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Survivorship, Migrations, and Diving Patterns of Sea Turtles Released From Commercial Longline Fishing Gear, Determined with Pop-Up Satellite Archival Transmitters

Progress Reports (PDF): FY 2008, FY 2007, FY 2006, FY 2005, FY 2004, FY 2003, FY 2002, FY 2001

Project Overview
Three of the five sea turtle species occurring in the Pacific (loggerhead, Caretta caretta; green, Chelonia mydas; and olive ridley, Lepidochelys olivacea) are listed under the U.S. Endangered Species Act as "threatened". The remaining two species (leatherback, Dermochelys coriacea; and hawksbill, Eretmochelys imbricata) are listed as "endangered". The number of nesting females for these species have declined dramatically and turtle nesting beaches throughout the Pacific region have been severely impacted upon. Recovery of all Pacific sea turtle populations is severely hindered by multiple factors, including the spread of the tumor disease, fibropapillomatosis, and incidental capture by longline fishing gear. The numbers of turtles incidentally captured by Hawaii-based longline fishery has increased each year and the situation is now approaching a state of crisis which may jeopardize the future of the fishery. Therefore, the impacts of hooking of threatened and endangered sea turtles in the Pacific fisheries are high-priority research and management issues.

Although turtles are currently hooked in the Hawaii fishery in numbers deemed unacceptable, very few of these animas are dead when brought aboard or along side the vessel. When possible, all live turtles are de-hooked, disentangled, and released at the site of capture1. However, the survival of these turtles has thus far been difficult to ascertain2. The duration of tracks from conventional satellite transmitters currently attached to turtles have been insufficient to determine the rates of long term survival or morbidity for the purposes of drawing solid scientific conclusions necessary for management.

Recent advances in electronic data technology now make it possible to construct devices that allow the storage of detailed records involving both vertical and horizontal movements of marine animals. Information on swimming depth, water temperature, and a daily record of geolocation can be stored and uploaded to ARGOS satellites from these devices known as "pop-up satellite archival tranmitters" or PSAT tags. PSATs can collect and relay data for periods up to 12 months depending on data recording intervals. Researchers believe this caliber of data collection and analysis will provide better information about the turtle's pelagic habitat, its long-term survival and overall fitness following release.

After short-term testing on captive turtles has been completed project researchers plan to attach approximately 50 PSATs to turtles caught at sea, from either commercial longline or scientific vessels. Researchers plan on attaching tags to 20 loggerheads turtles, 15 leatherback turtles, and 15 olive ridley turtles. PSAT tags will be attached to the carapace of hard-shelled turtles based on techniques refined by NMFS scientists. The PSATs will be mounted inside solid plastic tubes which will then be cemented to the carapace. When the tags are placed in the tubes they will be firmly compressed against an inner spring to insure the tag is completely ejected at the specified programmed date. Once at the surface the PSATs will transmit their stored data to the ARGOS Satellite System. As an added "safety measure" a glass link will also be attached to the tag. This link will be programmed to crush at a specified depth (e.g. if the animal dies and sinks) to insure that the tag will still float to the surface. Prior to releasing a "tagged" turtle, the hook location, severity of injury and general state of the turtle will be documented and photographed. All PSATs will be attached and deployed by trained personnel.

Year 1 funding for this project received December 2000.

(1) Balazs, G.H., S.G. Pooley and S.K.K. Murakawa(comps), 1995. Guidelines for handling marine turtles hooked or entangled in the Hawaii longline fishery: Results of an expert workshop held in Honolulu, Hawaii, March 15-17, 1995. U.S. Department of Commerce, NOAA Technical Memorandum NMFS-SWFSC-222, 41 pp.
(2) Balazs, G.H., 1994. Satellite monitoring: A potential method for evaluating post-release survival of hooked sea turtles in pelagic habitats. In G.H. Balazs and S.G. Pooley (eds.), Research plan to assess marine turtle hooking mortality: Results of and expert workshop held in Honolulu, Hawaii, November 16-18, 1993, p. 103-105. U.S. Department of Commerce, NOAA Technical Memorandum NMFS-SWFSC-201.


Principal Investigators:
Dr. Richard Brill
Virginia Cooperative Marine Education and Research (CMER)
Virginia Institute of Marine Science
Gloucester Point, VA 23062 USA
Phone (804) 684-7773
email: Richard.Brill@noaa.gov

Dr. Yonat Swimmer
National Marine Fisheries Service
Honolulu Laboratory
Kewalo Research Facility
1125-B Ala Moana Blvd.
Honolulu, Hawaii 96814 USA
Phone (808) 592-2813
FAX (808) 592-8300
email: Yonat.Swimmer@noaa.gov

Dr. George Balazs
National Marine Fisheries Service
Honolulu Laboratory
2570 Dole Street
Honolulu, Hawaii 96822 USA
Phone (808) 983-5733
FAX (808) 983-2902
email: gbalazs@honlab.nmfs.hawaii.edu
Dr. Jeffrey Polovina
National Marine Fisheries Service
Honolulu Laboratory
2570 Dole Street
Honolulu, Hawaii 96822 USA
Phone (808) 983-5390
FAX (808) 983-2902
email: Jeffrey.Polovina@noaa.gov
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This page updated August 7, 2008