Abundance from Mark-Recapture Data

Wisconsin YOY Walleye

Use multiple census mark-recapture techniques to estimate abundance of YOY Walleye in Pine Lake (WI).

Derek H. Ogle


Mar 8, 2019


Feb 13, 2023

Mraz (1968) examined the population dynamics of young-of-the-year (YOY) walleye (Sander vitreus) in Pine Lake, an inland lake in Wisconsin. In fall 1962, YOY walleye were captured, marked, and returned to the lake on five sampling dates. On each date, the number of fish caught, the number of caught fish that were previously marked, and the number of marked fish returned to the lake were recorded. The results from these sampling efforts are shown in the table below.

Sample Caught Recaptured Returned
1 321 -- 321
2 412 45 412
3 178 55 178
4 415 93 415
5 367 113 --

Use these results to answer the following questions.

  1. Estimate the initial population size, with 95% confidence interval, of YOY Walleye in Pine Lake. Carefully interpret the result.
  2. Comment on the validity of the assumptions for the model you used to estimate the size of the population.
Solution Code:

Available upon request to students not in a class. Contact fishR maintainers.


Mraz, D. 1968. Recruitment, growth, exploitation and management of walleyes in a southeastern Wisconsin lake. Technical Bulletin, Wisconsin Department of Natural Resources, Madison, WI.