Photo: Salmon: The latest casualties of climate change

(Photo credit: Jeffery Young)

Guest blog by Mark Angelo, a river conservationist, writer, teacher and paddler who founded B.C. Rivers Day and World Rivers Day

The long stretch of hot, dry weather in B.C. this summer is great for outdoor recreation. It's not so good, however, for local streams and the wildlife they support. I've spent lots of time in creeks close to my home in Burnaby in Metro Vancouver lately and I've never seen water levels so low this early in the summer. We're already seeing conditions in many creeks that you would normally expect to see in late August.

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In addition to low stream flows, we're seeing disturbing increases in water temperatures. We started experiencing record highs in coastal water temperatures in fall 2014 and they've continued this year. The optimal water temperature range for both trout and salmon is 13 to 18 C, with temperatures above 20 creating stress for the fish. Our Burnaby creek temperatures are now between 21 and 22 C. The neighbouring Fraser River has been recording temperatures close to 20.

Weather-related and climate-change-exacerbated events this year on both the South Coast and Vancouver Island have created a "perfect storm" for our waterways. We had a near-record low snowpack, followed by a warmer than usual May and June. What little snow there was disappeared quickly, followed by prolonged warm and dry conditions. In addition to the impacts on fish, this has also resulted in ideal conditions for the many forest fires raging around the province.

Fewer young fish are predicted to survive these conditions. We could also see less robust spawning rates for returning salmon, more fish dying before they spawn and a greater susceptibility of fish to parasites, disease and predators if these conditions persist. This could result in millions of premature salmon deaths across the province, with the Fraser River and east Vancouver Island perhaps most affected.

As stream flows continue to drop, fish will have less available habitat. I've already seen in several streams fish clustering in the few remaining deep water holes. In addition, we may be entering a new El Niño phase, which could result in even lower salmon returns in many places.

I'm concerned that extreme climate-impacted weather events such as we've been experiencing in B.C. will become more common. South Coast streams, which have traditionally been fed by both rain and snowmelt, could become largely rain-fed over time. That would mean higher flows in the fall, winter and spring, and much lower flows and higher water temperatures in the summer.

Fisheries and Oceans Canada is closing some fisheries to protect vulnerable salmon. It's still too early to know how effective this will be. The fact that the DFO is still keeping some coastal recreational chinook fisheries open is something that should be re-examined.

Sockeye salmon, pushed by climate constraints, are already at the southern extent of their range. Fraser River sockeye are under threat, with a recent study predicting up to 21 per cent less catch by 2050 due to climate change alone. Add in factors such as pollution and habitat destruction and the situation could be even more dire. All of this highlights the need for an even more precautionary approach to the fishery.

As a long-time river advocate, I know all too well that our rivers already face threats ranging from pollution and urbanization to excessive water extraction for resource development and dam building. In the end, climate change may pose the biggest threat of all — and what we're experiencing this summer may well be a harbinger of things to come.

July 15, 2015
http://www.davidsuzuki.org/blogs/healthy-oceans-blog/2015/07/salmon-the-latest-casualties-of-climate-change/

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