There’s no getting around it. The outlook for wild fisheries is bad. According to WWF’s Living Blue Planet Report, local and commercial fish populations declined by 50% between 1970 and 2012. While a number of factors have contributed to the deterioration of fisheries, including ocean warming and marine debris, overfishing has taken a massive toll. The UN noted in its 2016 State of World Fisheries and Aquaculture report that nearly a third of wild stocks are overfished and more than half are fully fished.
Aquaculture was once lauded as a responsible alternative to commercial fishing: Jacque Cousteau implored us to ‘use the sea as farmers instead of hunters’.
It became increasingly detrimental to the environment when industrial techniques were adopted. As those techniques quickly scaled - nearly half of our seafood now comes from aquaculture - the impacts intensified. Shrimp farms are responsible for the loss of coastal mangrove wetlands removed to build ponds. Farmed salmon, many genetically modified, escape ocean pens and breed with wild salmon, creating genetic inferiorities. Operators apply antibiotics liberally to farmed fish because close living quarters create vectors for disease and parasites. As a result, nearby wild populations, lacking such protections, are at increased risk from contagion. And aquaculture operations release discharge water tainted with massive amounts of fish excrement and chemicals.
Based on this grim context, we ought to be very concerned about our options for sourcing seafood in the 21st Century. Yet three billion people currently rely on it as their primary source of protein. Other mainstream sources of animal protein, such as raising cows and pigs, are far more resource and carbon intensive – while plant and insect proteins are far off their potential scale. Cracking the sustainable seafood conundrum is – or should be – one of the most pressing items on our sustainable nutrition agenda. Simply put, how can we meet demand for seafood without devastating the marine environment?
Innovators have addressed this challenge by developing aquaculture techniques that could unlock solutions at scale. Working with the environment, instead of against it, they have harnessed natural resources sustainably to create a new aquaculture that produces more without degrading ecosystems. Here are three areas for innovation that could change the aquaculture landscape.
Some farmed fish, such as salmonids, are carnivorous and as such their feed is sourced from wild pelagic fish species. This adds to the already high level of stress on fisheries. Alternative feeds are needed to reduce the use of wild fish. Microbial proteins can be produced through a fermentation process and simulate the proteins found in conventional feed pellets. Fermented alga is another alternative that contains proteins as well as other nutrients that replace those found in fish. Feed produced from the black soldier fly has a high quality nutritional profile and is similar to the natural insect diet of trout. Black soldier fly larvae feed on discarded food and farm waste, solving two problems at once. Seaweed can also be used in fish feed and new research shows that adding it to cattle feed dramatically reduces methane emissions. The Irish cattle industry is currently investigating this as an option.
Bren Smith, a former commercial fisherman, invented a technique for vertical ocean farming in which a matrix of ropes on the ocean surface holds kelp and other seaweeds growing vertically downward. Next to them are mussels and scallops growing in nets and below those are beds of oysters and clams. This ingenious model enables more productivity on smaller ‘plots’ of ocean and trains fishermen to be restorative ocean farmers. The mollusks filter out water pollutants and the seaweed absorbs five times more carbon than terrestrial plants. There are many uses for these products from the table to the farm. Smith has his own farm and is also training 25 vertical underwater farmers through his nonprofit GreenWave.
3. Recirculating Systems
A good alternative for land-based aquaculture operations, recirculating systems reuse water in the production process. This eliminates pollution and obviates the need for siting next to natural water bodies. Recirculation also reduces disease and results in a higher and more stable level of production. Aquaponic operations use a similar model with the addition of vegetation. Waste from fish tanks provides nutrients for the plants in a completely closed environment. Aquaponic operations have become popular in urban areas. Several commercial operations have sprung up in New York, including Edenworks, which produces tilapia and leafy greens.
Here is one example of a recirculating system by Veolia Water Technologies:
As more of the world develops an appetite for fresh seafood, our ability to produce it responsibly will be tested. These innovations give us the tools to farm fish more efficiently and sustainably while safeguarding our oceans now and into the future.