Scientists now know quite a lot about our resident killer whales' summertime habits, including their reliance on summer chinook salmon. But what they don't know about the rest of their year is becoming increasingly important.
Scientists with nets normally used to clean swimming pools tracked killer whales through Puget Sound last week, scooping up their oily poop.
The surprise February visit to Washington from members of J pod came just days after state and tribal leaders learned they may again have to cut back salmon fishing to boost the endangered whales’ survival.
The juxtaposition of the two events highlights a fundamental truth underscoring efforts to restore southern resident orca populations.
Scientists now know quite a lot about our resident whales’ summertime habits — but what they don’t know about the rest of their year is becoming increasingly important.
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A spate of recent research suggests the Sound’s 88 southern resident orcas rely almost exclusively on large chinook salmon for their summer meals — more than previously thought. And when chinook returns to area rivers drop, whale deaths tend to rise and birthrates decline.
Yet with whale populations far below their historical average of 120 to 200, no one knows how many more chinook are needed.
At the same time, scientists remain baffled about where whales go in winter and why — and what they eat once they get there. No one expected to see J pod whales off Vashon Island in February, which is why biologists took samples and plan to test their feces to identify their food.
All these issues will likely come to a head in the next few years, as the federal government, the state and Puget Sound tribes debate the future of chinook fishing and its potential impacts on whales.
That debate started in earnest last week, when the tribes and the state Department of Fish and Wildlife sought federal approval for a four-year plan to manage commercial and sport chinook fishing. Officials with the National Oceanic and Atmospheric Administration (NOAA) surprised everyone by saying they couldn’t approve it.
“They told us the risk was too high to orcas for them to accept a plan” that would remain in place that long, said Pat Pattillo, special assistant to the director of Fish and Wildlife.
Chinook fishing in recent years has been scaled back everywhere, from Oregon and Washington to Canada and Southeast Alaska.
But new calculations suggested the amount of chinook “available to the whales in comparison to their metabolic requirements is less than what we estimated in 2008,” federal officials wrote in a recent letter. Whale experts have noticed many orcas showing signs of malnourishment.
NOAA has asked the state and tribes instead to put together a two-year plan, and participate in science workshops with other agencies from Washington, Canada and Alaska over the next two years. By the end of 2012, NOAA officials said they hope to know how best to address chinook fishing on the West Coast.
“We don’t know enough to say how much or if we need to suspend or curtail harvest,” said NOAA spokesman Brian Gorman. “We need to base that on the best available science, and the best available science remains ambiguous.”
But it’s clear more than it was a few years ago that chinook are key to whale survival, and “the implication of that is that there may need to be more reductions in fisheries that take chinook,” said Donna Darm, NOAA Fisheries’ assistant regional administrator.
Scientists have long known that whales like chinook because they’re big and high in fat.
But in recent years scientists found correlations between whale deaths and low birthrates and low chinook years. And given how small the whale population is now, researchers are trying to proceed with caution.
NOAA’s rejection of the tribes’ and state’s fishing plan outraged Northwest fishermen, who generally seem to support the orca science — but not its implications.
“You can’t bring back orcas just on the backs of fishermen,” said Joel Kawahara, a commercial troller who works in Washington and Alaska. “What about improving habitat? What about the effects of the dams on the Columbia River?”
Zeke Grader, director of the Pacific Coast Federation of Fishermen’s Associations, finds the move ironic, “since we’ve been suing them to improve the salmon runs.”
“It’d be one thing if the salmon were fully protected throughout their habitat and if fishing was the only real cause,” he said. “But that’s clearly not the case.”
Brad Hanson, with NOAA, pointed out that the bulk of the agency’s information about killer-whale diets involves summer preferences for chinook when whales are in Puget Sound. Most of those chinook arrive from the Fraser River in Canada or from rivers in the Puget Sound region.
But he agreed that the only two direct samples taken after whales were seen eating salmon along the Pacific Coast were later proven by genetic analysis to be Columbia River spring chinook.
But for that part of the whales’ diet, “We still have an awful lot to learn,” he said.
Craig Welch: 206-464-2093 or email@example.com