Transcript CONSERVATION BIOLOGY Lesson 6. CAUSES OF EXTINCTION.

CONSERVATION BIOLOGY
Lesson 6. CAUSES OF EXTINCTION. Habitat degradation and lost. Biological impacts of Climate
change. Overexploitation. Species invasions.
Lesson 7. ASSESSMENT OF SUITABLE ELEMENTS TO BE PRESERVED. Areas assessment.
Species assessment.
Lesson 8. DESIGN AND MANAGEMENT OF PROTECTED AREAS. Types of protected areas in
Spain. Design of protected areas. Management of protected areas. Ecological restoration.
Lesson 9. SPECIES MANAGEMENT. Threat factors and resources management. In situ
management. Ex-situ management.
Lesson 6. CAUSES OF EXTINCTION. Habitat degradation and lost. Biological impacts of Climate
change. Overexploitation. Species invasions.
6.4. OVEREXPLOITATION.
Definition:
Overexploitation means harvesting species from the wild at rates faster than natural
populations can recover.
The unsustainable use of natural resources and overexploitation, which occurs when harvesting
exceeds reproduction of wild plant and animal species, continues to be a major threat to
biodiversity.
Lesson 6. CAUSES OF EXTINCTION. Habitat degradation and lost. Biological impacts of Climate
change. Overexploitation. Species invasions.
6.4. OVEREXPLOITATION.
History of the overexploitation
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The first human populations are in equilibrium with the environment.
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The increase in population and technology (initially very primitive) caused an increase in
the exploitation of natural resources.
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This particularly affects large mammals and most recently the oceans.
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Today, the only regulation of this consumption are market laws. Moreover, conflict zones
are particularly vulnerable to overexploitation.
Lesson 6. CAUSES OF EXTINCTION. Habitat degradation and lost. Biological impacts of Climate
change. Overexploitation. Species invasions.
6.4. OVEREXPLOITATION.
History of the overexploitation:
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Sometimes they become unavailable and rare species are no longer economically viable.
Ceases exploitation (commercial extinction) and residual stocks recover.
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In other cases they reach threat categories IUCN and protected (western gray whale,
critically endangered. https://www.iucn.org/wgwap/)
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They can also be artificially exploited (fisheries, crop, etc.) and wild populations are free
from exploitation.
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Finally, there are overexploited species incidentally as a result of the exploitation of others.
Example: turtles in setting nets.
Lesson 6. CAUSES OF EXTINCTION. Habitat degradation and lost. Biological impacts of Climate
change. Overexploitation. Species invasions.
6.4. OVEREXPLOITATION.
Types of overexploitation:
Commercial exploitation.
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Market for wild products.
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Domestic substitutes are not identical and often sell for less.
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Market price increases as it become rarer.
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Located in remote places where laws do not operate effectively.
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Expensive technology is now available for commercial users (helicopters!). The disparity among
national currencies makes it profitable.
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Wild resources are frequently communal resources owned by no one and everyone (Tragedy of
the Commons, Garret Hardin, 1968).
Lesson 6. CAUSES OF EXTINCTION. Habitat degradation and lost. Biological impacts of Climate
change. Overexploitation. Species invasions.
6.4. OVEREXPLOITATION.
Types of overexploitation:
Commercial exploitation.
"Therein is the tragedy. Each man is locked into a system that compels him to increase his herd
without limit—in a world that is limited. Ruin is the destination toward which all men rush,
each pursuing his own interest in a society that believes in the freedom of the commons."
(Hardin, 1968)
https://www.sciencemag.org/content/162/3859/1243.full.pdf
Lesson 6. CAUSES OF EXTINCTION. Habitat degradation and lost. Biological impacts of Climate
change. Overexploitation. Species invasions.
6.4. OVEREXPLOITATION.
Types of overexploitation:
Subsistence exploitation.
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Exploit wild life to directly meet some portion of their personal needs for food, clothing,
fuel, and shelter.
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Limited by the number of people living in this place.
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Easily converted into commercial overexploitation.
Lesson 6. CAUSES OF EXTINCTION. Habitat degradation and lost. Biological impacts of Climate
change. Overexploitation. Species invasions.
6.4. OVEREXPLOITATION.
Types of overexploitation:
Recreational and scientific exploitation.
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Fishing and hunting in the main. Pros and cons under a conservation perspective. Taxes,
contribution to conservation, etc.
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Naturalist (ecotourism!): Indirect impact.
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Collecting (butterflies, orchids, corals, etc.)
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Scientific collection.
Lesson 6. CAUSES OF EXTINCTION. Habitat degradation and lost. Biological impacts of Climate
change. Overexploitation. Species invasions.
6.4. OVEREXPLOITATION.
Types of overexploitation:
Incidental and indirect exploitation.
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Common in fishing (bycatch). Example: dolphins in setting nets of a school of tuna.
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Trawling net for shrimp: 90% is bycatch.
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Traps on land (non-discriminant): gorillas, giant pandas, etc.
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Indirect: roads, antennas, fences, etc.; Livestock overgrazing; House cats predating birds.