Robert Hanner is an associate professor at the University of Guelph Biodiversity Institute of Ontario and Centre for Biodiversity Genomics.

Lobster boils, shrimp on the barbie, fresh fish by the seaside – summer is for seafood. But before you tuck in to your next crab cake, ask yourself: do you really know what you're putting in your mouth? Chances are you don't; an estimated 30 per cent of seafood sold globally is mislabelled. We have all likely been victims of fish fraud, which means we are also unwittingly complicit in one of the single greatest threats to our oceans. The good news is: we have the power to fight it, if we know what to ask and where to look.

Simply put, fish fraud – which includes mislabelling and adulterating products – tricks consumers into buying products they may not want. Given that the U.K. Food Standards Agency estimates 10 per cent of foods on the grocery shelves aren't what they claim to be, the problem goes well beyond fish. But seafood is particularly vulnerable for two reasons: the global seafood supply chain is incredibly complex, and most of the seafood we buy is processed in some way. Even the fish-foodie experts among us would struggle to tell cod from basa (a type of catfish) in their fish and chips.

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What we don't know can hurt us. Falsely labelled products may conflict with our religious or social values. They can cheat us out of our hard-earned cash (for example, the chances of you buying a cheap piece of tilapia, but actually getting expensive Chilean sea bass are slim to none. The opposite is far more likely). And they may even put our lives at risk. Case in point, the two unfortunate Chicagoans who ended up in hospital after their monkfish dinner turned out to be highly-toxic pufferfish.

Fraud doesn't just hurt the consumer: it takes a toll on the entire food industry. The victims are the honest players – the organic farmers, the sustainable fisheries – doing their part to give us authentically better choices. That brings us to the other significant impact of fish fraud: it's wrecking our oceans.

Unsustainable fishing (and eating) practices are driving many of the world's fish stocks to the brink of collapse. Canadians know this better than anyone. Just ask a fourth generation fisherman from Newfoundland how the collapse of Atlantic cod impacted his family and livelihood. Seafood exports, by the way, contributed $6.6-billion to Canada's economy last year, so this is an issue that truly affects all of us.

If managed right, our oceans can provide an important source of wild protein for an ever expanding human population. We know a great deal more now than we did three decades ago about how to maintain fish stocks at a sustainable level. However, that knowledge is only useful if consumers know not only what fish they are eating, but where it came from and how it was harvested. With this information, we have collective power to transform the seafood industry for the better.

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Advances in DNA biotechnology have given us new tools. For example, the TRU-ID program offers DNA-based supply chain verification that helps unmask fraud. Credible third party certification programs can also help consumers choose wisely and confidently.

When it comes to wild seafood, among the most scientifically rigorous is MSC (Marine Stewardship Council). The MSC's blue fish label certifies that products are traceable from a trusted, sustainable fishery all the way to your plate. This differentiates it from other wild seafood sustainability programs in Canada.

The most important message here is that we can – and should – demand solid information about the fish we're buying and being served. That means asking direct questions: What species is this? Where did it come from? How did it get to me? What standard does it meet for sustainability?

June 8 is World Oceans Day and you do have the power to make a difference. It starts with becoming a pickier eater and consumer. When it comes to the food on your plate, that's not only your responsibility, it's your right.