Question

What would be the best method to measure the total population density of the number of fishes in river and why?

Answer 1

Total number is again not an easily adoptable measure if the population is huge and counting is impossible or very time-consuming. Sometimes, for certain ecological investigations, there is no need to know the absolute population densities; relative densities serve the purpose equally well. For instance, the number of fish caught per trap is good enough measure of its total population density in the lake.