3/10 (absent)

Question 1

What is the overall view on wildlife exploitation?

Answer 1

The majority of people accept hunting as a legitimate activity

Question 2

What is the difference between over-exploitation and sustainable exploitation?

Answer 2

Over-exploitation causes population to decline toward extinction (the rate of removal of individuals is greater than rate of growth) while sustainable exploitation allows for recurring yields while maintaining population at stable size (rate of removal is balanced by rate of growth)

Question 3

What are some basic aspects of exploitation?

Answer 3

• it removes individuals from a population and reduces abundance and density
• creates an oppotunity for growth to occur
• if rate of exploitation isn’t excessive, capacity for growht can counterbalance removals
• many rates of exploitation can be sustained over long periods of time (between no exp. and over-exp.)

Question 4

What are some examples of why exploitation is sustainable?

Answer 4

• when some individuals are removed from a population, the remaining individuals survive and reproduce better (as a result of density-dependence) and the population grows
• enhanced survival and reproduction compensates for the removals , population stabilizes at a reduced size
• on-going removals can be continued indefinitely

Question 5

What are the key roles of density dependence?

Answer 5

• Reductions in pop density can trigger:
  1. survival rates increase
  2. reproductive rates increase
  3. population growth is stimulated
• The resulting INCREMENT OF GROWTH can be harvested sustainably

Question 6

logistic growth and yield curve

Answer 6

… graph

Question 7

What is some essential information regarding the yield from a population

Answer 7

-to estimate the size of the sustainable yield of a pop. you need to know at least the 3 following values:
N (the population’s size or density)
K (the carrying capacity of the environ., expressed as an absolute # or density)
r (intrinsic rate of growth expected at N)

Question 8

What does N stand for? Where do the numbers for N come from?

Answer 8

N is the population’s size or density and it is estimated from censusing the population; can be expressed either as the absolute number of individuals or as their density

Question 9

What does K stand for? Where do the numbers for K come from?

Answer 9

K is the carrying capacity of the environment and is estimated from empirical observation or from allometric equations based on the body mass of the species

Question 10

What does r stand for? Where do the numbers for r come from?

Answer 10

r stands for the intrinsic rate of growth expected at N and is estimated from empirical observations (or from knowledge of K and N)

Question 11

How do wildlife managers become useful investors?

Answer 11

• they monitor an exploited population and estimate its size and rate of growth
• they advise on the size of the possible sustainable harvest, but the final decision on the actual harvest is often made by others (i.e. politicians)
• decision makers can choose to either harvest sustainably or overharvest (often in response to special interest groups that want higher yields)

Question 12

what is rN? How is it determined?

Answer 12

rN is the increment of growth;
rN=dN/dt
rN=SY

Question 13

What are some biological & social challenges associated with exploitation? (5)

Answer 13

• estimates of population size and growth are subject to error, key features of wild populations vary in unpredictable ways
• demand can be greater than the sustainable yield from a wild population
• political and economic pressures often cause decision makers to demand/endorse overharvesting
• individuals choose to ignore regulations and overharvest for selfish reasons
• numerically sustainable rate of exploitation can be ecologically unsustainable if it disrupts the ecosystem

Question 14

Which species can be harvested sustainably?

Answer 14

• any wild species of utilitarian value, if harvest is desired and socially acceptable
• variation in potential size and sustainable yield (species size potential varies)
• differences based on abundance and potential for population growth

Question 15

What is the key to sustainable harvesting? explain

Answer 15

regulation; harvesters and consumers will act in selfish interest unless constrained, laws and other coercive means show more sustainable harvesting

Question 16

What can managers do to achieve sustainability? (7)

Answer 16

Regulate following:

• number of permits available
• the per-hunter take
• where to harvest
• when to harvest
• how long to harvest
• whether to harvest selectively
• how to harvest

Question 17

What does regulating the take mean? What is the goal?

Answer 17

• limit the # of individual permits( ie by lottery)
• impose quota on # of animals taken by individual hunters
• Goal=limit the take to no more than (bag limit x number of hunters) which would be predicted to equal the SY

Question 18

How is the decision on where to harvest regulated?

Answer 18

• establish “closed areas” and limiting take to “open” areas
• sometimes the ratio of closed-to-open is important
• population in closed areas may be segment of pop. that produces the most of growth

Question 19

When to harvest? What are the main justifications of when seasons are open or closed? (5)

Answer 19

1. avoiding the breeding season
2. waiting for the young of the year to be independent
3. when harvesting is practical
4. when harvest is most valuable
5. when a targeted segment of pop. is available

Question 20

Why is it important to avoid breeding season?

Answer 20

• avoid disturbing animals when mating and rearing offspring

- open season after offspring are dependent

Question 21

How long to harvest

Answer 21

• setting the length of the season
• goal=allow harvesting to continue until it the predicted yield goal is taken
• depends on hunter success

Question 22

regulating how to harvest

Answer 22

• goal=reduce efficiency of hunter and insure harvesting is humane
• applied when predicted overharvesting or undue suffering

Question 23

What are some examples of regulating how to harvest

Answer 23

night-lighting, baiting, design of traps, archery equip., caliber of bullet etc.

Question 24

Selective harvesting

Answer 24

• harvest individuals that won’t contribute to the next years increment of growth
• possible when harvesters can distinguish between types of individuals (size, sexual characters etc.)

Question 25

Selective harvesting of the sexes

Answer 25

• some pops contain more males than needed to fertilize

- polygamous or promiscuous mating systems or unbalanced sex ratios

Question 26

What are some examples of animals that have selective harvesting based on sex?

Answer 26

white tailed deer & ring-necked pheasants