Fish Communities of Lake Ontario

By: Jennifer Phelan

Natural Resource Management

State University of New York- College of Environmental Science and Forestry

With David Andrews, UFI Research Scientist

Lake Ontario lies on the international border between the United States and Canada, its waters and biota shared and managed by environmental organizations of both countries. The watershed drains land in  Ontario and New York, and even a small portion of Pennsylvania. Of course, a major inflow is the Niagara River in the western portion of Lake Ontario, draining Lake Erie and the final stop on the journey from the upper Great Lakes before the St. Lawrence River and the Atlantic Ocean. The St. Lawrence River was critical to early colonization and remains an important route for shipping and transfer of goods to areas throughout the Great Lakes region and beyond.  This trade route, though economically beneficial, provided an ideal pathway for many invasive species that are present today in Lake Ontario today.  

Lake Ontario boasts a wide range of habitat that supports numerous fish species. Native species of fish present in Lake Ontario include Atlantic salmon (Salmo salar), northern pike (Esox lucius), and largemouth bass (Micropterus dolomieu) to name a few. These fish were well adapted to the Lake Ontario ecosystem prior to human development, and generally maintained a balanced population of healthy sportfish supported by abundant prey species.  Over 100 years ago, a small prey fish species, the alewife (Alosa pseudoharengus), invaded the Great Lakes and provided an additional abundant food source for large predatory fishes sought after by anglers. Alewives became so important to the sustainability of Lake Ontario fisheries that management agencies now track their abundance and adjust stocking rates of coldwater sportfish based on alewife biomass!

Without conservation and preservation management practices, native species struggle to maintain populations, and eventually can become extirpated, or cease to exist in Lake Ontario, with time. Although some nonnative fish species are bad for Lake Ontario fisheries, there are nonnative species that have been introduced to add species richness, aid biotic interactions within the ecosystem, and provide economically valuable services to the area. After European colonization, brown trout, coho salmon, rainbow trout and Chinook salmon were introduced to Lake Ontario and its drainage basin. These species help maintain a balance of the food web dynamics between predator and prey, and are popular sport fish that encourage tourism and economic opportunities.

The fish community in Lake Ontario is impacted by food web relationships, water and habitat quality, water levels in lakes and spawning streams, and human activities including harvesting and stocking . Regulations, including minimum or slot harvest size and limiting the number or species that can be harvested, and active stewardship of the watershed and lake can help to restore populations and their natural habitat. Lake Ontario is an intricate and delicate system that requires these measures to be taken to ensure the future vitality of the fisheries.

References:

• Lake Ontario. (n.d.). Retrieved November 2, 2021, from https://project.geo.msu.edu/geogmich/lakeontario.html

• Lewis, T., Cochran J., Keppner, S. (2018). U.S Fish and Wildlife Service. Early Detection and Monitoring of Non-Native Fishes in Lake Ontario, 2017. Retrieved November 2, 2021, from  2017_Lake_Ontario_EDM_Report.pdf (fws.gov)

• Loppnow, G., Vascotto, K., & Venturelli, P. (2013). Invasive smallmouth bass (Micropterus dolomieu): History, impacts, and control. Management of Biological Invasions, 4(3), 191–206. https://doi.org/10.3391/mbi.2013.4.3.02

• Stewart, T. (n.d.). FISH-COMMUNITY OBJECTIVES FOR LAKE ONTARIO. 24.