When we look at the sustainability of farm raised seafood at FishWise – Hy-Vee’s adviser in its Responsible Choice initiative to responsibly source its fresh and frozen Hy-Vee brand fish and seafood by the end of 2015 – we assess five main criteria: data; pollution, habitat impacts, and chemical use; feed; escapes and disease transfer; and the source of the eggs/larvae.
Here’s a closer look at each:
- Data – the quality and relevance of available data:
- Data poor operations are not sustainable. In some places where species are farmed, we don’t have data on the effluent, stocking density, and other sorts of parameters that can affect wild stocks and the health of the ocean.
- Pollution, habitat impacts, and chemical use – handling farm wastes to prevent pollution, minimizing damage to surrounding habitats during farm construction, and minimizing the use of chemicals:
- Pollution from farms comes from discharging wastewater into the surrounding environment. If a farm treats or recirculates its water, the risks of polluting the environment is much lower than for farms that flush their ponds/cages regularly without filtering or treating it.
- For habitat impacts, we consider what kind of habitat, if any, is damaged during farm construction. For example, farms that are built in ecologically valuable mangrove forests are not considered sustainable.
- Some farms use chemicals to disinfect ponds, treat the water, prevent or control disease outbreaks, and a variety of other reasons. Farms that use a lot of chemicals can have a negative impact on the surrounding environment and can contribute to diseases becoming resistant. In some very egregious cases, we’ve found farms that use the same antibiotics that would be prescribed for a human ailment, diminishing the efficacy of those antibiotics for their intended purpose.
- Feed – Consumption of resources, such as wild fish and other proteins, in feeds for the production of farmed fish:
- How much wild fish is being used in the feed for farmed fish depends on the species being grown.
- Carnivorous species like salmon require a high amount of wild fish, while vegetarian fish like catfish and tilapia require little to no wild fish in the feed. Most sustainable of all species in this area are filter feeders like oysters and mussels, which do not require any feed.
- A species like farmed salmon can take up to three pounds of wild fish to produce one pound of salmon. Ideally, we want a one-to-one ratio or better.
- The industry has strongly responded to concerns related to fish feed and we’ve seen a lot of improvement in this area.
- Escapes and disease transfer – risk of fish escaping from farms and risk of diseases from farmed fish spreading to wild stocks, negatively impacting wild ecosystems:
- If farmed fish that escape into the wild thrive and become established in an area in which they had not lived prior to the farm, they become known as invasive species. Invasive species can have negative effects on native species by outcompeting them for resources (food, habitat, etc.).
- Some invasive species can also interbreed with wild populations, reducing the biodiversity of the wild population and making the population more susceptible to diseases and other changes.
- We’ve seen aquaculture operations responding to this concern with mitigation measures, such as covering pens with nets that prevent fish from escaping over the top of the pen during storm.
- Source of eggs/larvae – independence of eggs/larvae (seedstock) from wild fish stocks:
- Some farming operations remove the eggs/larvae/juveniles from the wild population to grow, reducing the health of the wild stock.
- For example, Bluefin tuna farmed in the Mediterranean Sea are actually raised from juveniles that are caught in the wild in a practice that is often called “ranching.” This depletes the wild stock since those fish will not have a chance to reproduce in the wild.
The most sustainable type of aquaculture is done in land-based, closed-containment systems that recirculate and clean the water. At FishWise, we’re all about closed-containment aquaculture systems, and the technology is improving to make these systems more affordable.