Archive for August, 2011

The Door Opens Both Ways

August 8, 2011

Photo: U.S. Fish and Wildlife Service

As if Asian carp weren’t enough of a threat, the Detroit Free Press on Sunday  reported on a new potential invader that might attack the Great Lakes through the Chicago canal system: the snakehead fish, also known as the “Frankenfish.”

If you thought Asian carp were bad, check out this monster:

  • The snakehead uses its large jaw and big teeth to eat other fish – not just algae and microorganisms like the filter-feeding Asian carp.
  • Like the invasive carp, the snakehead breeds like a mosquito and eats like a hog. It lays thousands of eggs in multiple breeding seasons and guards its nests to protect its young. And although not quite as large as the Asian carp (adults are 3 feet in length), the snakehead also is a voracious eater.
  • The snakehead’s big claim to fame, however, is that IT CAN MOVE OVER LAND, from stream to stream! Like a snake, it wiggles along in ditches and can survive several days outside the water. It breathes air! Which means that once it establishes a breeding population, it’s very hard to contain.

The snakehead hasn’t been found in the Mississippi River…yet. But because it has established breeding populations at least one stream tributary to the Mississippi, fish biologists think it will soon reach the Big Muddy. Once there, of course, it’s only  a matter of time until they reach the Chicago canals and then Lake Michigan – unless a permanent barrier is erected first.

So the Chicago canals once again may be the conduit through which Great Lakes destruction can pass. But here’s the irony: the Chicago canal system is a door that swings both ways. The canals may soon bring species that wreak havoc on the Great Lakes; but the canals already have brought incalculable damage to the Mississippi River basin. Those canals have transmitted our very own scourge, zebra mussels, to most of the rest of the country.

You can watch that door swing right here. NWF’s Trilby Becker has worked with USGS to produce two motion maps. In one you can see the spread of Asian carp up the Mississippi , through the Chicago canals, right to the edge of the Great Lakes.  In the other, you’ll see zebra mussels start in the Great Lakes and move through the Chicago canals, down the Mississippi, to most of the rest of the country. And you can read Trilby’s blog about it.

These maps show visually what scientists found in a recent study, Aquatic Invasive Species Risk Assessment for the Chicago Sanitary and Ship Canal (Jerde, Barnes, McNulty, Mahon, Chadderton, and Lodge, 2010): that the Chicago canals pose an equally great risk to the Mississippi River and its tributaries (like the Missouri and Ohio Rivers) as they do to the Great Lakes. The study concluded that 17 species in the Mississippi River pose a high risk to the Great Lakes, and 10 species in the Great Lakes pose an equally high risk to the Mississippi. And that doesn’t count the zebra mussels that have already infested the Mississippi and its tributaries.

So putting an effective, permanent barrier to stop invasives from moving through the Chicago canals is imperative for the Great Lakes. It’s not just Asian carp we need to worry about; there are other monsters like the snakehead out there waiting to devastate our lakes. Electric fences and half measure won’t cut it.

But we also know that this isn’t just a Great Lakes problem. What starts in the Great Lakes won’t stay there, at least without that permanent barrier. As the motion maps make all too clear, the rest of the country needs protection from the Great Lakes, too.

Fixing the Chicago canals is a national problem, and we need a national solution, fast.


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