Aquaculture, the commercial farming of finfish like salmon, shellfish and seaweed, has exploded over the past 30 years, becoming a nearly $250-billion industry globally. More than half of all seafood now comes from farms, and that percentage is projected to rise if the human population expands, as expected, to 9.7 billion people over the next 30 years. However, environmental problems currently bedevil the aquaculture industry and a consensus on the most sustainable practices has yet to emerge.
A new report released May 8, “Towards a Blue Revolution,” aims to guide the private sector, NGOs and policymakers toward better aquaculture strategies that can both meet the growing global seafood demand and operate “in harmony with ocean ecosystems.”
“Transforming how we produce seafood through strategic investment in innovative, more sustainable production methods may ultimately represent the difference between a healthy, abundant, and profitable food system, and one that degrades the environment, destroys value, and fails to meet the growing food security challenge,” the report states.
Published by the Virginia-based environmental non-profit the Nature Conservancy and the New York-based impact investment firm Encourage Capital, the report urges the seafood industry to shift away from “business as usual” aquaculture practices. It argues that equally lucrative and more sustainable forms of aquaculture exist that investors would do well to nurture.
There has been a recognition in the last decade that there are challenges, and I think that the industry is moving in a more positive direction.
Robert Jones, global aquaculture lead, The Nature Conservancy
The report takes a notably hard stance against net pens in coastal waters, a common aquaculture practice that entails feeding the fish as well as treating them with antibiotics and pesticides to fight sea lice and other diseases.
Coastal net pen aquaculture can pollute surrounding waters with fish waste and uneaten feed. There is also a high risk of fish escaping the pens, which can introduce diseases to wild fish populations or weaken them genetically through interbreeding.
In place of such business-as-usual practices, the report advocates for three alternatives. The first is a land-based aquaculture strategy called recirculating aquaculture systems (RAS). These enclosed, onshore tanks have the technology to control water quality and monitor fish growth from egg to harvest.
“In the US and Europe, two of the biggest markets, we’re seeing significant development of RAS opportunities,” Robert Jones, global aquaculture lead at the Nature Conservancy and a co-author of the report, said. “The trend has been toward bigger RAS, compared to some previous farms that may have been sub-scale.”
Environmentally, these systems have the benefit of eliminating direct physical interaction with marine habitats, greatly reducing the risk of pollution or of escaped farm fish harming wild populations. But there are some pitfalls, as well.
“What are you raising in these tanks?” Amy van Saun, senior attorney at the advocacy group the Center for Food Safety in Portland, Oregon, asked. “Is it carnivorous fish that you’re going to have to feed? That still creates the problem of over-harvesting forage fish from the oceans to create fish meal and fish oil to feed these fish. Or are you going to raise vegetarian fish that can be fed on plant food?”
Van Saun focuses on cases involving aquaculture, industrial animal farms and genetically engineered crops, among other food-production systems.
While some RAS can recirculate as much as 90 per cent of their water, larger facilities, such as those in the salmon industry, may still end up dumping millions of gallons per day, according to the report. Proper storage and disposal of sludge and biowaste can also complicate large-scale operations.
RAS has seen less development in the private sector compared to other forms of aquaculture due to some expensive failures over the past 30 years and a lack of investment in research to improve key technical factors, such as water and energy efficiency for larger-scale operations. But the report argues that RAS technology has been catching up over the last decade, allowing investors to harvest more fish per unit area compared to coastal net pens, which could make it an attractive, if still somewhat risky, option going forward.
Even newer to the seafood industry are offshore aquaculture systems for salmon and other finfish, most of which have entered the market in the last five years. The report says these floating or submersible cages, placed in deep water away from sensitive shoreline habitats, offer another resource-efficient and environmentally friendly form of fish farming.
Done correctly, the cages could theoretically reduce disease and parasite outbreaks that can spread to wild populations from coastal net pens. Placed amid the strong currents of the open ocean, these operations also release less concentrated pollution, as food and biological waste are flushed away. In fact, changes in water quality surrounding finfish operations have been “imperceptible” beyond about 90 meters (about 300 feet), the report says.
As with RAS, investors struggled for years to develop the technology needed to run viable offshore commercial aquaculture operations, given the harsh conditions of the open ocean. And they face the added barrier of regulatory uncertainty: Many jurisdictions haven’t established a process for licensing offshore aquaculture.
Currently, the salmon industry deploys some of the largest aquaculture cages, operating in water as deep as 305 meters (1,000 feet) and as far out as 8 kilometres (5 miles) into the open ocean. They are supposed to be able to withstand 15-meter (49-foot) waves and hurricane-force winds. But the report warns that operations still face the risk of technological failure, which could result in the release of fish to the detriment of wild populations (as well as investors), along with other problems.
“You’re also talking about disrupting migratory patterns of wild marine species,” van Saun said, “because these operations are a magnet. There’s all this food that’s being thrown to these fish, attracting wildlife. They also attract predators, because you have this tasty facility full of fish sitting right there.”
A third form of aquaculture, farming bivalves and seaweed, has the potential to sidestep most of these environmental concerns while actually having a net-positive impact on surrounding waters, according to the report.
Seaweed and shellfish, often suspended on lines anchored to the seafloor in coastal waters, have been shown to provide habitats for invertebrates, marine mammals and birds. Seaweed can act as a buffer against local ocean acidification, a byproduct of global warming, by absorbing carbon dioxide from the water—an added benefit for organisms like reef-building corals that fortify their physical structures with calcium. Shellfish, meanwhile, clean the water as they filter feed, regulating nutrient levels.
The seaweed industry alone is worth more than $11 billion. And the demand continues to grow as the market for the algae expands from foods to beauty and wellness products, fertilisers and animal feeds. The report also highlights developing research into the use of seaweed in biofuel production.
Seaweed and shellfish farming use fewer chemicals and drugs than finfish farming. But, as with industrial crop farming on land, some companies go to great lengths to protect their harvests, introducing chemicals to kill native species that could hinder growth.
In Willapa Bay and Grays Harbor in Washington state, for example, shellfish growers have allegedly removed snails, starfish and sand dollars, and used herbicides to kill eelgrass, a key component of the area’s ecosystem.
The Center for Food Safety was one of four groups to take legal action against oyster growers’ attempt to use a neurotoxic pesticide there to kill off ghost shrimp, which were suffocating the oysters by burrowing in the mud. (The state eventually denied the growers’ permit request.)
The report warns against such methods, arguing that financial gain must be balanced with environmental effects and other factors.
“There’s a growing interest among the seafood industry to reduce its environmental impact and in the aquaculture industry to reduce its impact,” the Nature Conservancy’s Jones said. “There has been a recognition in the last decade that there are challenges, and I think that the industry is moving in a more positive direction.”
This story was published with permission from Mongabay.com
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