Fraser River sockeye salmon: data synthesis and cumulative impacts

change was in 1989, but there was no productivity decline that year. The more obviousdecline in productivity in B.C. occurred in 1992.Routledge: You could find a better fit, such as quadratic, for the pattern than a step. I don’t thinkyou can settle whether it’s a step or a shift from that graph.McKinnell: The point is that a shift in productivity has been not considered, yet it occurred inRivers Inlet and Long Lake, so you can’t rule it out.Q/A: The graph was based on median values for the 16 time seriesPeterman: This is intervention analysis. You need to take into account the autocorrelations inthe time series if you do formal hypothesis tests in the future. When you go to a shift vs. atrend, it’s formal intervention analysis.Rosenau: We had the most massive Harrison return in 2010 from the same 2007 sea entry. Fraserchum that went to sea in 2007 were down. So these are two stocks with almost the same lifehistory, but one is up and one almost collapsed.Groot: It’s probably ocean distribution.Rosenau: Once they get out of Georgia Strait, maybe there is a difference depending onwhere they go.Groot: Fraser chum go north through Johnstone Strait, Harrison River sockeye don’t.Rosenau: These two stocks provide almost a controlled experiment. They spawn in the samegravel and both went out to the ocean the same year at the same time.Q/A: By August, the anomaly would have subsided. Harrison smolts go out through Juan deFuca. Beamish found them in Georgia Strait in September 2007. They were found on theWest coast of Vancouver Is. the following March.Groot: The similarity with chum is the difference in timing. Most sockeye go right out butnot chum. Harrison sockeye also stay around. Probably it was a mismatch for sockeye.McKinnell: There are a number of these observations from 2007 that need to fall in line. Thesurvival for age-2.x Chilko Lake sockeye salmon smolts that went out in 2007 was about 4%vs. 0.3% for the age-1.x. So how did smolts from the same lake, passing through the Strait ofGeorgia at the same time have such a different survivals? Perhaps it’s because the age-2.xsmolts are larger and maybe they have more energy to get through bad times.Marmorek: Did you try to compare median recruits per spawner against the Mackas red and blueyears?McKinnell: The basic pattern holds, though there are some outliers for the ocean entry years1999-2002.Peterman: Fraser pinks that went to sea in 2008 also came back in 2009 in large numbers. Canyou do something similar for WCVI to explain the pattern for other stocks?McKinnell: In 2005, the whole Gulf of Alaska lit up, with positive extreme SSTseverywhere. It was followed by a general cooling trend everywhere. The major exceptionwas from northern Vancouver Island to SE Alaska in the summer of 2007. For northernVancouver Island, there was a blip of warm water beginning in July. We think that,because salinities were higher, that a different process was responsible for the warmer52