The fish you choose makes a difference

No one's saying you need a Ph.D. in marine biology to eat a piece of fish. But to find seafood that's healthy for you, and for the oceans and coastal communities, educate yourself before plunking down your money.

We offer suggestions here, but first you should know that how you spend your dollars makes a difference.

"What drives all the fishing is what people are buying," said Carl Safina, president of Blue Ocean Institute, a conservation organization. "If you buy better fish, it helps give a market advantage to people who are fishing sustainably and selling sustainable fish."

In a perfect world, your piece of fish would offer sustainability as well as great flavor, price and health benefits. Those fish are rare, but we found a few (sockeye salmon and sardines, take a bow). Sometimes you'll need to pick fish by making choices that align with your priorities.

• Support your local sardine. Salmon, we love you, but it's time to branch out and discover some of the unsung species of our oceans. Less obvious choices can be cheaper and equally tasty, plus, by buying a variety of fish you encourage variety at the supermarket.

Albacore tuna is a quarter of the price of salmon. Lingcod, a delicious, firm-textured whitefish, is half the price of halibut.

• Eat for omegas. The highest levels of this magic fatty acid, important for neurological development in children and cardiovascular health in all of us, are found in oily fish: salmon, yes, but also sardines and black cod (also called sablefish). Troller-caught young tuna are also high in omega-3s.

• Shrink your carbon footprint. Alaskan salmon might get a better grade on sustainability from the Monterey Bay Aquarium, but it probably won't be as eco-friendly because of the required refrigeration, trucking and distribution.

Shopping tips • Cultivate a good relationship with a fishmonger. Find a store, or a person, that seems to know about the fish in the case and cares about your preferences, then keep buying there.

• Ask questions. When did the fish come in and how was it caught? Is it wild? If imported, where did it come from? By federal law, seafood must be labeled with country of origin, though not all stores comply yet.

• Use the cards. Monterey Bay Aquarium's Seafood Watch Program (www.mbayaq.org/cr/seafoodwatch.asp), Blue Ocean Institute (www.blueocean.org) and Environmental Defense (www. environmentaldefense.org offer pocket guides to eco-friendly seafood. The Seafood Choices Alliance (www. seafoodchoices.com/smartchoices.php) also has online information on the best fish for eating.

• Look for Marine Stewardship Council (MSC) certification. Seafood producers covet the stamp of approval by the council (www.msc.org), an international nonprofit that promotes responsible fishing practices.

• Say skipjack. Look for "chunk light" on your tuna can, which contains only one-third as much mercury as canned white albacore tuna, according to the U.S. Food and Drug Administration (the FDA says it's safe to eat up to 6 ounces of fresh or canned albacore a week). But also check to see which species is in the can; the best choice is skipjack, because it's smaller and isn't overfished.

• For health, eat low on the food chain. At the bottom of the food chain you'll find lower amounts of pollutants. Think anchovies, herring, sardines, smelt, and sockeye and pink salmon -- all "filter feeders."

• Buck the trends. For bargains, seek out less-popular species that are healthful and sustainable: Sardines are packed with omega-3s and, when cooked with equally assertive ingredients, delicious. Mild lingcod is firmer than Pacific cod.

• Know your farms. Best for the environment are farms that use so-called closed systems, inland tanks where water is treated and recirculated, and fish species that are fed a vegetarian diet instead of wild fish or fish meal, which takes away food from ocean fish. Among the greenest are U.S.- or Latin America-grown tilapia, U.S. catfish and farmed trout.