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Mark-capture-release lab

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Presentation on theme: "Mark-capture-release lab"— Presentation transcript:

1 Mark-capture-release lab
How scientists estimate a population of animals in a given area

2 Capture-mark-recapture method
Each team gets a population of “pipefish”. Do NOT count the number of pipefish in your bag. Record the bag #. Decide who in your group will be: The sampler The data recorder The releaser

3 Capture-mark-recapture method
Next, we will walk outside and each group will be assigned a habitat. The releaser will sprinkle the pipefish into the habitat. BE RANDOM. When the data recorder says “Go,” the sampler will move around the habitat and collect as many pipefish as they can in 1 minute.

4 Capture-mark-recapture method
At the end of the minute, the group should count all the captured pipefish and record that number on the data table. Next, mark your pipefish with a bead so you know they have been caught and have the releaser redistribute them into the habitat.

5 Capture-mark-recapture method
When the data sampler says “Go,” the sampler should move around for 1 minute and collect a second sample. At the end of the minute, the group should meet and count the pipefish. Total # captured Total # recaptured (bead) Record your results.

6 Capture-mark-recapture method
Repeat procedure for a total of 10 times Plug in your values using the Lincoln index for each data set. Find the average population size. Ask teacher for your original population size (tell her your bag #) Compare

7 Questions (1 of 2) What could cause your results to be off from the actual population? How could sample size and population size affect these results? How would the number of samples affect these results? If you were predicting a large population (as in real pond), would the number you were off really have been that bad – relatively speaking?

8 Questions (2 of 2) What concerns should a biologist have about a species’ life history and habits before using this method to approximate the size of a population? Considering these concerns, should tagging be considered a viable method for biologists to estimate population size?

9 N= (n1 x n2)/n3 Lincoln Index
The formula for calculating population size is: N= (n1 x n2)/n3 N = population size n1 = total caught in all samples (minus 1st attempt) n2 = total MARKED (caught in 1st attempt) n3 = total recaptured (with tags)


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