Posted on: Friday, May 13, 2005

Tagged turtles may help set fishing policy

By Jan TenBruggencate
Advertiser Science Writer

Forty young loggerhead turtles, released last week about 1,700 miles west of Hawai'i, could help determine the fishing future of the Honolulu-based longline fleet.

The animals all carry satellite tags, and their route from where they were dropped off to the feeding grounds off Baja California could be used to establish boundaries for future longline fishing in those waters, said Irene Kinan, turtle program manager for the Western Pacific Regional Fishery Management Council.

Longliners fish the waters north of Hawai'i where the loggerheads are believed to migrate, but use special hooks and other methods in an attempt to reduce their catch of the animals.

Paul Achitoff, attorney for Earthjustice, which has fought longlining on the grounds that the turtles are killed during fishing, said a key problem is that the loggerhead turtles tend to be in the same places as the swordfish sought by longliners, and for the same reason: food.

"We've known for a number of years that they tend to line up north of Hawai'i at certain latitudes at the interface between currents — where the food is," Achitoff said.

Environmental groups have repeatedly challenged fisheries in federal court, arguing that all ocean turtle species are under threat, and that fisheries must not be allowed to operate in ways that endanger them further. Longliners occasionally hook threatened species of turtles, including loggerheads and leatherbacks. Several federal research projects on ocean turtles are being conducted in hopes of finding ways to reduce the catch.

One mystery — where, how fast and why the loggerheads travel — is being solved in the age of satellite radio tagging.

Hawai'i researcher George Balazs, with the NOAA Fisheries' protected species office, has conducted similar radio tagging work on the Hawaiian green sea turtle, and he has participated in the loggerhead project.

In previous research, roughly foot-long turtles were tagged off their hatching beaches in Japan and tracked until the batteries ran out just short of the international date line. Given the size of these animals, they can only carry a battery with a life of six to eight months, and that's where most of them were when the power died.

The latest research takes them through the next leg of their journey, expected be eastward on a course that should pass several hundred miles north of the Hawaiian Islands, Kinan said.

The Japanese training vessel Aichi Maru, which docked in Honolulu on Tuesday, had released 40 two-year-old loggerheads at a location 32 degrees north of the equator with a longitude of 176 degrees east. Researchers hope the new batch of batteries will last six to 14 months.

Preliminary research suggests that loggerheads move with currents most of the time, although they sometimes make big loops or hang around specific locations. "They don't seem to be in much of a hurry," Kinan said.

In the North Pacific, loggerheads nest only in Japan, but they appear to migrate with the currents westward and end up in large numbers feeding on small red crabs in that region, Kinan said. The turtles do not mature sexually until they are about 30 years old, and females go back to Japan to lay eggs. There are about 2,000 females nesting.

The turtle research is a U.S.-Japan project that involves the Port of Nagoya Public Aquarium, Pacific Islands Science Center, Southwest Fisheries Science Center, Joint Institute of Marine and Atmospheric Research at the University of Hawai'i, the Western Pacific Regional Fishery Management Council, and students from Hawai'i Preparatory Academy in Waimea and Miya Fisheries High School in Japan.

Reach Jan TenBruggencate at jant@honoluluadvertiser.com or (808) 245-3074.

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