# Can someone explain mark-recapture method/sampling?

If one of the assumptions is that population remains constant, how does mark-recapture method determine population size?

What is the point of recapturing?

### 2 Answers

- 1 decade agoFavorite Answer
Mark-recapture analyses of populations are an important tool in population biology. One can extend mark-recapture analyses by providing a link between mark-recapture data and demographic models such as matrix population models and integrodifference equation models. Issues that are commonly encountered during sampling, such as the fact that the sex or life-stage of some individuals is unknown during some sampling occasions and that individuals become unobservable during some life stages can be resolved with this method. Introduce a stage structure that permits simple conversion of estimated transition probabilities into a matrix population model. Then derive and describe a simple algorithm to simplify programming for parameter estimation. In aaddition there are methods to estimate the distribution of dispersal displacements (dispersal kernel) from mark-recapture data. Using some of the above methods, one can estimate the vital rates of the North Atlantic right whale (Eubalaena glacialis). To the estimated vital rates, apply demographic analyses including population viability analyses and sensitivity analysis. Finally, compare effects of environmental and demographic stochasticities on the viability of the population.

I hope this helps.

- HermoderusLv 41 decade ago
Assume that 100 animals are captured, tagged, and released. Assume further that tagged individuals mix randomly with the larger population under study before recapture.

If, of 100 animals recaptured, 10 are tagged, it can be assumed that the 100 initial subjects represented 10% of the total population (which in this case would be estimated at 1000). It is important to note that recapture is intended to be random and not a specific search for preiously tagged individuals.