Capture Mare Recapture Technique

Topics: Immigration, Population, World population Pages: 6 (1119 words) Published: March 22, 2014


COURSE TITLE: General Ecology
LAB INSTR/PROFFESOR:Dr. Jaime Namocatcat, PhD

Pundag, Naif Mohammad C.
Pascual, Kyna Angelica B
Nuñez, Maria Pamela S.
Tadeje, Sheena Jean C.

By the use of CMR technique, this activity aims to estimate a population size in a given area in a simple manner. In this method in which a sample is captured, marked, and released and the proportion of marked individuals to unmarked in a later sample is used to estimate total populations. The activity was conducted just in inside our classroom at s14 CNSM building. After this activity we are able to appreciate how MCR technique works.


A population maybe defines as a group of organisms of the same species occupying a given area at a particular time. The population has group properties which are statistical measures that cannot be applied to individuals. The first and most basic characteristics of the population that ecologies are very much interested in is its density or size. It is defined as a number of individuals the status of a population. Four processes – natality, mortality, immigration, and emigration interact together to determine the population size.

Since it is rarely possible to count all the individuals in an area (especially large ones), ecologies are usually content to count only a small fraction of population and to use this sample to estimate the total. Two of the most commonly used methods of sampling population to estimate its size are quadrant sampling and the capture-mark-recarpture method. The present exercise will focus only the latter. Quadrat sampling will be explored in the exercise on quantitative estimation of vegetation.

Odum (1970) describes the CMR techniques as the “method in which a sample is captured, marked, and released and the proportion of marked individuals to unmarked in a later sample is used to estimate total populations”. In other words, this method is based on an elegant idea wherein we somehow put a mark on some members of a population and then sample the population to find out what proportion of the sample bears the mark. We can then, by sample ration and proportion, estimate the total population size. The proportionality is

This is the basis for the equation used in the Lincoln- Petersen index (after C.G.J. Petersen and F.C Lincoln) which is

Enumerated below are the conditions that must be met to ensure the effectively of the Lincoln- Petersen method. 1. The population must be closed: no immigration, emigration, births nor details. 2. The probability of being caught must be the same for all individuals in the population, marked or unmarked. When tagged individuals are released they must mingle freely with the rest of the population. 3. The tags or marks must not be lost or unrecognizable.

4. The individual members of the population must not become “trap-happy” (usually in response to tempting bait) or “trap-shy” (in response to painful trapping method). 5. Trapping must not alter an individual’s probability of death; tagging must not wound, infect, or cause the individual to become attractive to predator. 6. Sufficient time must elapse between the first and second catches for tagged individuals to disperse throughout the whole area. After the completion of this exercise, the students should be able to know and appreciate the use of CMR method in estimating size of the populations.

Materials and Method
The mark and recapture method involves marking a number of individuals in a natural population, returning them to that population, and subsequently recapturing some of them as a basis for estimating the size of the population at the time of marking and release. In a given activity, materials are plastic...
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