After decades of new species emerging in the Great Lakes, the tides are finally starting to turn.
More than 180 foreign species have invaded the lakes in the past century, and while many continue to pose a threat to the waterways, there doesn’t appear to be any new ones arriving.
“There are a lot of [scientists for multiple agencies] out looking, especially in the Duluth-Superior harbour, that I’m pretty confident if something was established here, they would have found it,” Doug Jensen, aquatic invasive species expert for the Minnesota Sea Grant, told the Duluth News Tribune.
In fact, according to a recent report, a new aquatic invasive species hasn’t been confirmed in the Great Lakes since 2006, and experts are attributing the good news to more than just luck.
Instead, it’s considered evidence that the Coast Guard-enforced program requiring ships to flush their ballast tanks at sea is working.
Large ships often have ballast tanks that can be filled with water or emptied in order to ensure the boat’s stability, or to compensate for reduced cargo and fuel. With water often being taken on board at one port and released at another, it’s not hard to see how non-native species were able to spread into Canadian waterways in the past.
Since the St. Lawrence Seaway opened in 1959, providing oceangoing ships with unrestricted access to the Great Lakes, 54 non-native species have been reported in the waterways. More than half of those are believed to have arrived through ballast water discharge.
Round gobies, bloody red shrimp, and zebra mussels are just a few of the species supposedly introduced this way, and since their arrival, they’ve severely damaged Great Lakes ecosystems.
Invasive species like these are known to reproduce quickly, degrading natural habitats, out-competing native species, and effectively altering food chains. They also have a tremendous economic impact on the areas they inhabit, costing Canada and the U.S. hundreds of millions of dollars each year. That’s because most of these species are difficult, if not impossible, to eradicate once they establish a population. It’s also the reason prevention is considered the best way to manage invasive species.
But it wasn’t until 2006 that the ballast water exchange program, suggested by U.S. regulators more than a decade before, became mandatory in both U.S. and Canadian waters.
The program requires ships fill their ballast tanks while at sea, releasing them before entering the Great Lakes system. The blast of saltwater kills any living organism that thrives in freshwater environments, ensuring that freshwater species from other continents aren’t transported to the Great Lakes.
Craig Middlebrook, deputy administrator of the St. Lawrence Seaway Development Corporation, told the Tribune that “the results have been quite remarkable.”
According to a report recently released by the Great Lakes Ballast Water Working Group, 100 percent of international vessels bound for the Great Lakes Seaway received a ballast water management exam.
“To get to 100 percent inspection rate, that’s something,” Middlebrook said.
But despite the program’s apparent success, it doesn’t address the spread of invasive species already living in the Great Lakes. There are freighters that never leave the lakes, and according to reports, these boats move millions of gallons of ballast water between ports every year, providing an excellent mode of transportation for current invaders.
Invasive species can also be unintentionally spread further into river systems and lakes by attaching to fishing equipment or onto the hulls of recreational boats that haven’t been cleaned properly.
Government bodies are currently looking to everything from dogs to drones to help stop the spread, but they haven’t yet found an effective solution to the problem.
