Mark-recapture Method

Question 1

What does the mark-recapture method involve?

Answer 1

• a known number of individuals is caught and marked and then released
• after a suitable time period another sample is captured and the number of marked individuals counted

Question 2

What is the formula used in the mark-recapture method?

Answer 2

P = (M x C) ÷ R

Question 3

What does the P symbolise in the mark-recapture method formula?

Answer 3

P = estimated population

Question 4

What does the M symbolise in the mark-recapture method formula?

Answer 4

M = total number of marked animals

Question 5

What does the C symbolise in the mark-recapture method formula?

Answer 5

C = total number of animals caught in the second sample

Question 6

What does the R symbolise in the mark-recapture method formula?

Answer 6

R = total number of animals marked in the second sample (i.e. recaptured)

Question 7

What precautions must be taken for a reliable result in terms of time?

Answer 7

• only a short time should pass between the first and second sampling
• so that no births and deaths can occur

Question 8

What precautions must be taken for a reliable result in terms of repetition?

Answer 8

• sampling should be repeated several times and an average population calculated

Question 9

What precautions must be taken for a reliable result in terms of the actual marking?

Answer 9

• the marking must not damage the individual or affect its movement or behaviour

Question 10

What precautions must be taken for a reliable result in terms of the marked animal?

Answer 10

• the marked animal must mix freely with the rest of the population before a new sample is taken

Question 11

What precautions must be taken for a reliable result in terms of immigration and emigration?

Answer 11

• no immigration or emigration is allowed
• i.e. the population must be closed