It is a simulation of capture-recapture which is often used to estimate the size of populations, such as fish and wildlife, which are very difficult to count.
All pertinent information is given on the student sheet .
Paper cut-outs could be used instead of beans or macaroni to represent the fish. This exercise is designed to encourage students to think about how fish populations, in this case salmon, can be affected in a certain area over a period of time. Students should already be familar with how fish populations are estimated.