Chapter 5 (Overharvest-Over exploitation)

Question 1

How does technology effect the harvest of wildlife? What types of increasing technology increase harvest on land, or on the water?

Answer 1

-Advances in technology increases the harvest of wildlife
-Things like guns, advanced fishing tools, more advanced hunting tools increase harvest

Question 2

What changes as harvest of a species goes from consumptive to a productive use value? Why is it bad for a species if an international market develops?

Answer 2

-The harvest of the species will increase
-The animals can be overharvested or kept in poor conditions while travelling or being harvested.

Question 3

Can you provide several examples of animals/parts that are traded on international markets?

Answer 3

Birds, fish, reptiles for pets

Question 4

What is the maximum sustainable yield? What is a general way to estimate this? Why is population growth highest at ½ K? Why might K change over time?

Answer 4

-The highest amount that can be harvested without decreasing the population
-Estimate population growth and carrying capacity, typically occurs when population is at ½ K
-Because there is enough of the population to reproduce while still have uncompetitive resources.
-The environment may change over time, due to seasonal changes or natural/human disasters.

Question 5

What characteristics of species may make it difficult to quantify the MSY?

Answer 5

-Hard to qualify for animals
-Species that migrate are more difficult to regulate
-Natural population may go through cycles

Question 6

Explain direct and indirect effects of harvesting on wild populations of species.

Answer 6

-Population decline
-Bycatch: species caught by accident
-Loss of prey

Question 7

How can intense harvest serve as a force of selection?
How might a species change its life history traits (age at first reproduction….) in response to intense harvesting pressure? Why does this happen? How might size be affected?

Answer 7

-Could make reproduction age start earlier
-Occurs because they may die before they are able to reproduce, so animals that reproduce quicker have their traits passed down
-may decrease average size of species

Question 8

Why did the catch of Cod in the Grand Banks region remain fairly constant, even though the population size was declining?

Answer 8

-Catch was constant because they were increasing catching effort, pop still declining

Question 9

How could you check to see what you shouldn’t order from a restaurant menu?…

Answer 9

You can look at seafoodwatch.org

Question 10

Why does purchasing (an already dead fish) contribute to the over-harvest?

Answer 10

Increases demand

Question 11

What is Bycatch? Why does it happen?

Answer 11

-When marine animals are caught in nets not meant for them.
-Changes in nets, supposed to allow escape, lost fishing gear, waiting death traps

Question 12

How are Dolphins affected by the Tuna fishery?

Answer 12

-Steals their prey
-May get caught up in the netting

Question 13

How did consumer pressure affect the Tuna Fishery? What Law was first used to help protect Dolphins from this Fishery?

Answer 13

-People did not want dolphins dying/getting injured
-AIDCP: (agreement on international dolphin conservation program) Dolphin safe tuna

Question 14

Overfishing may increase competition between fishermen – but also perceived competition with top predators. Why is this bad for other predators? (consider dolphins…)

Answer 14

-Predators will fight and kill each other. Fishermen will also kill these predators.

Question 15

Could you list the general changes that occur as a harvest industry develops from local consumptive use to international markets?
What does it mean for a species when an international market develops?

Answer 15

-Will dramatically increase demand, increase harvest

Question 16

Many of the species harvested for the wildlife trade have been harvested by humans for decades (or longer) why is this harvest more of a problem now?

Answer 16

-It is being harvested for productive use instead of consumptive, we are harvesting more than we need.

Question 17

What is commercial extinction? Why might this NOT prevent an overharvested species from being driven to extinction?

Answer 17

-The depletion of a population of a species to the point where people cannot catch enough of them to make a profit.
-This would just make the species more expensive so would increase incentive.

Question 18

Why are sharks threatened? What is the most prized part of a shark? Why is this wasteful?

Answer 18

-Overhunting
-Fins
-Don’t use the rest of the shark

Question 19

Why are practices of traditional Chinese medicine (some that have been practiced for centuries) now endangering the wild species used in these treatments? (when maybe they weren’t a problem before…)

Answer 19

-Seahorses, tiger bones, and rhino horns for curatives
-Never harvested them at such a demand