New research published in the journal PLoS ONE by Katherine Ayres and collaborators shines light on the sources of stress in Southern Resident Killer Whales. Ayres used fecal matter to find markers of nutritional and psychological stress in the whales. Her results support the hypothesis that inadequate prey (Chinook salmon) is a larger cause of stress for the whales than is vessel traffic.
Note that the paper does not say there are no impacts from boats, only that the impacts from lack of food overshadow those impacts.
The story has been covered by Ashley Ahearn on KUOW and by Lynda Mapes in the Seattle Times.
Best quote (from the Seattle Times piece): ""I like to call it my buffet-in-a-bar example," said Katherine Ayres, lead author of a paper on the study published in PLoS ONE, released Wednesday. Patrons in a noisy bar won't mind the racket if all their favorite foods are piled high on the buffet. "But you go there and they are only serving rice and potatoes, and it's super noisy and crowded, then it's, 'I am not getting a good meal and these boats are driving me crazy.' "
An interesting section of the full paper: "The temporal trend in T3 concentrations within and between years suggest that the sampled SRKWs might be feeding on a nutritious early spring food source acquired prior to their arrival in the Salish Sea. The trend further suggests that the whales become somewhat food limited during the course of the summer. This result is somewhat unexpected, because the more confined waterways of the Salish Sea, combined with large runs of salmon returning through the area would seem to provide easier foraging opportunities for the whales than the outer coast. Nonetheless, the declining trend in T3 levels at least suggests the possibility that the early spring period when the whales are typically in coastal waters might be a more important foraging time than was previously believed."
As always, we encourage you to read the research for yourself. With PLos ONE it's easy to do, because the journal is free and open to the public. Here's the link to the full research report:
http://www.plosone.org/article/info:doi/10.1371/journal.pone.0036842
Photo by Kat Kellner via Flickr.