ExtinctMammals

Extinct Marine Mammals

Conditions that alter marine mammal environment can stress and bottleneck species, leading to extinction through many possible causes

Past Extinctions

• Basilosaurus (Gingerich)

• • Thought to be reptile, yet was discovered to be a prehistoric whale

• • very large and primitive blue whale ancestor

• Caribbean Monk Seal (King)

• • closely related to Hawaiian and Mediterranean Monk Seals

• • overhunting for oil, overfished food source

• • Extinct about 1986, last sighted near Jamaica in 1952(King)

• Japanese Sea Lion (Aurioles)

• • extinct in 1970s

• Baiji (Fisheries)

• • Considered to be Functionally Extinct

Causes

• Coral Bleaching

• Increase in ocean temperatures

• increased water turbidity

• overfishing/overexploitation

• predatory inflation

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

Fisheries, NOAA. "Chinese River Dolphin / Baiji (Lipotes vexillifer)  :: NOAA Fisheries". www.fisheries.noaa.gov. Retrieved 29 February 2016.

Aurioles, D. & Trillmich, F. (IUCN SSC Pinniped Specialist Group) (2008). Zalophus japonicus. In: IUCN 2008. IUCN Red List of Threatened Species. Retrieved 29 February 2016.

King, J. (1956). "The monk seals (genus Monachus)". Bull. Brit. Mus. (Nat. Hist) Zool. 3: 201–256.

Gingerich, Phillip D. 2007. Basilosaurus Cetoides. Encyclopedia of Alabama. Available from: [1]

Les Kauffman and Kenneth Mallory (eds).1984. Grew out of a public lecture series entitled 'Extinction: saving the sinking ark,' held in Boston, Massachusetts, at the New England Aquarium during the fall of 1984.

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