swordfish PFRP Home > Biology Projects List

The Associative Dynamics of Tropical Tuna to a Large-Scale Anchored FAD Array

See the SPC website at http://www.spc.int/tagging.

See also 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

Progress Reports (PDF): FY 2008, FY 2007

Large-scale fishing operations on fish aggregating devices (FADs) in the Western and Central Pacific Ocean (WCPO) have generated management concern due to their tendency to aggregate juvenile and commercially undersize tuna as well as bycatch species, e.g. billfish, oceanic sharks, and marine turtles (Hampton and Bailey 1993). Of particular management concern is the unintended catch of juvenile bigeye tuna by WCPO purse seine fleets as well as elevated landings of juvenile yellowfin tuna in drifting object sets. The purse seine catch of bigeye is directly related to the level of setting on drifting objects as bigeye are not taken in unassociated sets in the WCPO.

In the last few years, yellowfin and bigeye stocks have been pushed towards or into an over-fished condition. FADs fished by purse seine are considered a major contributor toward the overfishing situation as well as large-scale fishery removals by Philippine and Indonesian fisheries; many of which are also FAD based. The use of drifting FADs by major Distant Water Fishing Nations (DWFN) purse seine fleets has decreased since 1999. However, directed purse seine effort on anchored FADs has increased sharply since about 1996, particularly in the region of northern Papua New Guinea (Kumoru 2003). Approximately 1000 anchored FADs have been set or maintained yearly in support of domestic or joint venture purse seine activity in the Bismarck Sea: roughly between New Britain and the western limit of the PNG zone. This area is considered one of the most biologically diverse and "tuna rich" areas of the world and is an important spawning and nursery area for WCPO tropical tuna (Itano 2000).

A large proportion of tuna landings by PNG-associated purse seine vessels are taken from within archipelagic waters of the Bismarck Sea, north of the main PNG landmass. These catches include high proportions of juvenile yellowfin tuna and significant catches of juvenile bigeye tuna, oceanic sharks and billfish. The impact of these large-scale anchored FAD arrays and associated removals of tropical tuna and other species is of significant concern to regional management efforts and the Western and Central Pacific Fisheries Commission (WCPFC) in particular. The problem is that very little is known on the aggregative dynamics and behavior of tropical tuna on anchored FADs. In particular, information is needed on the retention rates, movement patterns and vertical behavior of FAD aggregated species. This information is considered essential for evaluating options to improve targeting (reduce bycatch) by purse seine fisheries. The WCPFC considers this kind of information as critical to examining methods to mitigate purse seine bycatch of juvenile bigeye tuna and undersize tuna of all species. The WCPFC has recommended that a large-scale tagging project be initiated in the WCPO with a priority on bigeye and yellowfin resources.

In collaboration with researchers from the SPC's Oceanic Fisheries Programme and the PNG National Fisheries Authority, project investigators will utilize a combination of conventional, archival and sonic tagging technologies and biological sampling to support stock assessment and to obtain information on FAD aggregation dynamics and trophic impacts of FADs on tuna. Project researchers will investigate the associative dynamics of tuna resources of the Bismarck Sea in relation to anchored FADs using sonic tags and automated receivers mounted to selected FADs. The technology has been well proven in Hawaii and should provide in situ observations of residency, catchability and between-FAD movements at fine temporal scales (Dagorn et al. in review).

A combination of individually coded sonic tags and depth sensing sonic tags will be deployed in bigeye, skipjack and yellowfin tuna to monitor their behavior on anchored FADs and seamounts. The SPC/OFP will coordinate tagging cruises and field operations with NFA and the PNG tuna fishing industry. A subset of the anchored FADs in the Bismarck Sea will be selected and equipped with a sonic receiver that will be regularly visited for data retrieval, battery replacement and re-initialization for another round of data acquisition. Sonic data will be evaluated in conjunction with concurrently collected data from conventional, archival and satellite tags as well as information on tropic relationships (gut sampling).

The specific objectives of the project will be, in relation to bigeye, skipjack and yellowfin tuna, to:

  • investigate residence times and movement rates between adjacent FADs;
  • examine fine-scale temporal patterns of arrival and departure to individual FADs;
  • examine schooling synchronicity and behavior of FAD associated tuna;
  • examine movements of tuna within a "cluster" of anchored FADs and what this may infer to between-cluster movements;
  • document fine-scale, species-specific vertical behavior of tuna on anchored FADs;
  • equip seamounts that are known to aggregate tuna in the region of the anchored FADs to examine the behavior of seamount associated tuna;
  • conduct this work on as wide a size range of tuna as possible to examine size-specific FAD related behavior;
  • analyze data, present progress reports at appropriate venues and document results in peer reviewed publications.

Funding for this project to be available mid 2006.


Dagorn, L., K. Holland and D. Itano. In review. Behavior of yellowfin (Thunnus albacares) and bigeye (T. obesus) tuna in a network of Fish Aggregation Devices (FADs).
Hampton J, Bailey K. 1993. Fishing for tunas associated with floating objects: a review of the western Pacific fishery. Noumea, New Caledonia: South Pacific Commission. 48 p. Tuna and Billfish Assessment Programme technical report no. 31.
Itano, D.G. 2000. The reproductive biology of yellowfin tuna (Thunnus albacares) in Hawaiian waters and the western tropical Pacific Ocean: Project summary. Pelagic Fisheries Research Program, Joint Institute of Marine and Atmospheric Research, University of Hawaii. SOEST 00-01, JIMAR Contribution 00-328. 69 pp.
Kumoru, L. 2003. Notes on the use of FADs in the PNG purse seine fishery. 16th Meeting of the Standing Committee on Tuna and Billfish. Mooloolaba, Queensland, Australia, 9-16 July 2003. Working Paper FTWG-4.
WCPFC. 2005. Western and Central Pacific Fisheries Commission - Tuna Fishery Yearbook 2004. T. A. Lawson [ed]. Western and Central Pacific Fisheries Commission, Pohnpei, Federated States of Micronesia. 188 pp.

Principal Investigators:

Dr. Kim Holland
Hawaii Institute of Marine Biology (HIMB)
University of Hawaii at Manoa
Coconut Island
P.O. Box 1346
Kaneohe, Hawaii 96744 USA
Phone (808) 236-7410/533-4110
FAX (808) 236-7443
email: kholland@hawaii.edu

Mr. David Itano
JIMAR, Pelagic Fisheries Research Program (PFRP)
University of Hawaii at Manoa
1000 Pope Road, MSB 312
Honolulu, Hawaii 96822 USA
Phone (808) 956-4108/cell: 387-5430
FAX (808) 956-4104
email: dgi@hawaii.edu

Dr. John Hampton
Oceanic Fisheries Programme
Secretariat of the Pacific Community
B.P. D5
98848 Nomea cedex
Phone (687) 26-20-00
FAX (687) 26-38-18
email: JohnH@spc.int

rainbow horizontal bar

This page updated August 7, 2008