Question

Students studying a population of salamanders in a vernal pool mark each salamander caught as it's entering the pool. During the first spring migration to the pool, the students mark 200 salamanders. The following year, they again capture 200 salamanders. Of these, 20 were from the previous year. Students use this information to calculate that they captured ________ of the total population and that the total salamander population in their pool is about ________.

Answer 1

Using the mark and recapture technique and given data, the students captured 10% of the total salamander population, and estimated the total population to be approximately 2,000 salamanders.

Step-by-step explanation:

The student has employed the mark and recapture technique to estimate the size of a salamander population in a vernal pool. The calculation uses a simple mathematical formula: Population Size (N) = (number of individuals marked first time × total number of second catch) ÷ number of marked individuals in the second catch. In the given example, the students marked 200 salamanders initially and in the following year caught another 200, out of which 20 were marked from the first year.

To calculate the population estimate: N = (200 × 200) ÷ 20, which simplifies to N = 40,000 ÷ 20, resulting in N = 2,000. So, the students captured 10% (200 out of 2,000) of the total population, and the total salamander population is approximately 2,000 individuals.

It's important to note that this method has limitations. Factors such as behavior changes after marking (avoidance or attraction to traps) and potential harm caused by marking could affect the accuracy of the estimate. Nevertheless, the mark and recapture technique remains a valuable tool for ecologists to estimate wildlife populations, alongside other methods like electronic tracking and analysis of commercial data.