NUMBAT OER - Open Educational Resources

4. Example calculation

Mark-release-recapture is used to estimate the population of turtles in a small lake. In the first sampling, 23 turtles are captured and the backs of their shells are marked with paint. The turtles are released into the lake. In the second sampling, 28 turtles are captured, of which nine carry paint markings. Using the notation in Section 2:

M1=23

M2=9

U2+M2=28

We can insert these values into the expression in Section 2, so that:

N = M1  (U2+M2)  =M1  23×28 ≈72
M2 9