Letter: Farm fishing practices not sustainable

Farm fishing practices not sustainable

Re: “Fish smart, eat happy now” (March 27). Despite your optimistic column on the future of aquaculture, the industry still has a long way to go to provide guiltless seafood eating. Current aquaculture practices threaten the sustainability of the marine food chain and are a potential source of drug resistance to the people who eat them.

As mentioned in the column, most of the currently farmed fish are carnivorous species; their diet is largely made up of other fish species. It is estimated that it takes, by weight, between two to five pounds of wild fish to produce one pound of farmed fish. If you do the math, this isn’t sustainable.

In addition, aquaculture is essentially factory farming of fish, with many of same unhealthy aspects. The risk of disease always occurs when a large number of one species is crowded into a small space. Precautionary control with drugs is a reality to ensure a return on the investment. With growing concern over antibiotic resistance due to eating factory farmed meat in this country, adding farmed fish to the list is hardly taking a step in the right direction.

The reasons detailed above are in addition to aquaculture’s poor record in many areas, such as habitat destruction, pollution and genetic and disease contamination of wild fish stocks. I urge readers to obtain a more balanced view of the industry from marine conservation organizations like SeaWeb.

Martha Smith

March 27

The writer is the Program Director for the Center for Coastal and Watershed Systems at the Yale School of Forestry and Environmental Studies.


  • AaronM

    Why does the fact that carnivorous fish species eat large amounts of smaller fish automatically make aquaculture unsustainable? Do not ALL carnivorous species in nature eat more than their body weight in meat as they grow to adulthood? I fail to see how a tuna grown via aquaculture would require more food than one living in the wild - are wild tuna unsustainable?

    Using up 5 lbs of small fish to make 1 lb of palatable bug fish is certainly "inefficient," but it is not automatically "unsustainable."

  • Anonymous

    It seems that a lot of the aquaculture opponents like Martha Smith, SeaWeb, and other ENGO’s have a bit of a group-think problem that keeps them repeating misleading or out of date information. For example, antibiotic use is now minimal in salmon farms, as vaccines and automated machines for injection have been developed (a change in the last decade). Antibiotic use is no longer a significant issue in aquaculture and antibiotics don't improve the growth rate of fish like they do pigs and chickens.

    The common comment about carnivorous fish is also misleading, in that the difference between a carnivore and herbivore can be described as carnivorous animals are often carbohydrate intolerant. For example, trout and salmon do very well (growth rate, feed conversion, etc) on a corn gluten meal (very high protein, low carbohydrate byproduct from corn processing) instead of fishmeal based diet, but at the present time fish meal is cheaper. Whether or not fishmeal, soy protein concentrate, corn gluten meal or spirulina aglae is used in a fish, shrimp or chicken diet is determined by economics and the nutrient requirements of the species (linear programming models to formulate a minimum cost diet) and has nothing to do with whether the species is defined as a carnivore or herbivore in the wild. Wolves will do fine on vegetarian dog food.

    With most of the world fishmeal production going into chicken, pig and pet diets, we also need to keep track of food conversion efficiencies (FCR). Salmon use about 1.1 kg of dry wt. feed to grow a kg of whole wt. kg of salmon, while chickens use about 2.5+ kg/kg and pigs about 3.5 kg/kg. Fish don't have to stand up and keep warm. When they aren't swimming fast or eating or digesting food, they are using very little energy.

    Overall, aquaculture is much more sustainable that either wild fish (aquaculture fish don't waste energy catching their dinner) or terrestrial animals like chickens, pigs or cows. Since fish use much less feed per kg of production than chickens and pigs, they also produce less waste. I could go on about the other points and how the common beliefs in the environmental community are false or misleading, but it takes a lot of space.

    If the predicted next 3 billion people on this planet want some meat, it will come from aquaculture.

  • FishyJim

    This professor should get her facts straight before condemning the aquaculture industry. Most farmed seafood is in fact not carnivorous. Oysters, clams, scallops, mussels and abalone are all pretty much farmed (what's on the market at least) and as filter feeders actually improve the water quality. Other species like tilapia and catfish are herbivorous and only a small portion of their feed is actually from fishmeal. Salmon farming is huge, but when compared to other species is a drop in the bucket. And if you want an example of a true pioneer in carnivorous fish farming, look to Hawaii's Kona Blue Water Farms, which raises kampachi, a yellowtail species that relies on far less fishmeal and is utterly delicious. Making sweeping statements about aquaculture is highly irresponsible.