That fish you ordered at a restaurant or bought at the grocery store may not be what you think it is. Investigative reports from across the nation have been discovering a common theme: Fish are frequently mislabeled, with one species being substituted for another. And it’s pretty hard to make sure it doesn’t happen to you.

Whether it’s intentional or accidental, mislabeling could affect a consumer’s health if the seafood contains unknown allergens or toxins. The seafood might have been caught by methods undesirable to the consumer. And, most obviously, if it’s not what you ordered, you’re probably paying more than you should.

How prevalent is it?

Mislabeling rates vary, depending on who did the DNA sampling and what kind of fish was sampled.

For example, Consumer Reports researchers found that one-fifth of 190 seafood samples from retail stores and restaurants on the East Coast were mislabeled or misidentified by employees. That fell in line with other studies that showed 20 to 25 percent of seafood globally is mislabeled, according to the December 2011 Consumer Reports magazine.

The Boston Globe had fish from 134 restaurants, grocery stores and seafood markets back east DNA tested. Results, published late last year, said nearly half of the fish were sold under the wrong species name.

A 2011 report from the ocean-protection nonprofit group Oceana said seafood may be mislabeled 25 to 70 percent of the time for fish like red snapper, wild salmon and Atlantic cod.

Salmon in Seattle

Closer to home, biology students in Seattle did some local testing of their own recently and found similar outcomes, specifically in salmon, a Pacific Northwest favorite.

Erica Cline, an assistant professor in the environmental sciences program at the University of Washington, Tacoma, led her students in some salmon DNA sampling between 2009 and 2011. Students bought salmon from stores and restaurants and then performed DNA sequencing on campus to determine where the fish were from and what species they were. They used 99 reliable samples.

“We saw higher rates of substitution in restaurants, and it was really pretty striking,” Cline said.

The most frequent substitution they found was passing off farmed Atlantic salmon for what’s marketed as wild-caught Pacific salmon.

“We found 24 percent of the restaurant samples were Atlantic salmon sold as Pacific salmon,” she said. Grocery stores fared better in the report, with only 2 percent of samples mislabeled.

Students also found a higher rate of substitution in the winter, as compared to spring. The Atlantic salmon substitution rate was more than 30 percent in the winter but 12 to 13 percent in the spring. Cline speculated that in the late winter, there are not a lot of salmon runs, but there’s always pressure to advertise fresh wild salmon. People in the Pacific Northwest seem willing to seek out wild salmon and pay more for it, she speculated, providing incentive for mislabeling.

“If you’re buying fresh wild salmon in late winter, early spring, I’d be suspicious,” Cline said.

Consumer tips

Most experts say seafood caught in the U.S. is less likely to be mislableled because laws and penalties exist to protect consumers. But convictions are usually the result of complaints, so it starts with an informed consumer.

Ask a lot of questions: Where is the fish from? Was it fresh or frozen? It helps to understand fish runs, but sometimes the answers don’t add up.

“I went to a restaurant and asked about the wild king salmon advertised on the menu,” Cline said. “They eventually admitted that it was farmed. But king is not farmed. So they finally admitted it was Atlantic.”

King salmon costs significantly more than Atlantic, she said. “There’s not yet a sense that it’s wrong. The sense that salmon is salmon might be part of it.”

Trusting the seller

There’s a lot of trust involved on the part of the consumer when ordering fish. In some cases, it just comes down to knowing the person you buy your fish from.

Duncan Laing, owner of Precious Cargo, a “fisherman direct” seafood retailer, said he is not worried about carrying mislabeled fish because knows where his products come from. He refuses to deal farmed fish, he said, and he trusts the fishing fleet operators that he deals with “based on relationships with people … They would not pull a fast one.”

Mike Rushing, an owner of High Tides Seafood Grill in Bend, said seafood is generally a high-end commodity and he believes the people who handle it are generally talented in their trade. He said the licensed wholesalers he buys from are reputable and have been in business for a long time.

