1. Chapter 13: Wildlife, Fisheries and Endangered Species

2. Overview Traditional Single-Species Wildlife Management
Improved Approaches to Wildlife Management
Fisheries
Endangered Species: Current Status
How a Species Becomes Endangered and Extinct
The Good News: We Have Improved Some Species
Can A Species Be Too Abundant?
How People Cause Extinction and Affect Biological Diversity
Ecological Islands and Biodiversity
Using Spatial Relationships to Conserve Endangered Species

3. Single-Species Wildlife Management
Each species viewed as a single population in isolation
Assumptions:
Population only represented by a single number- total size
Population would grow to its carrying capacity
Environment, except for human-induced changes, is constant

4. Single-Species Wildlife Management
This perception illustrated by the S-shaped logistic growth equation
Two management goals resulted:
For a species we intend to harvest: maximum sustainable yield (MSY)
For a species we intend to conserve: keep population at its carrying capacity

6. Single-Species Wildlife Management
This approach failed because none of the assumptions were accurate
Population cannot be represented only by a single number
Population does not remain at a fixed carrying capacity
The environment is not constant

7. Single-Species Wildlife Management
Necessary to include an ecosystem and landscape context for conservation and management
New goals:
For a species to be harvested: sustain a harvestable population in a sustainable ecosystem
For a species that is threatened or endangered: minimum viable population

8. Logistic Growth Curve Include the following ideas:
A population that is small in relation to its resources grows at a nearly exponential rate
Competition among individuals in the population slows the growth rate
The greater the # of individuals, the greater the competition and the slower the rate of growth
Eventually, a point is reached, called the “logistic carrying capacity”

9. Logistic Growth Curve Using this growth curve:
The number of births in a unit time equals the number of deaths, and the population is constant.
A population can be described simply by its total number
Therefore, all individuals are equal
The environment can be assumed to be constant

10. Carrying Capacity Three definitions Logistical carrying capacity-
Number of individuals is just sufficient for the available resources
An abundance at which a population can sustain itself without any detrimental effects that would decrease the ability of that species to maintain that abundance
Optimum sustainable population-
Maximum population that can be sustained indefinitely

11. Logistic Growth Curve Maximum sustainable yield (MSY)
Exactly one-half of the carrying capacity
Other estimating MSY will lead to overharvesting

14. Improved Approaches to Wildlife Management
Four principles of wildlife conservation
A safety factor in terms of population size, to allow for limitations of knowledge and the imperfections of procedures
Concern w/ the entire community of organisms and all the renewable resources

15. Improved Approaches to Wildlife Management
Maintenance of the ecosystem of which the wildlife are a part
Continual monitoring, analysis, and assessment

16. Time Series and Historical Range of Variation
Set of estimates over a number of years
Historical range variation
Known range of abundance of a population of species over some past time interval
Ex: American whooping crane

18. Age Structure as Useful Information
Additional key to successful wildlife management
Ex: Salmon from the Columbia River, WA
Shift in catch towards younger ages
Overall decline in catch
Suggests that the fish were being exploited to a point at which they were not reaching older ages
Early sign of overexploitation

19. Harvests as an Estimate of Numbers
Number harvested- method of estimating animal populations
Previous animal abundance can be estimated by catch per unit effort
Assumes same effort by all hunters/fisherman per unit time
If total time spent hunting and catch per unit effort is known, population can be estimated
Ex: Bowhead whale

20. Fisheries Fish are an important food source Continental shelves
16% of the world’s protein
6.6% of food in North America
Continental shelves
Only 10% of ocean area
Provide 90% of fish harvest
Areas of high algae production to support food chain
Upwelling

22. Fisheries
World fish harvest has increased greatly since the middle of the 20th century
Increased number of boats
Improved in technology
Increase in aquaculture production

24. The Decline of Fish Populations
Evidence that fish populations were declining came from the catch per unit effort
Suggests fishing depletes fish quickly
About 80% decline in 15 years
Commercial fisheries are mining a resource not sustaining it

26. The Decline of Fish Populations
Ex: Chesapeake Bay
Famous for oysters and crabs
Breeding and spawning ground for many commercially valuable species
Food webs very complex
Also influenced by runoff, introductions, development, alteration in salinity

29. The Decline of Fish Populations
Crisis has arisen for one of the living resources most subjected to science-based management
Management based on logistic growth curve
Fisheries subjected to the “tragedy of the commons”

31. The Decline of Fish Populations
Fishing gear can be destructive to habitat
Ground-trawling equipment destroys the ocean floor
Long-line fishing kills sea turtles and other non-target surface animals
Large tuna nets have killed dolphins

32. Can Fishing Ever be Sustainable?
Few wild biological resources can sustain a harvest at a level that meets even low requirements for a growing business
We can turn to farming fish (aquaculture)
Important food source in China, growing worldwide
Can create environmental problems
Ex: Atlantic salmon fisheries cause water pollution and loss of genetic diversity

33. Endangered Species: Current Status
Number of species listed as threatened or endangered increasing
IUCN maintains a list known as the Red List
20% of all know mammals at risk
31% of amphibians
3% of fish
12.5% of plants recently extinct or endangered

35. Endangered Species: Current Status
The term endangered species as defined by the Endangered Species Act
“Any species which is in danger of extinction throughout all or a significant portion of its range…”
With the exception of insect pests
The term threatened species
“Means any species which is likely to become an endangered species w/in the foreseeable future throughout all or a significant portion of its range.”

36. How a Species Becomes Endangered and Extinct
Local extinction
Occurs when a species disappears from a part of its range but persist elsewhere
Global extinction
Means a species can no longer be found anywhere

38. How a Species Becomes Endangered and Extinct
Rate of extinctions has varied over geologic time
From 580 million years ago until 1800s, ~1 species per year went extinct
Rate of evolution of new species = or > the rate of extinction
Average longevity of a species 10 million years
Other periods of “punctuated extinctions”

40. Causes of Extinction Population Risk Environmental Risk
Problem for species in low abundance
Environmental Risk
Variation in physical or biological environment
Natural Catastrophe
Sudden change in the environment
Genetic Risk
Reduction in genetic variation

41. The Good News…
Thanks to people, many previously endangered species have recovered
Aleutian goose
Elephant seal
Sea otter
Blue whale
Bald eagle
Osprey

43. Can a Species Be Too Abundant?
Protected animals can become locally overabundant
Sea lions in San Francisco Harbors
Sun themselves on boat
Pollute water with feces
Mountain lions in CA
People living in lion hunting grounds
More frequent human attacks

44. How People Cause Extinctions and Affect Biological Diversity
Hunting or harvesting
Disrupting or eliminating habitats
Introducing exotic species
Creating pollution
75% of Extinctions since the 1600s have been caused by humans

45. Ecological Islands and Endangered Species
Areas that are biologically isolated
Examples: islands, Small city parks (ex: Central Park in NYC) and large nature preserves are both isolated

46. Ecological Islands and Endangered Species
How large must an ecological island be to ensure survival of a species?
Depends on species requirements

47. Using Spatial Relationships to Conserve Endangered Species
Red-cockaded woodpecker
An endangered species
Nests in old dead or dying pines
Feeds on pine bark beetle which are a pest to the tree

48. Using Spatial Relationships to Conserve Endangered Species
A new approach to conservation
Overlay a map of one’s habitat requirements over a map of the other’s
Co-occurrence can be compared and allow maintenance of all three specie