Zebra mussel caught hitching ride

by Matthew Robbins | June 1, 2023
zebra mussel

One of Canada’s most notorious invasive species may have just found a new way to get around: on fish. 

During a recent fisheries assessment study on Lake Témiscouata, in southern Quebec, researchers Anthony Ricciardi of McGill University and Jaclyn M. Hill of Fisheries and Oceans Canada discovered a small zebra mussel attached to the side of a living lake chub (a common member of the minnow family). This finding is the first recorded observation of this behavior by any adult freshwater bivalve in the wild. The discovery could have significant implications for aquatic conservation. 

Zebra mussels are one of the most devastating and effective aquatic invasive species in North America, due to their direct impacts and ability to spread.

Until now, however, zebra mussels were not known to use vertebrates as a means of dispersal, though some other mussels do. In their paper, Passive transport of a zebra mussel attached to a freshwater fish: A novel Dreissena dispersal mechanism? the authors express concern over the implications of this behaviour. Such as the potential to allow invasive mussels to move upstream.  

Beyond what might be considered “natural dispersal”, the authors also point out potential implications for the issue of bait bucket dumping. Although illegal to dump the contents of a bait bucket into any water in Ontario (or within 30 meters of it), studies have shown this behavior still occurs within the angling community. Now that live fish are a potential vector for the spread of zebra mussels, the already harmful practice of bait-dumping has even more potential for ecological destruction. 

Ultimately, as the authors point out, the significance of this discovery cannot yet be precisely understood. Since it was an isolated incident, but the potential for serious consequences is very real.

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