The method is called “capture-recapture” (“catch – catch again”). If every fish caught is marked and released, then the probability of catching the marked fish will grow nonlinearly with the increase of the number of attempts. The size of the population can be estimated roughly as the square of the number of attempts before the first marked fish is caught.

For example, if the total of brilliant carassies is 10,000, you need to catch about 100. If you consider that another fish that you can shamelessly eat will be caught, the ecologist will have good fun, having fished for a couple of days and lived in nature with a fireplace, a tent and a knighted earpiece. An ecologist is not a vegan, he can.