March 27, 2018

FTV: The Big Carp Pond – Part 2

    In Part 1, we examined several ways that opening the Great Lakes to an ecological invasion of species began with the earliest attempts to ease transport of goods from the Atlantic Coast inland.  Using Dan Egan’s book The Death and Life of the Great Lakes as a guide, we looked at how opening the door, so to speak, to invasive species like the sea lamprey and the river herring upset the delicate ecological balance of the Great Lakes.  Some of the invasions were intentional (like the introduction of the coho salmon in 1966) but all can be traced back to human activity.

    Building the St. Lawrence Seaway was intended to turn Great Lakes ports into centers of international trade but the fly in the ointment here was the size of the locks built in the system.  The size of the ships being used to transport goods kept outgrowing the Seaway system which prevented the predicted economic boom from taking place. Entry of the sea lamprey and the river herring (also known as the alewife) into the upper Great Lakes was an unforeseen consequence of making a direct connection between the lakes and the Atlantic Ocean.  More recently, other invasive species have hitchhiked into the lakes in the ballast water of the freighters that have carried on a much smaller percentage of commerce than was predicted for the Seaway.

    By 1986, the Seaway stopped collecting tolls for Seaway traffic and by 2002, the Army Corps of Engineers reported that the Seaway could only handle about 2% of the cargo-carrying capacity of the world’s bulk carrier fleet and 5% of the capacity of the world’s container fleet.  Shutting down this meager amount of economic activity would be a small price to pay when compared to the billions of dollars that will be needed to undo the damage that will be done by the current and future crop of Great Lakes invasive species.

    When university students discovered the first specimens of the zebra mussel in Lake St. Clair, it was impossible to tell how far along the invasion was.  A quick review of the mussell’s history in Europe showed that it has rapidly colonized rivers and lakes all across the region via the networks of locks and canals that had interconnected much of Western Europe.  Egan characterized these canals as having “allowed biological trouble to course through the continent like cancer cells in a bloodstream,” much the same way the Seaway had now opened the Great Lakes watershed to invasion.  Zebra mussels don’t walk, fly or swim, but in their larval stage, they can be carried by currents. With their home port 3,000 miles away from their discovery in Lake St. Clair, the only explanation as to how they got there was in the ballast of a ship bound for the upper lakes.  In truth, the adult zebra mussels can drag themselves along at a snail-like 14 inches per hour, but the rapid spread throughout the Great Lakes watershed could only be accomplished with human help. A female’s one million eggs hatch into microscopic viligers that can catch currents for a few weeks.  Within a year, the surviving offspring will repeat the cycle. Even one female mussell transported unknowingly to a new location can have a devastating effect. Viligers transported in a ballast tank brought the first colonies to the Great Lakes and no doubt ship and recreational boat traffic within the lakes is helping them spread.

    Ten months after the discovery of zebra mussels in Lake St. Clair, mussel expert Gerrie Mackie from the University of Guelph spoke at a conference about the spread of the zebras.  Slide after slide of objects covered with clusters of mussels hushed the room. There were so many on some pier photos from Lake Erie that it was impossible to calculate a number per square foot.  When municipal water systems began to find their intake pipes clogged, they discovered the zebras attached with their own form of superglue. Costs to remove or control the mussels were estimated to be in the neighborhood of thousands of dollars per day – for one water plant.  The mussels will actually clear water as they filter feed, but trapping these nutrients can sterilize the water to the detriment of other species.

    When the zebra’s cousin the quagga mussel was discovered in Lake Erie in 1989,  shock waves rippled through the entire ecosystem. Why? Zebra mussels live in relatively shallow water while the quaggas can exist in much deeper water.  Zebras only feed during the warm months but the quaggas feed year round. By 1989, the mussels were being found in all corners of the Great Lakes from Buffalo to Duluth.  That same year, they were found in Chicago at the head of the Chicago Sanitation and Ship Canal that has been flowing from Lake Michigan into the Mississippi River watershed for almost a century.  If the zebra and quagga mussels can spread across the Great Lakes in a matter of decades, how long would it take them to colonize the 40% of North America connected by the Mississippi Rivers and its tributaries?  As we already know, the mussels can’t swim upstream, but they can certainly go with the flow downstream or hitch a ride!

    In 1963, a new type of weed control experiment was begun in Arkansas.  In the search for nontoxic method of controlling unwanted vegetation, the U.S. Department of the Interior’s Fish Farming Experimental Laboratory accepted a shipment of live fish from Malaysia.  These grass carp were supposed to mow down the river clogging seaweed and reduce the amount of noxious poisons that had previously been used to do the same job. Another Arkansas fish farmer had imported three other types of Asian carp (black, bighead, and silver) for the same reason, but he didn’t realize the blacks fed on mollusks and the bighead and silver were plankton eating filter feeders.  He offered them to the state fishery department and they hatched a plan (pun intended) to breed them to use in sewage lagoons. They were difficult to breed but eventually a Taiwanese professor named S.Y.Lin was able to help them get the breeding problem solved. They hoped to use the sale of the fish to help fund rural sewage treatment plant projects, at least until the U.S. Food and Drug Administration advised them that selling fish reared on human sewage was not legal.  Imagine the marketing job it would have taken to sell the product if it was legal!

