Thursday, December 9, 2010

Some Thoughts on Asian Carp

Okay, before I go off on this, I want to first reiterate that these are my own views and NOT those of my employer.  And with that, I want to weigh in on some of the reporting that has been flying around regarding the Asian carp issue. 

Today the Chicago Tribute published an editorial that began: “It's official: The dreaded Asian carp aren't an imminent threat to the Great Lakes, despite the hallucinatory anxieties of Michigan, Minnesota, Ohio, Wisconsin and Pennsylvania.”  The editorial goes on to state that “some biologists think the worries are overstated, and not just the part about getting whacked by a flying fish. It's possible the carp are happy where they are. The lake waters might be too cold and too still for them to spawn successfully. There might not be enough plankton to keep them fed.”

It is true that a handful of biologists around the region have piped up saying they are skeptical that conditions in the Great Lakes are suitable for Asian carp (i.e., silver and bighead carp).  But the vast majority of regional aquatic biologists are either expressing concern or uncertainty, or more frequently both.  We have learned enough about invasion ecology to know how industrious invasive species can be in expanding their range and how severe the costs are (e.g., nearly 900 trillion quagga mussels in Lake Michigan). 

It is highly likely true that the Great Lakes waters are “too still for them to spawn successfully.”  But the Great Lakes have rivers that flow into them and some of these likely have suitable spawning habitat.  It is also true that the open waters of Lake Michigan or Lake Huron likely do not currently have sufficient plankton densities to sustain Asian carp.  But these lakes have productive bays (e.g., Green Bay, Saginaw Bay, Western Lake Erie) and coastal wetlands that do have very high plankton densities.  These areas likely have suitable feeding habitat for Asian carp.  Incidentally, these highly productive bays and wetlands usually occur at the mouth of the rivers that are most likely to provide suitable spawning habitat.

I’m not going to weigh in on what needs to be done to prevent their entry into the lake.  I only want to make it clear that the science is still not out on whether these species will be able to establish in the Great Lakes.  And if they do, it is clear that the costs could be substantial (i.e. economic costs could easily be measured in millions of dollars annually, not to mention the ecological costs).  There is currently a coordinated study, with Canadian and U.S. partners, evaluating the invasion potential of silver and bighead carp.  This effort will be the best available assessment of their invasion potential in the Great Lakes.  The media needs to hold off making knee-jerk biological assertions until the science is truly out on this.