Good national news is rolling in about 5 new southern resident whales and no deaths in 2009, plus one new baby thus far in 2010. Howard, Ken, and Brad allude to looking for correlations or explanations in chinook salmon abundance:
It sounds simplistic, Garrett said, but “the way that we can tag the population fluctuations is directly from the chinook runs.”
Taken as a whole, the runs in the region have held steady over at least the past two years, he said.
It’s not that simple, said Brad Hanson, a wildlife biologist with the federal Northwest Fisheries Science Center in Seattle. He said that for much of the year, little is known about what salmon stocks the whales eat and where.
It’s frustrating to me that we don’t have a nice synopsis of west coast chinook populations for 2009, or at least 2008. The strongest correlation between killer whale mortality or birth indices is with 3-year running means of chinook abundance lagged 1 year relative to the KW index (Ford et al., 2009). So, we would need data from 2007-9 to compute a chinook abundance index value for 2008 that ought to explain the low mortality and high birth rate observed in KWs during 2009.
Does anyone have a handle on such chinook data?!