ExtinctMammals

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Extinct Marine Mammals

Past Extinctions

Causes

Effects

On Humans

• Overexploitation seems to be the main issue – loss of fish from overfishing and poor practices can destroy ways of life, jobs, industries, etc. (Read)

• Marine mammals are often caught as bycatch

• Unregulated harvest

• new and innovative solutions to this problem are required to take account of the socioeconomic conditions experienced by fishermen” (Read)

• Issue of regulation versus deregulation – looking at pros and cons of regulation seeing as it costs a lot, but is significant in saving a species (Read)

o Regulation = politically unpopular (Read)

• Poverty and the collapse of other industries can lead to abrupt changes in local fishing conditions – may start to prey on marine mammals once their value as food and bait is noticed (Read)

o Unregulated and usually unsustainable (Read)

o Peruvian dolphins; anchovy fisheries collapsed so people started hunting dolphins; led to depletion in population (Read)

On Ecosystems

• World’s fisheries are not only impacting marine mammals, but the trophic structure as well – by capturing huge amounts of fish they are causing changes in energy pathways and species numbers (Merritt)

o Affect marine mammals adversely

• Loss of biodiversity/ decline in mammals can cause population imbalances in other species (Munday)

Connection to Coral Reefs

• Lots of extinctions/endangerment is caused by loss of habitats – coral reefs have declined 40 percent world wide (Zimmer)

o Partly a result of global warming (Zimmer)

• Loss of coral due to bleaching/global warming have changed the structure of coral reef ecosystems and communities – lead to changes in the fish communities, which lead to more changes through the trophic levels (Munday)

• Direct relationship between abundance of coral and abundance of coral dwelling fish (Munday)

Prevention

• Oceans, unlike terrestrial ecosystems, are still mostly intact – could easily bounce back if they’re taken proper care of (Zimmer)

o Somewhat uncertain about this though – it’s much harder to track the health of ocean mammals than it is of terrestrial ones (Zimmer)

• Not irreversible yet (Zimmer)

• Regulations for overharvesting of fish – mammals such as dolphins often become entangled in nets and will be benefited by such regulation (Zimmer)

• Still time for humans to stop the damage with effect programs that “limit the exploitation of the oceans” (Zimmer).

• Slowing extinction = cutting back on carbon emissions (Zimmer)

References

Read AJ. 2008. The Looming Crisis: Interactions between Marine Mammals and Fisheries Journal of Mammalogy. Journal of Mammalogy 89:541–548.

Munday PL. 2004. Habitat loss, resource specialization, and extinction on coral reefs Global Change Biology. Global Change Biology 10:1642–1647.

Zimmer C. 2015. Ocean Life Faces Mass Extinction, Broad Study Says the New York Times [Internet]. the New York Times [Internet]. Available from: http://www.nytimes.com/2015/01/16/science/earth/study-raises-alarm-for-health-of-ocean-life.html?_r=0