1. Wildlife, Fisheries and Endangered Species
Chapter 14
Wildlife, Fisheries and Endangered Species

2. Why Preserve Endangered Species?
Justifications:
Utilitarian
Ecological
Aesthetic
Moral
Cultural

3. Traditional Single-Species Wildlife Management
Assumptions (Logistic Growth Curve)
Maximum Sustainable Yield (MSY): The population size that yielded maximum production
Minimal Viable Population: The goal for a threatened or endangered species

5. The Logistic Growth Curve
Def: The S-shaped growth curve that is generated by the logistic growth equation
In the logistic, a small population grows rapidly, but the growth rate slows down, and the population eventually reaches a constant size
Logistic Carrying Capacity:
The population size at which birth equals deaths and there is no net change in the population (number sufficient for resources available
Optimum Sustainable Population:
The population level that results in an optimum sustainable yield. The level is in some way best for the population, its ecological community, its ecosystem or the biosphere (sustained indefinitely)

8. More on the Logistic Growth Curve:
Small populations grow exponentially.
Competition slows the growth rate.
The greater the number of individuals, the greater the competition and slower growth rate.
Will eventually reach the “logistic carrying capacity”.
Number of individuals is sufficient for resources available
Births equals deaths per unit time
A population can be described simply by its total number, so all individuals are equal.
The environment is assumed to be constant.

9. Carrying Capacity
A logistic population is stable in terms of its carrying capacity; it will return to that number after a disturbance.
Carrying Capacity
Logistic carrying capacity
Optimum sustainable population

10. Problems… Carrying capacity varies with changes in the environment.
Requires accurate counts each year.
Requires the environment not vary or, if it does, that it vary in a way that does not affect the population.

11. Classic Cases of Wildlife Management or Mismanagement
The American Grisly Bear
The American Bison
A common goal in wildlife conservation is to “restore” the abundance of a species
Adequate information of the abundance of a species is very rare

12. Four Principles of Wildlife Conservation
Safety factor for population size which allows for limitations
Concern with the entire community and renewable resources
Ecosystem maintenance
Continual monitoring, analysis and assessment

13. Improved Approaches to Wildlife Management
Goal: achieve a minimum viable population in a minimum viable habitat
Time Series and Historical Range of Variation
- Time Series: an estimate of a population over a number of years
- Historical Range of Variation: the known range of abundances of a population over some past time interval
Age Structure as Useful Information
Harvests as an Estimate of Numbers
Catch per Unit Effort: estimates previous animal abundance. Assumes same effort by hunters.

15. Fisheries The Decline of Fish Populations
Can Fishing Ever Be Sustainable?
Past experience suggests that economically beneficial sustainability is unlikely for most wild populations
MSY: past management; often resulted in overfishing

19. The Current Status of Endangered Species
Red List
Endangered vs. Threatened
How a Species Becomes Endangered or Extinct
Local Extinction:
Occurs when a species disappears from a part of its range
Global Extinction:
Occurs when a species cannot be found anywhere
Survival of an endangered species
Depends strongly on the size of the ecological island the species lives on

24. Causes of Extinction Population Risk Environmental Risk
Natural Catastrophe
Genetic Risk

25. How People Cause Extinctions and Biological Diversity
Intentional hunting or harvesting
Disrupting or eliminating habitats
Introducing exotic species
Creating pollution

26. Trawling on Coral Reefs
Coral reef in the Florida Keys National Marine Sanctuary
Before and after trawling
Essentially nothing is left after the trawl has scraped the reef

27. The Good News
Many species have been successfully restored to an abundance
Success is achieved when the habitat is restored to conditions required by a species
The conservation of wildlife offers great rewards of long-standing and deep measure to people