Go Fish Lab
Collaborators: Emily Davis, Nikolai Cook, Melissa Daria, Khalilah Cozier
Introduction
In the process of catch and release, scientists and ecologists use the method as a way meant to monitor population sizes of fish. The method is conducted by repeatedly casting a fishing line into a body of water, and recording the species of each catch. One can therefore, using the observed percentage of the target species caught, estimate that species' population. In order to simulate this method, our lab group combined two varieties of goldfish, which varied in color, in a plastic bag, which represented a pond. With the goal of gaining an accurate estimate of one type of snacks population within the pond, we repeatedly drew handfuls of fish from the bag, recording the data of its contents. The mean percentage of the parmesan goldfish compared to the later revealed actual percentage was 8.2%, leading us to the conclusion of catch and release unreliability, particularly when we observed several factors within the lab and literal scientific technique that mitigate accuracy.
Problem
Is catch and release an accurate way to estimate population size?
Hypothesis
If the population size of an aquatic population is to be most accurately calculated, catch and release is not a viable method, as factors such as migration, population change, and fishing methods can easily obscure the results.
Parts of the Experiment
Experimental Group: 20 handfuls of fish from bag (pond)
Independent Variable: Amount of fish in catch and number of parmesan fish in each
Dependent Variable: Percent error of estimation versus actual number of parmesan fish
Controlled Variables: Number of catches, type of snack, catching method, size of bag.
Materials
- Plastic bag
- Plate
- Regular goldfish
- Parmesan goldfish
Method
1. Obtain a bag containing prepared goldfish amount (do not count the number of goldfish within the bag).
2. Have a group member remove a large handful of goldfish.
3. Place handful on plate, count the number of goldfish removed and write it in the table below.
4. Replace these goldfish with “tagged” goldfish (i.e. specialized goldfish)
5. Mix the bag well to redistribute the tagged goldfish among the rest of the goldfish.
6. One member at a time (and without looking), remove a handful of goldfish.
7. Record the number of total goldfish in the sample, the number of parmesan goldfish, and figure out the percentage of tagged fish. Record on the chart.
8. Return the handful to the bag
9. Continue process until group has recorded 20 samples.
Data (see below)
Introduction
In the process of catch and release, scientists and ecologists use the method as a way meant to monitor population sizes of fish. The method is conducted by repeatedly casting a fishing line into a body of water, and recording the species of each catch. One can therefore, using the observed percentage of the target species caught, estimate that species' population. In order to simulate this method, our lab group combined two varieties of goldfish, which varied in color, in a plastic bag, which represented a pond. With the goal of gaining an accurate estimate of one type of snacks population within the pond, we repeatedly drew handfuls of fish from the bag, recording the data of its contents. The mean percentage of the parmesan goldfish compared to the later revealed actual percentage was 8.2%, leading us to the conclusion of catch and release unreliability, particularly when we observed several factors within the lab and literal scientific technique that mitigate accuracy.
Problem
Is catch and release an accurate way to estimate population size?
Hypothesis
If the population size of an aquatic population is to be most accurately calculated, catch and release is not a viable method, as factors such as migration, population change, and fishing methods can easily obscure the results.
Parts of the Experiment
Experimental Group: 20 handfuls of fish from bag (pond)
Independent Variable: Amount of fish in catch and number of parmesan fish in each
Dependent Variable: Percent error of estimation versus actual number of parmesan fish
Controlled Variables: Number of catches, type of snack, catching method, size of bag.
Materials
- Plastic bag
- Plate
- Regular goldfish
- Parmesan goldfish
Method
1. Obtain a bag containing prepared goldfish amount (do not count the number of goldfish within the bag).
2. Have a group member remove a large handful of goldfish.
3. Place handful on plate, count the number of goldfish removed and write it in the table below.
4. Replace these goldfish with “tagged” goldfish (i.e. specialized goldfish)
5. Mix the bag well to redistribute the tagged goldfish among the rest of the goldfish.
6. One member at a time (and without looking), remove a handful of goldfish.
7. Record the number of total goldfish in the sample, the number of parmesan goldfish, and figure out the percentage of tagged fish. Record on the chart.
8. Return the handful to the bag
9. Continue process until group has recorded 20 samples.
Data (see below)
Conclusion
The average mean of tagged fish in our 20 samples was 24.82%, and using the population size formula, we conlcuded that there were 101 specialized fish in the pond. However, this was an 8.2% error from the actual number of fish, 110. From these results we concluded that although catch and release can give a general idea of the number of fish in a pond, it is not an accurate method of counting. These results confirmed out hypothesis of the method being unrealistic and inaccurate. The lab itself did not take into account real world factors involved such as time of day, section of pond, method of fishing, and seasons that can change results of population. Additionally, life and death cycles were not represented in the lab. An error our group made in the lab was that we did not rotate on taking handfuls, but rather had a single collaborator draw each turn. This was a miscommunication with the directions and may have effected the way our data was collected, in that a single hand will take out a set range of goldfish, whereas varied hands can take out different amounts. There were no sources in the introduction of the lab directions, however in order to understand catch and release, because it was the focus of this lab, external research was required. A paper published on the National Oceanic and Atmospheric Administration's Southeast Fisheries Science Centers website elaborated on the method of catch and release, its uses, as well as included an in depth analysis of the process. However, only its explanation of catch and release was analyzed for the prelab.
Citations
Cooke, Sami J., and H. L. Schramm. Catch-and-release Science and Its Application to Conservation and Management of Recreational Fisheries. N.p.: Blackwell Publishing, 2007. PDF.
The average mean of tagged fish in our 20 samples was 24.82%, and using the population size formula, we conlcuded that there were 101 specialized fish in the pond. However, this was an 8.2% error from the actual number of fish, 110. From these results we concluded that although catch and release can give a general idea of the number of fish in a pond, it is not an accurate method of counting. These results confirmed out hypothesis of the method being unrealistic and inaccurate. The lab itself did not take into account real world factors involved such as time of day, section of pond, method of fishing, and seasons that can change results of population. Additionally, life and death cycles were not represented in the lab. An error our group made in the lab was that we did not rotate on taking handfuls, but rather had a single collaborator draw each turn. This was a miscommunication with the directions and may have effected the way our data was collected, in that a single hand will take out a set range of goldfish, whereas varied hands can take out different amounts. There were no sources in the introduction of the lab directions, however in order to understand catch and release, because it was the focus of this lab, external research was required. A paper published on the National Oceanic and Atmospheric Administration's Southeast Fisheries Science Centers website elaborated on the method of catch and release, its uses, as well as included an in depth analysis of the process. However, only its explanation of catch and release was analyzed for the prelab.
Citations
Cooke, Sami J., and H. L. Schramm. Catch-and-release Science and Its Application to Conservation and Management of Recreational Fisheries. N.p.: Blackwell Publishing, 2007. PDF.