NOAA’s funded researchers acknowledge very little is known about the cumulative, long-term environmental effects of growing hundreds of thousands of fish in cramped cages. “The nature and intensity of impacts cannot be predicted due to limited experience thus far within the industry,” a recent NOAA report found.²

The NOAA-funded report challenges the core premise of offshore aquaculture––that the environmental problems of salmon farming and other near-shore operations would be avoided by moving them into deeper waters: “One might expect that many of the issues associated with coastal aquaculture will confront open ocean aquaculture as well.” ³

Pollution

Untreated fish waste, excess feed, and fish carcasses empty directly from cages into the ocean. Based on the little research conducted so far, this waste has been shown to cause oxygen-depleting algae blooms, pollute the seafloor, and alter fragile habitats. Researchers do not know whether the oceans, which have already been damaged by industrial and agricultural pollution, can absorb yet another of source of waste.

“Little is known about the assimilative capacity of the marine environment for these pollutants,” concludes a 2007 report commissioned by the Woods Hole Oceanographic Institution. “Pollution from a greatly expanded industry could have significant effects locally and regionally.” ⁴

Such environmental problems have been reported at one of the nation’s four experimental fish farms. A farm affiliated with the University of Hawaii “grossly polluted” the seafloor and “severely depressed” sea life. (See Cates International – Hawaii.)

Antibiotics, pesticides, growth enhancers, and other drugs or chemicals used in these operations also can be damaging. Maine lobsters have been harmed by pesticides used to control sea lice in salmon farms along the Maine and Canadian coasts. Antibiotics can kill beneficial seafloor bacteria and spawn antibiotic-resistant organisms.⁵ Like the waste problem, little is known about the long-term effects of aquaculture drugs. And almost nothing is known about the problem as it relates to the type of offshore aquaculture being promoted by NOAA.

Disease

These drugs are used to overcome the high risk of disease that exists when thousands of fish are packed together in cages. When the drugs do not work or are not available, diseases can infect wild marine life. In addition to sea lice from salmon farms, Whirling disease has spread from farmed to wild trout in more than 20 Northeastern and Western states. This parasite, which deforms and disorients young fish, has killed up to 90 percent of wild trout in some western U.S. streams.⁶ Disease transmission is a particularly difficult problem to assess and prevent, because very little is known about disease mechanisms among wild fish.⁷

Disease struck the University of New Hampshire’s experimental fish farm several years ago, killing most of the entire stock of 200,000 juvenile cod, though apparently not entering the environment. (See Atlantic Marine Aquaculture Center – New Hampshire.)

Also being released into the environment are the fish themselves. Fish raised in aquaculture operations are often the offspring of a small number of parents, or broodstock. As a result, they have far less genetic variation than wild fish of the same species. When farmed fish escape from their cages and breed with their wild counterparts, their offspring can suffer genetic weaknesses and have diminished survival skills.

Escaped Fish

Escape has been a major problem with salmon, whose recovery is being jeopardized by genetically inferior, domesticated interlopers.⁸ About 2 million farmed salmon escape into the North Atlantic each year, equal to the number of wild fish there.⁹ In the first six months of 2007 alone, more than 100,000 Atlantic salmon escaped from four facilities on the west coast of Scotland. The incidents led a representative of one Scottish fishing group to recommend an outright end to open ocean aquaculture.¹⁰

Several years ago, thousands of fish escaped from Kona Blue Water Farms in Hawaii when a cage broke. (See Kona Blue Water Farms – Hawaii.)

Pressure on Wild Fish

Raising large amounts of fish in captivity requires huge amounts of feed, made mainly from fishmeal and oil. These ingredients are derived almost exclusively from small ocean fish such as sardines, anchovies, and herring, caught in mass quantities in the Northeast Atlantic and off of North and South America’s Pacific coast. Due to its tremendous growth, aquaculture is now the world’s largest user of these products, consuming 80 percent of the world’s fish oil and half the fishmeal each year.¹¹ From 1999 to 2003, the industry’s use of fishmeal and oil tripled, to 3 million tons and 800,000 tons, respectively.¹²

Touted as a solution to the overfishing crisis, the aquaculture industry may actually be hastening it––by taking wild fish to feed captive fish, essentially borrowing from Peter to pay Paul. Many species of small fish ground up for aquaculture feed are being harvested beyond sustainable levels, meaning the predatory finfish, such as tuna, salmon, grouper, and snapper, that depend on them for survival also are in jeopardy.¹³

