Population Abundance/Mark-recapture Describe the basic principles involved in a
ID: 149178 • Letter: P
Question
Population Abundance/Mark-recapture Describe the basic principles involved in a Mark-Recapture study (and review the equation we used in class) You want to estimate the population size of pink salmon (Qncorhynchus gerhuscha) in the Indian River and use a Mark-Recapture technique to do so. You mark a total of 1500 individuals as they pass under the Lion's Gate bridge. Two weeks later you recapture 2000 individuals in the Indian Arm, of which 200 have marks on them. What is your estimate of the population size using the approach you learned in class? What assumptions did you have to make to obtain this estimate?Explanation / Answer
Mark recapture technique is used to calculate the total population study of an animal in ecology. A portion of the population is captured, marked or tagged and then released. After few days another portion of the population is captured and the number of marked population (of the previous one) is counted. As the number of the marked individuals within the second sample is proportional to the number of marked individuals in the whole population, an estimate of the total population can be obtained by the following formula:
N = (n*m)/c
Where N is total population size
n is number of individual initially captured and marked
m is number of captured individuals in the 2nd time
c is the number of individuals found marked in the 2nd time sampling.
In first sampling no of marked individuals is 1500.
2nd time sampling recaptured individuals is 2000
During recapture the marked individual is 200
Total population size is = (n*m)/c
. = (1500*2000)/200
. = 15000
Therefore the total population size is 15000.
Assumptions: 1. All the individuals marked in the 1st sampling should be representative of the total population. They should behave same as the rest of the members.
2. Marking should not interfere with the survival and behaviour of the animals.
3. Marked individuals should mix with the population so that during recapture marked individuals are also got.