Great Lakes Fishery Commission

Updated 2026-08-20 15:00:27

Lake Huron -> 1.0 Salmonine (Salmon and Trout) -> Lake Trout Abundance

1.2.4. Average catch of wild adult lake trout on spawning grounds greater than or equal to 17 individuals per 305 m of gill net per night

An increase in the abundance of wild adults on spawning grounds was expected to occur 7-12 years after the initiation of stocking if Lake Trout recovery in Lake Huron was keeping pace with restoration objectives.  The target catch-per-effort to achieve the spawner abundance milestone was 17 wild adults (total length greater than 351 mm) per 305 m of gillnet per night. The spawning stock size associated with the target catch rate was found to result in measurable production of wild offspring in Lake Superior (Ebener et al. 1998).

Relative abundance of wild adults on spawning reefs in Ontario waters of Lake Huron, including Georgian Bay and the North Channel, has remained below target since the Ontario Ministry of Natural Resources (OMNR) commenced targeted spawning surveys in 2008 (Figure 1).  To date, OMNR has assessed the Gore Bay population in the northern main basin (2012, 2013, 2021); the Limestone Islands (2008, 2019), Nottawasaga (2017), Owen Sound (2018), and Tobermory (2019) populations in Georgian Bay; and the Point Clark (2016) and west Bruce Peninsula (2022) populations in the North Channel.  Most of the populations surveyed on spawning shoals still consist primarily of hatchery-origin fish, with the exception of the Limestone Islands population in 2019, which suggests that trout populations in Canadian waters are still in the early stages of recovery.  However, it should be noted that the combined catch of wild and hatchery-origin trout in the Nottawasaga population in 2017 (52.9 trout per 305 m gill net) and the Owen Sound population in 2018 (34.7) was above the target catch rate. 

In contrast, mean catch-per-effort of wild adult Lake Trout on spawning reefs in Michigan waters met or exceeded the target catch rate each year of the current reporting period (2018-2022).  Catch rates of wild trout on spawning grounds sampled by the Michigan Department of Natural Resources have exceeded the target rate every year since the surveys began in 1991 (Figure 2), and catch-per-effort of wild adults on offshore reefs has exceeded the target threshold since 2007 (Figure 3).  Recovery of the Lake Trout stock at Drummond Island has lagged other populations in Michigan waters of Lake Huron, but catch-per-effort there in 2019 (17.6 trout per 305 m gill net), which was the most recent survey year, exceeded the target level (Figure 4). Trends in catch rates and natal origin (wild vs. hatchery) in Michigan waters tend to demonstrate the expected stocking-to-recovery trajectory with an increase in hatchery-origin adults after several years of stocking, followed by an increase in wild fish due to successful spawning by the maturing population of hatchery-origin individuals.

Trends in catch of wild adults on spawning grounds in the main basin of Lake Huron suggests that Lake Trout recovery is further along in Michigan waters than in Ontario waters.  Some surveyed reefs in Ontario waters (e.g., West Bruce Peninsula) were not active stocking areas, so interjurisdictional differences in recovery status may be related to spatial variation in stocking effort. 

Figure 1. Catch-per-effort (number caught per 305 m of large mesh gillnet per night) of wild adult Lake Trout (total length > 531 mm) on spawning reefs in Ontario waters Lake Huron. Catches of individual populations were averaged by year and lake basin (main basin, Georgian Bay, North Channel). The horizontal line denotes the target catch-per-effort of 17 fish per 305 m of large mesh gillnet in overnight sets. Note that temporal trends in catch-per-effort (CPE) are potentially confounded with survey location because the same reefs are not always sampled each year (Assessment Survey: Ontario Ministry of Natural Resources large mesh gillnet survey).

Figure 2. Catch-per-effort (number caught per 305 m of large mesh gillnet per night) of wild adult Lake Trout (total length > 531 mm) on spawning reefs sampled by the Michigan Department of Natural Resources in Michigan waters of the main basin. The horizontal line denotes the target catch-per-effort of 17 fish per 305 m of large mesh gillnet in overnight sets (Assessment Survey: Michigan Department of Natural Resources spawning reef gillnetting survey).

Figure 3. Catch-per-effort (number caught per 305 m of large mesh gillnet per night) of wild adult Lake Trout (total length > 531 mm) on the Six Fathom Bank and Yankee Reef mid-lake reef complex. The horizontal line denotes the target catch-per-effort of 17 fish per 305 m of large mesh gillnet in overnight sets (Assessment Survey: United States Fish and Wildlife Service Six Fathom Bank/Yankee reef fall gillnet survey).

Figure 4. Catch-per-effort (number caught per 305 m of large mesh gillnet per night) of wild adult Lake Trout (total length > 531 mm) on spawning reefs at Drummond Island (northern main basin, Lake Huron). The horizontal line denotes the target catch-per-effort of 17 fish per 305 m of large mesh gillnet in overnight sets (Assessment Survey: Sault Tribe Drummond Island Refuge survey).