Zebras and Quaggas in the St. Lawrence

From May, 1996 (Update #27)

The proportion of quagga mussels in the St. Lawrence River has been steadily increasing over the past four years, according to Environment Canada scientists. The proportion of quagga mussels in the overall population of mussels has increased at a rate of two percent per year, and last summer represented six percent of the total number of mussels attached to navigation buoys, according to Yves de Lafontaine, chief of the Aquatic Contaminants Section at the St. Lawrence Centre of Environment Canada. The increase was more pronounced in Lake St. Francis, where quagga mussels now represent a fourth of all mussels sampled in 1995. The St. Lawrence Centre of Environment Canada is operating a program to monitor the distribution and abundance of zebra mussels from Cornwall to Quebec City. Every fall, mussel densities are recorded from more than 250 navigation buoys retrieved from the St. Lawrence River. "Considering that quagga mussels presumably prefer deeper waters," de Lafontaine said, "the measured relative proportion of quagga mussels attached to buoys occupying the first 1.5 meters of surface water may represent a minimal estimate of the relative abundance of quagga mussels for the St. Lawrence River. It is, however, relatively clear that quagga mussels have gradually increased in numbers over the last four years.".

ID: 199605-12.

The Zebra Mussel Update was a 4- to 8-page quarterly national newsletter published by the University of Wisconsin Sea Grant Institute from May 1990 through May 1997. The ZMU documented the spread of the zebra mussel -- an exotic nuisance mussel -- through North America's freshwater environments, especially the Great Lakes, and on efforts to control it.