At Sacramento Natural Foods Co-op, the seafood case is more than just an eye-pleasing display of deep orange wild king salmon, delicate pink opah and pristine white petrale sole. Greenpeace recently named the Sacramento, Calif.-based co-op the number one sustainable seafood grocery retailer in California and number two in the nation.

Sacramento Natural Foods Co-op offers valuable lessons for retailers who feel overwhelmed by the complexities involved in selling sustainable seafood. For the last six years, the co-op has partnered with FishWise, a Santa Cruz, Calif.-based nonprofit dedicated to improving both the sustainability and revenues of seafood retailers, distributors and producers. For $1,200 a year (prices vary depending on store size and services provided), the Sacramento co-op can access FishWise's sustainability ratings for every type of seafood, get a quarterly audit of its seafood case signage, and receive staff training on everything from catch methods to mercury testing.

The partnership pays off for the co-op in a number of ways. Not only has the Greenpeace ranking resulted in increased publicity—Sunset magazine recently named the co-op's seafood department one of the best in the West—but it has also helped the retailer ring up more sales. Seafood revenues increased 16 percent last year, according to General Manager Paul Cultrera.

But what if you don't work with an organization like FishWise? Statistics show it's still profitable to stock sustainable seafood. Between April 2010 and April 2011, sales of refrigerated and frozen seafood increased 10.5 percent in natural foods stores nationwide, according to Schaumburg, Ill.-based market research firm SPINS. "Many of the top 20 food retailers in the country, including Walmart, Safeway, Target and Whole Foods, found it's good for business to establish sustainable seafood departments," says FishWise Executive Director Tobias Aguirre.

According to research by the Monterey Bay Aquarium's Seafood Watch, consumers want to know how their seafood is sourced, but they don't want to do the work themselves. "They want information at the point of sale, from the people selling the product," says Sheila Bowman, Seafood Watch senior outreach manager. That opens up marketing and merchandising opportunities for your store.

Here are expert recommendations on the best ways to stock your fish case sustainably, boost sales and educate customers.

Know where to get info

You can't always rely on your distributors to tell you if their stock is sustainable. In fact, Sacramento Natural Foods Co-op's meat, poultry and seafood manager, Robert Duncan, says his suppliers often call him to determine the sustainability of their latest catch. Do your homework by checking sustainable seafood rankings from third-party organizations. (See "Top sustainable seafood sources")

Vet your distributors

Aguirre says if your seafood supplier can't answer the following three basic questions about the sourcing of its fish, that's a red flag that traceability issues exist. Where was the fish caught or farmed? What method was used to catch or raise it? What is its scientific name?

Bone up on toxins

This is easier said than done, Bowman says, because there is no organization that reliably tests seafood for toxins on an annual basis, so data can be out-of-date. Mercury and PCBs are the two main culprits to watch for. In general, the larger and more carnivorous the fish (think tuna and salmon), the more toxins, she says.

Expand your offerings

According to Bowman, the top three seafood choices for U.S. consumers are salmon, tuna and shrimp. "You have sustainability issues if millions of people eat the same thing," she says. "When you ask 99 percent of people what fish is healthy and the only one they can name is salmon, you have a problem." Use signage to steer customers toward other sustainable fish options that also are high in omega-3s, such as lake trout, Atlantic bluefish and U.S. farmed sturgeon.

Don't overlook the freezer case

This is a good option for customers who want out-of-season fish, such as salmon patties and crab cakes, or specialty products such as gluten-free frozen haddock or cod nuggets, Duncan says.