“It’s usually not an issue for us. We go with more regional fish, from the Northwest,” he said. And “salmon is an easy thing to identify.”

“There’s a big concern and I know there is mislabeling. I personally have been doing this for so long, it’s something that I can recognize, for the most part. I’m confident with what I buy … I have the ability to visually identify (species.) I’d guess it happens, in cod for instance, (because) some species have dozens of varieties.”

But Rushing said his biggest concern with fish is freshness. “That’s going to cause the most dissatisfaction, taste-wise, or potential for illness.”

He and others said they hear that Oregon rockfish gets sold as snapper sometimes — snapper being the more expensive commodity. But, Rushing said, “Personally, I’d rather have a fish caught closer and more recently than something from the Gulf of Mexico. I’m not so sure rockfish from the Coast is inferior.”

Of course no one wants to be misled, taken advantage of, he said. But “I don’t think it’s going to hurt you, if you enjoy the fish. If you didn’t question it, it’s not the end of the world.”

Health concerns

However, according to the 36-page report on the issue from Oceana, called “Bait and Switch: How Seafood Fraud Hurts Our Oceans, Our Wallets and Our Health,” seafood mislabeling opens the door to a array of potential contaminants, pathogens and allergens.

The report and regional Food and Drug Administration officials say the most significant health risk is probably from allergens. Fish and shellfish have some of the most potent food allergies, along with peanuts and tree nuts, according to Oceana’s report.

Another health concern is ciguatera, a foodborne illness which used to just be found in tropical regions. It could be imported with large reef fish that carry it. It causes nausea, diarrhea, cramps, numbness, an irregular heart rate and other symptoms. It can be debilitating, according to the report, and even create lifelong neurologic symptoms.

Some kinds of fish contain more mercury than others, a concern for pregnant women and children.

Selling farmed fish as wild or vice versa can result in different health risks. Farmed fish raised in aquaculture pens can carry antibiotics and dyes that would not be present in wild fish. And sometimes, higher levels of certain contaminants are found in the farmed versions of salmon and sea bass.

How it happens

The Oceana report explains the many steps in the supply chain during which fraud can happen: The fish might have been mislabeled in a restaurant, or by the distributor who supplied it to the restaurant. The processors who package fish have ample opportunity for substitutions.

Illegally caught seafood products can come from vessels that violate international conventions formed to prevent overfishing and ecosystem destruction. Illegally caught fish can be mixed in with “responsibly” caught fish. Paperwork might be illegal, or inspectors might be bribed, the report said.

“There are opportunities all along the way for people to take advantage of the system,” said Christina DeWitt, director of Oregon State University’s seafood research laboratory in Astoria. “There are also a lot of people working on solving it.”

Fraud is a concern for the industry, and most of the people in the industry are probably doing the right thing, she said. Groups like the Virginia-based National Fisheries Institute are trying to get those working in the industry to pledge against fraud. Distributors have sent “strongly worded” letters to suppliers threatening “serious consequences” if the distributor finds out it’s getting mislabeled fish, she said.

The FDA enforces “The Seafood List,” a guide to acceptable market names for seafood. It outlines the rules for labeling seafood sold in the U.S. to keep fish identity consistent and accurate. It’s necessary, according to the FDA, “because of the exceptional number and variety of species represented by this unique category of foods.” In many cases, a common name can represent a group of fish, but not the specific species.

Take salmon, for example: There’s farmed or wild. There’s Chinook (king), coho, sockeye and more.

The problem stems from the fact that there’s no established traceability system in the industry, DeWitt said. It would have to start with the fishermen labeling fish right away with all sorts of valid information about what it is and where and how the fish was caught.

DNA sampling exists and is accurate, but not immediate; the testing process takes hours, and that’s aside from any time involved with shipping the product to the testing sites. And testing sites are not ubiquitous.

“We’re looking at DNA technology and will try to get a better handle on the extent of the problem,” said Seattle-based FDA spokesman, Alan Bennett. “We have to move forward with that science because you as individual consumer are going to have a tough time determining whether something has been substituted.”