Consider that a species of salmon lays 20,000 eggs per pair when it spawns and dies. At the end of five years, an average of one pair of mature salmon from this group of hatched eggs returns again to spawn in the parent stream (19,998 have died) . What is the per capita rate of increase?

A) 10,000, because there were that many eggs produced per parent fish (r)
B) 2,000, because this must be divided by five years
C) zero, because there is exact replacement of the previous generation
D) -2,000, because there was this much average die-off per year
E) -19,998, because there was this much total loss

Question

Valle Ayesta · Accepted Answer

Final Answer : C, Explanation :  The per capita rate of increase (r) is defined as the difference between the birth rate and the death rate, divided by the initial population size. In this case, since exactly one pair returns to spawn for each pair that dies, there is no net increase or decrease in the population over the five years. Therefore, the per capita rate of increase is zero.

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