Which one of the following methods is best suited to estimate the population size of fish?

Correct option is D

The Mark-Recapture Method (also called the Lincoln-Petersen Index) is the most effective technique for estimating the population size of fish, particularly in aquatic ecosystems where direct observation is difficult.

 Mark-Recapture Works:

1. A sample of fish is captured from the water.

2. The captured fish are marked (e.g., with a tag, fin clip, or dye) and released back into their habitat.

3. After some time, another random sample of fish is captured.

4. The proportion of marked fish in the second sample is used to estimate the total population using the formula:

   $$N = \frac{M \times C}{R}$$​ 

   Where:

   • N = Estimated population size
   • M = Number of marked individuals released
   • C = Total individuals caught in the second sample
   • R = Number of marked individuals recaptured

 Mark-Recapture is Ideal for Fish:

• Fish are mobile and difficult to count directly.
• It provides statistical accuracy in estimating populations.
• Works well in rivers, lakes, and marine ecosystem

Additional Information

• Option (1) Camera Trap (Incorrect)

  • Works best for terrestrial wildlife (e.g., tigers, leopards, deer) but not effective in water.

• Option (2) Line Transect (Incorrect)

  • Suitable for large mammals and birds in open habitats, but not for fish in water.

• Option (3) Point Count (Incorrect)

  • Used for birds and stationary animals, but not for mobile fish populations.