FINFISH AQUACULTURE--ADDRESSING THE RISKS

 

Aquaculture has become a hot topic on the coast.

Here in the United States, farming various invertebrates—typically oysters, clams, and mussels—has become a well-established industry with little downside; it can even be seen as benign, as the farms introduce large numbers of filter-feeding mollusks into areas suffering from phytoplankton blooms, and so positively impact water quality.  Recent efforts to farm kelp are expected to bring similar benefits.

Unfortunately, finfish aquaculture has no such environmental upside, but does pose real risks when conducted in net pens or similar facilities. 

Aquaculture's best-publicized failure was probably the 2017 collapse of net pens that Cooke Aquaculture, a Canadian fish-farming conglomerate, maintained in inshore waters off the State of Washington.  As a result of such collapse, more than 250,000 non-native Atlantic salmon escaped into the waters of the Salish Sea, where they might have further imperiled already-threatened runs of native Pacific salmon.

An article distributed by the University of California—Davis noted that

“Farmed Atlantic salmon can carry viruses, bacteria and parasites such as sea lice that can infect wild salmon.  The release of thousands of salmon that were actively experiencing a disease outbreak could have huge ramifications for wild salmon…

“While we have not seen data on the health of disease status of the released Atlantic salmon, it was reported that they were treated for a bacterial infection called yellow mouth in July 2016 but were believed to be disease-free at the time they escaped.

“Without detailed disease testing data, it is difficult to know what the potential for disease transmission could be in this most recent release.  An evaluation of the risk of disease transmission from farmed Atlantic salmon to wild Pacific salmon conducted over a decade ago classified the risk as low due to existing disease testing protocols and the state’s prohibition on bringing new Atlantic salmon stocks or eggs into Washington (which limits new diseases from entering)…

“As to whether released farmed salmon will compete with native salmon for food and breeding or spawning space, studies have shown that while their performance and reproductive success in nature vary, farmed salmon are often outcompeted by wild salmon of similar size.

“…while released farmed Atlantic salmon will compete with wild salmon for food, many also don’t make the transition from being fed pellets in farms to catching and eating wild food.

“For those that do, though, stonefly nymphs found in the stomachs of Atlantic salmon caught in the Salmon River (Vancouver Island) suggest that escaped Atlantic salmon also can be predators in freshwater as well as in the ocean…

“On balance, though, the science looking at past net pen releases of Atlantic salmon in this region suggests that there can be negative impacts to native salmon including disease transmission, competition for food and breeding habitat, and the potential for long-term establishment of an introduced Atlantic salmon run…”

Fortunately, the Cooke Aquaculture net pen collapse does not appear to have resulted in any such negative impacts.  In fact, the only significant impact the collapse appears to have was an arguably positive one:  Legislation that bans the farming of non-native fish in Washington waters was passed in 2018; the ban will become effective when the last of the current aquaculture leases expires in 2025.

Elsewhere, native salmon runs have not been fortunate enough to escape the negative impacts of aquaculture and non-native species, with both escaped fish and introduced diseases causing harm to wild populations.

In northwestern Europe, pink salmon, a Pacific species introduced into the region by Russia during the latter half of the last century, are invading rivers as far away as Scotland and Iceland, and posing a potential threat to already-dwindling Atlantic salmon stocks.

It’s not completely clear how much damage the pinks have already done to native European salmonids, but biologists are concerned.  There’s not too much information publicly available from Russia, where the invasive salmon have been present the longest.  However, research published by a team of Russian scientists in 2015 found that

“pink salmon had a substantial negative effect on the recruitment and abundance of the freshwater pearl mussel (Margaritifera margaritifera) in two rivers in the White Sea basin.  This was likely caused by a concurring reduction in density of juvenile Atlantic salmon, which is the obligate host of mussel glochidia larvae in these rivers,”

which research suggests, but does not conclusively confirm, that pink salmon may have a negative impact on Atlantic salmon recruitment.

In Norway, where pink salmon straying from Russian rivers have established spawning populations, scientists are also worried.  A paper published in the open-access Springer Link in 2018 observed that

“Pink salmon is reported to be aggressive on the spawning sites, which may lead to negative interactions with Atlantic salmon and brown trout.  It has been documented that groups of pink salmon may attack Atlantic salmon that are at the spawning sites preparing for spawning.  The result is that the Atlantic salmon move to river sections less suitable for spawning.”

The same paper considered other potential negative impacts, ranging from rotting pink salmon carcasses leading to depleted oxygen levels in the rivers, and so reducing the survival of larvae of later spawning fish, to competition between pink salmon fry and that of other species, but could draw no conclusions from the limited information available.