The numbers reveal aquaculture’s unsustainability. In some cases, it can take two to six pounds of wild fish to produce one pound of farmed fish.¹⁴ The search is on for alternatives, such as protein from soybeans, canola, wheat gluten, and peas. While some success has been achieved with omnivorous freshwater fish such as tilapia and catfish, progress is slow finding replacements for meat-eating, marine species raised in offshore farms. In one experiment, all cobia fed diets without fishmeal died within five weeks.¹⁵ This is the same species raised at the Snapperfarm offshore facility in Puerto Rico. (See Vegetarian Carnivores or Snapperfarm)

Kona Blue in Hawaii has pledged to find such replacements, but so far it has only been able to replace half of its fishmeal and a fourth of its fish oil with vegetable ingredients. (See Kona Blue Water Farms – Hawaii.)

Human Health Concerns

Perhaps the worst news for the offshore aquaculture industry is that the fish it produces may be hazardous to human health. In the case of salmon, farmed fish contain higher levels of PCBs, dioxin, flame retardants, pesticides, and other toxins than wild fish because these contaminants are often present in the fish that are ground up for feed.¹⁶

Kona Blue’s tests indicate that its fish contain no detectable levels of mercury,¹⁷ and Snapperfarm says its fish contain no PCBs, mercury or other harmful contaminants.¹⁸ But the nation’s other two experimental farm, Cates International and the Atlantic Marine Aquaculture Center, have released no such information about their fish.

In addition to these problems, many other challenges await solutions:

• Competition with Fishermen: Many commercial fisherman already suffering from the low prices caused by cheap imported seafood believe offshore aquaculture represents another threat to their livelihoods. Many fishing groups in Alaska, which banned open ocean aquaculture operations within its state waters in 1990, oppose offshore aquaculture and are calling for a five-year moratorium until the environmental and socioeconomic effects can be studied.
• Introduction of New Species: Escaped non-native or genetically modified species could invade local areas and breed with natural populations, creating new species and altering ecosystems. Or the escaped fish could simply overtake and displace native varieties. California, Maine, Maryland, and Washington have banned genetically modified fish in their state waters because of this concern.¹⁹ Among existing fish farms,“there is considerable evidence of damage to the genetic integrity of wild fish populations,” the 2007 Woods Hole report says.²⁰
• Conflicting Interests: Fish cages could have difficulty coexisting with the many activities already taking place in the open ocean, such as shipping, commercial and sport fishing, military operations, marine reserves and recreational boating.
• Safety of Marine Mammals: Dolphins and other marine mammals have become entangled in fish farms.²¹ At Kona Blue in Hawaii, spinner dolphins occasionally swim within the farm, and a humpback whale was seen swimming between the cages, though none has become stuck.²²
• Damage to Habitats: The dredging, drilling, and other work needed to install fish farms can harm seafloor habitats and displace sealife.
• Logistical Problems: Because open ocean fish farms would be located between three and 200 miles from shore, workers and supplies could have to travel very long distances. Building farms to withstand extreme winds, waves and temperatures would be difficult. Their location also would complicate clean-up of chemical spills, rescues, and other emergencies responses. Many questions linger because none of the four main U.S. fish farms is located more than three miles from shore. The head of New Hampshire’s offshore fish farm says the practice is “expensive and dangerous even in the best circumstances.” (See Atlantic Marine Aquaculture Center – New Hampshire.)

Some of the conclusions of the 2007 Woods Hole report is worth quoting at length and should serve to caution NOAA policy-makers, Congress, research institutions. and investors placing great expectations on this untested technology:

The few demonstration projects conducted to date show negligible to modest impacts on the marine environment. However, these projects were conducted on small-scale operations mostly at low densities of fish, so their application to large-scale and/or concentrated marine fish farming is limited.

***

It is challenging to estimate the absolute and relative magnitude of these risks in a different environment in which we have little experience to date.

***

Additional research needs to be conducted on the effects, including cumulative and secondary impacts, of aquaculture on the marine environment. The idea of farming in the ocean, which has been traditionally regarded as a wilderness open to all, adds a complicating dimension to the discussion.²³

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