HR: 14:30h
AN: NB33U-05 INVITED     [Abstracts]
TI: Fish Population Estimates: A Comparison of Methods
AU: * Fuller, R
EM: rfuller@mail.colgate.edu
AF: Colgate University, Biology Department, Hamilton, NY 13346
AB: This exercise is designed to demonstrate two methods for determining the density of mobile animals. By sequentially sampling fish in a pool we estimate fish population size using the Removal-Summation Method (RS), and then we mark and release the fish. The next day a second lab section returns and repeats the sequential sampling and also records the total number of fish marked and unmarked so we can use the Capture-Mark-Recapture Method (CMR) as a second estimate of fish population density. I often use this as the first exercise in my ecology class to make students aware of the importance of measuring variability in data sets and to make them think about the assumptions that are made when using each of these methods. The difference in the estimated population size between days for the RS method is usually striking and they often get very different population estimates when comparing the RS and CMR methods for the samples taken on the second day. They must then consider which assumptions for each method might have been violated and explain how each might affect their estimates. Because we can obtain variability estimates for each method, they also can see just how much variability is associated with each of their population estimates.
DE: 0800 EDUCATION
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly