each summer may have to be earmarked for endangered resident killer whales if
the whale population is to recover, a new paper says. "If the aim on both sides of the border is to not only stop the decline of killer whale populations, but also help increase their numbers, then we have to ensure the salmon they require are there when they need them," said lead author Rob Williams of the University of Washington and University of B.C.
killer whale populations, but also help increase their numbers, then we have to
ensure the salmon they require are there when they need them," said lead author
Rob Williams of the University of Washington and University of B.C.
That could mean adjusting fishing plans to include an allocation of chinook
for the whales and underlines the need to increase chinook salmon runs,
according to the paper, published this week in the online scientific journal
"Temporary reductions in fishing quotas may buy some time while salmon
spawning habitat is improved to increase salmon returns," Williams wrote.
"An intriguing policy solution would be to give killer whales a salmon catch
allocation under the (Pacific Salmon) Treaty. This would be consistent with the
spirit of Canada's wild salmon policy, which places conservation needs ahead of
The study estimates that 87 whales in the three resident pods consume between
12 and 23 per cent of the average 300,000 chinook that head for the Fraser
River each summer. Each whale needs about 670 fish a day and 42 per cent more
if it is a nursing female.
"Our research indicates that southern resident killer whales easily consume
100,000 chinook each year and, depending on their winter diet, their
requirements could easily be double that," said co-author Erin Ashe.
In comparison, the average total catch in fisheries is 18,000.
If the population recovers to 155 animals over the next 28 years — the goal
of a U.S. recovery strategy — the whales' need for food would increase by up to
75 per cent, the paper estimates.
Resident killer whales specialize in feeding on chinook, often ignoring other
species of salmon. The newly-released Canadian recovery strategy, under the
Species At Risk Act, says adequate supplies of prey must be available to the
But one problem facing researchers and fisheries managers is that both
resident orcas and chinook are at risk, which means the needs of one species has
to be balanced against another.
"When one protected species relies almost exclusively on another protected
species, it can be difficult to develop management frameworks that meet the
needs of both species," the paper says.
he fear is that the more charismatic species will unfairly trump the prey
species, it says.
In 1908, an estimated 690,000 chinook returned and an ecosystem-based
approach to fisheries stock assessments and management is needed for the runs to
recover, it says.
John Ford, senior research scientist with the federal Fisheries Pacific
Biological Station in Nanaimo, B.C., said the efforts to estimate how many
chinook are needed by killer whales falls in parallel with work at joint
workshops involving the Department of Fisheries and Oceans and the National
Oceanic and Atmospheric Administration .
An independent scientific panel is looking at how to balance the needs of
whales and chinook salmon, Ford said.
"There is a strong link between chinook abundance and resident killer whale
survival," he said.
One of the unanswered questions is what the whales eat in winter, Ford
"Is it chinook? We know so little about their whereabouts," he said.
"All these questions are getting a lot of attention now as we look at whether
there's a need to modify the human-based harvest."
Victoria Times Colonist
Read more: http://www.canada.com/technology/Cutting+salmon+catch+could+save+voracious+endangered+orcas+study/5703916/story.html#ixzz1dch9JyvY