This summer of research that we've been pursuing from Galactic was motivated by the collapse of the Pacific cod fishery in the Gulf of Alaska. Our work is aimed at understanding how young fish are faring post-collapse, and thus what the outlook is for recovery of the stock.
There's an interesting side to that stock collapse, in that we have a good scientific understanding of what caused it.
Cod in Alaska are very intensively studied and managed, so there are good data for understanding how the collapse happened in terms of the fate of different ages of fish within the population. This evidence points very clearly to the effects of the 2014-2016 North Pacific marine heatwave on younger fish, which apparently could not find enough food to meet their increased metabolic needs in the warmer waters.
An entirely separate body of research tells us that the heatwave was a result of human changes to the atmosphere, most notably our carbon dioxide output. Our best scientific understanding is that you can't get the North Pacific as warm as it was in 2016 without these human changes to the atmosphere.
So while cod populations have waxed and waned through the centuries in response to natural changes in the climate, we find ourselves in new territory, where the climate it outside the envelope of natural variability. The poor returns for many sockeye salmon populations in the Gulf this summer put us on notice that the fisheries repercussions will likely not be restricted to cod.
For as long as I've been working as a marine biologist the Alaskan marine science community has mostly dealt with human-caused changes to the climate as a pressing concern of the near future, the impacts of which would become apparent in a few decades. Suddenly we find that that future is now. For individuals and communities that were counting on income from cod or sockeye salmon the impacts of global warming are now immediate and concrete. And we have a very good scientific understanding that these are only the first shocks, and that the rate and magnitude of climate change affecting Alaskan fisheries will increase dramatically as the years go by.
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This post was sent via our high-frequency radio as we're far from internet range. Pictures to follow when we reach internet again. We can't respond to comments for now, though we do see them all!
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