Can capture, release, and Recapture be used to determine the
number of fish in each species that are in a pond?

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Is it possible to find how many fish of each species of all the fish species in a pond without counting every fish?

Scientists use a method called capture and recapture to estimate animals' or a particular species' (kind or ainmal) population.

Purpose: To simulate counting fish populations of all the species in a pond using ratio and proportion

Materials: container or bowl; different kinds/ colors of beans, cubes, or counters; pencil, erasable marker or stickers.

Procedure

Put an unknown number of the different kinds objects (each kind represents a species of fish) for a combined total of a hundred or more in the container. The container, or bowl represents the pond. Different colors of cubes could represent the different species of fish populations in the pond. The pencil, marker, or stickers will be used to mark the fish that are captured, released, and maybe recaptured later.

Decide how many fish to capture, tag and release (20, 25, 33).

Catch a fish, tag it, release it, and continue until the determined amount are tagged.

Then begin to catch the fish one at a time, record if it is marked or unmarked, release it, and continue to catch more fish until 20 or more have been caught. (be sure to draw the beans, cubes, or counters without looking, record if it is marked or not, put it back into the container, and draw another until 20, 25, or more have been drawn).

With the information you have, you should be able to estimate the total number of animals in the population...

 Tagged animals caught by species Untagged animals caught by species total animals caught tagged and untagged by species Total Population by species Simulation number Species red Species brown Species black Species white Species yellow Species red Species brown Species black Species white Species yellow Species red Species brown Species black Species white Species yellow Species red Species brown Species black Species white Species yellow 1 2 3 4 5 6

hint: solve a series of problems like captaure and recapture

Dr. Robert Sweetland's Notes ©