Hoping more carp DNA is scarce
One can only hope for failure in the current combined efforts of the U.S. Fish & Wildlife Service, Ohio Department of Natural Resources, and Michigan Department of Natural Resources in their concerted effort to detect the presence of dreaded Asian carp in western Lake Erie.
A year ago, four samples from Sandusky Bay tested positive for bighead carp eDNA, while two samples from north Maumee Bay, in Michigan waters, were positive for silver carp eDNA. The findings indicate the presence of genetic material left behind by the species, such as scales, excrement, or mucous, but not the establishment of Asian carp in Lake Erie, the agencies said. Now, the hunt is on in earnest.
As you read this, surveys are under way to collect water samples for eDNA analysis, followed by electroshocking and netting surveys. The positive eDNA samples, a mere handful from among 417 samples in the two prime western Erie bays in August, 2011, are an indication of how good science has become at detecting the minutest traces of biological material. A generation ago we never would have known.
But what if? What if fish biologists now find that the worthless but ecologically disastrous carp have become established in the lake, thus poisoning the most valuable fishery spawning and nursing grounds on the Great Lakes, if not the world? What then?
Then nothing. There is little that can be done to stop the Asian carp once they are successfully spawning. What – dump rotenone in the lake and kill all the fish? No, the horse will be gone and it will be too late to slam shut the barn door. All we will be able to do in such case is sit back and watch how much damage will be done, just as we have seen with the ecosystem-changing zebra and quagga mussels and round gobies, among other invasive species.
So keep your fingers crossed that the eDNA samples found a year ago are minor fluke – a stray bighead or silver carp here or there, dumped by some cueball in a creek or the bays, but not a breeding population. Or maybe it was just carp debris in some tank-water drained off a fish-truck smuggling Asian carp to market in Toronto. Something like that.
But please not Carpageddon.