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The Risks of Aquaculture

April 9, 2012

There is a decent article over at Seafood Source on the strong recovery of the Chilean farmed salmon industry.  This industry was rocked four years ago by the ISA virus and production plummeted.  While everyone is talking about this ‘success’, I think it underscores how environmentally risky aquaculture really is.  The industry now knows it was risking an epidemic with their production measures.  Could this really be an isolated event?  Here’s an excerpt:

Just four years after a devastating outbreak of infectious salmon anemia (ISA), Chilean salmon farmers are expecting a new production record in 2012 — more than 700,000 metric tons (round-weight) of Atlantic and Pacific salmon…

Nearly 30 years of dramatic production growth in southern Chile was interrupted in 2008 when the ISA virus was discovered in net pens around Chiloe Island, an aquaculture area south of Puerto Montt. Atlantic salmon production, which had been growing at an average rate of 25 percent per year, peaked at 650,000 metric tons in 2008.

Two years later, that total had been halved, as producers harvested fish early or shut down operations altogether to clear the waters of the virus.

While the ISA virus appears to have arrived with salmon eggs imported from Norway, critics both inside and outside the industry blamed it on the exponential growth, which led to overcrowded pens that created an environment susceptible to the virus.

“We weren’t paying attention to the long-term effects of these mega-farms,” said Adolfo Alvial, a highly respected marine biologist and consultant who has worked with the industry for three decades…

“We were so arrogant,” he explained. “This little country in South America showing the world how to build a world-class aquaculture system. And we weren’t listening to the people who were telling us, ‘You’re taking too many risks, not enough research, not enough regulation.’”

So what happens when it’s a disease that devastates natural ecosystems?   This gives me a chill as I think of Lake Titicaca and the risk of epidemic in the trout industry.  In 2010, one Peruvian government scientist told me that it was only a matter of time and it would be far worse in the closed lake ecosystem than compared to a coastal ecosystem.  Producers that I visited in Puno told me they already had mortality rates of 50-70%!

Similarly, I think of the Mekong Delta where Pangasius is produced in high intensity operations.  The industry has grown much like Chilean salmon, though not to the same gross amounts.  How will this “biological treasure trove” handle this?

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