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Aquatic Sustainability (Ocean exploitation and degradation (Overfishing (E…
Aquatic Sustainability
Ocean exploitation and degradation
Overfishing
80% of fish stock exploited, overexploited
or depleted/recovering
Predatory fish reduced
Increased fish production, decreased stocks
Bycatch
E.g. Tuna and Dolphins
Tuna and dolphins swim together
Caught in purse net
Marine Mammals Protein Act addendum for Dolphins
Driftnets or gill nets banned in 1989
E.g. Shark: 100 million killed per year for shark fin soup
Commercial Whaling
Sealing
see slide section 3.1
Coral Reefs
Largest structures created by living organisms
Highly fragile, need specific habitat
Many different types
Fringing reefs
Barrier reefs
Atolls
See diagram on slide
See diagram on slide
Only 30% still healthy
Degradation from fishing:
Dynamite fishing
Cyanide fishing
Pollution from drainage pipes
Fertilizers
nitrogen, Phosphorus
Marine Pollution
Main Types of Marine Pollution
Petroleum
Made of various hydrocarbons
toxic compounds in petroleum
e.g. Exxon Valdez oil spill
e.g. deepwater horizon
Cleaning oil spills: High fatality rates for marine organisms
Preventing Oil spills:
Oil pollution act 1990
Single hulled tankers barred from US ports
Redesigning ships
Japanese owned freighter intentionally burned
Sewage sludge
Semi solid material after treatment
Primary treatment
secondary treatment
No dumping of sludge in ocean after 1981
DDT and PCBs
Once widely used
toxic
long life
Decline in bird populations
Thin eggshells
Mercury
Toxic to most living organisms
Neurological disorder
Bioaccumulation
Biomagnification
non point source pollution and trash
Plastics
Vast majority of marine debris
not readily biodegradable
Nurdles: small pre-production plastic pellets
Entangle fish, marine mammals and birds
Pacific garbage patch
Trash
Pesticides
Biological Pollution: non native species