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Conservation Biology > Overexploitation > Flashcards

Overexploitation Flashcards

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1
Q

What is overexploitation?

A
  • harvesting of a species from the wild at a rate that is faster than natural populations can recover
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2
Q

What is maximum sustainable yield (MSY)?

A
  • greatest amount of a resource that can be harvested without damaging population (assumption is what is taken is replaced through pop growth)
  • sustainable yield is often an overestimate of what we can sustainably harvest
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3
Q

How commercial harvesting influence effective population size (Ne)?

A
  • you can change the age structure. Not all individuals are equal. If disproportionately catch adults or one sex for ex.
  • but this is not taken into account when estimating sustainable yield
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4
Q

What variables are used when calculating maximum sustainable yield ?

A
  • intrinsic growth rate (r) and carrying capacity (k)
  • these can vary due to changes in resources, changes in other factors which would make MSY calc incorrect over the long term
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5
Q

What is an effective population size?

A
  • the size of an ideal theoretical pop that would lose heterozygosity (H) at the same rate as the actual pop of interest
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6
Q

the basic formula for effective population size?

A

Ne = # breeding individuals in a population

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7
Q

What determines the effective population size? (Ne)

A
  • species
  • founder group size
  • breeding strategy
  • founder contributions to gene pool
  • rate of population growth
  • generation time
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8
Q

What are the two formulas utilized to understand how sex ratio and fluctuations in population size will influence Ne?

A
  1. Effect of fluctuation in pop size:
    1/Ne = 1/t (1/N0 + 1/N1……+ 1/N(t+1))
  2. Effect of variation in sex ratio:

Ne = 4NfNm/ (Nf+Nm)

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9
Q

Calculate the effects of fluctuations in pop size for bugs in a pond at four different generation times:

N0 = 1000, N1= 1000, N2= 50, N4= 1000, t=4

A

1/Ne = 1/4 (1/1000 + 1/1000 + 1/50 + 1/1000).

Ne = 173.91 individuals

***past bottlenecks affect current effective population size

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10
Q

Calculate the effects of fluctuations in population for fisher three generations:

N0= 10, N1 = 5000, N2= 50000

A

30? (not matching the other answers)

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11
Q

Calculate the effects of sex ratio on the Ne for a gag groupers pop with a current sex ratio of 1 male to 99 females, and N= 10,0000.

A

Ne = 4(9900)x(100)/ (9900+100) = 396 individuals

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12
Q

Calculate the Ne of a pop of fish that is experiencing demographic stochasticity, with a ratio of 75% males to 25% female, with an N= 5000.

A
  • f = 0.25 x 5000 =1250
  • m = 0.75 x 3750
  • Ne = 4(1250x3750)/ (1250+3250)
  • Ne = 3750
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13
Q

What is a minimum viable population?

A
  • for any given species, in any habitat, is the smallest isolated population having a 99% chance of remaining extant for 1000 years despite the foreseeable effect of demographic environmental and genetic stochasticity and natural catastrophes
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14
Q

Describe the relationship between minimum viable population and risk of extinction

A
  • non linear btwn extinction risk and pop size
  • MVP is the critical threshold density at which risk of extinction greatly increases
  • SO MVP is the SMALLEST number of individuals that can meet goal of long term persistence
  • *good as a warning sign that a pop is in trouble
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15
Q

Why are open access resources prone to overexploitation?

A
  • they are open access (everyone can use them)
  • there is no incentive for cooperation to prevent overexploitation bc others will overuse the resource (so you should too)
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16
Q

Give an example of the “Tragedy of the Commons”?

A
  • basically involved shared pastoral lands
  • multiple herds can graze the land
  • too many animals is a shared cost (overgrazing reduces the health of all animals that use land) but benefits (extra animals) are individual gains
  • so it is each herders best interest to maximize the number of animals he/she put son land (to maximize benefits before land is destroyed)
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17
Q

What is the “tragedy of the commons”?

A

describe a situation in a shared-resource system where individual users acting independently according to their own self-interest behave contrary to the common good of all users by depleting or spoiling that resource through their collective action.

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18
Q

What is overgrazing?

A
  • plants exposed to intensive grazing/grazing over long periods, and cannot recover, leading to biodiversity losses / damage to ecosystem

**Tragedy of commons is an example of this

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19
Q

What aresome examples of negative impacts of overgrazing?

A
  • livestock that are poorly managed
  • wild native grazers in areas that have become too fragmented to support them
  • overgrazing damage reduces the productivity of the area further , decreasing the number of grazers it an support
  • it can also increase the spread of invasive plants, further damaging the ecosystem
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20
Q

How can environmental factors in a marine setting influence population size? (broadly)

A
  • water temp is correlated with fluctuations in pop size for various species
  • catch size fluctuates with indices of atmospheric circulation and water temp
  • climate change could influence atmospheric circulation and water temp , impacting catch size of future
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21
Q

How are warming oceans reshaping fisheries?

