Updated 2023-11-08 15:31:25
Lake Michigan -> 2.0 Planktivore (Prey Fish) -> Alewife Biomass
Reporting Interval
2016 - 2021
Area
Lake Michigan
Meeting Target?
Meets
Indicator Trend
Upward trend
Confidence?
Medium
2.1.1 Lakewide biomass of alewife at or above 220 million lbs
This indicator target is based on mean of biomass of alewife predicted by the Predator-Prey Ratio statistical catch at age model, which includes relative biomass estimated from acoustic and bottom trawl prey fish surveys. Recent annual Lake Michigan alewife biomass during the 2016 – 2021 reporting period ranged from 165 – 322 million pounds and was at or above the indicator target of 220 million pounds in 5 of 6 years (Figure 1). The mean for the period was 266 million pounds.
Figure 1. Combined biomass (millions of pounds) of age-1 or older alewife predicted by statistical catch at age modeling of the Lake Michigan population.
Methodology
Lakewide biomass of alewife was predicted from a statistical catch at age (SCAA) model. An SCAA typically relies upon inputs such as numbers of fish harvested by fisheries, age composition of fish harvested, survey relative catch and abundance data, and recruitment data. Because there are currently no commercial or recreational fisheries for alewife in Lake Michigan, consumption of alewife by predators serves as a proxy for fishery harvest. Fishery independent survey-derived inputs to the model include relative abundance estimates of age-0 and age-3 and older alewife from the USGS bottom trawl survey, as well as age-0 and age-1 and older alewife from the multi-agency acoustic survey. Likewise, proportions at age for the alewife population were derived from biological samples collected by surveys. Full details of model development and implementation were reported by Tsehaye et al. (2014) and Clark, Tsehaye, and Jones (2014).
Other Resources
- Annual model run updates are available on the GLFC website at PPR Summary for Outreach_8-18-2022.pdf (glfc.org).
- Clark, R., M. Jones, and I. Tsehaye. 2014. Instruction manual for the Lake Michigan Chinook salmon-alewife predator-prey ratio analysis. Michigan State University, Quantitative Fisheries Center Report.
- Tsehaye, I., M. L. Jones, J. R. Bence, T. O. Brenden, C. P. Madenjian, and D. M. Warner. 2014. A multispecies statistical age-structured model to assess predator–prey balance: application to an intensively managed Lake Michigan pelagic fish community. Canadian Journal of Fisheries and Aquatic Sciences 71:1-18.
- Tingley, R. W., D. B. Bunnell, D. M. Warner, C. P. Madenjian, and P. Armenio. 2021. Status and trends of pelagic and benthic prey fish populations in Lake Michigan, 2020. A report to the Great Lakes Fishery Commission, Lake Michigan Committee. http://www.glfc.org/pubs/lake_committees/common_docs/LM_Forage_Report_2021_For_Dissemination.pdf
- Tingley, R. W., Jr., D. M. Warner, C. P. Madenjian, P. M. Dieter, B. Turschak, and D. Hanson. 2023. Status and trends of pelagic and benthic prey fish populations in Lake Michigan, 2022. A report to the Great Lakes Fishery Commission, Lake Michigan Committee.
Contributing Author(s)
- David Warner - USGS
- Ben Turschak - MDNR
- Charles Madenjian - USGS
- Dale Hanson - USFWS
- Ralph Tingley - USGS