July 3, 2013
According to a recent report by the Earth Policy Institute, global aquaculture production overtook beef production in 2011. Production of farmed seafood reached 66 million tons in 2012—three million tons more than beef.
It’s not just beef production that is being overtaken; it is projected that aquaculture yields will exceed edible seafood from wild fisheries in the next couple of years. This trend is not surprising, as most wild fishery stocks are either fully exploited or overexploited and cannot meet the rapidly rising global demand for seafood.
The rising costs of grains is also helping to propel aquaculture production. Most farmed fish require expensive feed, which contains grains like corn and soy or a mix of grains with fishmeal and fish oil. Despite the rising cost, however, it’s still more cost-effective to feed grains to fish than to terrestrial animals like pigs and cows, because fish convert food to flesh more efficiently. (The current feed conversion ratio for farmed fish averages two pounds of feed per pound of product versus seven pounds of feed per pound for cattle raised in feedlots.) In addition to these factors, the environmental impacts of aquaculture are generally less harmful than intensive terrestrial animal production, and the public has become more aware of health benefits of seafood as a source of protein in comparison to red meat. This appears to be a positive trend—but not all types of aquaculture practices are environmentally sustainable and conducive to public health.
Aquaculture includes a variety of aquatic species and farming methods that have diverse impacts on the environment and public health. Generally, the farming of shellfish like oysters is more environmentally sustainable than the farming of large carnivorous fish like salmon, because shellfish do not require feed and actually remove waste and dissolved nitrogen from surrounding waters. On the other hand, the farming of large finfish like salmon requires large amounts of feed containing fishmeal or fish oil that are derived from smaller pelagic fish like anchovies, sardines, and mackerel, which are fished from increasingly depleted oceans. In addition to the ecological concerns of removing large amounts of these smaller fish to feed the larger ones, the fish feeds can contain persistent organic pollutants and heavy metals, which bioaccumulate in larger fish. Additionally, intensive aquaculture operations with many animals in crowded conditions often use large amounts of antibiotics that may contribute to a rise in antibiotic resistant bacteria.
As the industry continues to grow, tougher regulations will be needed to counteract the negative ecological and public health implications of large-scale aquaculture operations.
Photo: Chris Stevens, 2013.