Updated 2024-11-22 15:05:40
Lake Superior -> 7.0 Brook Trout -> Brook Trout Catch Rates
Reporting Interval
2017 - 2021
Area
Lakewide
Meeting Target?
Does Not Meet
Indicator Trend
No trend
Confidence?
Low
7.1.2. Wild brook trout catch rates in shoreline assessment surveys is increasing
The number of agencies implementing the Coaster Shoreline Survey increased throughout the 5-year reporting interval. Twenty independent shoreline locations were surveyed across all jurisdictions as agencies explored locations and identified shoreline habitats to survey. There was inconsistency among locations sampled, variation in the number of locations sampled per year (n=1-10), and variation in the number of shoreline kilometers among locations sampled from year to year. Additionally, only one shoreline location lakewide (Grand Portage) was sampled in all years due to 2020 pandemic related operational constraints. As a result of these factors confidence in the indicator is currently low. In all years, the lakewide catch rate was considered low (Lake Superior Brook Trout Working Group) (Figure 1). No shoreline surveys were conducted in MI or ON in 2020 or 2021. Figure 2 shows the long-term data set for Tobin Harbor, Isle Royale, Michigan, as an example of what is desired for selected shoreline locations lakewide, with catch rates at or above 6 wild brook trout per km of electrofishing. The lack of survey effort in MI and ON likely contribute to the slight decline in brook trout relative abundance indices during the reporting interval. Improved consistency of agency effort and locations surveyed is needed to improve confidence in this FCO indicator. Shoreline habitats east of Nipigon Bay, ON and Marquette, MI are currently underrepresented in the lakewide effort.
Figure 1. Wild brook trout shoreline electrofishing catch rates in Lake Superior, 2015-2021.
Figure 2. Wild brook trout shoreline electrofishing catch rates at Tobin Harbor, Isle Royale, MI, 2004-2019.
Methodology
Agencies identified areas of Lake Superior shoreline presumed suitable habitat for coaster brook trout. In general, these are habitats where coasters were historically reported or where agency assessments and/or anglers currently encounter coaster brook trout. Shoreline habitat is sectioned into one-kilometer segments and brook trout catch and biological data are reported for fish captured in each segment from electrofishing surveys. Agencies consider catch rates to be low at 0-2 coasters/km, moderate at 2.1-6.0/km, and high at >6.0/km. References provided describe night-time coaster habitat utilization and shoreline electrofishing procedures. For additional information on survey design please see the LSTC Coaster Survey Protocol.
Other Resources
Mucha, J.M., Mackereth, R.W. 2008. Habitat use and movement patterns of brook trout in Nipigon Bay, Lake Superior. Trans. Am. Fish. Soc. 137:1203–1212, 2008.
Boone, E.C., Quinlan, H.R. 2019. Occurrence of Salmincola sp. on brook charr Salvelinus fontinalis in Lake Superior. Hydrobiologia: https://doi.org/10.1007/s10750-018-3871-x..123456789().,-volV()0123456789().,-volV).
Boone, E.C., Brouder, M.J., Quinlan, H.R. 2021. Status and movement of adfluvial brook trout Salvelinus fontinalis at Isle Royale, Michigan, Lake Superior. J. of Great Lakes Res. 47:1804-1813.
Contributing Author(s)
- Lake Superior Technical Committee -