Lake trout, smallmouth share space in winter: study

by Barney Moorhouse | June 3, 2020
winter fish behaviour scene

New research tracking tagged fish has confirmed that lake trout and smallmouth bass co-exist during portions of the winter.

University of Toronto-Mississauga Assistant Professor of Biology Bailey McMeans has been studying freshwater fish under the ice in partnership with the Harkness Laboratory of Fisheries Research, including the winter movement and interactions of both species on Lake of Two Rivers in Algonquin Provincial Park. 

Her research paper, co-authored with PhD student Timothy Fernandes, revealed that fish behaviour under the ice is radically different than that exhibited during open-water seasons.

Little science previously

Previously, researchers had little scientific data on winter movement and their work was the first to track both smallmouth bass and lake trout in the same water system. By using acoustic receivers placed on the lake bed, the researchers determined where the species lived throughout the winter. Tags attached to study fish would “ping” every few seconds, providing data that helped determine location, depth, and movement about the lake.

Over the past two years, the researchers learned that when the lake temperature hovers between 0 ̊C and 4 ̊C lake trout move from their deep-water haunts into the shallows where their distribution overlaps with smallmouth bass.

No serious competition

The study also confirmed that while the lake trout are actively feeding, the bass are in a state of semi-dormancy, which indicates the two species are not seriously competing for food in winter. 

“One of the really interesting things about this paper is that it highlighted that with changing winter lengths we might expect to see changes in species’ coexistence. As winter get shorter, bass will be dominant for more of the year and may start excluding lake trout in lakes where they coexist,” said Fernandes. “The exception is probably in lakes that have offshore forage.” 

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  1. Wil Wegman wrote: Great article and wonderful research. Shows how important it is to continue work like this because only good science will dispel previously held biases and beliefs. So many of Ontario's lake's have 'offshore forage' so lots of exceptions for smallmouth bass and lake trout to co-exist.
  2. Gary Lee wrote: Great Article!