Canadian Asian Carp Study Ups the Ante: Fewer Than 10 Pairs of Carp May Be Enough to Overrun the Great Lakes
Posted July 12, 2012
Today the Canadian Department of Fisheries and Oceans released a long-awaited risk assessment of the likelihood of Asian carp surviving and spreading in the Great Lakes should they successfully infiltrate Lake Michigan through the Chicago Area Waterway System (CAWS). Much that was released today simply reinforced what we have known for a long time: there is a serious, imminent threat that Asian carp will invade the Great Lakes through the CAWS and spread throughout the system, threatening the vitality of native fish species (and the ecosystem itself) as they spread.
But there is one key finding that is new in today’s report: with a population of 10 females and 10 males or fewer there may be as big as a 50% chance of a breeding Asian carp population establishing. Those are very low numbers, which stand in stark contrast to federal officials’ past estimates that a population of several hundred carp was probably need for there to be a significant risk.
What the Canadian study emphasizes is that even small number of Asian carp getting into Lake Michigan may put the Great Lakes at risk. This is why the latest positive environmental DNA (eDNA) results for silver carp within 6 miles of Lake Michigan are significant: if those tests are indicators of live fish being present that close to the Lake, that should cause serious alarm that current efforts to stop the carp need to be accelerated and strengthened.
Unfortunately, federal officials have continued to downplay the eDNA results, suggesting that because we can’t say with certainty that there are live Asian carp present in the CAWS that we should assume the negative: that current efforts are working fine and buying time to study long-term solutions.
This is false confidence that borders on hubris. As John Rogner of the Illinois DNR pointed out in yesterday’s public meeting in Chicago, trying to catch an Asian carp in an area where they are present only in small numbers is like trying to catch a needle in a haystack. There is consensus among scientists who know the Asian carp’s behavior well that it is very difficult to catch using conventional methods when present only in small numbers. We can’t afford to rely on the Feds’ inability to catch a live fish as a reason to believe that this threat is under control.
Today’s Canadian study reinforces this. Can we really say with certainty that 10 females and 10 males won’t be able to slip into Lake Michigan, given the repeated positive eDNA results we’ve seen and the well-documented weaknesses in the Army Corps’ electrical barrier? No, we can’t, and anyone who says otherwise is not telling the truth. And if that happens, then there may be a 50% chance that a thriving population takes off?
I’m not a betting man, but I don’t like those odds.
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