Aquaculture has a bad environmental rap. Possible negative impacts associated with fish farms include eutrophication or the loss of oxygen in water, greenhouse gas emissions, land occupation, excess energy demand, and biotic depletion stemming from feeding wild fish to farmed fish.
But Blue Frontiers, a recent report co-produced by the WorldFish Center and Conservation International, reveals that not all fish farms are equally destructive and that some farms can even have a positive environmental impact.
The report honed in on Asia in particular, since that continent is responsible for 90% of the world’s farmed fish stocks, though most of the major producers were evaluated.
Asian aquaculture has the worst environmental record not only because of the sheer volume of its production, which increases its impact, but because the species favored there, Carp, exacts one of the largest tolls.
Here’s a brief breakdown of the relationship between species and the environment:
- Inland pond culture and carp farming have the highest absolute impact;
- Shrimp, prawns and other carnivorous species stand out as especially biophysically demanding;
- Salmonids are demanding as a result of the use of fishmeal for feeding;
- Bivalves and seaweeds place low demands on the environment and actually reduce eutrophication
Compared to farming livestock, a global warming nightmare given the vast quantities of land and grain required to feed them and highly polluting methane pumped into the atmosphere, fish farming is fairly benign.
Aquaculture products contribute less per unit weight to global emissions of nitrogen and phosphorus than pork and beef and convert a higher percentage of the food they eat into consumable protein.