标志重捕法实验报告

Population Quantity Investigation (Marked-Recapture Method)

Name: Ramsey (Shi Mu-xin)

Number: 201321031101

1.Investigation Objective

(1) Study and grasp the utilization of Marked-Recapture Method,

and use it to record the number of community from this experiment.

Grasp the method of how to mark the individual creatures. Learn the calculating method.

(2) Investigate the number of Pseudorasbora Parva in the BUA’s

pool which is nearby relational area.

2. Research Method

(1) Definition: Capture a part of individuals from this population which live in this surrounding. Mark this part of individuals and let them return the surroundings they live. About a period later, recapture this part of individuals, calculating the number of this population underlies the ratio of one individual which occupies the overall number. This is one of the methods which is often used to investigate population density.

(2) Statistical Principle: Underlie some creature which can move flexible in a pointed area and be investigated. While, referring the cultural individuals’ratio relationship has influence on overall number by mathematics method.

(3) Theoretical Calculation Formula: N=M*n/m

(4) Premises and Assumptions:It will get stable figures, marked individuals can distribute among the overall individuals, re-marked operation can not impact the behavior and death of animals.

3Operation Procedure

(1)First day, we selected a pool which is nearby relational area and

utilized a fish cage which is contained with some chicken bones. We made our mind to catch 20Pseudorasbora Parva(Because it has strong survival capability and it has active action) and mark it. First of all, we chose the needle filled ink to inject the fish, but we found it is tough to operate. Hence, we used a clipper to cut a small piece of fishes’ tail one by one and let them return to the pool. We still put some chicken bones in the cage and waited for a day.

Fig.1 Experiment Place

(2)A day later, we returned back to the pool, and we got 41(at least 40)

Pseudorasbora Parva from the cage, and we observed whether the fishes’ tail is cut or not one by one cautiously. After that we let them

return to the pool, because they need be alive too.

Fig.2 Marked Method

(3)After observation, we got 1fish which was cut from these 41 fish.

Fig.3 Re-marked Fish

(4)After calculation, we got N=820

4. Error analysis and Result

(1) We thought Pseudorasbora Parva informed their friends that there was a track to get them, and they would not be caught again.

(2) We were convinced that we damaged their balance capability and they got eaten by The Brazilian Tortoise.

After serious consideration, we got a result that the population we calculating is relative correct except these two random errors.