Final answer:
In a mark-recapture survey, the ratio of the number of marked individuals to the total estimated population is the same as the ratio of the number of marked individuals recaptured to the total number of individuals caught in the second capture, leading to an estimation of the population size using a specific formula.
Step-by-step explanation:
For a mark-recapture survey, the ratio of the number of marked individuals to the total population is equal to the ratio of the number of marked individuals recaptured to the total number of individuals in the second capture. This method allows scientists to estimate the total population size by using the proportion of marked to unmarked individuals from a recaptured sample. For instance, if 80 animals are marked and released in the first capture, and during the second capture 100 animals are caught with 20 of them being previously marked, the population size (N) is estimated using the mark-recapture equation:
N = (number of marked in first capture × total number caught in second capture) / number of marked recaptured in second capture
Using this formula, the estimated population size would be (80 × 100) / 20, which results in an estimation of 400 individuals. It's vital to acknowledge that the mark-recapture method can have limitations like learned avoidance or preferential recapture, potentially impacting the accuracy of the estimate.