A cool breeze carries the sound of sizzling grills and popping wine corks across the bay: it's summer in Santa Cruz, and that means the time has come to eat, drink and be merry. But preparing for a summer feast can be a headache, especially for the environmentally minded host. And if fish is on the menu, forget it. Is there any fish species that isn't verboten for a sustainable barbecue anymore?

Pollution, habitat fragmentation and overfishing have caused some serious scientists to predict the collapse of most wild fisheries by 2050. Locally, seafood lovers can look at the decision to close the commercial salmon season along the entire West Coast this summer to get a sense of how this scenario might play out.

The cure for stressed wild fish stocks, many say, is more fish farms--a move akin to transitioning from hunting to cattle ranching. These operations are already part of humanity's diet and will be for the foreseeable future; fish farms made up over 32 percent of global seafood production in 2004, according to the U.N. Food and Agriculture Organization, and the industry has been growing at a rate of over 8 percent per year since 1970.

However, hatching and raising fish to maturity in close quarters can have negative impacts on the surrounding ecosystem, especially if the operations are in the open ocean. For the average consumer, it isn't clear whether it's a better environmental choice to buy from these factory farms of the sea or from overfished wild stocks.

Corey Peet, who works as the resident expert on farmed fish operations for the Monterey Bay Aquarium's Seafood Watch program (see sidebar, page 30), studied aquaculture at the University of Victoria's Marine Ecology graduate program in British Columbia. Up until six months ago, George Leonard, who received his doctorate at Brown University, also worked on Seafood Watch. He now directs the Ocean Conservancy's Aquaculture Program from his perch on the Santa Cruz Wharf. These two are among the best and brightest when it comes to sorting fish farms that harm the environment from fish farms that have a minimal impact--or in some cases, can even help clean up polluted watersheds.

"You have to be careful not to paint all aquaculture with the same brush," notes Peet. "The reality is it's a very diverse industry. Pretty much every [commercially-sold species] is produced in aquaculture--all the way from creatures that eat plants or are plants, to creatures that eat other fish. There is a different suite of impacts as you go up that scale."

Code Red
First, there are the bad players in the farmed fish world, which generally end up in the red column: salmon and tuna. These tasty species have become very popular in recent decades as the number of people who can afford them has increased. To meet demand, salmon farms and tuna "ranches" have cropped up in coastal areas off Europe, South America, Canada and the Eastern United States with increasing frequency. There are a number of reasons, environmentally speaking, that this is a bad thing.

(1.) The waste. Piles on piles of poop are generated in the pens of the larger farms, and many times, the stuff simply drifts out into the surrounding environment to the detriment of native species. This massive shitstorm is a result of #2 (no pun intended).

(2.) Their appetites. Salmon and tuna are top-level predators--which means they eat a lot. In fact, these predators eat more meat than they end up producing. For example, a typical farmed salmon has to eat anywhere from 2 to 5 pounds of fish to gain a pound of body mass. For tuna, the ratio is even worse: attendants must shovel over 25 pounds of wild fish to put a pound of sushi-grade meat on a ranched tuna. To help illustrate the absurdity of these ratios, Peet makes an analogy to a hypothetical land-based operation.

"It's like trying to raise hundreds of lions on the Serengeti in a confined space," he says. "These animals are on the absolute top of the food chain, so they require a lot of food and protein throughout their lives."

Leonard, for his part, compares it to raising a pen full of gas-guzzling Hummers. So when someone buys 5 pounds of farmed tuna, 125 pounds of wild fish go down the hatch. More often than not, these are smaller fish at the bottom of the marine food chain. This is no way to take the burden off of a fragile marine ecosystem, argues Leonard.

"You basically end up taking more from the bottom of the food web instead of directly from the top of the food web," he explains. "If you're interested in taking pressure off of ocean ecosystems, you can't do it that way."

Those are the two biggest reasons not to buy ranched tuna (the fish are usually caught in the wild as juveniles and then raised in pens until maturity, hence the term "ranching").

With farmed salmon, two other dangers loom.

(3.) Disease. Many, though not all, salmon farms are located either in the ocean or in a bay that connects to the ocean. The farms usually consist of a series of cages that have been densely packed with as many fish as possible. The bars or mesh walls prevent salmon from swimming away but allow water to pass through. Think factory farms in the sea, but with fishing nets instead of solid walls. This means that if one fish gets sick with a contagious disease, the rest are almost guaranteed to come down with it as well. Environmentalists and fishermen realized this was a big problem when a parasite known as sea lice spread from fish farms off the coast of British Columbia and ended up decimating wild populations. A 2006 University of Alberta study found that native salmon populations with migration routes near offshore salmon farms infected with sea lice were 73 times more likely to be infected with the parasite than the average salmon population. This makes sense, notes Leonard, since parasites such as sea lice don't require physical contact--they just need to get close enough to swim to another host they can infect.

