Something's Fishy - Population Study Lab
Purpose: The purpose of this lab is to estimate the size of a sample population by fishing for fish, and then marking them with marker to show how the mark-recapture technique is really used. Then compare the mark-recapture technique to other methods of population estimating.
Background: A technique that's called sampling, is used to estimate population size. When sampling organisms in small areas are counted and are projected to the entire area. Another way to determine population size is by a technique called tagging, where you tag a certain type of specie. We use these tags to track migration patterns, health, and range as well as to help determine population numbers of species in an area. By doing this biologists are able to to estimate the population size of an area.
Procedure:
1. Obtain a bowl with your “species” in it. (“fish” crackers).
2. Do NOT count the number of fish in your pond yet!
3. Have one member of your group remove a large handful of fish. Write that number here: 38
4. Count the number of fish you just removed and replace these fish with “tagged” fish (in this case,
colored “fish”)
5. Mix your pond well to redistribute the tagged fish among the other fish.
6. One member at a time (and without looking), remove a handful of fish and record the number of total
fish in the sample, the number of “tagged fish”, and figure out the percentage of tagged fish. (see chart)
7. Return your handful to the bowl!! Continue with this until you have taken 20 samples.
Data:
Background: A technique that's called sampling, is used to estimate population size. When sampling organisms in small areas are counted and are projected to the entire area. Another way to determine population size is by a technique called tagging, where you tag a certain type of specie. We use these tags to track migration patterns, health, and range as well as to help determine population numbers of species in an area. By doing this biologists are able to to estimate the population size of an area.
Procedure:
1. Obtain a bowl with your “species” in it. (“fish” crackers).
2. Do NOT count the number of fish in your pond yet!
3. Have one member of your group remove a large handful of fish. Write that number here: 38
4. Count the number of fish you just removed and replace these fish with “tagged” fish (in this case,
colored “fish”)
5. Mix your pond well to redistribute the tagged fish among the other fish.
6. One member at a time (and without looking), remove a handful of fish and record the number of total
fish in the sample, the number of “tagged fish”, and figure out the percentage of tagged fish. (see chart)
7. Return your handful to the bowl!! Continue with this until you have taken 20 samples.
Data:
Questions:
1. What is the mean (average) of your percent tagged fish from your 20 samples? 29.08%
2. Using the following formula, determine an estimated population for you pond: 68 fishes
3. Now, actually count the number of fish in your bowl: 78 fishes
4. Find you percentage error by using the following formula: 13%
5. What concerns should a biologist have about a species' habits before (s)he uses this method to approximate the size of a population?
That the species might migrate somewhere else so the biologists might have a difficult time getting the data they need.
Conclusion: How did you fulfill the purpose? What did you learn?
I fulfilled the purpose by estimating the population by using the mark-recapture technique. We tagged many fishes with marker and released them back into the water 20 times keeping track of the total of fish, and tagged fish. I learned that
1. What is the mean (average) of your percent tagged fish from your 20 samples? 29.08%
2. Using the following formula, determine an estimated population for you pond: 68 fishes
3. Now, actually count the number of fish in your bowl: 78 fishes
4. Find you percentage error by using the following formula: 13%
5. What concerns should a biologist have about a species' habits before (s)he uses this method to approximate the size of a population?
That the species might migrate somewhere else so the biologists might have a difficult time getting the data they need.
Conclusion: How did you fulfill the purpose? What did you learn?
I fulfilled the purpose by estimating the population by using the mark-recapture technique. We tagged many fishes with marker and released them back into the water 20 times keeping track of the total of fish, and tagged fish. I learned that