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

2. Wildlife, Fisheries, and Endangered Species
Common history of exploitation, management and conservation
When saving a species, what is it we really want to save?
1. A wild creature in a wild habitat
2. A wild creature in a managed habitat.
3. A population in a zoo.
4. Genetic material only.
Many reasons for wishing to save endangered species.
Policies and actions are in place

3. Single-Species Wildlife Management Approach
Conservation and management often viewed each species as a single population in isolation.
1. The population could be represented by a single number, its total size.
2. Undisturbed by human activities, a population would grow to a fixed size, called the “carrying capacity”.
3. Environment, except for human-induced changes, is constant.

4. This perception illustrated by the S-shaped logistic growth equation.
Two goals resulted:
1. For a species we intend to harvest: maximum sustainable yield (the size of a natural population at which it produces a maximum rate of increase, typically at half the carrying capacity.)
2. For a species we intend to conserve: remain at its carrying capacity
This approach failed.
None of the assumptions were true.
Population cannot be represented only by a single number.
Do not remain at a fixed carrying capacity.
The environment is not constant.

6. 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 (smallest population size at which it can exist without facing extinction)

7. 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”.
At this level, the # 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 #.
Therefore, all individuals are equal.
The environment is assumed to be constant.

8. Carrying Capacity Has three definitions.
1. Logistical carrying capacity- the # of individuals is just sufficient for the available resources.
2. An abundance at which a population can sustain itself w/o any detrimental effects that would decrease the ability of that species to maintain that abundance.
3. Optimum sustainable population- the maximum population that can be sustained indefinitely.
Another key concept is that the population size that provides the max sustainable yield
Exactly one-half of the carrying capacity.
Other estimating MSY will lead to overharvesting.

11. The Grizzly Bear An endangered species
US Fish and Wildlife Service must meet the requirements of ESA (Endangered Species Act)
Became endangered as a result of hunting and habitat loss.
Removed because dangerous to humans and livestock

12. Restore to what? Past abundance (this is unknown)
Also lack good estimates of present abundance
Estimates include 1,200 in contiguous states, 32,000 in Alaska and 25,000 in Canada
Based on Lewis and Clarks records (and a number of assumptions)
The # of grizzly bears in 1805 in the US was 12,000
Another approach is to ask what the minimum viable population is.

13. The American Bison Brought close to extinction for 2 reasons
Hunted to make coats that were fashionable in Europe.
Killed as part of a warfare against the Plains peoples.

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 with the entire community of organisms and all the renewable resources.
Maintenance of the ecosystem of which the wildlife are a part.
Continual monitoring, analysis, and assessment.
Principles broaden the scope from a narrow focus on a single species to inclusion of the ecological community and ecosystem.

15. Time Series and Historical Range of Variation
set of estimates over a # of years.
Historical range variation-
the known range of abundance of a population of species over some past time interval
E.g. American whooping crane

17. Age Structure as Useful Information
An additional key to successful wildlife management.
E.g. salmon from the Columbia River, WA
Shift in catch towards younger ages, along with an 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

18. Harvests as an Estimate of Numbers
Another method of estimating animal populations is to use the # harvested.
Previous animal abundance can also be estimated by
Catch per unit effort
Assumes same effort by all per unit time (same tech)
So if you know the total time spent in hunting and catch per unit effort, you can estimate total population
E.g. bowhead whale

20. Fisheries Fish are an important food source
16% of the world’s protein
Continental shelves provide 90% of fish harvest
Areas of high algae production to support food chain
Upwelling

22. Fisheries
The world’s fish harvest has increased greatly since the middle of the 20th century
Increase in # of boats
Improvements in technology
Increases in aquaculture production

27. 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.

30. The Decline of Fish Populations
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

33. 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”

35. 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.

36. 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
E.g. Atlantic salmon fisheries cause water pollution and loss of genetic diversity

37. The Current Status of Endangered Species
The # 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

39. The Current Status of Endangered Species
The term endangered species as defined by the ESA
“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.”

40. 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

41. How a Species Becomes Endangered and Extinct
Rate of extinctions has varied over geologic time
From 580 million years ago until industrial revolution about one species per year
Rate of evolution of new species =or > the rate of extinction
Average longevity of a species 10 million years
Other periods of “punctuated extinctions”

45. How People Cause Extinctions and Affect Biological Diversity
By hunting or harvesting.
By disrupting or eliminating habitats.
By introducing exotic species.
By creating pollution.

46. How People Cause Extinctions and Affect Biological Diversity
The IUCN estimates 75% of the extinction of birds and mammals since 1600 have been caused by humans.
Current extinction rate estimated to be 1,000 times greater than extinction rate in Pleistocene

47. Good News Species whose status has improved Elephant seal Sea otter
Many bird species effects by DDT, including bald eagle, brown pelican, white pelican, osprey and peregrine falcon.
Blue whale
Gray whale

48. Can a Species be too Abundant?
Sea lions now number 50,000 and have become a problem in S.F. and S.B. Harbors
Mountain lions in California
Both mountain lion and human population growing
People building in lion habitat
Attacks more common

49. The Kirtland’s Warbler and Environmental Change
Many species are adapted to natural environmental change.
If change eliminated the species can become endangered
Kirkland’s warbler in Michigan
From found to be declining
Nest in jack-pine woodlands that are between 6-12 years old

51. The Kirtland’s Warbler and Environmental Change
Jack pine adapted to fire
Cones open only after they are heated
Trees intolerant of shade
Abundance of dead branches
Kirkland’s warbler requires change at short intervals
Fire approximately every years

53. The Kirtland’s Warbler and Environmental Change
Fire suppression became the practice in 1927 and area replaced with economically useful species.
Now the Recovery Plan calls for prescribed burns

54. Ecological Islands and Endangered Species
An ecological island
an area that is biologically isolated, so a species living there cannot mix w/ any other population of the same species.
Mountain tops
Ponds
Real geographic islands

58. Ecological Islands and Endangered Species
Almost every park is a biological island.
How large must an ecological island be to ensure survival of a species?
Depends on species requirements

59. 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 hare a pest to the tree
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