You can view a videotaped recording of this meeting HERE.
Lake Huron and Georgian Bay, is the fourth largest lake in the world, and is and an international one at that, is one of the world’s most complex bodies of water with a bathymetry – or topography – quite different from other lakes. Jason reviewed the transformations of the lake over the last 100 years to explain some of the changes in the lake’s ecology, including its food web and the approaches taken to preserve the lake’s native fish species in the face of overwhelming challenges.
In the early 1900s, Lake Huron supported strong commercial fisheries in both Canada and the U.S. However, theis level of fishing was not sustainable and, harvests declined and mademaking native fish more vulnerable to invasive species. In the 1940s, Lake Huron’s ecology faced a strong challenge from thefollowing the invasion of the non-native sea lamprey and the alewife that were introduced- through the Welland Canal from the Atlantic Ocean. Over the next twenty years, lake trout, whitefish and lake herring cicsco populations were devastated as a result of lamprey-induced mortality while populations of alewife and smelt flourished without predators and competition from other fish. But the smelt population flourished since it was not prey to either.
In the 1960s, non-native Chinook and coho salmon were introduced to control smelt and alewife populations and to create a new sport fishery. This approach recognized that diversity among fish stocks would be important to the diversity of the fish community as a whole and to achieve this there would need to be a balance throughout Lake Huron between predator and prey fish. With the introduction of new predators,Consequently, alewife numbers decreased while, and numbers of native species increased – like sculpin, burbot and various types of trout.
By the 1980s, other invasive species such as- zebra and quagga mussels - had arrived, brought in by cargo ships; they spread throughout the Great Lakes and inland waterways. These mussels are filter feeders, consuming the plankton that feed small fish from the water column and concentrating nutrients at the bottom on the lake. As a result of their introduction, Lake Huron became clearer. However, they also caused a reduction in plankton though the water column that feed small fish causing ripples throughout the food chain with aincluding a startling decrease in forage fish. The overall biomass of the fish population decreased over the next twenty years, and populations of predatory fish such a salmon rapidly declined. Jason’s charts illustrated the rise in density of mussels in Lake Huron in the early 2000s.
As anglers know, the salmon population did have declined but other many native fish species populations have grown. Without alewifes, walleye and lake trout have been able to flourish as have emerald shiners, bloaters and smallmouth bass. Jason finished on an upbeat note: native fish species, including sturgeon, grow and thrive showing that the Lake Huron ecology continues to evolve.
Copyright (c) Bruce Peninsula Environment Group, 2018