Updated 2023-11-03 18:51:27
Lake Michigan -> 1.0 Salmonine (Salmon and Trout) -> Chinook Fall Age-3 Female Weight
Reporting Interval
2016 - 2021
Area
Lake Michigan
Meeting Target?
Meets
Indicator Trend
No trend
Confidence?
High
1.1.3 Female Chinook salmon age-3 weight from fall harbor and weir assessments at or above 15.4 lbs
Weight of mature age-3 (years) female Chinook salmon returning to Lake Michigan weirs and harbors in the fall is an indicator of prey availability and growth conditions in Lake Michigan, as well as egg production potential (Clark, 2012). Because Chinook salmon are nearly completely reliant on alewife prey while feeding in the open waters of Lake Michigan (Leonhardt et al. 2020; Turschak et al. 2022), larger weight of tributary/harbor returning adult Chinook salmon at age 3 indicates relatively high alewife biomass per Chinook salmon and good growth conditions in Lake Michigan. In contrast, low weight of tributary/harbor returning adult Chinook salmon indicates lower alewife biomass per Chinook salmon and poorer growth conditions.
Average weight of age-3 female Chinook salmon returning to Lake Michigan weirs and harbors ranged from 17.8 to 21.1 lbs. during the 2016-2021 reporting period, which is well above the management target of 15.4 lbs (Figure 1). Weights during 2018 and 2019 were 20.4 and 21.1 lbs (Figure 1), respectively, and were the highest recorded in the time series that began in 1985. These results are consistent with high alewife prey availability relative to predator abundance, very good growth conditions and high egg production potential in Lake Michigan.
Figure 1. Average weight of age-3 (years) female Chinook Salmon returning to Lake Michigan weirs and harbors, 1985-2021. The management target weight is greater than 15.4 lbs.
Methodology
Chinook salmon were collected in Lake Michigan tributaries at weirs or via harbor electrofishing efforts during annual fall spawning migrations. Sex, length, and weight information were recorded, and coded-wire tags, which provide information on each fish’s year class, were collected to determine age of marked individuals. Basin-wide weight of age-3 females was calculated as the average weight across each sampling location and weighting to the average by number of known age fish collected at each location. Collection locations include Illinois Harbors, Wisconsin tributary weirs (Strawberry Cr., Kewaunee R., and Root R.), and Michigan tributary weirs (Little Manistee R., and Medusa Cr.).
Other Resources
- Clark, R. D. 2012. Review of Lake Michigan red flags analysis. Michigan State University, Quantitative Fisheries Center Technical Report T2012-01.
- Leonhardt, B.S., Happel, A., Bootsma, H., Bronte, C.R., Czesny, S., Feiner, Z., Kornis, M.S., Rinchard, J., Turschak, B., and Höök, T. 2020. Diet complexity of Lake Michigan salmonines: 2015–2016. J. Great Lakes Res. 46(4): 1044–1057. International Association for Great Lakes Research. doi:10.1016/j.jglr.2020.05.010.
- Turschak, B.A., Bronte, C.R., Czesny, S.J., Gerig, B.S., Happel, A., Hook, T.O., Kornis, M.S., Leonhardt, B.S., Matthias, B.G., Rinchard, J., and Bootsma, H.A. 2022. Temporal Variation in the Niche Partitioning of Lake Michigan Salmonines as it Relates to Alewife Abundance and Size Structure. Can J. Fish. Aquat. Sci. 79(3): 487–502. Available from https://doi.org/10.1139/cjfas-2021-0027.
Contributing Author(s)
- Lake Michigan Technical Committee - Salmonid Working Group