NOAA’s Forensics Identify Fish Fraud02 January 2013
US - When Trey Knott gets an overnight package from NOAA’s Office of Law Enforcement, he doesn’t even know what’s in it. He opens it up and, as the package exhales a mist of dry ice, he reaches in and pulls out the evidence. It might be whale flesh, or fraudulently labeled grouper, or illegally landed Bluefin tuna, to name just a few of the species involved in recent cases. But the NOAA law enforcement agents who sent the package to him do not divulge their theory of the case. That way, he can investigate without bias.
Mr Knott is a forensic analyst with NOAA’s Marine Forensics Programme. He and his colleagues use science to combat seafood fraud and trade in protected species. Seafood fraud often involves mislabeling less expensive fish as something pricier, or smuggling contaminated or illegally caught seafood into the country. Such crimes cost consumers money, endanger the public health, and undercut the business of law-abiding fishermen.
Mr Knott uses many of the same techniques of forensic DNA analysis that are used in the nation’s crime labs. But there’s one major difference. In most human cases, the analyst already knows the species that they’re dealing with. When Knott begins his analysis, he often doesn’t know even that.
Preventing Seafood Fraud
“The bread and butter of our work is DNA species identification,” he says, “because very often what the law enforcement agents come across is pieces and parts.” That’s because parts are harder to identify than whole fish and are therefore easier to mislabel. In 2007, Mr Knott worked on a case where the owner of a Florida business, Panhandle Seafood, smuggled several hundred thousand pounds of fillets into the United States and Canada by mislabeling them as grouper.
Mr Knott used DNA analysis to identify the true species as Vietnamese catfish. Further analysis found that some of the fillets were contaminated with Enrofloxin, a dangerous food additive that is banned in the United States. The smuggler pleaded guilty and was sentenced to 51 months in prison and ordered to pay $1.13 million in restitution.
Protecting Endangered Species
Piper Schwenke is an analyst in the Forensic Unit at the Northwest Fisheries Science Center. Given that she’s based out of Seattle, it’s no surprise that her specialty is salmonids, a group that includes salmon and trout.
In one case she worked on, all Schwenke had to go on were some fish eggs. Investigators had observed steelhead trout trapped beneath a dam in California as they were trying to get upstream to spawn. Steelhead, a close cousin of salmon, is listed as threatened under the Endangered Species Act in many areas, including Central California. When officials returned to rescue the steelhead, they were gone, and the property owner claimed that there were never any steelhead there to begin with. But investigators did find some fish eggs at the scene.
“It was like a murder case with no body,” Ms Schwenke said.
Ms Schwenke used DNA analysis to prove that the eggs were from either a steelhead or a rainbow trout. Steelhead spend most of their lives at sea and then return to their natal stream to spawn, whereas rainbow trout live their whole lives in rivers and streams. Despite this behavioral difference, the two are the same species, and they are so genetically similar that DNA analysis cannot tell them apart.
But telling them apart was important in this case because steelhead trout are a protected species while rainbow trout are not. Other scientists at NOAA’s Northwest Fisheries Science Center used isotopic analysis to tell them apart. This technique is based on the fact that the atoms of some elements come in two varieties, heavy and light. These varieties are called isotopes, and chemists can tell them apart in the lab. In this case, the fish eggs carried the isotopic signature of the ocean, proving that they were from an ocean-going steelhead trout. The landowner pleaded guilty to violations of the Endangered Species Act.
The Really Big Cases
Kathy Moore is another forensic DNA analyst at NOAA. She works on marine mammal cases. Trade in marine mammal products—everything from whale sushi to whale bone carvings to seal pelts—is illegal under the Marine Mammal Protection Act. Sometimes, proving that the species in question is a marine mammal is simple. “When you look at a whale bone,” she says, “you usually know it’s a whale just by its sheer size.”
The Marine Mammal Protection Act protects all whales, so in some cases, determining that a bone comes from a whale is as far as Moore has to go. Some whales, however, are also protected as endangered species. If law enforcement suspects an Endangered Species Act violation, Moore will do further DNA analysis to determine the exact species the evidence comes from.
Protecting and Preserving
Using forensic science to identify the victim is a common theme on television. Analysts with NOAA’s Marine Forensics Program are doing the same thing, even if they don’t have their own show on TV. But the work they do is vital to protecting consumers, fishermen, and endangered species. When the cases come in, these forensic analysts are ready for prime time.
TheFishSite News Desk