Global warming has already significantly changed our Fraser River. Its waters are warming and its flows are shifting to earlier in the year. By summer when the legendary salmon runs surge into the river to spawn, the river is more often becoming too warm and low for their survival. Already more and more salmon are dying en route to the spawning grounds. Fishing quotas are being cut back to make up for it.
Experts predict far more "dramatic changes" lie ahead unless humans switch away from climate polluting energy sources. They say our salmon will be hard pressed to survive and thrive in the new overheated Fraser River we are creating.
The Fraser River drains a watershed larger than the state of Washington. The CO2 from the burning of oil, coal and natural gas has changed the climate significantly in this huge watershed. Average air temperatures are rising, average snowpack is declining and rainfall has changed throughout of the year. The river that drains his huge changing landscape is being changed as a result.
Water is now coming down the Fraser River earlier and earlier as the climate warms.
The mid-point of the annual flow now happens much earlier on average than in 1950.
For example, my chart below shows the percentage of annual flow each year that already passed Hope by July 1st. The trend towards more and more of the annual flow passing before summer starts is clear.
Fisheries and Oceans Canada (DFO) expect this trend to continue as long as global warming keeps getting worse. Their climate models show "dramatic changes in the flow of the Fraser River" as more and more of the flow shifts away from summer and into the winter and early spring. The lower the summer flow the warmer the water.
The cause of this shift in flow away from summer is the decline in our late-season snow pack as BC's climate heats up. The Fraser River is a "typical snow melt dominated river". That means flows are lower in winter while snow is accumulating, followed by rapidly rising flows in spring as snows melt and rains start. But now snowfall is decreasing and rising temperatures are melting it sooner. Less and less snow remains by summer.
Global warming is causing the Fraser River, like the air around it, to get warmer. The BC Ministry of the Environment's climate change website states: "The average summer temperature of the Fraser River increased by 1.1°C between 1953 and 1998." Here is their chart:
This warming appears to have increased significantly in recent decades.
A technical report for the Cohen Commission -- A Review of Potential Climate Change Effects on Survival of Fraser River Sockeye Salmon (CCCC) -- states that the Fraser has now warmed by 2.0 C in the last sixty years, with 0.7 C of that occurring in the last two decades.
Fisheries and Oceans Canada also expect this heating trend to get much worse as long as global warming continues:
"By the end of this century, throughout all of July and August, the average daily temperature will exceed the highest average daily temperature (see dashed line) that was observed during the normal period."
Here is their chart:
Rising temperatures are very bad news for salmon. The CCCC report summarized 64 scientific studies trying to understand the impact of just 0.7 C warming over the last two decades. It found "survival of returning adults has very likely decreased" and "the cumulative impacts of climate change on survival across life stages could have been substantial."
Both this CCCC report and the DFO predict an increasingly hostile and tenuous future for Fraser River salmon if we allow global warming to continue.
The Fraser is the largest salmon producing river in Canada. And it is heating up relentlessly...
Temperature is the "master environmental factor" for salmon, as it is for almost all fish. As the graphic at the top of this article illustrates, warmer river temperatures stress adult salmon in many ways, causing more to die before spawning. Females with their extra energy needs are even more susceptible than males. The DFO is blunt about what is coming if we don't switch away from dirty energy...
By the end of the century it is expected that at least every second year will have conditions that are more detrimental to spawning than the worst year in the normal period [1960-1990].
We are creating a river in which half the years will become more deadly to salmon than the worse year they had to deal with normally. In case that isn't clear enough they provide the following chart using dead salmon as symbols:
The CCCC report states:
The relationship between river temperature and survival during the spawning migration has been extensively studied. Migration mortality of adults (termed en route mortality) becomes elevated at temperatures > 18 C
River temperatures in the summer months when salmon are migrating upstream have increased by 0.33 C per decade since 1950. Thirteen of the last 20 years have been the warmest ever recorded for the Fraser River.
As water temperatures have risen, en route mortality has increased. The CCCC report says that the abundance of sockeye salmon in the river has been studied since 1977 but it wasn't until 1992 that any significant en route mortality was reported:
Generally, en route loss begins to be reported in 1992 for Early Stuart, Early summer, and Summer-runs, but not until 1996 for Late-runs. Relative to total catch and spawning ground escapement, levels of en route loss have been increasing
The BC Minsitry of Environment, the DFO and the CCCC report all describe numerous examples of how climate change is impacting almost every life stage of salmon. They all say these impacts will grow much worse as if we allow the climate to warm further.
Death by a thousand cuts
It is a tale of death by a thousand cuts. Each cut isn't enough to kill, but at some point the cumulative impact is deadly. Only recently have experts turned their focus on the cumulative climate impacts on salmon. The CCCC report tells of a recent report (in press) that evaluates the combined impact of each of these individual impacts:
the author used his expert knowledge to argue that the cumulative impacts of climate change across life stages will be much greater than the impacts on individual stages. He concludes that the 'impacts will also carry forward to the next generation, potentially leading to a downward spiral of productive capacity' and predicts a bleak future for Fraser River sockeye salmon, in which most of its habitats may become inhospitable.
We rapidly warmed BC's forests and our pine trees were decimated. Our pine forests won't recover their former health and range because we have destroyed the climate conditions they require. We've handed the keys to our forests over to our arch-competitors: insects and fire. Now our iconic and economically important timber industry is on the ropes. Triage apparently includes cutting into formerly protected forests because there just aren't enough living trees left in the traditional timber supply areas. And then what?
We are also rapidly warming and altering our great river systems like the mighty Fraser River. Our iconic and economically important wild salmon are already suffering as we destroy the climate conditions they require. Quotas have been cut for the wild salmon fishery in recent years to offset the increasing en route deaths caused by warming rivers. The future for our wild salmon and the people who love and depend upon them looks bleak if we don't quickly switch away from oil, coal and natural gas.
- Climate “catastrophe” of 6C dead ahead: IEA : "The world is perfectly on track for a six-degree Celsius increase in temperature. Everybody, even the schoolchildren, knows this is a catastrophe for all of us." And that is without climate tipping points kicking in.
- Half of BC pines dead from fossil fuel pollution. Is it over? : Half our pine trees have been eaten alive in just the last nine years. A killing plague of billions of native pine beetles has been unleashed by the rapid, fossil-fuelled warming of BC.