Something Fishy Lab
Hypothesis: Population tagging is an ineffective way to estimate population size. This is because the same tagged individuals may be caught repeatedly without representation of the other individuals of the species.
Problem: How effective is population tagging at estimating population size?
Materials:
-30 plain goldfish
-Unknown number of colored goldfish
-Zip-Loc Bag
-Plate or flat surface
Procedure:
1. Obtain a bowl with the goldfish.
2. Do not count the number of fish in the bag yet.
3. Remove a large handful of fish.
4. Count the number of fish removed and write it in the table.
5. Replace these fish with “tagged” fish.
6. Mix the bag well to redistribute the tagged fish among the other fish.
7. 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.
8. Return the handful to the bowl.
9. Continue with this until twenty samples have been taken.
Observations and Data:
Problem: How effective is population tagging at estimating population size?
Materials:
-30 plain goldfish
-Unknown number of colored goldfish
-Zip-Loc Bag
-Plate or flat surface
Procedure:
1. Obtain a bowl with the goldfish.
2. Do not count the number of fish in the bag yet.
3. Remove a large handful of fish.
4. Count the number of fish removed and write it in the table.
5. Replace these fish with “tagged” fish.
6. Mix the bag well to redistribute the tagged fish among the other fish.
7. 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.
8. Return the handful to the bowl.
9. Continue with this until twenty samples have been taken.
Observations and Data:
Analysis and Conclusions:
Lab Questions:
1. What is the mean of your percent tagged fish from your 20 samples?
The average was 36.361% tagged per sample.
2. Determine an estimated population for your pond.
Population=(30/36.361)*100=82.5 fish.
3. What is the actual number of fish in your bowl?
There were actually 100 fish in the bowl.
4. Find the percentage error.
The percentage error is 17%.
5. Does this method appear to be an effective way to assess population size? Why or why not?
The percentage error was too high in this experiment for this method to considered effective. However, if this experiment were to be repeated many more times the percentage error would probably go down and the method would be considered effective.
6. What concerns should a biologist have about a species' habits before he/she uses this method to approximate the size of a population?
He/She must keep in mind the life spans and reproductive rates of the individuals in the species and where the species travels (its full range of habitat/patterns of migration).
General Conclusions/Analysis:
Many factors such as life span and habitat range must be taken into account to approximate the size of a population. These are not as noticeable in example samples like the goldfish, but in real-life situations they can make all the difference. While population tagging can be effective, it has the potential to be quite ineffective. The percentage error of 17% does not fall within the acceptable 10% range, proving the hypothesis true. However, if the experiment were to be done over a long period of time and many observations were made of the life span and habitat range, population tagging would probably be much more effective.
Lab Questions:
1. What is the mean of your percent tagged fish from your 20 samples?
The average was 36.361% tagged per sample.
2. Determine an estimated population for your pond.
Population=(30/36.361)*100=82.5 fish.
3. What is the actual number of fish in your bowl?
There were actually 100 fish in the bowl.
4. Find the percentage error.
The percentage error is 17%.
5. Does this method appear to be an effective way to assess population size? Why or why not?
The percentage error was too high in this experiment for this method to considered effective. However, if this experiment were to be repeated many more times the percentage error would probably go down and the method would be considered effective.
6. What concerns should a biologist have about a species' habits before he/she uses this method to approximate the size of a population?
He/She must keep in mind the life spans and reproductive rates of the individuals in the species and where the species travels (its full range of habitat/patterns of migration).
General Conclusions/Analysis:
Many factors such as life span and habitat range must be taken into account to approximate the size of a population. These are not as noticeable in example samples like the goldfish, but in real-life situations they can make all the difference. While population tagging can be effective, it has the potential to be quite ineffective. The percentage error of 17% does not fall within the acceptable 10% range, proving the hypothesis true. However, if the experiment were to be done over a long period of time and many observations were made of the life span and habitat range, population tagging would probably be much more effective.