PFRP Home > Biology
Up: Linking FAD-associated Local Behavior of Tuna to Regional Scale
Movements and Distributions
Instrumented Buoys as Autonomous Observatories
of Pelagic Ecosystems.
See also Trophic Ecology and Structure-Associated
Aggregation Behavior in Bigeye and Yellowfin Tuna in Hawaiian Waters
Reports (PDF): FY
2010, FY 2009,
FY 2008, FY
The following project addresses several specific research priorities
recently identified by the PFRP in its 2005
Research Priorities Workshop Report and related Request for Proposals.
The overarching PFRP priority addressed here is the need to understand
the pelagic ecosystem on a variety of scales and to determine the functional
sizes of pelagic ecosystem units as they pertain to tuna and similar
species Within this overall area of emphasis, this project addresses
several explicit PFRP priorities including:
movements to define functional sizes of ecosystem units (PFRP Workshop
Report section 5.2)
tagging programs to provide information on movement at different scales
the effects of FADs on local and wider scale ecosystems and on pelagic
fish production (section 5.2)
new tagging techniques and technologies (section 7.2.1).
of pelagic fish behavior and dispersal are limited logistically to a
few localized sites of interest such as seamounts and FADS or to islands
where researchers have the best chance of releasing large numbers of
tagged animals. Acoustic tagging experiments can yield highly precise
data about very localized movements (for instance around FADs), and
standard tag-and recapture data can give 'course-grained' indication
of longer term dispersal but produce no behavioral data to assist in
interpretation of the results. However, as was expressed in the 2005
PFRP scoping workshop, there is now a pressing need to know more about
how pelagic fish populations are linked across a range of spatial and
temporal scales and about the behaviors that link these different scales.
Embedded within this general theme of understanding the functional sizes
of ecosystem units, there are specific topics that need to be addressed.
These include knowing if local-scale behaviors reflect or predict larger
scale movement patterns and, within this topic, what role do arrays
of FADs play in the larger scale, longer-term behavior of tunas? How
accurately does the sub-set of fishes found around FADs reflect the
status and behavior of the regional population? Can FAD-associated abundances
be used as a proxy for assessing the status of regional populations?
Elucidating the influence of FADs on tuna behavior is a specific regional
PFRP priority but this phenomenon is also of global importance in terms
of fisheries management and stock assessment. Results acquired in the
proposed research could be integrated with larger-scale tag-and-recapture
experiments proposed for the western and central Pacific.
Therefore, it is important to extend the geographical range and duration
of observations of the movements of tunas that at some point in their
lives associate with FADs. By so doing, we will not only get a better
picture of the role of FADs in tuna behavior but we will also address
the key question of the functional size of a tuna's ecosystem - at least
as it pertains to remote archipelagos such as Hawaii. The appropriate
data can be acquired by double tagging fish with both acoustic and data
archiving tags. These tags will provide complementary information at
different scales for the same fish. The acoustic tags will produce fine-scale
data regarding the association of fish with instrumented FADs, while
the archival tags will indicate if the fish remain in the general area
of the island (Oahu) or leave to visit other islands or depart the Hawaiian
archipelago completely. It is possible that some fish will be reacquired
at the instrumented FADs after having left the area for prolonged periods
- we have some preliminary data to show that this occurs. The archival
tags should show us where these fish went. While the light-based geolocation
data acquired by archival tags cannot provide fine-scale positional
data, they can certainly provide data of sufficient precision to address
the questions outlined above (Sibert et al., 2003).
The experiment will use three types of tags (coded acoustic, internal
and external archival) to give short, medium and long-term movement
and behavioral data for fish originally caught in association with Hawaiian
coastal FADs. This protocol will elucidate the functional size of the
ecosystem unit within which "Hawaiian" tuna exist.
1. Determine what role FADs play in the short, medium and long-term
movement patterns of tuna. Determine the functional size of the pelagic
ecosystem within which Hawaii resides.
2. Determine the impacts of FADs on the vertical movements of tuna
and to determine if specific vertical distribution patterns can serve
as a proxy for determining when tunas are associated with floating
3. Test a newly developed tag anchor and attachment method for attaching
pop-up tags to tunas and marlins The attachment system is based on
veterinary and biomedical design principles enunciated by veterinarians,
pathologists and fishery scientists who attended a PFRP-sponsored
tag attachment workshop held in Hawaii in 2002 (Holland and Braun,
4. Collect data that will allow improvement of light-based geolocation
funding for this 2-year project to be available mid 2006.
Kim N. and Melinda J. Braun. 2003. Proceedings
of "Tying One On" - A workshop on tag attachment techniques for large
marine animals. SOEST Publication 03-02, JIMAR Contribution 03-349,
13 pp. (PDF, 164 KB).
J., M. K. Musyl and R. W. Brill. 2003. Horizontal
movements of bigeye tuna (Thunnus obesus) near Hawaii determined by
Kalman filter analysis of archival tagging data. Fisheries Oceanography
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)