Asian Carp Invasion: Notes

Five experts, knee-deep in dealing with the controversy that has become “Asian Carp,” presented their research and views on April 6 at the Shedd Aquariums Phelps Auditorium.

In this venue, feet from living examples of the invasive species, the history of the Great Lakes water flows , the ecology, and policy perspectives of plans of action were discussed.

To put it into perspective, Duane Chapman of the U.S. Geological Survey (USGS) makes note that when the media refer to “Asian Carp,” they are actually talking about the Big Head and Silver Carp species.  These are but two types of carp species, out of hundreds, that exist throughout the world.

How did they get here?  And better yet, how did they make it past the electric barrier set up to keep out invasive species?  Professor David Lodge of the University of Notre Dame weighs in on three possible scenarios, those being:

• the electric barrier is not always working properly, it may go down at times allow species to traverse
• juvenile fish are used as bait
• the carp are released by humans into the water system

A new tool used by Chapman to detect these carp, the eDNA test, has already changed ideas about the proximity of the carp to the Chicago Sanitary and Ship Canal.  In short, they are further along than anyone expected.

The tested water samples reveal microscopic bits of Silver carp tissue have been detected as close as Calumet Harbor.  No evidence has been found, yet, of the Big Head.

However, each researcher made note that this is not, solely, an “Asian Carp” issue.  Other species, since recording started in 1850, have come in and made the Great Lakes their new home, the Zebra Mussel is but one example of these.  Each speaker impressed upon the audience that the greater discussion should be shifted away from talk about “Asian Carp” to that of addressing invasive species in general.

The gradual accumulation of these already present invasive species has already begun to change the ecology of the water systems, causing millions of dollars in damage.  Because of the way the canal flows, it is possible for any of more than 180 species to move north or south (into or out of) the canal system.  The Big Head and the Silver carp are in this category, but so are the Spiny Water Flea, the Water Chestnut, and a host of fishborne pathogens and parasites.

QUICK BITS

• “Asian Carp” (Big Head and Silver carp) eat 20% of their body weight per day.  Not the 40% that is being reported
• They are Lake fish (could do really well in Lake Erie – Lake Michigan is larger and colder than what they are used to)
• They eat Plankton
• Fist Silver carp caught in the early 70’s
• First Big Head carp caught in 1982
• Spawn in large (100 km long) turbulent waterways
• No evidence of spawning
• Any problems to the local ecology won’t be felt for 20-25 years
• No numbers, no invasion (large numbers have not yet been detected)
• The effect to area ecology and economy will be unequal  (some areas will be worse than others)
• Failure of Big Head carp in Lake Michigan may be due to propagule pressure (the number and quality of propagating species)