Monday, November 10, 2014

To Keep Invasive Asian Carp from the Great Lakes, Carp Catchers Get Creative

*Guest post by Noemie De Vuyst -one of several posts selected from the graduate EES3001 Scientific Literacy course at University of Toronto-Scarborough.

Some say fishing is a peaceful pursuit. Not so if you're one of the self-dubbed Carp-Hunters, a pair of Illinois fishing guides whose carp-catching antics have turned them into YouTube celebrities. Over the last three years, videos of their over-the-top methods have racked up hundreds of thousands of views.

They've netted carp while on water-skis, and speared them with samurai swords and costume Wolverine claws. In Illinois' rivers, the Asian carp are so abundant they practically jump into the outstretched nets themselves. In an ecosystem where the invasive species has largely displaced native fish, the Carp-Hunters’ new hobby has a higher purpose; “We care greatly about preserving out natural ecosystem”, their video’s intro reads. “Since we can’t bass fish anymore we have taken on this burden.”

Silver Carp in the Illinois River, 2009. Nerissa Michaels/Illinois River Biological Station, via Detroit Free Press. 

Kooky as their methods may be, the Carp-Hunters have something in common with government agencies on either side of the Great Lakes; they're both battling the highly invasive Asian carp.
Though the U.S. and Canadian officials may not be going after the invaders with the same flair – not everybody gets to name their fishing boat the “Carpocalypse” - they've been labouring to keep the fish out of the Great Lakes since escapees from fish farms were discovered in the 1990's. With their enormous appetites and extraordinary ability to reproduce at speed, Asian carp would be disastrous to ecosystems and economies if they ever reached the Great Lakes.

First brought to North America in the 1970's, Asian carp already dominate some US waterways. The town of Havana, Illinois, just 85km downstream of Carp-Hunters fishing grounds, is thought to have one of the highest abundances of Asian carp on Earth. Here, the carp make up 60% of the fish community.

The uphill battle to keep carp from the Great Lakes has popped up in the news recently. In early October, the routine testing of 200 sites found a single sample of silver carp environmental DNA (or eDNA) in the Kalamazoo River, a tributary to Lake Michigan.

What does it mean that this one sample tested positive? The presence of eDNA shows only that silver carp material was present at the site. What it can't tell us is whether the carp was alive, or how many fish there might have been. In fact, the presence of eDNA doesn't tell us that a silver carp was present at the site at all; it's possible that scales or tiny amounts of mucous were transported by boats or fishing equipment, or even in bird droppings. With no silver carp sightings in the Kalamazoo, it seems likely the positive result comes from one of these explanations.

Despite the low likelihood that silver carp had really spread to the Great Lakes, news of the positive eDNA result was quickly picked by many local news outlets. Within days, the US Fish and Wildlife Service sped through the collection and testing of 200 more samples, and appealed to anglers to report any carp sightings.

Why such a quick response for a finding with such high uncertainty? If Asian carp were to spread to the Great Lakes, it's feared they take over aquatic ecosystems and cause the fishing and angling industries millions of dollars of loss. Silver carp are especially worrisome, since they have a taste for the same microorganisms and algae that many native species rely on.

By late October, the results of Michigan's second batch of eDNA testing were announced; all samples were negative. For now, it seems the silver carp have crept no closer to the Great Lakes watershed. Canada and the US continue to monitor their waterways closely and to put in new measures to prevent the spread of the fish. This past July, Fisheries and Oceans Canada opened a new Asian Carp Science Lab. In a political climate that has squeezed environmental sciences from all sides, the funding of a new facility highlights the carps' immense potential to cause damage.

So even with their home-built contraptions, it looks like Illinois’ Carp-Catchers are doing their bit for the Great Lakes.

For more information on eDNA sampling at the Michigan Department of Natural Resources:,4570,7-153--340230--rss,00.html

For details on the new Asian Carp Lab at Fisheries and Oceans Canada:

And to see those Carp-Hunters do their thing:

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