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Investigation of Pacific Broadbill Swordfish Migration Patterns and Habitat Characteristics Using Electronic Archival Tag Technology
Progress Reports (PDF): FY 2000, FY 1999, FY 1998 (see below)
The overall objective of this project is to develop knowledge and understanding required to provide scientific advice to the WPRFMC for the eventual management of North Pacific broadbill swordfish. Specific objectives include: determine seasonal large-scale, regional, and local horizontal movement patterns of swordfish needed for understanding fishery interactions; determine vertical distribution and diel vertical movement patterns needed for understanding catchability; obtain information on ocean thermal characteristics of swordfish habitat for understanding environmental influences on swordfish distribution and availability; and incorporate findings in models for understanding swordfish migration, movements, and habitat.
Geolocating archival tags have begun to provide detailed information on the movement and thermal environment of southern bluefin tuna (SBT). The development of these devices will be extended by integrating archival tag and satellite communications hardware to create a "pop-up" archival tag. The four core elements of these devices will include: (1) components from the Australian SBT archival tag; (2) and ARGOS platform transmitter to broadcast data to satellites; (3) a microprocessor controlled mechanism to release the device from the swordfish; (4) a solar power cell. The hardware and software contained in these devices proved the capability of logging data for up to five years, storing in non-volatile memory chips for up to 20 years, and, at a time specified by the user, transmitting summarized data to ARGOS receivers flown on NOAA satellites.
Dr. Christofer Boggs
National Marine Fisheries Service
2570 Dole Street, Room 212
Honolulu, Hawaii 96822
Phone (808) 983-5370
FAX (808) 983-2902
Dr. John Gunn
Division of Fisheries
CSIRO Marine Labs
P.O. Box 1538
Hobart, Tasmania 7001
Purpose of the Project:To understand harvest impacts and interactions among fisheries across the Pacific, information is needed on swordfish and bigeye tuna migration patterns and on how environmental factors influence distribution and catchability. Recent advances in electronic data storage technology have, however, made it possible to construct devices that allow the long term (months to years) recording of detailed records of vertical and horizontal movements of fishes. The so-called "archival tags" are carried by the fish and record ambient light levels, swimming depth and temperature (external and internal) and estimates of geographical position based on day length (latitude) and local noon (longitude). When the fish is recaptured, a detailed record of both the migrations and vertical movements can then be constructed. For species such as the marlins and swordfish, in which recapture rates are likely to be very low, the high cost of archival tags is a major deterrent to their use. Recognizing this, a new pop-up, satellite-transmitting archival tag (PSTAT) is under development that will come off the fish, float, and upload the data to satellites. Although significant progress in developing the pop-up tags have been made by the project, no fully functional PSTATs have yet been manufactured and in the interim the project has proceeded with conventional archival tag deployments in bigeye tuna.
Progress in FY 1998:Under the subcontract to CSIRO in Australia, further software development for the PSTAT system continued in FY 1998 to upgrade the geopositioning programs, address potential low-light problems, provide for early release of the PSTAT if the tag exceeds its depth tolerance, and to optimally summarize the data for uploading. Also, with its own funding, CSIRO has ordered PSTATs from two vendors for delivery in late 1998. Consultations on a dvancement of PSTAT designs were at the Forum on Wildlife Telemetry in September 1997, and at the 49th Annual Tuna Conference in May 1998.
The project conducted a joint research cruise with NMFS aboard the NOAA vessel Townsend Cromwell in March-April 1998, specifically to deploy archival tags on bigeye tuna near the Hawaiian Islands. The operational area was centered on the western (leeward) coast of the Island of Hawaii. In a total of 16 longline sets (3 daylight and 13 nighttime), 24 bigeye tuna were captured that were suitable for the placement of archival tags. The fish ranged in size from 87-131 cm fork length. The best catch rates for bigeye tuna were achieved by setting the longline gear in manner used by commercial fishermen to target swordfish, rather than by traditional tuna longline methods. The 24 fish were implanted with Northwest Marine Technologies (NMT) archival tags. Two of the smaller fish had the tags placed in the body cavity (i.e. intra-peritoneal). The remainder had the tags placed into the dorsal musculature immediately adjacent to the first dorsal fin. This placement of the tags was chosen because studies conducted at the NMFS Kewalo Research Facility (Brill et al. 1997) on juvenile yellowfin tuna showed that this technique was highly suitable. Moreover, experience on the cruise showed that intramuscular implantation could be accomplished more quickly, and with less risk of serious injury to bigger fish than with intra-peritoneal placement.
Plans for FY 1999:We expect the first PSTATs to be available by the end of calendar 1998. New funds were awarded in FY 1998 to purchase PSTATs but then the funds never appeared and will not be forthcoming. Funding for the project staff will run out in December 1998 and all remaining funds will also be used by the end of FY 1999 but the work will continue at the NMFS Honolulu Laboratory and at CSIRO in Hobart, Australia using other sources of funds. We are committed to deploying the balance of the 80 conventional archival tags purchased by the project on bigeye tuna in FY 1999.
Papers:Weihs, D. and D. Levin. 1997. A pop-up archival tag for long term monitoring of large pelagic fish. Page 75 in: Forum on Wildlife Telemetry, Innovations, evaluations and research needs, 21-23 September 1997, Snowmass Village, Colorado
This page updated August 15, 2006