About Lesson
Capture-Recapture Method
Involves catching organisms, counting, marking and releasing them back into the habitat for about 24 hours and again captured, counted and recorded.
It’s suitable for highly mobile animals like; insects and fish.
Procedure
- Select the study area and species to be studied.
- Capture some organisms, count, mark and release them without harming them. This is the first capture recorded as 1st marked (FM).
- After about 24 hours, collect as many organisms as possible in the same area. Record the number collected as Second Capture (SC).
Record the number of those previously marked as Marked Recapture (MR).
Then P represents the total population.
Formula;
Where;
FM = first number marked
SC = second capture
MR = marked recapture
P = total population
Marking techniques
- Light coloured paint e.g. coloured nail vanish
- Use of tags (for large animals)
Assumptions
- No organism moves in and out of the area between the two counts.
- The marked animals mix freely with the remaining population.
- The mark does not alter the animal’s behavior.
- The marked animals will have enough time to mix freely with the rest.
- The population number does not vary during the study period.
Join the conversation
