Wednesday, December 8, 2010

Are San Juan Orca Starving?

Guest Blog by Howard Garrett, Orca Network,

When the Southern Resident orcas were declared endangered under the Endangered Species Act in 2005 after a population drop of 20% between 1996 and 2001, a variety of research projects were launched to find out why. Effects of vessel traffic on orcas were studied, persistent toxins were described, and researchers studied what these orcas' eat and how much of it is available to them.

Research on the orcas' hunger problem has uncovered the clearest results. NOAA researchers have examined fish scales and fecal material in the wakes of the whales and have concluded that: "Chinook salmon, a relatively rare species, was by far the most frequent prey item, confirming previous studies."

Prey availability studies have repeatedly yielded convincing correlations: drops in Chinook salmon numbers preceded higher mortality rates of Southern Resident orcas. Using 25 years of demographic data from two populations of fish-eating killer whales in the northeastern Pacific Ocean, that population trends are driven largely by changes in survival, and survival rates are strongly correlated with the availability of their principal prey species, Chinook salmon.

Whale watch tour boats can at times disturb the whales and those incidents should be
reported widely and some reprimand should be, and is, delivered to the captains and owners. The Q13 story (a tv news report) almost completely failed to mention the lack of food, the primary factor resulting in starvation, although they promise to do another story entirely about how the depletion of Chinook is starving the orcas. The boats do disturb the whales at times, but that is minor in comparison to the lack of Chinook.

Some naturalists talk about the very complex and politically charged salmon issue, but much more needs to be done to make sure the boats provide a good overview of the environmental degradation that has reduced the availability of Chinook for the So. Residents.


Jeff Friedman said...

"The boats do disturb the whales at times, but that is minor in comparison to the lack of Chinook."

Great post, Howard. I think this quote is right on.

On a brief visit out on the water with the southern residents I was amazed at how many boats were around them all day. At one point a group of transients passing through had boats on both sides. I didn't see anything that would constitute violations, but its difficult to imagine that there is no impact.

But the salmon issue is the elephant in the room in the news story mentioned above. Without an abundant and healthy supply of Chinook, the southern resident population will not be able to survive or grow to pre-capture numbers.

The salmon issue needs to be addressed as the orcas primary challenge. I'm hoping Q13 follows through with their promise of a story on this.

Hardy said...


Hardy said...

Testing new log in