Seeker Blog

Yale Environment 360 highlights a hopeful aquaculture advance. We need farmed fish for the future, so we badly need farming technologies that avoid the severe negatives of most coastal saltwater farming of predator fish (e.g., Atlantic Salmon). I am surprised that they have achieved a 1:1 input/output ratio; typically farms feed 4 to 5 kilos of fish meal to yield one kilo of salmon. And the imprint of the Monterey Bay Aquarium is a big deal — they are very serious about the whole life cycle of the farms:

(…) The salmon are raised in closed pens on land, rather than in open net pens near coastlines, eliminating dangers from the spread of disease to wild fish and ending the problem of farmed salmon escaping and breeding with wild salmon. The AquaSeed salmon also are raised in freshwater, as opposed to saltwater, and the company uses Pacific salmon rather than Atlantic salmon — currently the most common pen-reared form of salmon. In addition, through advances in breeding and changes in feed formulas, AquaSeed says it can raise a pound of salmon using roughly a pound of fish food; traditional salmon farms use about four pounds of fish meal to produce one pound of Atlantic salmon.

(…)

Since 2007 Open Blue Sea Farms has raised cobia in six enormous, pyramidal underwater pens, or “aquapods,” off the Panama coast.

Yale Environment 360 caught our attention with this report on fish farming - especially offshore farming of predator species.

We need to quickly get global overfishing under control. The only alternative we know of is aquaculture. But the inshore farming efforts are a VERY mixed bag. We know because while cruising we encounter fish farms regularly. You “don’t want to know” what the farms do to the neighborhood…. And as you would predict, the regulatory framework is a mess.

Most of the premium farmed fish that you know about are predator fish (like salmon) that consume 4 to 7 times their weight in fishmeal pellets. That obviously is not the solution to a global supply/demand imbalance. Taking the pens offshore may help with the pollution blight we have experienced, but only raising vegetarian fish (tilapia, carp, catfish) addresses the waste of precious fish protein feeding predator fish.

Most aquaculture operations are located inshore or in sheltered areas just offshore. This makes economic sense: It’s both cheaper and easier to run a fish farm in a pond or an inlet, say, than something miles out to sea. But pollutants and waste easily concentrate in relatively calm, still water and hurt the dense, complex webs of life that inhabit shorelines. As a result, fish farms have fouled coastal zones with waste and antibiotics. Farmed fish that slip out of their enclosures can harm wild populations by breeding with, eating, or displacing them. Disease can run rampant, spread by large numbers of fish penned in close quarters. Salmon farms — including operations in Chile, Canada and Scotland — have been plagued with sea lice, a parasite that has spread to wild populations. In Peru, China, Thailand, Vietnam, and elsewhere, shrimp farms have polluted vast coastal areas and destroyed mangrove swamps.

But offshore operations have several crucial advantages that make them a potentially promising long-term solution to the “fish gap.” Cages located miles offshore in deep water have a lighter ecological footprint because the ocean environment is so vast and the water — driven by wind, waves, and currents — is constantly moving.

“With the amount of water flowing through in an hour and the amount of waste from our fish,” said O’Hanlon, the cobia farmer, “the dilution is so massive you cannot detect the waste downstream. The current is so brisk you never see the same effects as you do inshore. We are over 200 feet deep. It’s a sandy muddy bottom, there’s no coral reefs. We are purposely going to a type of environment that has a carrying capacity for what we are doing.”

Only a handful of scientific studies have been conducted on offshore fish farming, but they’ve been positive. One series of analyses cited by the U.S. Government Accountability Office showed that a fish farm off the Hawaiian coast had some effects on water quality, but that they fell within allowable federal limits.

The example of the lone, tiny fish farm surrounded by miles of open water is not an ideal indicator, though. O’Hanlon and other fish farmers say that to be profitable they’ll need to scale up.

“It’s an industry that will achieve better economics as it scales,” says Neil Sims, the co-founder and CEO of Kona Blue Farms, an offshore operation in Hawaii that farms a local species of yellowtail it calls Kona kampachi. “We need to grow this industry. Larger pens are going to be more efficient than smaller ones. Better technology, more automation is going to be better than using manpower. We need to locate closer to the market or find ways to get product to market more inexpensively.”

Economist Jeff Sachs promotes aquaculture and global fisheries controls in the July Scientific American. Included are some interesting factoids — e.g., China is now producing about 2/3 [by weight] of global farmed fish. I’ll look into this further to verify how much of that Chinese production is “good fish”, like carp or catfish raised on plant matter, as opposed to carnivore “bad fish”, like salmon — raised on other fish species. Farmed salmon consume between three and five times their market weight in fish meal so they are a significantly net-negative food source.

…Into the breach has arrived the Blue Revolution, first in China, and now in many other parts of the world. Aquaculture yields have increased from around two million metric tons in 1950 to almost 50 million metric tons today. Thus, even though the global fish catch peaked in the late 1980s, aquaculture has enabled a continuing rise in human consumption of fish. China now accounts for around two thirds of total aquaculture production worldwide by weight and roughly half by market value.

Fish farming in China is of course an ancient activity, with several carp species grown among rice fields for thousands of years. The inter-mixing of rice production with fish farming, rather than with animal husbandry as in Europe and the Americas, made good ecological and economic sense in densely populated China. A cow requires around seven kilograms of feed grain for each kilo of meat, while a carp requires around three kilos or less. Fish farming economizes on feed grain, and of course on the land area needed to produce it.

The exciting news, however, is that recently Chinese scientists have both improved the efficiency of aquaculture and revolutionized the range of species that can be farmed. An insightful study by coastal ecologist Carlos Duarte and his colleagues in the April 7 Science documents the dramatic rate of domestication and commercialization of marine species. Of the more than 400 farmed marine species, as many as 106 have been domesticated in the past decade alone. In contrast, there has been almost no concurrent increase in the number of domesticated land species.

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…they report that the loss of ocean populations and species has been accompanied by plummeting catches of wild fish, declines in water quality, and other costly losses. They even project that all commercial fish and seafood species will collapse by 2048.

Dr. Sean Chamberlin of UC Santa Barbara has published a summary of the 3 November, 2006 paper “Global Loss of Biodiversity Harming Ocean Bounty” [you must be a Science subscriber to access the full text].

Worm and his colleagues call for the creation of new marine reserves, sustainable management of fishing, and tighter control of pollution. Those are well-worn recommendations, but Worm says the team’s analysis of the consequences of not taking action, especially the loss of wild fisheries, gives them greater weight. “If you can see the bottom of the barrel, that changes things.”

The national press has played up the Science article — the disaster prediction makes for good headlines. But marine scientists won’t find any new concepts here — biodiversity is well understood to be a necessary condition to healthy fisheries. Unfortunately fish don’t vote, while the fishing lobbies have a lot of $$ to spread around… So the headlines are a good thing — it’s probably not yet too late for at least some of the fisheries.