– Submitted by Kwiaht staff
The response of juvenile Chinook salmon to this year’s unusually warm El Niño is a preview of the longer-term impacts of climate change on Salish Sea salmon. That is the message Kwiaht’s community salmon team brings to its seventh annual SalmonAtion celebration on Saturday, Jan. 23 at Lopez Center, from 5:30 to 7:30 p.m..
According to Kwiaht director Russel Barsh, “it’s a good thing we began collecting data years earlier, since what we are seeing now is nothing like what we observed previously and considered normal.”
Compared to Kwiaht’s 2009-2014 baseline years, outbound juvenile Chinook this past summer were far fewer, smaller, and eating less fish.As a result, their probability of survival at sea is poor, and there may be a substantial decrease in adult Chinook returning to spawn in SalishSea streams four to six years from now.
The impact of warmer waters was greater on juvenile Chinook from Puget Sound than those that had reared in British Columbia before migrating through the San Juan Islands. With seven years data from Lopez and Watmough study sites,Kwiaht researchers have found that good years and bad years for juvenile Chinook migrants can be predicted from the Multivariate ENSOIndex, a measure of temperature trends in the North Pacific Ocean used by NOAA for long-term forecasting of weather conditions at sea.
Pacific Ocean weather oscillations also explain much of the variation in “forage fish” consumption by young Chinook, Barsh says. “During the coolest part of the cycle, a few years ago, each small Chinook was eating twice as many herring and sandlance as we saw in 2015.” The abundance of young herring and sandlance in island waters actually grew in 2014-2015, judging from Kwiaht seine data, but juvenile Chinook did not benefit from the increase: “perhaps because they were smaller, and less active due to heat stress” Barsh suggests.
Barsh says that of the thousands of small fish identified in stomachs of Chinook in the course of the study since 2009, fully 98 percent have been herring or sandlance. Other fish occasionally seen in gut contents range from larval flatfish and sculpins to tubesnouts and greenlings.
San Juan County continues to spend most of its salmon recovery funding on smelt-spawning beaches, however, despite the overwhelming absence of evidence that juvenile Chinook target smelt as they migrate through the islands each summer.
“There is a critical need to re-vise our salmon recovery strategy,” Barsh said.
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