- Marking method does not harm and does not make organism liable to predation.
Population (lincoln index) = (sample1 × sample2) / Number marked in sample2
-Assumes that population is stable, and there no births/deaths or emigration/immigration took place between the first and second samples.
- To sample different areas
- Mapping out area into grid selecting using random numbers from tables or computer program, to prevent bias
- To measure change from one area to another
Interrupted belt transect - taken at intervals along the line
Continous belt transect
Point transect - just the species touching a particular pont on the line are recorded