In an effort to measure the size of a bluegill population in a pond, you capture 40 bluegills and mark each with a tag on the tail fin and then release them. A week later you return to the pond and catch 40 more, of which 8 have a tag on the tail fin. What is the best estimate of the bluegill population in the pond?
A) 100
B) 160
C) 200
D) 320
E) 400

Question

Quizplus · Accepted Answer

This is an example of the mark and recapture method. The equation used to estimate population is:
(Number of individuals marked in first sample × Total number of individuals in second sample) / Number of individuals marked in second sample
Plugging in our values:
(40 × Total) / 8 = 5 Total
Therefore, the estimated population would be 5 times the number of individuals marked in the first sample (40), which equals 200. Therefore, the best choice is C, 200.

In an Effort to Measure the Size of a Bluegill