October 3, 2007
Scientists Amazed at Fish Tag Journey
PORTLAND, Ore. (AP) - In 2005, a 2.9-inch steelhead left a Washington state hatchery in 2005 with a tiny implanted electronic tag. In April, Maori hunter Dale Whaitiri on Big Moggy Island off Southern New Zealand killed a young sooty shearwater chick, and found the tag.
It had traveled 7,700 miles, fascinating scientists an ocean apart who are trying to figure out how it got there.
"It is amazing it made it all that way," said Jen Zamon, a research fisheries biologist with the NOAA Fisheries in Hammond, near Astoria. "It's even more sort of miraculous that someone noticed it."
Scientists believe the fish was eaten by an adult sooty shearwater, and have two theories about the tag:
- That a shearwater off Oregon ate the young steelhead as it headed to sea, and the electronic tag from the fish lodged in the bird's stomach. There it remained for more than a year, until the bird, in New Zealand, regurgitated its stomach contents to feed its chick.
- That the steelhead was inadvertently caught in a fishing net, perhaps near Japan or Russia, cut up on a factory ship or another fishing boat, and its remains and the tag were tossed overboard, to be eaten one of the masses of shearwaters that follow fishing vessels.
"We know it went into the ocean, and we know it ended up in New Zealand," said Dave Marvin, who tracks Columbia River PIT tags for the Pacific States Marine Fisheries Commission in Portland. "But what happened in between is speculation."
The tags are known as PIT tags, which is short for passive integrated transponder, and are similar to identification chips implanted in dogs and cats. Each tag carries an individual code that can be read by an electronic scanner.
Nearly 2 million fish leave the Columbia system with such tags each year, most heading north and west on a more mundane circuit toward Alaska.
Although shearwaters are not well known in Oregon, thousands migrate each year from nesting grounds in New Zealand to forage off the Oregon coast. They flying 40,000 miles a year, and more than 500 miles a day, in figure-eight patterns around the Pacific, according to tracking studies.
In New Zealand, the shearwater is known as a muttonbird, or by its native Maori name, titi. The islands where the birds nest in tunnels among the roots of trees are called the Titi Islands.
The masses of birds, which are related to the albatross, "carpet the surface of the ocean," said Zamon, who is studying the birds and the salmon they eat.
Information from: The Oregonian, http://www.oregonlive.com