Barramundi

A series of filters and pumps treat water in the recirculating aquaculture systems (RAS) used to farm barramundi, minimizing environmental impacts. Many RAS facilities either utilize previously existing buildings or are built on previously converted land which results in no further habitat conversion or loss of habitat functionality. According to Seafood Watch’s 2020 recirculating aquaculture systems report, RAS operations are considered to have relatively small physical footprints due to intensive production volumes. Floating net pens like the ones used to farm barramundi in Vietnam have little direct habitat impacts, according to Seafood Watch, but discharges can affect water quality and biodiversity.

The recirculating aquaculture systems used to farm barramundi rely on food that contains some animal ingredients, though there are ongoing improvements in aquaculture feeds and their efficiency. Seafood Watch gave this farming type a yellow score for feed in its most recent RAS report, noting that it does vary by species. According to its 2014 report, Seafood Watch notes that net pens used to farm barramundi in Vietnam pose a moderate conservation concern as there is moderate use of wild fish in feed, with a protein loss of 34%. The feed footprint is moderate as well and is estimated at about 11 hectares/ton.

If they are in a stressed environment, (i.e.extreme temperatures, poor handling, low dissolved oxygen, poor nutrition), Barramundi can experience bacterial, fungal, viral, and parasitic diseases. But according to Seafood Watch’s 2014 report on net pen farmed barramundi in Vietnam, operational data has shown a low incidence of diseases. The risk of disease amplification is low as well. Although diseases can occur in recirculating aquaculture systems, Seafood Watch reported little risk of transferring these diseases to wild fish as a result of the limited volumes of water discharged, and the ability to treat or control those discharges.

Escapes from recirculating aquaculture systems are highly unlikely given how many screens and filters the fish would have to pass through first, and the fact that they’re land-based also minimizes survival outside the building. Seafood Watch gives this farming type a green score for escapes. Net pen systems have an inherently moderate to high risk of escapes. The potential risk is mitigated in Vietnam through the use of tanks during certain production stages. According to Seafood Watch, there is a history of escape-free production and a low invasiveness score due to the use of local broodstock.

Recirculating aquaculture systems often use a variety of treatment systems for discharged effluent, Seafood Watch reported in 2020. RAS operations that capture solids and have waste treatment systems in place are not considered to cause or contribute to cumulative ecological impacts at a waterbody/regional scale while those that don’t can potentially have impacts on that scale. Net pen operations in Vietnam actively monitor potential impacts and, according to Seafood Watch, major impacts from effluents beyond the farm sites are considered unlikely to happen. Seafood Watch did note that as more data became available, this criterion should continue to be monitored carefully.

Barramundi are hardy, fast-growing, and have a high reproductive rate, making them ideal for aquaculture. In Vietnam, net pen farms culture native species of barramundi, using domesticated broodstock that have low escape numbers. Fingerlings are also hatchery-raised. Seafood Watch also noted in its report that any future collections of wild brood fish would occur at levels that would not impact wild populations. Most recirculating aquaculture systems around the world rely on hatchery-reared broodstock instead of wild-caught fish, resulting in a green score for barramundi.