"The key here is that it doesn't require salmon to escape from the farm, because these pens have water flowing through them," Leonard says. "In the same way that if you are sick and I am near you, the infected particles go through the air onto me and off I go getting sick. I don't have to have any physical contact with you."

(4.) Unholy unions. The problem of escaped salmon, usually the result of malfunctioning equipment, storms or boating accidents, is subtler. Salmon have survived in the wild for centuries by adapting to their surroundings through genetic variation. Conditions in the Atlantic are drastically different from the Pacific. So when an Atlantic salmon escapes from a pen off the coast of British Columbia and does the dirty with a wild Pacific salmon, the offspring are less likely to survive. Peet and other scientists call this trend "compromised genetic fitness." Over time it can greatly reduce the numbers of already stressed wild populations.

"If an individual salmon doesn't have enough fat in their bodies to survive the swim upstream, they won't lay the next generation of eggs," says Peet. "This can be a real problem for certain species that are already facing endangered status."

Chickens of the Sea
It's not all gloom and doom at the fish counter. There are actually more farmed fish under Seafood Watch's "Best Choices" column than under the heading "Avoid."

First, there are the smaller fish lower on the food chain. The two main species in this category are tilapia and catfish. There are two reasons these farmed fish varieties are considered sustainable summer barbecue fare.

(1.) They're vegetarian. These fish can survive on a mostly vegetarian diet, and when they do eat other fish, they don't usually consume too much. By the time they reach maturity, they've actually produced more meat than they've eaten; it takes less than 1 pound of wild fish to raise 1 pound of farmed tilapia or catfish. This makes these two species relatively harmless to the surrounding food web, and it also means they excrete a lot less harmful waste. For environmentalists like Leonard, this makes them an obvious choice.

"It's hard to make generalizations, but generally things lower on the food web are inherently more sustainable," explains Leonard. "Catfish and tilapia can be staples-the chickens of our diets. I've been making a lot of fish tacos lately, and species like tilapia make really good fish tacos. Put the fish in a marinade with peppers, and for some reason tilapia really sucks that stuff up nicely."

(2.) Terrestrial farms. The second reason these varieties are smiled upon is that they are generally farmed in systems on land where waste is treated and escapes are rare, instead of in open-net pens in the ocean where fish can easily escape and waste or disease can flow freely into the surrounding ecosystem. This isn't always the case, warns Leonard, but more often than not this segment of the aquaculture industry takes steps to self-regulate.

"Tilapia and catfish are often raised in closed systems on land," says Leonard, adding, "There are cases where tilapia has been farmed in the open ocean. In many of those cases there have been escapes, and it's a very invasive and hardy fish, so it has become established [as an invasive] in many parts of the world. So that reduces the sustainability. But when it's farmed in a non-open pen system, it's a really good, sustainable choice."

Perhaps the most sustainable seafood available is shellfish. In contrast with catfish and tilapia--which are good because they have minimal impacts on the environment--shellfish aquaculture can actually be beneficial to a near-shore ecosystem. The reason is simple: shellfish love to gobble up the nutrients that run into rivers from farms and urban runoff.

"Shellfish aquaculture holds promise because it's a filter feeder," says Leonard. "They eat particulate matter from the water, so they can take excess nutrients out of the water and consume it."

Shellfish that make Seafood Watch's green list include abalone, clams, oysters, mussels and scallops.

One reason tools like the Seafood Watch Guide are so powerful is that they help fish-hungry consumers try new experiences, instead of always grabbing for species guaranteed to be tasty, like tuna or salmon. Making up a spicy tilapia taco or munching on marinated fried abalone can open up whole new culinary avenues, all while promoting industries that are good environmental stewards. Leonard and Peet both hope a growing segment of the population will embrace these sustainable choices, leaving salmon and tuna as food eaten only during special occasions.

"When I was a kid, salmon was a luxury product. You ate it at weddings and funerals," remembers Leonard. "If these fish were still recognized as products to be enjoyed infrequently, it would probably be sustainable. In many ways, the salmon problems we see today are a result of the commoditization of our food system. It's about taking something special and making it not special anymore."

Feeling Fin

The good folks at Monterey Bay Aquarium's Seafood Watch Program are here to help sort out the wild-vs.-farmed seafood conundrum. Here's how it works: A crack team of researchers dig up everything they can about wild-caught and farmed fish species, taking into account populations, feeding habits, fishing practices and impacts on the environment. Then they place each species in one of three color-coded categories: Best (Green), Good (Yellow) and Avoid (Red). The results are printed up on wallet-size cards tailored to one of seven North American regions. The smart consumer should never go shopping--or to a restaurant--without this guide in hand. But don't take our word for it. At a recent Aquarium event, TV chef Alton Brown brandished a Seafood Watch card and proclaimed that "this little card here, this Seafood Watch, this changed my life personally, and it single-handedly got the attention of chefs."

For a copy of the Seafood Watch card, visit www.mbayaq.org.

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