Bio 103 Lab - Lab 8. Ecology

EXPERIMENT 1: How many fish were tagged with blue tags in the initial marking session?

100

EXPERIMENT 1: Calculate the population estimate (N) for the initial bluegill population using the equation: N=M(n/m) where Mis the number of marked individuals in the first sample; N is the total population size; m is the number of marked individuals in the second, or recaptured, sample; and n is the total number of individuals in the second, or recaptured, sample.

1000

EXPERIMENT 2: How many fish with red tags were recovered from the second mark and recapture experiment?

13

EXPERIMENT 2: What are the average length and mass, respectively, for the second marked bluegill population?

15.7 cm and 481.931 g

EXPERIMENT 1: What are the average length and mass, respectively, for the initial recaptured bluegill population?

19.2 cm and 445.763 g

EXPERIMENT 1: What is the mass/length ratio of the initial marked bluegill population? The mass/length ratio is determined by dividing the average mass of the population by the average length.

24.9

EXPERIMENT 2: Calculate the population estimate (N) for the bluegill population after predators were introduced using the equation: N=M(n/m) where M is the number of marked individuals in the first sample; N is the total population size; m is the number of marked individuals in the second, or recaptured, sample; and n is the total number of individuals in the second, or recaptured, sample.

769

CONCLUSIONS: Which of the following is NOT another environmental factor that could affect the bluegill population in the sample lake?

The bluegill's competitor goes extinct in a nearby lake.

CONCLUSIONS: Based on the assumptions described in the introduction why might the mark and recapture method of population estimation be more accurate in the lake setting we are studying than in a stream or river?

The fish would not be able to leave the lake sampling area, whereas in a stream or river they can go upstream or downstream of the sampling area.

CONCLUSIONS: What effect did the introduction of the predators have on the bluegill population? Was the hypothesis in the introduction correct?

The population size decreased; the hypothesis was correct.