Pink salmon spawning has also taken place in Scotland.  Although fishery managers there have not yet identified any self-perpetuating populations, the Scottish Environmental Agency is monitoring the situation closely, with one of its fisheries management team leaders stating that

“Wild Atlantic salmon stocks are already under great pressure from a variety of sources.  The introduction of novel parasites or diseases from invasive species, such as Pacific pink salmon, could potentially represent an additional risk to the viability of the species.

“We therefore want to better understand the immediate risk that pink salmon could represent to our important wild salmon stocks.”

Professor Eric Verspoor, the director of the Rivers and Lochs Institute at Inverness College, warned that

“It might be argued by some that another salmon species might be desirable in Scotland’s rivers.

“However, the potential for negative impacts on native species and the fact that they are the least desirable of the Pacific salmon from an angling and commercial fishery perspective suggest that there are unlikely to be any positives from their doing so.

“The fact that they are running up Scottish rivers is worrying as that suggests a spawning intention – the species normally spawns from July to October across its native range…

“It is a situation which should be closely monitored in respect of the threat it poses to Scotland’s native salmon, given the latter’s great socio-economic value and biological uniqueness.”

The Scottish government has labelled the pink salmon an invasive species; under Scottish law, it is illegal to fish for or possess them, which puts fishermen in an odd position, as the government also tells fishermen not to return such salmon to the water if accidentally caught, and to report such capture to the relevant District Salmon Fishery Board, and thus seemingly requires fishermen to violate the law, which law also states that if a fisherman

“had taken all reasonable steps and exercised due diligence to avoid committing [the offence]”

of accidentally catching and/or retaining a pink salmon, such actions “may be” a defense to any resulting charges.  However, the words "may be" seem to offer little comfort to Scottish anglers who inadvertently find themselves with a pink salmon in hand.

Still, given the potential threat that pink salmon could pose to Scottish Atlantic salmon and sea trout, its understandable that the government would want to do all that it can to assure that the invasive fish don’t gain a foothold in Scottish rivers.

Unfortunately, the threat posed by introduced and aquacultured fish isn’t limited to pink salmon, Europe, or competition in the spawning rivers.  Here in North America, aquacultured Atlantic salmon appear to have transmitted a virus to native chinook (also known as “king”) salmon stocks in British Columbia.

From what scientists could tell, such transmission has been going on for a very long time—probably more than thirty years.  But the disease that's callled Piscine orthoreovirus-1, or PRV-1, and causes heart and skeletal muscle inflammation in the farmed Atlantic salmon, manifests itself very differently in the wild chinooks, which incur fatal liver and kidney damage.   Since about 97% of all farmed Atlantic salmon in British Columbia contract the virus by the time that they are 18 months old, and since the virus is believed to have been introduced into British Columbian waters in 1989, after the farms imported infected eggs from Europe, wild chinook salmon have been extensively and continually exposed to PRV-1, which is spread when the farmed salmon’s feces are released into the water.

Scientists determined the timing and the origin of the virus in chinook salmon through the use of genetic sequencing.  Dr. Gideon Mordecai of the University of British Columbia, who led the study, said that

“Both are genomic and epidemiological methods independently came to the same conclusion, that salmon farms act as a source and amplifier of PRV transmission…

“The study’s genome sequencing clearly indicates that PRV is not native to [British Columbia] waters—it originated in the Atlantic Ocean and has been spread around the world through salmon aquaculture.”

In response to that finding, Dr. Andrew Bateman, of the Pacific Salmon Foundation, who was a co-author of the study, advised that

“The PRV findings, in particular, support calls to transition from open-net salmon farming towards farming technology that doesn’t allow disease transfer between farmed and wild salmon.”

Of course, salmon aren’t the only fish that suffer from viruses, nor are they the only fish which are raised in open-net pens.  Dr. Bateman’s advice has much wider application. 

Anglers here in the United States ought to be paying particular attention, because encouraging open-water aquaculture has become a national priority, and right now, it appears that fish farming in federal waters may be conducted with very little control.

Back in 2016, the National Marine Fisheries Service issued regulations for permitting and regulating aquaculture operations in the Gulf of Mexico.  A consortium of environmental, commercial fishing, recreational fishing, and food-safety groups brought suit to challenge such regulations, arguing that the Magnuson-Stevens Fishery Conservation and Management Act’s definition of “fishing” did not include aquaculture, and that NMFS lacked the authority to issue permits for offshore aquaculture operations. 

