## Something Fishy Lab

**Purpose:**The purpose of this lab was to determine if we would get the same percentage of how many there is in the pond by determining the mean.

**Background:**A technique called sampling was used in this lab to determine if we would find the sampler fish or new fishes. In this lab, the organisms in a few small areas are counted and projected to the entire area.

**In this lab there was a pond(bowl) and we had to see if we would get the same fishes we tagged on.**

**Hypothesis:**If goldfish are "tagged" and then random samples are chosen, then there will be up to 20 % error because tagging is not effective.

**Variables:**

**Independent Variable:**Population Size

**Dependent Variable:**Degree of accuracy

**Control Variables:**Type of non-tagged goldfish and tagged goldfish, and the person counting the fish

**Procedure:**

- Obtain a bowl with your fish.
- Do NOT count the number of fish in your pond yet!
- Have one member of your group remove a large handful of fish.
- Count the number of fish you just removed and write it in the table below.
- Replace these fish with “tagged” fish (in this case, colored “fish”)
- Mix your pond well to redistribute the tagged fish among the other fish.
- 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)
- Return your 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 samples?__

**19**

**2.**

__Using the following formula determine an estimated population for your pond:__

**20 x 19/4= 95**

**3.**

__Now, actually count the number of fish in your bowl:__

**74**fish

**4**.

__Find your percentage error by using the following formula:__

**28%**

**5.**

__what concerns should a biologist have about a species habits before (s)he uses the method to approximate the size of a population?__

**Some concerns that a biologist that should have about a species' habit before using this method to approximate population size are predators in the area, climate changes, and the crude death rate. All of these factors can change the amount of the species alive when they are counted later.**

**Conclusion:**

The hypothesis was very close to what the actual percent error was. From prior knowledge, I knew that population tagging was not always effective so the estimate of the percent error was aimed rather high, but close. Throughout this lab, there were not actually that many areas where error could have occurred. Goldfish being lost, or not the correct amount of fish being tagged may have effected the final result. In order to fix this, fish should be counted multiple times to ensure that there are still the same amount of fish and that the data is correct. Also, percentages could have been miscalculated due to estimation. To fix this issue, a more specific place to round to such as the tenths or hundredths place would help.