Orca study proposes using tags

BREMERTON – 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.

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 hearing.

Fred Felleman, vice-president of the board for The Whale Museum, said 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 the 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 is not a trivial thing.”

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.

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.

Each transmitter is about the size of a 9-volt battery. A saltwater switch turns the unit on when a whale surfaces. Signals are sent to U.S. weather satellites.

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 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. “I spent almost 10 or 11 years in Hawaii. Wild whales there will often have lesions in their blubber layer from what we call cookie cutter sharks. There are large bacterial flora in Hawaiian waters as well as Puget Sound. They survive that. They are designed to stay healthy.”