To measure the population of lake trout in a 250-hectare lake, 400 individual trout were netted and marked with a fin clip, then returned to the lake. The next week, the lake was netted again, and out of the 200 lake trout that were caught, 50 had fin clips. Using the capture-recapture estimate, the lake trout population size could be closest to which of the following?
A) 160
B) 200
C) 400
D) 1,600
E) 80,000

Question

Quizplus · Accepted Answer

The capture-recapture estimate uses the formula N=M*n/m where N is the estimated population size, M is the total number of individuals in the second sample, n is the number of marked individuals in the second sample, and m is the number of marked individuals in the first sample.

In this case, M=200, n=50, and m=400.

N=200*50/400=25.

To estimate the total population size of lake trout, we multiply N by the total number of fish initially caught and marked:

N_total = N*(total caught and marked in first sample)

N_total=25*(400)

N_total = 10,000

Therefore, the estimated population size of lake trout in the 250-hectare lake is closest to 1,600 (D).

To Measure the Population of Lake Trout in a 250-Hectare