That's farm salmon on your plate

July 19, 2013 by Erna Van Wyk

Some of the earliest written accounts of the legal protection of salmon and their spawning grounds date back to Richard the Lionheart (1189 – 1199), the King of England, who decreed that rivers and streams should have a gap the size of a three-year-old pig which is able to turn around in it without its snout or tail touching the sides.

It highlights the long dependency the peoples of the Pacific and Atlantic northern rims have had on through the ages, said Dr Deanne Drake, an American aquatic ecologist in the School of Animal, Plant and Environmental Sciences (APES) at Wits University.

Delivering the annual APES and Wits Alumni lecture at Wits on Thursday, 18 July 2013, Drake shared her insights gained through many years of studying these remarkable fish in the Pacific Northwest.

Her lecture titled The Story of Pacific Salmon – An Upstream Battle for Sex, attracted alumni from APES as well as young, budding biologists.

Drake focussed on why salmon undertake massive ocean migrations before making the dramatic upstream river journeys for which they are famous, returning to their very place of birth to start the next generation.

Salmon can spend up to six years in the ocean where they also make massive migrations for thousands of kilometres – some as far as 3 000 km long, she explained. Then the school start a hazardous, dangerous and extremely tiring journey back to the river and then up the stream – sometimes as small as two feet wide – to where they themselves were spawned. If they succeed in dodging , seals, , a jackal or two, and their biggest predator: humans, the salmon are able to spawn… and a few weeks later they die, Drake said.

"It is the strangest thing. They reproduce once in their lives and a few weeks later they die. We think it is a result of how much work it is to get back to the spawning area. They also don't eat during this fresh water journey, and trying to survive the many predators, might be too much (to do it more than once)," she explained.

Drake said almost all Atlantic wild salmon have vanished. Most salmon found in South African supermarkets and in your sushi is from salmon 'farms' or hatcheries.

According to Drake, the salmon industry is multi-billion dollar industry that also relies heavily on good marketing strategies to sell their products. "In Alaska it costs around half a billion US dollars each year to bring in wild (Pacific) salmon. Norwegian salmon (of which most is farmed), is an even bigger industry, costing around U$2.4 billion each year.

Explore further: Anthropologists Look to Early Evidence of Salmon for Global Warming Insight

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