Experts examining killer whales' salmon diet
Published Sunday, October 30, 2011 10:15AM EDT
Huge chinook salmon are the most prized catch on the Pacific coast for fishermen on both sides of the Canada-U.S. border, but they may soon have to share the bounty if a scientific panel links chinook and the survival of endangered southern resident killer whales.
The independent, cross-border panel has recently completed the first of three workshops looking at studies connecting the abundance of chinook and the well-being of the rare killer whales.
There's great interest from sport, commercial and First Nations fishermen in the recommendations because of the implications on the lucrative fishery, said panel member Andrew Trites.
"Everybody is watching this very closely," said Trites, director of Marine Mammal Research at the University of B.C. Fisheries Centre.
Panel chairman Ray Hilborn said their job isn't to make a fisheries management recommendation but to evaluate the science behind an assessment that limiting the fishery will benefit the whales.
The panel has about three dozen studies and reports to analyze before a decision is made at the end of 2012.
Several studies have shown there's a correlation between poor survival of southern residents and low chinook abundance, Hilborn said.
The professor of aquatic and fishery science at the University of Washington said both the Department of Fisheries in Canada and the Fisheries Service in the U.S. know a decision to limit the fishery will be controversial.
"So if they're going to go forward with regulating these fisheries they want to be able to say, `You know it's not just our own scientists, we've had an independent panel review this stuff."'
William Stelle Jr., the regional administrator with the U.S. Department of Commerce, said in a letter issued earlier this year that if the panel recommends changes, the goal could be to implement the fisheries restrictions for the killer whale recovery plan starting as early as the 2013 salmon fishing season.
Studies show that up to 90 per cent of the summer diet for the 88 southern killer whales is made of the large and fatty chinook and that a large percentage of those are returning to British Columbia's Fraser River.
Experts estimate adult orcas need up to about 290,000 calories a day. That's 10 to 34 salmon a day, depending on the size and species, or over 800,000 salmon a year.
Lynne Barre, a marine biologist with the fisheries service of the National Oceanic and Atmospheric Administration in Washington state, said it's too soon to determine if limits would be placed on fisheries in order to protect the whales.
"This is an impact we're considering," she said. "We haven't identified how or in what way a fishery would be changed in order to accommodate a need for the whales. We haven't gotten to that point."
Barre, who leads the Orca recovery program in the United States, said the effort is part of an action plan to restore Washington state's Puget Sound by 2020.
Plans are also in the works to keep the whales from oil spills and reduce contaminants. There's even a proposal to start tracking a whale with a satellite to see where the three pods winter.
New regulations implemented this year in American waters limit the possibility of whale-vessel impacts. Limits were doubled to keep ships away from whales from 90 to 180 metres. Canadian no-go zones have been set at 100 metres.
Barre said one of the most exciting proposals is an application by the National Oceanic and Atmospheric Administration to apply a small satellite tracking tag to one of the whales. Researchers are hoping the device can solve one of the biggest mysteries about where the whales travel in the winter.
"It would increase our data with one deployment, to help us see how far off shore they're going, if they're staying in localized areas for extended times or if they're just transiting to and from feeding hot spots," she said.
There are two different groups of resident whales off the B.C., Washington state coasts. The northern residents, which spend most of their known time in the waters off British Columbia, and the southern residents which split their time between Canadian and U.S. waters.
The northern residents, with a population of about 200 whales, are similar to southern residents and have the same diet.
There are also about 500 other killer whales off the Pacific coast divided into transient and offshore groups that have a diet of mammals or sharks.
Barre said helping the southern residents survive and thrive has been difficult.
"It's definitely challenging because it is a trans-boundry issue because it covers a number of different types of threats, the prey, the contaminants and pollution and then vessel impact and sound."
The population of the whale dipped dangerously low in the 1990s and while Barre said experts don't think it had anything to do with oil spills, they're working on a plan to keep the mammals away from potential harm.
"We can use sounds, we can use these banging pipes, we can use a helicopter from the air to sort of encourage them to go in a certain direction. There's also these little underwater explosives that are generally used to keep seals and sea lions away."
She said there's been plenty of concern this month about how to heard whales after several killer whales were spotted going up an Alaskan river. Three of them, including a pregnant whale, died.