## What is Capture Recapture?

Capture recapture is a method used to estimate a population size where counting the whole population isn't feasable. It is often used for estimating the population of animals and insects.

The method involves catching and marking a sample of the animals before releasing them back into their environment. The population can then be estimated by taking a second sample of animals and based on the proportion these animals that are marked the population can be estimated.

## Capture Recapture Example Question

### Example Question

A scientist wants to estimate the number of fish in a lake.

He catches 50 fish from the lake and marks them with a dye.

The fish are then returned to the lake.

The next day the scientist catches another 80 fish.

4 of these fish are marked with the dye.

Work out an estimate for the total number of fish in the lake.