Connecting people with nature in Ontario's Mississippi Valley

Fish, Fisheries and the Aquatic Environment: Past, Present and Future – a lecture by Dr. John Casselman

Press Release

Mississippi Valley Field Naturalists

November 10, 2008

Submitted by Pauline Donaldson

MVFN to host another presentation by fish and aquatic environment expert John Casselman

Mississippi Valley Field Naturalists’ (MVFN) lecture series From the Ground, Up: Celebrating the Mississippi Valley Field Naturalists’ First 20 Years continues November 20. MVFN welcomes back fish expert John Casselman to talk about fish, fisheries and the aquatic environment. Dr. Casselman has had a remarkable career as an aquatic biologist in the role of Ontario government senior scientist for Lake Ontario fisheries, and has published extensively on fish and fisheries around the world. In recent years he has focused on predicting changes in fish populations and in sharing these insights to promote protection of the aquatic environment and adaptation to environmental change. Casselman is currently an adjunct Professor at Queen’s University, science advisor to the Ontario Federation of Anglers and Hunters, and is the most recent recipient, in 2008, of the prestigious American Fisheries Society Award of Excellence.

In 2007 Casselman took part in the ‘Weathering the Change’ climate change workshops in Almonte. “How will we respond and adapt to take advantage of increasingly valuable fish resources, which can sustain body and soul” asked Casselman. “First, let’s make fisheries and fish an important part of our 100-mile diet!”

In his 2006 MVFN lecture, Casselman explained that subtle changes in water temperature may lead to gradual or even relatively rapid population changes in a particular fish species depending on whether it is a warm-water species such as smallmouth bass, a cool-water one such as walleye or a cold-water species such as lake trout. Using tools of environmental physiology and ecology to examine fish age, growth rate, survival of fry, and the impacts of subtle changes in the aquatic environment, predictions can be made of likely changes in fish populations in a given lake or river. The next step is to transfer this science-based information to groups who may need to adapt. Since his presentation two years ago, Dr. Casselman and members of Mississippi Valley Conservation completed a study for Natural Resources Canada looking at the sensitivity to and impacts of a changing climate. The results give us an in depth look at the past, present and future status of fish populations, with particular focus on the Mississippi River watershed.

In Thursday’s presentation Professor Casselman will guide an exploratory journey with insights and side-trips into familiar and unfamiliar waters and climate change. The presentation takes place 7:30 PM, November 20 at the Almonte United Church Social Hall, 106 Elgin St., Almonte. All are welcome ($5 fee for non-members). For further information, please contact MVFN’s Program Chair Cathy Keddy at 613-257-3089 or visit


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Climate Change, Fish and Fisheries in the Great Lakes Basin

Press Release

Mississippi Valley Field Naturalists

Submitted by Pauline Donaldson, MVFN Public Relations Chair

March 6, 2006

Learn how global weather changes are affecting Ontario fish and fisheries

Extremes in global weather, such as those associated with the Pacific’s El Niño and La Niña, and more gradual change such as global warming, affect fish communities in Ontario. Average water temperatures in local freshwater bodies change and this affects spawning, growth, food resources, predation, and, ultimately, the numbers of fish available for recreational and commercial fisheries. This topic will be discussed Thursday March 16, in a seminar by retired Ontario Ministry of Natural Resources scientist Dr. John Casselman, at the Mississippi Valley Field Naturalists meeting in Almonte. According to Casselman, impacts on fish communities and their habitats depend on whether the fish are a warm-water species such as smallmouth bass, a cool-water species such as Northern pike or walleye, or a cold-water species such as lake trout. He plans to use long-term water temperature data for the Great Lakes Basin and age assessments to explain how populations are impacted by temperature change. For example, some very poor years for smallmouth bass were associated with cold temperatures following the 1991 eruption of Mt. Pinatubo. On the other hand his studies suggest a global warming of only 2°C will increase numbers of these fish six-fold, while greatly decreasing the numbers of cool- and cold-water fish.

Dr. Casselman has decades of research experience throughout Ontario and Canada and is currently Scientist Emeritus at Glenora Fisheries Station, an Adjunct Professor at Queens University, and a lead author for fish and fisheries for a key report on climate change in Canada. Dr. Cassleman is also known internationally for his work on the American eel, whose dramatic decline will also be discussed at Thursdays’ talk. In 2003 he convened a conference which led to a global call for immediate measures to sustain eel stocks, which have been negatively impacted by changes in North Atlantic Ocean currents and the Gulf Stream. Remarkably mysterious, all populations of eels live most of their lives in fresh water but return to the Sargasso Sea to spawn, forming a single genetic population. The larval stage drifts on ocean currents for a year before becoming ‘glass eels’ which move to the coasts where, as adults, they inhabit freshwaters in different parts of the world.

The presentation, “Climate Change, Fish and Fisheries in the Great Lakes Basin”, is 6th in MVFN’s series “Change in our Natural World” and takes place Thursday March 16th at 7:30 pm at the Almonte United Church on Elgin St. Host for the evening will be MVFN member Michel Vermette. All are welcome. A non-member fee of $5 applies or MVFN memberships may be purchased. For further information visit or contact Pauline Donaldson at 256-9399.


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