Fish Selection Lab
Purpose: You will be expected to estimate the size of the sample population using the mark-recapture technique. Be able to apply the technique to new population problems and compare the mark and recapture technique to other methods of population estimating.
Background: The technique of sampling is used for the estimation of populations and their size. The amount in a small area are counted and projected to a whole are. Sometimes following this method scientist use the method of tagging which is usually different for different animals. For instance for butterflies it can be stickers and for others animals it can be ear clip, or notches such as in fins of fish. It is used for the knowing of the health , migration patterns, and range to determine population sizes. When scientist do random sampling they can determine the estimate of the number of fishes in the 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 the number here : 23
4. Count the number of fish you just removed and replace these fish with "tagged" fish
5. Mix your pond well to redistribute the tagged fish among the other fish
6. One member at a time (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
7. Return the handful to the bowl!! Continue with this until you have taken 20 samples.
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 the number here : 23
4. Count the number of fish you just removed and replace these fish with "tagged" fish
5. Mix your pond well to redistribute the tagged fish among the other fish
6. One member at a time (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
7. Return the handful to the bowl!! Continue with this until you have taken 20 samples.
Questions:
1) What is the mean average of your percent tagged fish from your 20 examples?
-It was 33.33%
2) Using the following formula determine an estimated population for your pond:
33 x 23/11 x 100 = 69
3)Now, actually count the number of fish in your bowl : 70 fish
4) Find your percentage error by using the following formula: -1.43%
100 x (your estimate of population - Actual population size) / (Actual size of population)
(69-70)/70
5) What concerns should a biologist have about a specie's habits before (s)he uses this method to approximate the size of the population
- The population might leave the area, their might be migration, resources they need during certain times, seasonal
Conclusion: how did you fulfill the purpose? what did you learn?
- We fulfilled the purpose by being one off purpose number of fish and understanding the concept of random sampling which in this case helps a lot if their is a low number the less you have in total the closer the estimate might be.
1) What is the mean average of your percent tagged fish from your 20 examples?
-It was 33.33%
2) Using the following formula determine an estimated population for your pond:
33 x 23/11 x 100 = 69
3)Now, actually count the number of fish in your bowl : 70 fish
4) Find your percentage error by using the following formula: -1.43%
100 x (your estimate of population - Actual population size) / (Actual size of population)
(69-70)/70
5) What concerns should a biologist have about a specie's habits before (s)he uses this method to approximate the size of the population
- The population might leave the area, their might be migration, resources they need during certain times, seasonal
Conclusion: how did you fulfill the purpose? what did you learn?
- We fulfilled the purpose by being one off purpose number of fish and understanding the concept of random sampling which in this case helps a lot if their is a low number the less you have in total the closer the estimate might be.