A
  • Temperate and subtropic oceans: as open temp increases, catch comp in subtropic and temperate areas slowly changed to include more warm water sp and fewer cool water sp
  • Tropics: catch comp changed and stabilized, likely bc there are no sp with high enough temp pref to replace those that declined

**could lead to loss of traditional fisheries, decrease in profits, jobs, conflicts over new fisheries emerge bc of distribution shifts, food security concerns and a large decrease in catch in the tropics

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22
Q

Are marine fisheries being over exploited rn?

A
  • YEP
  • 80% of em
  • Why? Commercial fisheries use maximum sustainable yield estimates to support current fishing targets , even as fishing efforts change species Ne Values
  • government typically sets targets too high to protract business interests, jobs and economy (bc it is open resource)
  • fish migrate across international borders, increasing diff of regulation
  • illegal fishing adds to these issues
23
Q

Explain the overfishing and regime shift in the Gulf of Maine and Georges bank (1990s).

A
  • bottom up changes via climate change and top down changes from cod over fishing led to huge changes in the ecosystem
  • increased meltwater, increased salinity, changed ocean circulation patterns
  • Beaufort gyre decreased in size bc of warm saline Atlantic water entering Barents sea, this led to an increased flow of salinity water out of Canadian shelf waters
  • Once the low salinity water reached Georges Bank, it caused an ecological regime shift in plankton, plankton stayed closer to surface and exp greater PS , increasing their biomass
  • More phytoplankton means more zooplankton and herring which feed on zooplankton
  • All at the same time cod over fishing was happening, leading to the fishery to collapse, accelerating the previously mentioned regime shift
24
Q

Which of the following statements DOES NOT match your
understanding of overfishing?

A. Population sizes of commercially valuable fish fluctuate over
time due to predictable changes in water temperature

B. One reason it is difficult to regulate fisheries is because fish
move across international borders

C. Maximum sustainable yields are an accurate way of controlling
fish exploitation

D. Overfishing of cod contributed to a regime shift in the food web
of Georges Bank in the 1990s

E. More than one of the above

A

C. Maximum sustainable yields are an accurate way of controlling fish exploitation

**- sustainable yield is often an overestimate of what we can sustainably harvest

25
Q

What is by catch?

A
  • non-target species being caught

* *includes bottom trawling with land damage cold water reefs/benthic ecosystems

26
Q

What is the survival rate like for by catch sp? What species are at greatest risk?

A
  • between 25-75% of all by catch dies

- organisms at risk = skates rates, pelagic birds, sea turtles, dolphins

27
Q

What did public outcry over dolphin drownings lead to?

A
  • safer nets
  • less dolphin deaths
    L> now tuna are harvested using dolphin safe nets which is why tuna is more expensive now
28
Q

What is water stress?

A
  • surface water used by humans via domestic, industrial or agricultural
  • > 40% of available water
  • *basically demand for water exceeds the available amount

**2/3 global populations will experience water stress by 2050

29
Q

What is water over drafting?

A

when ground water usage exceeds amount of aquifer recharge, causing ground water levels to decline over time

30
Q

How does rainfall and temperature affect water availability?

A
  • low rainfall = low stream flow

- high temp = greater need for water

31
Q

How does climate change impact avail water?

A
  • lifting cloud bases means less water added to high elevation habitats
  • increase glacial melt = changes to stream flow (impacts down stream habitats )
32
Q

Why are Mediterranean climates at risk for water over drafting and stress? How will climate change inful this?

A
  • they naturally are water scarce
  • includes areas of high agricultural potential, centres of wine production
  • high human pop increases stress and can result in overdrafting
  • with climate , there could be greater summer droughts and higher temperatures, meaning greater arid and thus higher water stress
    L> this will be exasperated with increased water use as temps increase
33
Q

What is deforestation? What is overlogging?

A
  • deforestation: removal of tree stands and conversion of land to other habitats
  • overlogging: over exploitation of forests that leads to unsustainable deforestation and permanent habitat destruction
34
Q

How does deforestation occur?

A
  • habitat is converted to farm or ranch lands, or to urban habitats
  • can also result from desertification as a result fo shifting cultivation (original intent was not permanent loss of the forest but that is the outcome)
35
Q

How does overlogging happen?

A
  • overlooking occurs when the original intent was often too sustainably log a forest (many legal logging operations)
  • but overlooking also occurs in areas due to illegal logging operations
36
Q

Where is overlogging a huge problem? What does this cause?

A
  • Tropical rainforests
  • many sp found here (50% of all sp)
  • they are warm adapted and sensitive to drought
  • developing countries over log to sell on global market
  • logging requires roads etc causing fragmentation of non logged areas
  • desertification can occur if forest in more arid areas becomes damaged
  • trees are large carbon pools, so deforestation is the second largest cause of global climate change
37
Q

Explain the ecosystem feedback happening in the Amazon.

A
  • moisture recycling
  • evapotranspiration from one area produces moisture for rainfall in the next
  • moisture recycling across Amazon to Andes
  • If Amazon dries out enough that loses forest in an area, could cascade through entire system
  • decrease in forest cover over large areas and increased Cos via decomposition , increases in greenhouse gases in atmospheric = positive feedback
38
Q

What does REDD stand for?

A

Reduced emissions from deforestation and degradation

39
Q

What is REDD?