Last year, in the matter of Gulf Fishermen’s Association v. National Marine Fisheries Service, the United States Court of Appeals for the Fifth Circuit agreed, finding that NMFS lacked any authority to permit and/or regulate offshore aquaculture facilities.

The decision had unintended consequences.

While the plaintiffs brought the action hoping to prevent the construction of offshore aquaculture facilities in the Gulf of Mexico, and probably elsewhere off the United States coast, the appellate court's decision did not further that goal.  Instead, it merely removed NMFS, the agency with the greatest expertise with respect to marine fish and related issues, from the permitting process, leaving all permitting up to agencies such as the Environmental Protection Agency, which would only have jurisdiction over the discharge of pollutants, and the Army Corps of Engineers, which promotes marine conservation in about the same way that the tobacco industry promotes respiratory health.  NMFS’ role is now limited to consultation on matters such as protected species interactions and impacts on essential fish habitat.

Right now, a proposed Florida pilot project run by the Hawaiian company Kampachi Farms is waiting for the permitting process to be completed.  Located about 45 miles off Sarasota, the pilot aquaculture facility would feature a pen 50 feet wide and 20 feet deep, the top of which would be just 20 feet beneath the ocean’s surface.

The Kampachi Farms pen is only designed to hold 20,000 Almaco jack, a local Gulf species.  However, Neil Anthony Sims, the head of Ocean Era Inc. (apparently, the owner of Kampachi Farms) has much larger ambitions, saying

“The goal of the project is to show to the Florida fishing and boating community that offshore aquaculture can be something that they can learn to love and embrace.

“Our goal here is to set up a very small-scale single cohort, one batch of fish, only 20,000 fish, which that’s [sic] about one percent of what the size of a commercial farm might be, and then grow those fish through to harvest size.  [emphasis added]”

Right now, there are quite a few people who don’t yet “love and embrace” the proposed project, and might be expected to have an even colder reaction to the sort of “commercial farm” that might keep 2,000,000 fish penned up in a small expanse of ocean.  One op-ed, written by an angler and professor at Florida Southwestern State College, which appeared in The [Cape Coral] News-Press, objected to an aquaculture facility

“smack dab in the middle of the red snapper and grouper grounds of recreational anglers in Southwest Florida and from all over the country,”

and expressed concern over

“20,000 almaco jack fish packed like cattle, in an oversized bait ball of synthetic feed, waste, and pharmaceuticals,”

fearing that it would

“alter the ecology and pollute and deform Florida’s natural, heretofore, uncorrupted west coast.”

His concerns were echoed by representatives of various environmental groups who, according to The News-Press, argued that

“Ocean Era’s facility will feed harmful algae blooms, present dangers to the genetics of native species if the fish escape and degrade the nearby ecosystem by polluting the Gulf with fish waste and pharmaceuticals.”

Ocean Era, of course, disagrees, but in April, an EPA administrative judge acceded to such concerns by delaying action on the required pollution discharge permits.  Final action is expected this Tuesday, June 1.

Should the permits be granted, it is likely that other would-be offshore aquaculture operations will soon be seeking permits for other facilities, some of which will probably seek to culture species that, unlike Almaco jacks, are not native to the area.  Should such facilities be developed, it will probably only be a matter of time until the same problems currently facing salmon aquaculture—pollution, the escape of invasive, non-native species, and the transmission of disease to wild fish stocks—will erupt in the ocean as well.

At the same time, people want to eat fish, and as the population expands, wild stocks will probably be unable to supply their needs.  Well over a century ago, the market hunters who once supplied elk, deer, and waterfowl, along with such other now-extinct species as passenger pigeons and Eskimo curlew, to urban markets were replaced by meat produced on terrestrial farms.  It is only reasonable to expect seafood to follow the same path.

And, in the end, following exactly the same path is probably the right answer.  For the ideal aquaculture operation should exist not in the open ocean, but on terrestrial farms, where water can be cleaned and recycled, and fish can be raised without any fear of them escaping, of polluting local waterways, or of spreading disease to wild populations.

The basic technology already exists, and some land-based operations are already producing product.  Land-based operations don’t have the same parasite and disease problems found in net pen facilities.  They don’t have escapes, and they don’t pollute.  At the same time, the technology is not yet mature, so some problems remain.  And land-based fish farms are more energy-intensive than those that depend on the sun and ocean currents to regulate temperature and circulate the water in the pens.

Land-based farms are also—at least for now—more expensive to run, and produce a more costly product.

Balanced against such costs is the question:  What price are we willing to pay for healthy and abundant wild stocks of fish.  Because, as experience already shows, wild stocks will always be at risk when fish pens are nearby.