NRES 348 — Lec 6: Applied Population Ecology

What is the main goal of sustainable harvesting?

Harvest a population at about the same rate that the population increases, so the harvest can continue over time.

What is compensatory mortality?

When one source of mortality replaces another, so the total mortality rate does not increase.

What is additive mortality?

When harvesting adds extra deaths on top of other mortality, increasing the total mortality rate.

What is inversity?

A negative relationship between population density & natality or recruitment. Lower density can increase survival & reproduction.

What is sustainable yield?

A level of harvest that can be recreated without causing the population to decline.

What is maximum sustainable yield (MSY)?

The largest amount of population growth that can be harvested sustainably, usually when the population is around K/2.

What 3 values are needed to estimate sustainable yield?

N = current population size

K = carrying capacity

r = intrinsic population growth rate

What is optimal sustained yield (OSY)?

A management approach that considers both ecological & socioeconomic factors instead of only maximizing the number harvested.

Why can harvest quotas be difficult to set?

Population size is hard to estimate, carrying capacity changes with the environment, & people may not always follow harvest limits.

What is the Allee effect?

A decline in fitness or per-capita population growth when population density becomes very low, such as when individuals have trouble finding mates.