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Hawaii Tuna Tagging Project Two (HTTP2)
Hawaii Regional Tuna Tagging Project,
Previous tagging initiatives in Hawaii have been funded by the Pelagic Fisheries Research Program. These were primarily focused on issues of local importance but the results of these studies definitely had broader relevance. Two priorities were identified for these earlier studies; 1) the role of the Cross Seamount and its associated fishery in the dynamics of tuna fisheries in Hawaii and 2) the impact of anchored FADs on the biology and behavior of yellowfin and bigeye tuna. In response to these concerns, PFRP funded FAD-related research and the Hawaii Tuna Tagging Project (HTTP) that primarily focused on the yellowfin and bigeye populations associated with the Cross Seamount and the offshore weather buoys targeted by Hawaii fleets. The HTTP deployed over 15,000 conventional tags on bigeye and yellowfin tuna to address issues of movement between geographical areas and different fishery sectors and to derive life history parameters. The project was very effective in quantifying residence times of bigeye and yellowfin tuna on the seamount, exchange rates between major fishing grounds or fisheries and providing size-dependent estimates of natural and fishing mortality (Adam et al, 2003; Sibert et al., 2000; Holland et al., 1999). Similarly, PFRP funded FAD related research has elucidated important aspects of the biology of fish aggregations associated with these devices (Dagorn et al. 2007; Itano and Holland, 2000, inter-alia).
In the decade since the HTTP was concluded, local fisheries have changed. The seamount fishery has developed new methods and targets different species and sizes while privately set "bigeye FADs" have proliferated closer to shore. These and other developments in the domestic and expanding international fisheries have created a new set of potential user group conflicts and management concerns. In order to update movement and life history parameters of tuna in Hawaiian waters and to address current fishery issues in Hawaii (and the broader WCPO) we propose HTTP2. This time, more emphasis will be placed on coastal fisheries (although there will be an important seamount component) and skipjack tuna will be included in the tagging program.
Objective 1. Obtain estimates of growth rates, fishing mortality (F), 'natural' mortality (M) and movement (dispersal) parameters for yellowfin, bigeye and skipjack tuna in Hawaiian waters. This will be the first time that these parameters have been quantified for skipjack tuna in Hawaii. Amongst other things, these experiments will allow us to define the size of the ecosystem of "Hawaiian fish" and elucidate any connectivity with other regions of the Pacific. This component will include an emphasis in FAD-associated bigeye tuna. Privately deployed FADs (PFADs) have become an important aspect of the Hawaiian fishery and these FADs are specifically designed to exploit bigeye tuna - a species about which there is concern regarding overall population status. Tag and release of FAD-associated bigeye tuna will provide estimates of residence times, dispersal patterns and growth rates.
Objective 2. Document the FAD-associated behavior of skipjack tuna. Although skipjack tuna is the most common species found in association with FADs, no previous work in Hawaii has focused on their FAD associated behavior (either residence patterns or depth distribution). We will use pressure sensitive acoustic transmitters to monitor the residences patterns and vertical distribution of FAD-associated skipjack tuna. In order to place their behavior in perspective with other FAD associated species, acoustic tagging will aim to simultaneously tag skipjack and yellowfin tuna of similar sizes so that their behavior can be compared under similar oceanographic conditions.
Objective 3. Determine the diurnal vertical behavior of bigeye tuna associated with the Cross seamount. Seamounts play an extremely important role in the tuna fisheries of the world. In Hawaii, the Cross Seamount plays an important role in local fisheries and has received considerable attention in terms of its physical oceanography and fisheries biology (Holland and Grubbs, 2007; Holland et al, 1999). However, we still know little about how tuna exploit the forage resources at seamounts. Therefore, a component of HTTP2 will use acoustic telemetry to document the vertical behavior of bigeye tuna caught in association with Cross seamount. An additional benefit of this component will be to obtain residence duration data to compare with previous studies that used tag-and-recapture methodologies (Holland et al, 1999).
HTTP2 is designed and implemented as a compatible sub-regional component
of the broader-scale Pacific Tuna Tagging Program (PTTP), we have established
protocols for data sharing between HTTP2 and PTTP so that maximum use
can be made of the data acquired by the two projects.
funding for this 2-year project to be available late 2008.
This page updated January 31, 2013