A researcher captured 45 fish from a lake on day 1, tagged and released them back. On day 2 the researcher caught 50 fish out from the same lake, of which 15 were already tagged. Estimate the population size of fish in the lake with this information and pick the correct option.
150
Fish Population Estimation using Capture-Recapture
The question asks us to estimate the total population size of fish in a lake based on capture-recapture data. This is a common ecological method used when a complete count of a population is impractical. The underlying principle is that the proportion of tagged fish in a second sample should be representative of the proportion of tagged fish in the entire population.
The method used here is the Lincoln-Peters index, which provides a simple way to estimate population size based on two samples.
Capture-Recapture Formula
The formula for the Lincoln-Peters index is:
\( N = \frac{M \times C}{R} \)
Where:
- \( N \) = Estimated total population size
- \( M \) = Number of individuals captured, tagged, and released in the first sample (Day 1)
- \( C \) = Total number of individuals captured in the second sample (Day 2)
- \( R \) = Number of tagged individuals recaptured in the second sample (Day 2)
Applying the Data
From the question, we have the following information:
- Number of fish tagged on Day 1 (\( M \)) = 45
- Total number of fish caught on Day 2 (\( C \)) = 50
- Number of tagged fish recaptured on Day 2 (\( R \)) = 15
Calculating the Population Size
Now, we substitute these values into the Lincoln-Peters index formula:
\( N = \frac{45 \times 50}{15} \)
First, multiply the numbers in the numerator:
\( 45 \times 50 = 2250 \)
So the formula becomes:
\( N = \frac{2250}{15} \)
Now, divide 2250 by 15:
\( N = 150 \)
Therefore, the estimated population size of fish in the lake is 150.
Estimated Population Size
Based on the capture-recapture data, the estimated population size of fish in the lake is 150.
Important Questions from Applied Ecology
Which one of the following was recently reported to be the first mammal to have become extinct as a result of climate change?
Given below is a list of natural disturbances.
A. Coral bleaching
B. Rising sea levels
C. Shifts in species distribution
D. Lowering of sea levels
E. Increase in glacial sheets
Which one of the following combinations of disturbances can be attributed to global warming?
The following information refers to ecological interactions.
Which one of the following options represents the correct match between column X and column Y?Column X Column X A Bass introduction into
aquatic systems(i) Bioaccumulation B Beavers (ii) Aposematism C Sea bird (such as puffins) (iii) Keystone species D Yellow and black stripes in a wasp (iv) Trophic cascades Which one of the options given below is NOT desirable when setting up nature reserves in the tropics?
In many sexually reproducing organisms females make mate choice decisions based on male display traits. Several models have been proposed to explain the evolution of exaggeration in male traits. Two of them have been given below in column P and their possible descriptions in column Q.
Column P
Column Q
A.
Runaway Se- lection (i)
Males exploit a pre-existing sensory bias in females. Females choosing such males have higher quality offspring. B.
Chase-away selection (ii)
Female choice for male trait occurs due to perceptual errors leading to poor quality offspring. Thus, females will evolve to run away from males with such traits. (iii)
Female choice for male trait results in a positive feedback loop favouring both, males with such trait and females that prefer them. (iv)
Males exploit pre-existing sensory bias in females. Females do not benefit by choosing such males, driving the evolution of females that discriminate against such males. Match the models to their appropriate description and choose the correct option.
