The Great Lakes and inland waterways are receiving unwanted, invasive species due to inadequate regulation of the bait fish trade and carelessness on the part of anglers, according to a scientific paper released Thursday.
Researchers from Central Michigan University and the University of Notre Dame said they tested water samples from tanks containing small fish for sale as bait at more than 500 shops across the eight states that border the Great Lakes and found that 27 tested positive for the invasive species’ DNA. Positive hits for silver carp, one of the Asian varieties threatening to reach the Great Lakes, were recorded positive in three water samples from shops along the Lake Erie shore in Ohio.
The team also found genetic material from round goby, tubenose goby and Eurasian rudd, which are already in the Great Lakes although authorities are hoping to prevent them from reaching inland lakes and other waters. They also detected traces of goldfish, which are classified as an invasive foreign species despite being widely sold at pet stores across the country.
“While overall only a small percentage of bait shops had evidence of invasive species, it is nevertheless alarming that at least some invaders are being spread by anglers, the very group of people that value the Great Lakes fishery the most,” said Andrew Mahon, a co-author of the paper and a molecular ecologist at Central Michigan’s Institute for Great Lakes Research. The report was being published in the journal Conservation Biology.
Many states urge anglers to not dump their unused bait into the water but not everyone abides by this, Notre Dame scientists Christopher Jerde said. In fact, a study in Canada found that over 30 percent of anglers were releasing unwanted minnows into waterways rather than disposing them in trash cans or freezing them for future use.
This study is being described as the first systematic effort to document the presence of invasive species in bait supplies using the tool known as “environmental DNA,” in which water samples are examined in a laboratory for signs of genetic fingerprints from certain fish.