The Lake Ontario Joint Lake Trout Survey is a lake-wide, coldwater gillnet program targeting Lake Trout populations. The survey is conducted by the Ministry of Natural Resources (MNR) in collaboration with U.S. Geological Survey (USGS) and New York State Department of Environmental Conservation (NYSDEC).
The goal of the program is to monitor the composition of the coldwater fish community, and gain a whole-lake perspective on the state of Lake Trout rehabilitation through the implementation of a bi-nationally standardized netting protocol.
Prior to the Joint 2024 Lake Trout Survey, the Canadian waters of Lake Ontario have not been sampled in this way since 2008.
There are 9 fixed-transects in Canadian waters, at which a series of 4 to 5 gillnet sets are made. In years with 5 gillnet sets per transect, the first (shallowest) set is made at the depth where the 12°C isotherm intersects within 2–3 metres off bottom.
The second set is made at the depth where the 10°C isotherm intersects within 2–3 metres off bottom.
In years with only 4 sets per transect, 10°C is the target bottom temperature of the first gillnet set. Subsequent sets are made at 10 metre bottom depth intervals, along the transect. For example, if 10°C is encountered at a bottom depth of 36 metres, then nets will be set at 36, 46, and 56 and 66 metres.
A gillnet set is comprised of a single gang of 9, 15.2 metre monofilament multi-mesh panels of 51, 64, 78, 89, 102, 114, 127, 140 and 152 millimetre mesh.
Data from the Lake Ontario and Bay of Quinte Fish Community Index Gillnetting (LOA_IA24_GL1) Eastern Basin deep sites (EB01-EB06) will be shared with this program to extend its geographic reach.
Update: Due to logistical and technical complications, USGS was unable to sample the Toronto, Bronte and Grimsby transects as planned. No data was collected for these sites in 2024.
