One from the archives, Kerry Banks reporting on the stunning sockeye salmon and its perilous journey upstream from sea to river in Canadian Wildlife magazine, Mar + Apr 2015 edition. Find out how you can get your copy here.

Charismatic, colour-changing and a cultural symbol. The sockeye salmon has a lot of things going for it, and its bright red colouring has attracted it a lot of admirers and crowds to its annual breeding grounds.

Every 3 or 4 years, when it is time to breed, sockeye salmon complete a gruelling 500-kilometre journey from the Pacific Ocean upstream, swimming against the Fraser River’s rough rapids, and inland towards Kamloops. Here in the clear waters of Adams River, they lay their eggs on the rocks and gravel and then die.

Considering all this, and how intently it has been studied in the past, it is surprising how much we do not understand about this iconic fish.

Their numbers have been in decline since the 1990s, in 2009 the number of migrating salmon crashed to 1.3 million, from a total which was once 100 million. An official inquiry was announced in 2009 by the federal government, but no singular threat was identified. Rather, the report found a collection of factors is probably the cause.

“Climate change and warming waters present perhaps the most daunting long-term threat to the Fraser River sockeye. » – Bruce Fraser, a B.C. Supreme court judge tasked with the investigation.

Without knowing what causes a decline, predictions are also very hard to make.

“I’d like to force all the sockeye to show an I.D. card as they enter the Fraser,” said Tony Farrell, a fish physiologist with Simon Fraser University. “One of the major obstacles is that we don’t know what they are doing for half of their lives – the part they spend in the ocean.”

Brian Riddell, a  former a scientist with DFO, said research has shown that there are more sockeye dying in the early saltwater phase of their lives than compared with their time spent in freshwater.

Salmon sacrifice a great deal to complete their dangerous journey to the breeding grounds. This process, what’s known as being a “big bang producer”, ensures lots of eggs are laid, and only the fittest salmon continue in the gene pool.

“The drawback with this kind of all-in strategy,” said Scott Hinch, a professor at UBC, “is that it doesn’t work so well in an unpredictable habitat.”

And with climate change throwing a big curve-ball at the sockeye salmon, crowds of tourists and researchers will wait eagerly on the banks of the Adams River every four years to find out if the redfish can step up to the plate.


Laisser un commentaire