WHAT ABOUT THOSE WHITEFISH?
Review of Dan Egan, The Death and Life of the Great Lakes. W.W. Norton: New York, 2017
I don’t know about you, but I have always considered evolution a long, drawn-out process, requiring thousands of years of mutations for genes to adapt.
That was before I got to thinking about recent developments among our Whitefish.
The Great Lakes, chockablock with fresh water fish like Lake Trout, Perch, Whitefish, Walleye and Chub, were landlocked for millennia. Few adaptions were needed in such static conditions. until the St. Lawrence Seaway and its associated locks opened pathways for creatures like the Sea Lamprey, Alewife, Quagga and Zebra Mussels to invade us.
And we all know what happened then.
Dan Egan’s The Death and Life of the Great Lakes (which is also a compellingly readable history of sportfishing) accounts for the invasions and die-offs that have plagued our fisheries since the 1950s. First, the dread Sea Lamprey attached itself to the bellies of Lake Trout and Whitefish to suck their blood dry. They were no sooner extirpated by a scientifically produced toxin than the Alewives, their natural predators having been decimated by the lamprey, multiplied exponentially. However, overpopulation, predation from the newly introduced Chinook and Coho Salmon, and kidneys inefficient at processing fresh water cut Alewife numbers significantly.
Quagga and Zebra Mussels, flushed into lake waters with ship ballast, went to work on the surviving Alewives’ plankton supply, that also happened to feed the little shrimp-like critters Whitefish need to survive.
Fortunately, there was an ugly little invasive bottom feeder called a Gobie, whose round mouth is ringed with razor sharp teeth to crack mussel shells and get at the flesh inside.
Which brings me back to our Whitefish. Almost overnight, they suddenly adapted to eat not only the invasive mussels but the sharp-toothed Gobie. Scientists were surprised to find “a paste of crushed mussel shell” in Whitefish excrement, causing them obvious pain from a kind of fish hemorrhoids.
“But then nature stepped in,” Egan explains; they developed a “stiff ridge on their bellies” to help digest the tough shells. Not only that, they began to eat the Gobies, sharp teeth and all, creating a whole new food chain.
A traditional Great Lakes Fisherman named Ken Koren, who was one of the first to report these sudden developments, said that he felt like he was “watching evolution at work.”
If evolution works that fast, can other plants and creatures adapt fast enough to maintain abundance despite the ravages of climate change?
The problem is humans. Or, as Pogo puts it, “we have met the enemy, and he is us.”
Egan quotes a fishermen named Hendrickson who insists he is “’absolutely’ convinced the species is evolving before his eyes.
‘What we’re seeing with the whitefish, well, they might be the most adaptable fish in nature…..They’re more adaptable than some people I know.'”