On Sunday, July 14, 2019 nearly 49,000 fish escaped from Norwegian salmon farmer SinkabergHansen’s net pen farm at Oksabåsen, near Trondheim. It was determined the escape occurred after mechanical delousing had been carried out in a cage. The cage contained only 76,115 fish, down from the previous total of 125,000. This most recent escape is by far the largest reported in that country this year; according to Norway’s Directorate of Fisheries, at the end of May, the total number of escapees from twelve incidents was 7,147. In an effort to catch the escaped salmon, SinkabergHansen engaged an emergency net to seal the tear in the cage, deployed nets around the site, and employed a remotely operated vehicle (ROV) for control and observation. Additionally, anglers who catch salmon in the area are being offered a bounty of £28 for submitting a clipped adipose fin as evidence. As of a week ago, only 418 escapees had been caught.
According to SeaChoice.org, net pens (or sea cages) are considered a “High Risk” form of aquaculture. Found in coastal areas or freshwater lakes, net pens are anchored to the sea floor. Among the concerns, is the interaction between the fish contained in the pens, the surrounding environment, and wild species including: concentrated waste (uneaten food pellets and fish waste) polluting the water and depleting oxygen for plants and sea life; diseases and parasites which can spread to wild species; pesticides and antibiotics (used to control diseases and parasites) accumulating in the environment. All this is added to the escape potential, which can take the form of a large-scale event (as in Norway) or “leakage” in which low-level escapes occur throughout the farm cycle. Salmon farmed in North America and Europe are genetically different from those found in the wild and interbreeding can produce negative effects. SeaChoice.org states: “The consequence of interbreeding, between farmed and wild Atlantic salmon, results in genetic diversity dilution, generational fitness degradation, and adaptation loss (i.e. the ability to effectively adapt to environmental changes).”
In August of 2017, more than 250,000 salmon escaped from a net pen (owned by Canadian company Cooke Aquaculture) into Puget Sound off the coast of Washington in the United States. It was determined that nearly half of the anchor lines holding the net pen in place had broken a month before the incident occurred. Cooke Aquaculture was fined $332,000 for negligence. Escaped salmon from this event have been found as far as 250 km from the site. The state of Washington has since passed legislation that will ban non-native fish farms by 2022. Until then, the Washington Department of Ecology will require updated permits focused on increased underwater video monitoring; regular inspections of structural integrity by a marine engineer; improved cleaning and maintenance; site-specific response plans and preparedness trainings; and contacting local tribes and state agencies if escapes occur.
The Food and Agriculture Organization of the UN (FAO) projects that by 2030, fish farming (aquaculture) will be responsible for nearly two-thirds of the fish consumed worldwide. The oceans can no longer meet our demands for seafood as every major commercial fishery in the world is declining or has collapsed. As aquaculture continues its rapid growth, what can be done to avoid “High Risk” methods?
One strategy is to move net pens out into the open ocean. Strong, steady currents continually flush fish waste and pests from the farms. The water temperature and salinity are more consistent which leads to less stress on the fish; less stress means less need for antibiotics. Another strategy, developed by Thierry Chopin, professor of marine biology at the University of New Brunswick, is called “integrated multi-trophic aquaculture.” Mussels, sea urchins, and sea cucumbers are placed downstream from salmon net pens to feed on the wastes from the salmon.
However, opponents of net pens point to land-based recirculating aquaculture systems (RAS) as a means of addressing and remedying the problems associated with net pen fish farming. Considered “Low Risk” by SeaChoice,org, water used in these systems is treated and recirculated, with minimal (and sometimes no) discharge back into the environment. RAS use 100 times less water per kilogram of fish than traditional land-based aquaculture systems. Because the water is monitored continuously, the risk of disease is lessened as is the need for antibiotic usage. In addition to shrimp, almost any type of marine finfish can be raised using RAS. Perciformes Group in Taft, TX, USA has had great success culturing and raising Sablefish(black cod) using a recirculating system; other common species include Arctic char, striped bass, barramundi, and sturgeon. Because the level of discharge is minimal or non-existent, pollution is reduced, as is disease and parasite transfer, and fish escapes are virtually impossible. Even in the case of anadromous fish such as salmon and trout (which are born in fresh water, migrate to the ocean, then return to freshwater to spawn), some new recirculating systems are capable of alternating between fresh and salt water environments, allowing these species to be grown in entirely land-based systems.
“Most aquaculture operations are far more sustainable than animal food production,” says Pete Malinowski, former aquaculture director of the New York Harbor School. “People are getting educated, and it’s becoming unacceptable to farm fish in a way that’s harmful to the environment.”