Studying Lake Trout Movements in Peace Reach

Project Year: 2016-2017

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Williston Reservoir

Project Lead

Diversified Environmental Services


Peace Region


Project Type

Research & Information Acquisition

FWCP Contribution


Action Plan Alignment

Reservoirs Action Plan

Project ID


Peace Reach Lake Trout Movements

Williston Reservoir has seen a dramatic increase in Lake Trout abundance in the past decade, however, no information is available on the movements, life history, and reproductive behaviour of these fish.

This project involves implanting 40 acoustic transmitter tags in adult Lake Trout within the Peace Reach of Williston Reservoir, and the subsequent monitoring of fish movements using an array of 28 acoustic hydrophone receiver stations, already deployed and maintained by a fisheries research team from Carleton University. Fish movement data downloaded from hydrophone receiver stations in Year One will be used to guide more detailed tracking of tagged fish in Year Two, with the objective of identifying seasonal movement patterns, with specific focus on fall spawning habitat selection.

Final Report: Executive Summary

The formation of the Williston Reservoir resulted in large-scale habitat changes in the upper Peace watershed due to a shift from a riverine to reservoir environment. In response, changes in the composition of the fish community occurred and some species, such as kokanee and lake trout, have increased in abundance. The expansion of lake trout is generally regarded as a potential threat to native bull trout. A lack of life history information with respect to the status, population trend, and reproductive cycle of lake trout in Williston Reservoir, limits the understanding of interactions between the two char species and future implementation of appropriate management and conservation measures. Research actions directed towards understanding these issues are specifically identified by the Peace Basin Reservoir Action Plan (Action 1a-1, FWCP 2014).

In 2015, a fisheries research team from Carleton University deployed an array of 27 fixed acoustic hydrophone receiver stations along the Peace Reach to monitor bull trout movements as part of an investigation of entrainment through the WAC Bennett Dam. Through discussions between Diversified Environmental Services (DES) and the Carleton team, the data logging capability of the acoustic receiver array has been made available to monitor the movements of additional fish species within the Peace Reach.

In 2016, DES completed Year 1 of a multi-year FWCP study aimed at identifying seasonal movements and potential spawning locations of lake trout in Williston Reservoir. In May/June 2016, 40 mature adult lake trout were captured by angling and implanted with acoustic transmitters compatible with the Carleton acoustic receiver array. An additional 26 lake trout were captured by angling and sampled for additional biometric data. The mean weight of captured lake trout was 5.4 kg (range 0.82-11.3) and mean age was 16 years (range 8-28).

Due to the anchoring configuration of the fixed station hydrophone receivers and annual drawdown patterns, data stored onboard the fixed hydrophone array can only be accessed at minimum reservoir elevation in the spring of each year. As a result, logged detection data for implanted lake trout will not be available until May 2017. Once analyzed, this movement data will be used to guide further investigations of seasonal movement and spawning behaviour in Years 2 and 3 of the project.

Preliminary boat-based tracking was conducted during the spawning period in September/October 2016 throughout the eastern half of the Peace Reach, including the vicinity of 4 shoal features where significant aggregations of large lake trout were recorded during sampling activities in June and July. No transmitter-implanted lake trout were detected. During limited mobile monitoring by snowmobile in March 2017, seven implanted lake trout were located on 2 of the identified shoal features, suggesting that implanted fish had undertaken a fall pre-spawn movement beyond the range of mobile monitoring and that a proportion had returned by March. It is anticipated that analysis of the downloaded acoustic receiver array data in May 2017 will provide insight into this apparent seasonal movement.

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