

 approach used in this research may prove useful in other ar- 

 eas where resource allocation issues need to be addressed. 



Materials and analytical method 



Data and tag attrition model 



The analysis includes recaptures of tagged bigeye and yel- 

 lowfin tuna released between August 1995 through Novem- 

 ber 2000 in the Hawaiian pelagic fishery in the geographic 

 region 165°W to 153°W and 14°N to 26°N (Fig. 1). A total 

 of 12,848 tag releases from within the area are examined 

 here of which 7541 (59Cf ) were bigeye and 5307 (41^^ ) were 

 yellowfin tuna. Releases were made primarily at the Cross 

 Seamount which is located about 290 km south of Oahu at 

 approximately 18°42'N, 158°16'W. Releases were also made 

 at NOAA data buoys 51001, 51002, and 51003 (identified as 

 buoy 1, buoy 2, and buoy 3 in this paper, see Fig. 1) and at 

 inshore areas immediately surrounding the main Hawai- 



