Satellite tracking of endangered killer whales considered

Dec 6 2010 - 3:04pm

BREMERTON, Wash. -- Federal biologists are proposing to track Puget Sound's endangered orcas by using tiny satellite transmitters, attached to the whales' dorsal fins with a dart fired from an airgun.

The new study is considered important because the transmitters may stay on for up to three months and help researchers identify unknown forage areas. Protecting areas where the three pods of killer whales hunt for food during winter could be a key to restoring this population of fish-eating orcas, known as "Southern Residents."

Darting the whales is considered the best way of attaching the transmitters with current technology, according to Brad Hanson, principal investigator with NOAA's Northwest Fisheries Science Center. The technique has been used with no apparent harm on many species of whales and dolphins, including seal-eating transient killer whales.

Even so, some killer whale advocates -- including The Whale Museum in Friday Harbor -- have begun raising questions about whether the benefits of tracking the whales during the winter outweigh the risks of piercing their skin with a dart, creating a possible entry point for disease.

The Whale Museum has requested a public hearing on the issue before a permit is issued by the National Marine Fisheries Service, which oversees protection of marine mammals. In a letter to the agency, Whale Museum officials complained that the public has not been fully informed about the proposed study and has had little time to review various aspects of the project.

"Our letter is not taking a position, pro or con," said Fred Felleman, vice-president of the board for The Whale Museum. "We just need a lot more information."

Felleman noted that numerous blood vessels pass through a killer whale's dorsal fin, which is a critical part of a whale's circulatory system. For male orcas, such circulation is used to cool their reproductive organs.

Felleman said he has discussed the issue with marine mammals veterinarians, who have told him that "even relatively small wounds in a disease environment (are) not a trivial thing."

The researchers must justify why they need satellite transmitters, Felleman said. "What will these data do to advance the science of the whales? How many permits have been issued to work on these whales? We have to look at cumulative impacts. And why should we keep doing research if it is not going to be used to mitigate the problems?"

The proposed permit includes provisions for increasing the number of suction-cup tags from 10 to 20 each year for Southern Residents. These tags can collect only short-term information because they fall off quickly. Also, researchers are planning to take more live tissue samples for biopsy.

Monica Allen, spokeswoman for the fisheries service in Washington, D.C., said she has learned that the comment period on the permit will be extended to about Dec. 23 -- though she had no word on a possible hearingFrom about January to June of each year, the Southern Residents generally travel along the Washington Coast sometimes as far south as Monterey Bay, Calif. Between infrequent sightings, their location remains a secret to human beings trying to protect the whales and their habitat.

Hanson said the current technique of applying satellite tags by inserting a pair of barbs into the dorsal fin has proved safe and reliable through various studies involving the application of 180 tags among 13 or 14 species of whales throughout the Pacific Ocean.

The satellite tags were instrumental in determining the range of a small population of false killer whales in Hawaii, said Hanson, who served on the biological review team. Such information was important in the recent proposal by his agency to list the population as endangered, he said.

The transmitters themselves are about the size of a 9-volt battery. They have a saltwater switch that turns the unit on when a whale surfaces. Signals are sent to U.S. weather satellites.

To extend the battery life, the transmitters are programmed to operate when a satellite passes overhead and they may be switched off for days at a time. When signals are received, a computer maps the general path of a whale's movements.

Hanson said ongoing experience with these tags has prepared him to use them on the endangered Southern Resident population.

"We did not rush right out and apply this technology several years ago when it first became available," Hanson said. "I felt very strongly that it was important to take a go-slow approach to make sure we would know what the tissue response would be."

The six killer whales to be tagged will be adult males along with females past reproductive age, "... not because we think there is a problem, but we are erring on the side of caution," Hanson said.

The darts are targeted toward the center of the dorsal fin to avoid the majority of blood vessels, he said.

Dr. Pete Schroeder, a veterinarian who has worked with marine mammals for years, said the risk of injury or infection from these darts is not zero, but it is minimal.

"These whales receive a lot more in everyday lesions," he said

(Christopher Dunagan is a reporter for The Sun in Bremerton, Wash., at www.kitsapsun.com.)

 

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