Are farm-raised salmon “good” to eat?

While working on a response to Ray Hilborn’s silly and misleading op-ed in the NYT urging American’s to eat more fish, I ran across a great article about the complex issue of choosing farmed versus wild-caught salmon (and other fish).  The article “The Wild Salmon Debate” is superbly written and the author, David Dobbs, is well-informed about the science surrounding the issue. You can read his piece here.

One of the major problems with farming salmon is outbreaks of salmon lice that can infect wild salmon passing by the farms. There is a growing literature on this problem. One study Ford and Myers (2008) A global assessment of salmon aquaculture impacts on wild salmonids (you can view the paper here in the open access journal PLoS Biology) concluded “we find a reduction in survival or abundance of wild populations of more than 50% per generation on average, associated with salmon farming”

Also see an excellent review article on wild salmon and sea lice here.

 

Condensed author summary from Ford and Myers: The impact of salmon farming on wild salmon and trout is a hotly debated issue in all countries where salmon farms and wild salmon coexist. Studies have clearly shown that escaped farm salmon breed with wild populations to the detriment of the wild stocks, and that diseases and parasites are passed from farm to wild salmon. In this study, we used existing data on salmon populations to compare survival of salmon and trout that swim past salmon farms early in their life cycle with the survival of nearby populations that are not exposed to salmon farms. We have detected a significant decline in survival of populations that are exposed to salmon farms, correlated with the increase in farmed salmon production in five regions. …we find a reduction in survival or abundance of wild populations of more than 50% per generation on average, associated with salmon farming. Many of the salmon populations we investigated are at dramatically reduced abundance, and reducing threats to them is necessary for their survival.

4 Responses to “Are farm-raised salmon “good” to eat?”

  1. Dan S. says:

    I’ve just read the Ford & Myers paper as part of an ecosystem module at university, a pretty depressing read 🙁

    I’ve cut out all fish from my diet for good, which is tough, but I don’t see how anyone with a conscience can still eat fish

    • Shafkat says:

      I agree that this isn’t happy news/reading. To comment on how one can still eat fish: just pick species that aren’t threatened/over harvested, e.g. shad, mullet, etc. Don’t always have to have chilean sea bass and atlantic cod/salmon for every other meal, have we?

  2. Kath says:

    For every article published stating that farmed salmon (and sea lice in particular) are having a negative impact on wild populations, there is another finding that there is no correlation between the two. Most recently the article by Marty et al. in the Proceedings of the National Academy of Sciences (http://www.pnas.org/content/107/52/22599). It is easy to blame the declines in wild salmon populations on salmon farming. I will not argue that the system is perfect, but the industry has worked very hard to reduce its environmental impacts. The conversion ratio of feed has dropped dramatically in recent years, and integrated multitrophic systems, as well as seagrass beds and artificial reefs are being researched to reduce benthic impacts. To say that sea lice are to blame for declines in salmon stocks is to be completely ignorant of other issues involved, including overfishing, habitat degradation, and potential reduction in species fitness caused by releasing millions of hatchery fish.

    • John Bruno says:

      Thanks for commenting Kath. I take your broader point and I had not see the literature you referred to; I will take a look at it. But it seems a bit extreme and unfair to argue “To say that sea lice are to blame for declines in salmon stocks is to be completely ignorant of other issues involved”. I did not say that salmon farming and lice ALONE are to blame for declines and I am very aware of the other causes of salmon losses.

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