A
  • allows reductions in deforestation to be quantified, rewarded and traded on Carbon Market
  • this is huge since, many tropical countries were originally excluded from Carbon markets set by the Kyoto Protocol (developing countries exempt from emission reductions)
    L>COP-11 (Mtl, 2005); tropical forest countries pushed for deforestation to be include din emissions framework
40
Q

What are two critical challenges of REDD?

A
  1. Leakage
    L> risk that deforestation from one country will move into neighbouring ones (aka no decrease in emissions if illegal operations just country hop)
  2. Equitable distribution of revenues
    L> nations participate in REDD, but local ppl are the ones impacted by emissions reduction strategies
    L> local ppl should receive most of rewards of carbon payments but national governments are the ones getting $
41
Q

Which of the following is an example of water overdrafting?

A. A town in central Ontario is co-opting about 55% of the
available ground water for its own use.

B. A company wishes to build on a wetland so they drain it.

C. A logging operation is not very careful with their equipment
and pollute a local river.

D. A water company removes more water from an
underground aquifer than is replaced by rainwater, causing
the size of the aquifer to shrink over time.

E. More than one of the above.

A

D. A water company removes more water from an
underground aquifer than is replaced by rainwater, causing
the size of the aquifer to shrink over time.

42
Q

What is bushmeat?

A
  • meat from non domesticated mammals, reptiles, amphibians and birds hunted for food in tropical forests
  • typically this sustains local ppl via food provisioning instead of purchasing from markets BUT it is not always sustainably harvested
43
Q

What factors can influence bushmeat use?

A
  • civil conflicts can shut down supply chains, increasing the amount of bushmeat harvested when other food isn’t avail
  • logging can increase number of ppl in the area (and increase access to bushmeat) , increasing the chance of overexploitation
  • logging infrastructure can connect hunters/harvesters to areas where meat is sold
  • many of the sp are considered exotic, once they show up in global markets, this increases the demand for them
44
Q

Explain the relationship between bushmeat and the international wildlife trade.

A
  • Bushmeat sold one foreign markets is part of the issue with IWT but these animals are usually dead before getting on the market
  • live animals are sold for fur, food and as pets, plants sold as decoratives
  • illegal and legal trade of wildlife is valued at >10billion per year
    -endangered sp are often deliberately mislabeled and sold under a diff name in markets
  • illegally traded sp are a source of invasive
    L> can lead to transmission of disease btwn exotics and local sp; and exotics and humans
45
Q

What happens during the shipping and collection process of exotic animals?

A
  • usually many more die than those that are successfully shipped
46
Q

Who are the major exporters and importers for exotic animals?

A
  • exporters: developing countries, esp tropical ones.

- Importers: Canada, USA, China, EU, Japan, Singapore etc

47
Q

Give an example of an exotic animal market sp

A
  • chinchillas were over harvested for fur and pets, now they are critically endangered

** more endangered tropical birds in captivity than the wild

48
Q

Why are rhinos in the exotic animal market?

A
  • for their horns
  • used in traditional medicine as health supplement, virility booster, or hangover cure but they have no actual medicinal value
  • baby rhinos are killed for mucous membranes
  • sold for high values

**many endangered animals are killed to obtain heir organs or body parts for medicine or aphrodisiacs

49
Q

What is CITES?

A
  • Convention on International Trade in Endangered Species
50
Q

What did CITES do with the ivory trade?

A

-instituted an international ban
- led to large decreases in illegal harvesting of ivory
- lasted until 1997
L> restricted trade became permitted instead..leading to an increase in illegal harvesting for countries that could trade internationally
L> ex China was given permission to be a destination for ivory being traded in 2000s…led to a large smuggling operation. Eventually china banned all ivory trade in 2017

51
Q

How can species losses affect communities ?

A
  • directly and indirectly
  • trophic cascades: when the rate of consumption at one trophic level results in a change of sp abundance / composition at lower trophic levels
    L> ex sea otters being hunted t o near extinction for fur trade, increasing sea urchin numbers which removed kelp forests (these are habitat for many sp)
52
Q

What are some ways overexploitation can be stopped?

A
  • conservation project sneed to be linked with education, esp of local pops in a real with species at risk
  • commercial practices need to be certified as sustainable (so ppl need to be willing to pay greater prices)
  • people need to obey regulations
  • update technology to reduce by catch and ban destructive harvesting
  • use science to inform maximum yield and take into account effective pop sizes not actual sizes when determining yield numbers
53
Q

Which of the following is NOT correct regarding
overexploitation?

A. It can result from a lack of regulation over open access
resources, but it can also result from people failing to heed
regulations that are in place

B. The disruption of food distribution networks due to civil conflict,
can result in overexploitation of local food resources.

C. Overestimating maximum sustainable yield can result in
overexploitation of the species in question.

D. Bycatch from commercial fishing can cause overexploitation of
these species, but this can be solved by returning these
organisms to the ocean when they are accidentally caught.

E. None of the above

A

D. Bycatch from commercial fishing can cause overexploitation of
these species, but this can be solved by returning these
organisms to the ocean when they are accidentally caught.

Conservation Biology (13 decks)

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