By Scott Akenhead
This summer, Fisheries and Oceans Canada released a beautiful-looking report “State of Canadian Pacific Salmon: Responses to Changing Climate and Habitats” which your intrepid editor, asked me to “process into layman terms” for TAKE 5. She didn’t actually say, “Your mission, should you choose to accept it,” but … you remember that music?
I definitely heard it.
The unspoken message behind this report is: “You get the world you deserve.” The report provides observations and details about how the Northeast Pacific Ocean (that’s us) is changing from careless use of fossil fuels and what that means to Pacific salmon. I was glad to read this bit: “The planet is warming, and the most recent five years have been the warmest on record. The increase in global temperature above pre-industrial levels is irreversible over the coming centuries.” More people need to realize that the increased carbon-dioxide (CO2) in the atmosphere controls the rate of warming, not the amount of warming. I am not alone when suggesting we don’t want to push that accelerator down any further. Our ocean is shifting to become a new ocean, as marked by a massive “blob” of warm water that formed in 2013 and drifted into BC 2015 and 2016 (Figure 1) (2).
As the NE Pacific Ocean changes, the ocean ecosystems change, and our weather changes. The change in weather means less snow, earlier melting, summer droughts and heat waves. This means that salmon are affected throughout their life, in every habitat they move through while trying to complete their life cycle, while trying to bring those eggs back home. Salmon are kind of unique because they experience the changes on land and the changes in the ocean. This makes them “the canary in the coal mine” for global warming. Well, okay, so how is our canary doing?
Mostly bad (Figure 2). Some glimmers of hope, some confusing bits, some sit-down-and-cry bummers. There are two stories happening together: one about how northern salmon are reacting differently than southern salmon; the other about different species of salmon reacting differently.
First: Where it is becoming too warm for salmon, at the southern end of their range, they are disappearing (with exceptions). Where it used to be too cold for salmon, at the northern end of their range, they are thriving and expanding as the world warms. At the same time as sockeye salmon trying to get up the Fraser and Columbia Rivers are dying from the heat, sockeye in Alaska are breaking records for massive runs, and salmon are showing up across the Canadian Arctic. Salmon in the Skeena and Nass Rivers in Northern B.C. seem to be okay in the middle, but the report mentions that Northern B.C. sockeye have recently slipped badly.
This isn’t in the report, but I like to point out that Pacific salmon are entering the warming Arctic from the west, while Atlantic salmon are entering from the east. So, one of these days, perhaps as you are reading this, an Atlantic salmon will meet a Pacific salmon for the first time in 23 million years (3).
Second: For reasons that are not clear, the salmon that eat fish as adults (coho, chinook, and steelhead) are declining compared to the salmon that eat plankton (pink and chum, sockeye sort of). Which is confusing because cold water plankton are big and fatty, but warm water zooplankton are scrawny little things that seem hardly worth eating. Chum salmon sometimes eat jellyfish, which some biologists think has helped their success, but where’s the nutrition in that? I’d eat a jellyfish, too, if sufficiently starved. Meanwhile, salmon with a short life in freshwater (pinks and chums go to sea immediately after hatching) are not in nearly as much trouble as salmon with a long life in freshwater (sockeye in lakes; steelhead, coho, and Chinook in rivers). But salmon are cunning and tricky: the Chinook salmon in some rivers (populations), and some sockeye salmon (notably Harrison River) go to sea in the first summer of their life. Those salmon are doing much better than their cousins, who don’t go to sea until the second or even third summer of their life.
These observations are clues for ecological detectives to sort through and come up with theories, and then to challenge those theories with data. The Department of Fisheries and Oceans (DFO) assures us they are earnestly doing their best to figure all of this out. To my reading, the response is more and bigger committees, more and bigger meetings, but let’s keep watching. Of course, many ecologists in many countries are struggling with this problem. A Canadian initiative, the International Year of the Salmon (IYS)(4), is organizing collaboration across the North Pacific and the North Atlantic, with the objective of ensuring, as best we can, resilience (5) of salmon in a changing world. You might have noticed that IYS organized, and funded, an international expedition this spring, to study salmon on the high seas. DFO scientists participated. IYS is organizing a larger expedition for 2021.
Please appreciate that salmon were having a bad time before global warming became clear in the 1970s, starting with careless placer mining during the Gold Rush in 1857, then careless railroad building (Hope slides 1911 and 1912 that destroyed massive 1913 Fraser sockeye runs), then 150 years of careless logging (centuries are required before erosion and river sediment settles down), then a careless salmon war between US and Canada in the 1970s and 1980s. What else? Oh yes, dams, very effective. Farms and ranches. Urban and rural sprawl. And hatcheries – scientists warn that salmon are genetically weakened by careless hatcheries. From the report: “Broad-scale landscape change has been occurring in salmon habitats over the long term. Urban development, agriculture, mining, forestry, and other human activities are contributing to increased pollution, nutrient inputs, water extraction, and deforestation. Such changes can make freshwater ecosystems even more vulnerable to the impacts of climate change, through their effects on water availability and water quality for salmon.” Despite our careless behaviour, salmon persist. Must we wait for the straw that breaks the canary’s back? The salmon’s back. If a salmon was a camel.
The news in the report is not good news. Salmon locally and world-wide are generally in trouble and we do not understand why. Figure 2 summarizes, as best anyone can, the complexity of the response of thousands of populations of Pacific salmon to our direct (habitat degradation, fishing) and indirect (climate change) changes to their world. I think it is valuable for the Government of Canada to have said, in one breath, “Numbers of Chinook are declining throughout B.C. and the Yukon. Many sockeye and coho populations are declining in Southern B.C. We are the principle authority for managing Canada’s Pacific salmon.” DFO hastens to point out other agencies are responsible for parts of this problem and thus parts of any solution. Fine, the responsibility is widely shared. But these are your governments, you are the voter, so, ultimately, you are the one that is responsible. Or careless.
Scott Akenhead — that’s a Vancouver Island name that goes back to Nanaimo in the 1860s — ran the marine ecology and oceanography program for DFO in St. John’s NF in the 70s and 80s, then kicked around in high-tech startups in Vancouver before settling down on Ladysmith Harbour. Scott describes himself as “old dog, new tricks” and works as a freelance programmer/analyst for salmon scientists at the Pacific Biological Station in Nanaimo.