05/05/2015 12:20 EDT | Updated 05/05/2016 05:59 EDT

The Big Footprint of Tiny Shrimp

I used to eat a lot of shrimp, but based on my travels examining foreign shrimp farms and various unsustainable and sustainable fishing practices, now I am much more selective. Supporting more sustainable options is a good start but with the vast majority of the global shrimp industry based on destructive harvesting methods, widespread change will take a long time.

Frozen shrimps in a strainer bowl

Do you eat shrimp? If so, do you know where your shrimp comes from and whether it was wild caught or raised on a farm, where most shrimp now comes from? The answers will help you make wise choices and there are several great sources to purchase sustainable shrimp if you know what to look for. It may seem insignificant to know these things, but Canadians eat a lot of shrimp and much of shrimp harvested in the world today unfortunately causes tremendous environmental damage, and can even be bad for your health to consume.

I used to eat a lot of shrimp, but based on my travels examining foreign shrimp farms and various unsustainable and sustainable fishing practices, now I am much more selective.

Almost all shrimp is harvested today using one of two methods, bottom trawl fishing or shrimp farming. As the name implies, bottom trawling involves dragging a large net along the seafloor, and these nets are very effective at catching shrimp. Unfortunately, bottom trawl nets are also very good at catching just about everything else they touch. Although shrimp fisheries only produce 2 per cent of the world's seafood catch, shrimp trawlers are responsible for over 30 per cent of global bycatch (marine life that is caught or killed unintentionally). Shrimp trawlers kill an average of 5-10kg of marine life for every 1 kg of shrimp that is pulled up by nets.

Not only do bottom trawls kill indiscriminately, but they also do untold damage to the bottom habitat by ripping up corals and killing hundreds of thousands of endangered sea turtles every year.

In Canada and the U.S., shrimp trawlers must follow strict standards and are required to use special nets that allow larger fish and sea turtles to escape while retaining shrimp. This has allowed some domestic shrimp fisheries to reduce bycatch rates to about 2-5 per cent of their total catch, but approximately 53,000 sea turtles still get killed in the U.S. Gulf of Mexico shrimp fishery every year.

Although North American shrimp fisheries make a bigger effort to reduce bycatch than many foreign tropical shrimp fisheries, oftentimes consumers have no easy way of identifying the difference between the two at a grocery store or restaurant.

With shrimp trawling being such a destructive practice, one might assume that shrimp farming on land is a much more environmentally friendly alternative. However, this is simply not the case. Shrimp farming now produces 55 per cent of the shrimp we eat and the vast majority of these farms are located in tropical countries like Thailand, China, Vietnam, India, Indonesia, Bangladesh and a smaller amount in Latin American countries like Brazil and Mexico. Environmental regulations for shrimp farms in these countries are not very strict or are rarely enforced.

Most shrimp farms require the removal of precious mangrove forests that act as a coastal storm barrier and key habitat for juvenile marine life that take refuge in their root systems. About a fifth of mangrove forests worldwide have been cleared since 1980 and much of the destruction is connected to the spread of shrimp farms.

As waste builds up in farm ponds, the land eventually becomes useless and most ponds cannot be used for longer than 10 years. Once a pond is deemed unusable for shrimp farming, the soil will have already become too salty to grow any other crops and more mangrove forest must be cleared to make room for new farms. It is a vicious cycle that I witnessed first-hand during a recent trip to Bangladesh, where poor farmers are being forced off their land to make room for expanding shrimp farms.

Another controversial issue is how farmed shrimp are fed. To produce feed for shrimp, fishermen must go out and catch wild fish, which are then ground up into fishmeal and fish oil. Not only does shrimp farming increase pressure on wild fish stocks, but a recent investigation found that slave labour is rampant in the shrimp fishmeal processing industry in Thailand and South-East Asia.

To keep prices low, shrimp are raised in crowded conditions and diseases spread rapidly. The spread of two diseases -- White Spot Syndrome and Early Mortality Syndrome -- have decimated shrimp farming communities in recent years. To combat this, antibiotic and pesticide use is commonplace.

Farmed shrimp imports into Canada have repeatedly been flagged by food inspectors for having high amounts of anitbiotics and drugs in the shipments they test, such as the antibiotic tetracyclines and nitrofurans, an antimicrobial drug and known carcinogen banned in Canada.

While the Canadian Food Inspection Agency does inspect imported shrimp, the truth is that, according to the CFIA, at best only 5 per cent of imported farmed shrimp shipments are actually being tested for these banned chemicals. In the U.S., less than 2 per cent of shrimp import shipments are tested. If you eat farmed shrimp, it is entirely possible you are consuming harmful and carcinogenic chemicals.

Thankfully, not all shrimp is bad for the environment or your health. In fact, Canada is home to some very sustainable, seasonal shrimp fisheries that catch shrimp using traps instead of dragging nets. There is one fishery for trap-caught shrimp in Chedabucto Bay, Nova Scotia and another for Spot Prawns in B.C. that have both been widely recognized for their sustainability. Because the traps are only set for a few hours, bycatch rates are very low and most species caught unintentionally can be released back to the wild still alive.

In the U.S. some shrimp farms are raising shrimp in closed containment systems that do not require the destruction of mangroves or the use of dangerous chemicals.

Supporting these more sustainable options is a good start but with the vast majority of the global shrimp industry based on destructive harvesting methods, widespread change will take a long time. One simple reason for this is that our demand for cheap shrimp requires cheap harvesting methods, and if we want to eat sustainable and healthy shrimp without the guilt of doing harm to the environment, we should expect to pay a little but more.

In the meantime, if your local grocery store or restaurant can't tell you where your shrimp was from or how it was caught or grown, it's probably best for your health, and the health of the ocean, to just say no thank you.

Alex Mifflin and brother Tyler Mifflin host the award-winning eco-adventure series, The Water Brothers, exploring the world's most important water stories. The third season airs Tuesdays at 7:00 p.m. from April 7 to May 19 on TVO and at Learn more about sustainable shrimp fishing in "The Least Deadliest Catch" the next episode of The Water Brothers airing May 5.