Tuesday, March 22, 2011

What Do They Know That We Don't?

Canadian Harp Seals Showing Up In U.S. Waters

Harp Seal in Boston Harbor
PORTLAND, Maine -- Harp seals from Canada are showing up in U.S. waters in greater numbers and farther south than usual, and biologists want to know why. Small numbers of juvenile harp seals are typically found each winter stranded along the coast of the northeastern United States. But this year, well over 100 adult harp seals - not juveniles - have been spotted, said Mendy Garron, regional marine mammal stranding coordinator for the National Oceanic and Atmospheric Administration in Gloucester, Mass. The sightings are reported by 14 seal stranding and rehabilitation organizations in New England and the Middle Atlantic. "In some areas they're reporting three times the normal number of sightings," Garron said. "This year, we've had four sightings of adult harp seals in North Carolina, which we've never had before. We typically don't see them that far south."
When tropical fish, birds, or insects are found further north than their established ranges, it is commonly asserted to be evidence of a global warming climate change screwing with the ecology and causing species ranges to migrate in response.  What are we to make of this?  I dunno, there's really not much evidence of sufficient warming or cooling to cause an effect of this type, although, certainly, some people, notably the Russians, have been predicting a cooling trend.

I tend to think of it in terms of either a response to overpopulation of Harp Seals in their northern habitats, which forces some to look further afield for food, or a decrease in their favorite prey, again sending them further afield.  However, they have a diverse diet, it seems unlikely that hunger is driving them south.

Harp seals are one the species of seal that Inuit and other Native Americans hunt on the ice, primarily on a subsistence basis, but also for commercial sale.  In Canada they used to hunt the cubs, the "whitecoats", for their pure white pelt, but that hunt was stopped in 1987 because of the the bloody images and videos of the hunt.  Catches are reputed to be well above the estimate sustainable yields, which would also argue against food limitation as a reason for moving south.

Maybe they really would prefer warmer waters, but have been kept by spreading to them by competition or agression from other seals, however, this article suggests that other seal populations have expanded, so that seems unlikely.

Or maybe, just maybe, they feel the northern ocean getting colder and are getting out of Dodge while they can...

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