Fish Farming: Impacts of the Most Rapidly Growing Food System
While capture fisheries used to be vastly predominant 20 years ago, aquaculture production has doubled since then and has surpassed the consumption of wild-caught fish.
Fish farming is done in inland ponds and tanks, as well as in net enclosures and cages in marine and coastal waters (Figure 1). It originated from the need to control fish production under a growing demand and the overexploitation of wild stocks, and it has become the fastest growing food production system in the world, particularly in Asia. It contributes to global food security and may alleviate the pressure put on oceans, but it has numerous drawbacks (FAO 2016).
Fish farming is done in inland ponds and tanks, as well as in net enclosures and cages in marine and coastal waters (Figure 1). It originated from the need to control fish production under a growing demand and the overexploitation of wild stocks, and it has become the fastest growing food production system in the world, particularly in Asia. It contributes to global food security and may alleviate the pressure put on oceans, but it has numerous drawbacks (FAO 2016).
Figure 1 - Aquaculture in indoor tanks (above) and underwater net pens (below).
It is not actually a true alternative to capturing fish, as it depends on it: 70% of fish in aquaculture is fed with wild fish, and they consume 13% of wild-caught fish. For instance, producing 1kg of salmon requires about 3kg of dried wild fish. In addition, farmed salmon is higher in fat and contaminants, and lower in omega-3 than wild salmon due to the fatty fishmeal and oils it is fed with.
Another issue that arises is that of welfare, as farmed fish are stocked at high densities, what can alter their natural behaviours and sociality, increase their rate of diseases and cause stress from handling procedures. The increased transmission of disease in densely-populated enclosures poses another problem, that of spreading pathogens outside of the farms that are integrated into natural environments. And along with pathogens, waste water from farms is loaded with feces, drugs, chemicals and nutrients that cause eutrophication and pollution when released in coastal areas. Moreover, the development of farms also interferes with natural environments, for instance shrimp farming has destroyed significant areas of mangrove forests. And finally, farmed fish can be non-native to the area, genetically modified or have a different genetic pool than wild relatives, thus they threaten wild populations when they escape from enclosures into the wild.
Diego Garcia-Vega - November 26th 2017
Another issue that arises is that of welfare, as farmed fish are stocked at high densities, what can alter their natural behaviours and sociality, increase their rate of diseases and cause stress from handling procedures. The increased transmission of disease in densely-populated enclosures poses another problem, that of spreading pathogens outside of the farms that are integrated into natural environments. And along with pathogens, waste water from farms is loaded with feces, drugs, chemicals and nutrients that cause eutrophication and pollution when released in coastal areas. Moreover, the development of farms also interferes with natural environments, for instance shrimp farming has destroyed significant areas of mangrove forests. And finally, farmed fish can be non-native to the area, genetically modified or have a different genetic pool than wild relatives, thus they threaten wild populations when they escape from enclosures into the wild.
Diego Garcia-Vega - November 26th 2017