Updated 2024-11-22 14:24:32
Lake Superior -> 2.0 Prey Species -> Adult Cisco Biomass
Reporting Interval
2017 - 2021
Area
Lakewide
Meeting Target?
Meets
Indicator Trend
No trend
Confidence?
High
2.1.4 Adult cisco biomass is stable or increasing from assessment surveys
The principal commercial fisheries for prey fish in Lake Superior are for cisco in western Ontario, Grand Portage Tribal waters, Minnesota, and Wisconsin. Fisheries for cisco elsewhere in the lake and for rainbow smelt and deepwater cisco throughout the lake are comparatively small. Routine hydroacoustic surveys are conducted in each jurisdiction for assessing biomass trends.
During the 2017-2021 reporting period, biomass trends are decreasing (score = -1), increasing (score = 1) and slightly increasing (score = 0) in Grand Portage, Ontario, Minnesota, and Wisconsin, respectively (Figure 4). Collectively, the average score is increasing (average score = 1).
Figure 1. Adult cisco biomass estimates (MT) by jurisdiction
Methodology
Hydroacoustic surveys and biomass calculations vary by jurisdiction. The slopes of ordinary least squares regressions of log transformed biomass by year in each jurisdiction were used to assess if trends were negative, positive, or neutral. Scores of -1, 1, and 0 were assigned to slopes with values less than or equal to -0.1, greater than or equal to 0.1, and in between -0.1 and 0.1, respectively. Scores were averaged across jurisdictions to calculate a lake-wide score for the indicator.
Other Resources
Contributing Author(s)
- Lake Superior Technical Committee -