The Promise of Aquaculture

By Sarah M. Shoffler | July 01, 2015
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Driving in Baja at a vista point off the toll road just north of Ensenada, you might notice a set of large rings in the ocean below. These are pens holding bluefin tuna that Mexican fishermen catch as juveniles and fatten for up to two years. They are eventually sold, mostly to Japan, as high-quality sashimi-grade fish.
This type of fish farming—open net pen aquaculture, where fish are fattened like cows or pigs—is the most common aquaculture system in North America and Europe. And more of it has been proposed for our local waters.

What Are We Eating?

"The United States imports over 90% of the seafood it consumes. And half of all we consume is farmed," says Russ Vetter, senior scientist for fish genetics and aquaculture at NOAA Fisheries in La Jolla.

Clearly, we are not very connected to our seafood sources in the United States. Given that most of the seafood we San Diegans eat probably traveled farther to get here than most tourists—seafood travels an average of 5,000 miles from ocean to plate—local aquaculturists are interested in farming seafood in California waters. They cite reduced carbon footprint, increased number of local jobs, a reduced trade deficit and decreased pressure on wild fish populations as some of the benefits of farming fish locally.

Don Kent
Todos Santos Baja
Photo 1: Don Kent, President of Hubbs-SeaWorld Research Institute HSWRI)
Photo 2: Todos Santos Baja

"Plus, we'd be growing it by our standards," says Don Kent, president of Hubbs-SeaWorld Research Institute (HSWRI). "There is a need to increase supply to meet the demand for fish and it has to come from aquaculture."

Even if all the seafood that California fishermen catch were kept in state— much of it is exported and some of that re-imported in a ready-to-eat form—it wouldn't be enough to meet dietary recommendations of a half pound of seafood each week per person in our state (around 500,000 metric tons per year).

Filling the Gap between Supply and Demand

To fill this gap in California and around the country, HSWRI has proposed an aquaculture operation about five football fields in size 4.5 miles offshore of San Diego. The Rose Canyon Sustainable Fisheries Aquaculture Project would be the largest of its kind and eventually harvest up to 5,000 metric tons of yellowtail (AKA hamachi), white sea bass and striped bass each year. Unlike tuna ranches, HSWRI would produce fish eggs from broodstock at one of their hatcheries and transfer young fish to cages at the Rose Canyon site for fattening. Fattened and delicious, they'd go to market at about two years old.

"Our waters are in some ways ideal for fish farms," says Vetter. "We have few hurricanes or major storms. The ocean floor becomes quite deep not far from shore. This, with the deep water and gentle currents, prevents fish waste from accumulating on the bottom or degrading water quality." Plus, "hatchery-reared fish that are good candidates for farming are already locally available. And many of these species are suited to our temperate waters," says Paula Sylvia, research fish biologist at NOAA Fisheries in La Jolla.

"It's incumbent on us to provide what we can to others who can't produce seafood locally," says Kent, who envisions providing seafood year round. And because the Rose Canyon operation and local fishermen will harvest different species, Kent suggests they will not compete.
But are we entitled to fresh fish, of any variety, year round?

John Volpe, principal investigator at the Seafood Ecology Research Group at the University of Victoria, argues that no, we are not. "We have to challenge the notion that all species have to be available all the time. Just because there is a market for them, doesn't mean it must be saturated at all costs." He contends that the market should operate on what can be removed without putting the environment at risk.

Some ranchers believe that tuna farming takes pressure off wild populations. "Farming produces fattier bluefin, which command higher prices than the wild purse-seine catch does," says Luis Rodriguez, a biologist at HSWRI and former head biologist for Baja Aqua Farms SA de CV. "This means we can fish less intensively because of the value added."

"Aquaculture can only take pressure off wild populations if demand stays static," says Volpe. "Yet, fish farming tends to increase demand and pressure on the wild population." Some salmon fishermen now have to catch more fish because they have to sell it more cheaply to compete with farmed fish prices.

Aquaculture can stress wild populations in other ways: Escapees can outcompete them or breed traits not suited to the wild life. Disease and parasites can spread easily to wild populations. Some farms, like those built on mangrove forests, destroy habitats.

Plus, as the scale of an operation increases, so can the overall impact.

Feeding the Food

"Feed is one of the biggest costs in aquaculture," says Sylvia. Ranchers feed their bluefin Pacific sardines and other small fish. "These come from a well-managed fishery but are a finite resource," she says. Until recently, they were locally abundant and cheap. For animals like yellowtail, raised from egg to market in captivity, feed can be supplemented with other products, like algae and soy.

Kent is exploring ways to reduce environmental impacts of farming fish including those associated with feed. He says, "165,000 tons of fish are caught in California each year, most of which is processed in Southern California. We're assessing how to use leftover scraps from that processing for diets to grow farmed fish with a minimal carbon footprint." This could reduce operating costs and use something that would otherwise have gone to our landfills.

The promise of aquaculture is to produce in large quantities that which is limited in nature. "But to say this is to feed North America's growing population is disingenuous," says Volpe. Most aquaculture uses about 1½ pounds of pellet feed to produce one pound of fish (though bluefin require 14–20 pounds of sardines to produce one pound of fish—profit margins are high enough to support this). "There's a net loss of protein. If industry was interested in feeding the world, there are more efficient ways to do it." But the problem isn't shortage of food, many argue. The problem is access to food.

Any Questions?

The world now eats more farmed than wild-caught seafood, and we have questions. Businesses ask, how can I get fish to market so that I can maximize profit? A good aquafarmer asks, how can I produce fish without harming them, the environment or people? The entrepreneur asks, will we import seafood or grow it ourselves? Biologists ask, how can we increase production and not affect the natural system? Really, how can we know if our approach to aquaculture is good unless we study it?

Where does farmed seafood fit in? As an everyday fish for all Americans? As a shot to our local economy?

But we should also ask: Are we entitled to fresh fish all year round, no matter where we live? And for those of us who view food as a manifestation of our culture, how does aquaculture fit in? For resources and continuing conversation around these issues, visit this website.

Article from Edible San Diego at
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