swordfish PFRP Home > Biology Projects List

Nursery Origin of Yellowfin Tuna (Thunnus albacares) in the Hawaiian Islands

Progress Reports (PDF): FY 2010, FY 2009, FY 2008

The aim of the proposed work is to provide information on the origin of young yellowfin tuna (age-1 and age-2) in the Hawaiian Islands using natural tracers that are linked to ambient physicochemical conditions of the water. Our first step will be to develop a reference library that describes the otolith chemical signatures of age-0 yellowfin from putative spawning/nursery areas in Hawaii and the broader WCPO (i.e. are ambient chemical conditions in regional nurseries sufficient to impart unique signatures in the otoliths of yellowfin?). It has long been assumed that juveniles from the equatorial region are purported to be the main source of recruits to the Hawaii-based fisheries and will therefore be a critical sampling location for the proposed work. Next, we will target age-1 and age-2 (sub-adult to young adult) yellowfin from the Hawaiian Island fisheries to determine their source (natal origin). Three hypotheses will be tested using otolith chemistry: H1: chemical signatures in the otoliths of yellowfin from regional nurseries differ, H2: inshore fisheries for yellowfin around the Hawaiian Islands are supported primarily by local recruitment (i.e. resident populations), H3: juveniles from the equatorial region are the main source of the recruits to the Hawaii-based fishery. We will then be able to determine whether residents (versus transients) constitute the primary source of yellowfin recruits to the Hawaii-based fisheries.

Research Objectives
1) Characterize the nursery habitat signatures of age-0 yellowfin from putative nurseries
in the WCPO using otolith chemistry (stable isotopes and trace elements)
2) Determine the origin of age-1 & age-2 yellowfin in the Hawaii-based fisheries using
otolith chemistry
3) Evaluate resident and mixing behaviors of yellowfin in the Hawaiian Islands by
constructing otolith-based life history transects

Methods
Young-of-the year (YOY) or age-0 yellowfin tuna will be collected from five regional nursery areas: 1) Hawaiian Islands (Inshore FADS), 2) Cross Seamount, 3) equatorial central Pacific (Line Islands-Palmyra Atoll), 4) western Pacific (transshipment operations in the Marshall Islands), 5) western Pacific (transshipment operations in Papua New Guinea). We will target 30 samples from each region in 2008 and 2009 to investigate inter annual variability (30 individuals x 5 regions x 2 years = 300 samples), and the chemical signatures in otoliths from the YOY tuna will be used to construct our library of natural tags for the different nursery areas in the WCPO. Sub-adult yellowfin used for assessing stock structure and mixing will come from Cross Seamount and Hawaii-based fisheries in 2008 and 2009. In addition, samples from the high-seas fishery will be targeted in both years of the proposed study. Our target sample size is 100 individuals each year from both Hawaii-based and far-seas fisheries (ca. 200 sub-adults and adults x 2 years = 400 samples).

Linkages to other Components of PFRP
This project will make a significant contribution to the PFRP mandate to provide science-based information useful for the management of WCPO pelagic resources. YF and BE tuna represent one of the most important resources to Pacific Island countries and territories, yet the degree of their movement and residency remains poorly understood. This is particularly true in higher latitude areas, i.e. Hawaii, where understanding the degree of exchange with core equatorial populations is critical to effective management. Tagging data suggests that movement of some tropical tuna species may be more restricted than previously assumed, while genetic data have been insufficient to resolve population structure. The use of the technologies proposed here to examine finer-scale population components and natal origin will provide improved data inputs to stock assessment and sub-regional management efforts. The proposed research is directly related to the top-ranked topic from the Biology and Life History Session at the PFRP Workshop in Honolulu in November 2005 (“development of chemical and electronic tagging methods” to investigate long-term basin scale movements”). Results from the proposed work will provide strong links to PFRP research priorities related to Ecosystem Integration (examine movement and influence of mesoscale oceanography to define functional sizes of ecosystem units) and Biology and Life History (studies on the early life history of tuna, particularly in relation to the use of area closures as a management tool). The project will also provide supportive links to PFRP socio-economic studies by providing information on the origin and movement patterns of tuna resources. This information is necessary to support management measures at domestic or sub-regional scales.

Year 1 funding for this 2-year project to be available late 2007.

References

Sibert, John, Scott McCreary, and Eric Poncelet, 2005. Pacific Ocean Connections: Priorities for pelagic fisheries research in the twenty-first century. Report of PFRP Research Priorities Workshop, November 16-18, 2005, SOEST Publication 06-01, JIMAR Contribution 06-358, 25 pp. (PDF, 393 KB)

Principal Investigators:

Dr. Jay Rooker
Texas A&M University
Dept of Marine Biology
5007 Ave U
Galveston, TX 77551 USA
Phone (490) 740-4744
email: rookerj@tamug.edu

 

Mr. David Itano
University of Hawaii at Manoa
Pelagic Fisheries Research Program (PFRP)
JIMAR
1000 Pope Road, MSB 312
Honolulu, HI 96822 USA
email: dgi@hawaii.edu
rainbow horizontal bar

This page updated September 29, 2010