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Use of pop-off data storage tags to reveal fine-scale depth and temperature preferences of Lake Ontario salmon and trout

Video by Danny Favato (Moby Nick Fishing Charters, Mississauga, ON).
Project Background & Significance 

Lake Ontario contains a diverse community of salmon and trout (salmonids). With six such species overlapping in their distributions, there is potential for competition among species for food resources. Non-native Chinook salmon (Oncorhynchus tshawytscha) and rainbow trout (Oncorhynchus mykiss) have come to provide highly valuable recreational fisheries since their introduction to Lake Ontario in the 1960s. However, these non-native Pacific salmonids are sometimes perceived to be in conflict with efforts to restore native salmon and trout – specifically Lake Trout (Salvelinus namaycush) and Atlantic salmon (Salmo salar), owing to concerns about competition for food and suitable habitat. We only have a coarse understanding of the movements and habitat preferences of these species in Lake Ontario, owing to the inherent difficulty in studying fish movements in such a large system.


Pop-off data storage tags (pDSTs) first became available for use in freshwater in 2013 and provide a useful tool for collecting high-resolution data on depth and temperature preferences of fish in the wild. These tags (see photo), manufactured by Cefas Technology Ltd., are designed such that they can be externally attached to aquatic animals, record variables of interest at regular intervals, and subsequently pop-off the animal and float to the surface after a pre-programmed period of time. In Lake Ontario, we have now released 118 fish across three years (2014-2016) with externally-attached pDSTs. The tags are programmed to record the fish’s depth and temperature every 70s and to pop off the fish and float to the surface after approximately one year of data collection and storage. The tags do not transmit any information (i.e., they are data loggers, not transmitters), meaning that we rely on tags being found by members of the public and returned to us by mail so that we can download data from the tags for analyses. The bright orange colour of the tags increases the likelihood of them being found when floating on the surface or after having washed up on beaches. In addition to a $100 reward, interested citizens who find and return tags have also been sent ‘report cards’ with an example of the data from the tag they returned (see figures at the bottom of this page).

We anticipate that the novel data generated by this project will result in multiple scientific papers and presentations, and help advance fundamental areas of ecology while also addressing knowledge gaps in fisheries management. For example, while the primary goal of the project is to define the temperature and depth preferences of the different salmon and trout species in Lake Ontario, the data from the tags will also reveal fine-scale behavioural patterns, including diel (time of day) and seasonal patterns in behaviour, and the behavioural responses of fish to extreme weather events. Particularly novel will be information of the behaviour and temperature experiences of these fish during winter. The data generated by the tags will also be relevant to making predictions about the responses of these fish to climate change, and reveal what role behavioural flexibility might have in the capacity of these fish to cope with warmer and more variable conditions. Two figures at the bottom of this page provide an example of some data for a five-day period in October 2014 for a Chinook salmon (Figure 1) and for a lake trout (Figure 2).


Throughout the project we are working with users of the resource (recreational charter operators and anglers) and have reached out to the broader fishing community through clubs and forums (e.g. Lake Ontario Salmon & Trout Symposium). Fisheries management agencies are also directly involved in all aspects of the research, including the Ontario Ministry of Natural Resources and Forestry (OMNRF) and New York State Department of Environmental Conservation (NYSDEC). OMNRF research scientist Tim Johnson and his team at the Glenora Fisheries Station have been particularly integral in helping to fund and carry out the project. The project will benefit fisheries management in Lake Ontario by providing a refined definition of species-specific habitat requirements (temperature and depth), information that can be used to inform stock assessment programs and bioenergetics models.


Core project team


Aaron Fisk (GLIER, U Windsor)

Graham Raby (GLIER, U Windsor)

Steven Kessel (GLIER, U Windsor, and Michigan State University)

Tim Johnson (OMNRF)

Tom Stewart (OMNRF, retired)

Jana Lantry (NYSDEC)





Great Lakes Fishery Commission

Ontario’s Great Lakes Protection Fund

Ontario Ministry of Natural Resources and Forestry

Canada Research Chairs Program



Assistance with fish capture and tagging


Nick Foxcroft, Moby Nick Fishing Charters (Mississauga, Ontario)

Ernie Lantiegne, Fish Doctor Charters (Oswego, New York)

Figure 1: Approximately five days of depth (blue line, left-axis) and temperature (red line, right axis) data (Oct. 10-14, 2014) from a returned tag that had been attached to a Chinook salmon earlier in 2014. The shaded grey areas represent night time.
Figure 2: Approximately five days of depth (blue line, left-axis) and temperature (red line, right axis) data (Oct. 10-14, 2014) from a returned tag that had been attached to a lake trout earlier in 2014. The shaded grey areas represent night time.

Numbers so far (updated 2017-05-12)


Note: 26 tags remain scheduled to pop-off fish in July 2017.


Number of tags released (total = 118):


Lake Trout = 50

Chinook salmon = 31

Atlantic salmon = 21

Rainbow trout = 11

Brown trout = 5



Number of tags found and returned (total = 38):


Lake Trout = 12

Chinook salmon = 10

Atlantic salmon = 10

Rainbow trout = 4

Brown trout = 2

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