Updated 2024-11-22 14:17:26

Lake Superior -> 2.0 Prey Species -> Nearshore Percent Indigenous Prey Biomass

Reporting Interval

2017 - 2021

Area

Lakewide

Meeting Target?

Does Not Meet

Indicator Trend

No trend

Confidence?

Medium


2.1.1 Percent of indigenous prey biomass greater than 80% for nearshore waters of Lake Superior

Thirty-three prey fish species/groupings, of which 29 are indigenous and four are non-native, have been captured during the USGS annual nearshore bottom trawl survey. Principle prey fish captured during this survey (i.e., > 5% of the catch by number) include rainbow smelt (non-native), cisco (indigenous), ninespine stickleback (indigenous), bloater (indigenous) and lake whitefish (indigenous). Rainbow smelt mostly inhabit the nearshore areas of Lake Superior, are short lived (typically < 6 years), and have high reproductive potential but variable recruitment. This results in “boom-bust” cycles of rainbow smelt abundance which is largely responsible for the variability in the indicator for nearshore waters (Figure 1).

During the 2017-2021 reporting period, prey fish communities were greater than 80% indigenous in nearshore benthic surveys during 2019-2021 but below 80% during 2017 and 2018 (Figure 1). 

Confidence in this metric is medium because the waters closest to shore (< 15 meters) are not well sampled but likely have concentrations of indigenous and non-native prey fish that are not considered for this metric.

Figure 1. The percent of fish, by mass, captured during USGS benthic and pelagic surveys in nearshore waters that are indigenous. The horizontal reference line indicates the target value of 80%.


Methodology

The USGS annual nearshore bottom trawl survey was used to address this indicator. This survey is conducted lake-wide, began in 1978, and typically samples waters 15-130 meters in depth.



Other Resources

Vinson, M.R., D.L. Yule, L.M. Evrard, and S.B. Phillips. 2023. Status and trends in the Lake Superior Fish Community, 2022. Great Lakes Fishery Commission. Available at: LS_2022_FishSurveyReport.v4.FINAL.pdf (glfc.org)



Contributing Author(s)

  • Lake Superior Technical Committee -