Capture-Recapture Model Unknown number of fish in a lake Catch a sample and mark them m++, Let them loose Recapture a sample and look for marks Estimate population size n1 number in first sample 15 n2 number in second sample 10 n12 number in both samples 5 N= total population size assume that n1/N= n12/n2 therefore 15/N 5/10 N=(10X15)/5=30Capture-Recapture Model ◼ Unknown number of fish in a lake ◼ Catch a sample and mark them ◼ Let them loose ◼ Recapture a sample and look for marks ◼ Estimate population size ◼ n1 = number in first sample 15 n2 = number in second sample 10 n12 = number in both samples 5 N = total population size assume that n1/N = n12/n2 therefore 15/N = 5/10 N = (10 x 15) / 5 = 30