    The story should have stopped when the projects funding from the U.S. Environmental Protection Agency was halted, but the Arkansas Fishery division made the mother of all environmental assumptions.  They assumed that because the Asian carp were difficult to breed in a hatchery, it would be okay to release them into the wild. The bighead and silver carp spread like wildfire and as they gobbled up the plankton the native fish populations needed to support their food chain, they began to dominate the river systems into which they spread.  An adult bighead carp can reach 100 pounds and consume 20 pounds of plankton per day. The small fish that eat the plankton diminish and this results in the native fish populations who rely on the small plankton eating fish for prey also falter. Silver carp don’t get quite as large as the big heads, but they do get irritated by things like the noise of an outboard motor which will cause them to launch themselves like wingless flying fish.  Some parts of the Illinois River have become dangerous places to enjoy water sports like water skiing or jet skiing for fear of being bombarded by the flying silver carp stirred up by the motor noise. Yes, the same Illinois River system that connects to the Chicago Sanitary and Ship Canal. The carp are moving north and the backdoor isn’t wide open, but it isn’t locked, either.

    An electronic barrier has been built in the canal to the tune of $1.5 million to keep the invasive species already in the Great Lakes from spreading into the Mississippi watershed.  By the time it was activated in 2002, it was probably too late to have prevented the southward migration and it would have no effect at all on the mussel veligers. It has been repurposed (between 2009 and 2014 to the tune of $318 million) to try and halt the northward migration of the Asian carp species, but the jury is still out on how effective it may be. The only sure way to prevent invasive migrations in either direction would be to close the locks on the canal and

re-establish the Chicago River’s original path to the north and the Illinois to the south.  That is right; return the natural flow of the connected watersheds to where they were before the Chicago canal was ever built.  The price tag for this could reach $18 billion dollars, but $12 billion of this cost would actually be needed to rebuild municipal water and sewer systems.  To fishery biologists, this action should be a no brainer, but unfortunately, the decision is now firmly in the hands of the politicians (did I say ‘no brainer’?).  As one biologist put it, “If we don’t do something soon, the Great Lakes will end up to be one big carp pond.”

    It took the Great Lakes thousands of years to develop the geological and biological profiles that were in place when the Europeans arrived.  It took only a few hundred years for humans to mess it up. In spite of our best efforts to play with mother nature, biology may have the last laugh in the end.  Evolution, it seems, is unfolding before our eyes. Remember the mussels? They cleared the lakes of plankton which depleted the shrimp-like plankton eaters that were the preferred food of the whitefish.  They, along with the native lake trout, perch and chubs that had been the backbone of the commercial fisherman since the 1800s, were all but starving. Ken Koyen, the last remaining full-time commercial fisherman on Wisconsin’s Washington Island had to resort to marketing what had previously been considered a trash fish – the burbot.  By 2005, Koyen was ready to get out of the fishing business until he noticed something unusual in his nets: an alewife sticking out of the mouth of a whitefish.

    Why would this be unusual?  Whitefish are not a fish-eaters and they have no teeth.  Not only did Koyen begin to catch whitefish with other fish in their bellies, but also mussels.  The round gobies that are a more recent Great Lakes invaders have the teeth and jaws that allow them to eat their fellow invasive zebra and quagga mussels.  The whitefish then eat the gobies and the nutrients that had been previously locked in the mussel’s shells are released back into the lake food chain. The previously starving whitefish are beginning to rebound.  Before Koyen observed this change in the whitefish diet, he had noticed he was catching whitefish whose bellies were full of ground mussel shell. The mussel eating whitefish have developed a rigid muscle line on their belly that now gives them the ability to grind the mussels into digestible paste.   Not only are the whitefish populations thriving, they are expanding their range into lake tributaries and their numbers in the open lake are giving recreational fisherman a new sport species.

    There is certainly enough evidence in hand to tell us that we have mismanaged the Great Lakes and will continue to do so unless we mend our ways.  One only need to look up the former Aral Sea to get a glimpse of how much damage humans can do in a short period of time. We owe it to our grandchildren to take the steps needed now to insure they won’t be telling their grandchildren about the demise of the lakes formerly bestowed with the title ‘Great’.

Top Piece Video:  Nitty Gritty Dirt Band does their fishing song with guest Bernie Leadon – from 1987