As Environment Minister Ian Campbell laments the playing of politics at the International Whaling Commission meeting in Ulsan (South Korea) today, I wish we had a better idea how population numbers of the different whale species are fairing – and also the ecosystems they are a part of.
For perhaps two weeks now the Australian media has diligently reported the Minister including while he has traveled the world rallying against whaling, but the average Aussie would still not have much of an idea about their ecology.
There is a theory in a research paper published in 2003 by Alan Springer et al (Proceedings of the National Academy of Sciences of the USA) that commerical whaling has resulted in the decimation of populations of seals, sea lions and sea otters because killer whales have not had enough ‘regular whales’ to feed on. The abstract to this research paper includes:
We propose that decimation of the great whales by post-World War II industrial whaling caused the great whales’ foremost natural predators, killer whales, to begin feeding more intensively on the smaller marine mammals, thus “fishing-down” this element of the marine food web. The timing of these events, information on the abundance, diet, and foraging behavior of both predators and prey, and feasibility analyses based on demographic and energetic modeling are all consistent with this hypothesis.
According to John Whitfield writing in 2003, “The finding points to the importance of whales in the entire ocean ecosystem, and supports the International Whaling Commission’s decision to ban hunting until whales have returned to their original numbers.”
And I wonder, so what was the original number of regular whales? (I would be interested in links/references to estimates of whale population numbers.)
The same article by Whitfield quotes Andrew Trites of the University of British Columbia, Vancouver, suggesting that “It’s a compelling story, but it’s also a flawed one.” Trites believes that climatic shifts, leading to changes in fish populations, are behind the sea mammals’ decline.
What does he mean by this?
I thought of a piece written about the Pacific Decadal Oscillation and salmon that I read sometime ago by Ned Rozell from Geophysical Institute, University of Alaska Fairbanks. It includes:
Flipping through old issues of fishing journals, Steven Hare of the International Pacific Halibut Commission was struck by the correlations he saw between Alaska and Pacific Northwest fisheries. In 1915, a reporter in Pacific Fisherman wrote that Bristol Bay salmon packers returned to port early due to a lack of fish. At the same time, the chinook salmon run up the Columbia River that borders Oregon and Washington was the best in 25 years. In 1939, the Bristol Bay salmon run was touted as “the greatest in history,” while the chinook catch down south was “one of the lowest in the history of the Columbia.”
The salmon disparity occurred again in 1972, then most recently in 1994, when Alaska fisherman broke a record for salmon harvest while Washington and Oregon managers were forced to close the chinook fishery on the Columbia because so few fish were returning. The current woes of Pacific Northwest salmon fishermen are not due to salmon’s preference for a northern life; Alaska and Pacific Northwest salmon rarely mingle, and many are of different species. So why the correlation between good years here, bad years there?
Ocean conditions must affect the fish. That’s the theory of Hare and Nathan Mantua, an atmospheric scientist at the University of Washington. Simply put, the Gulf of Alaska and Bristol Bay since 1977 have been better places for salmon to be than the northern Pacific off the coast of California, Washington and Oregon. In the twenty years before 1977, years when Alaska’s fisheries were struggling, the northern Pacific were the better waters for salmon.
The researchers think the pattern has to do with a climate phenomenon similar to El Nino. Instead of El Nino’s recurrence pattern once every two to five years, the one that may affect salmon has phases that last 20 to 30 years. This Pacific Decadal Oscillation, as the researchers call it, has its strongest effect in the North Pacific Ocean, while El Nino’s more widespread effects originate closer to the equator.”
This is the third in a series of posts on whaling, see also
http://www.jennifermarohasy.com/blog/archives/000653.html (June 10)and
http://www.jennifermarohasy.com/blog/archives/000646.html (June 7)