Chapter 11 - Sustaining Aquatic Biodiversity

Many marine species are dissapearing

due to overfishing, pollution, habitat destruction and degredation

Coastal Wetlands

half of the worlds ___ have disappeared since 1800

70% of coral reefs could be gone by 2050

due to increasing ocean temp, ocean acidification, sediment runoff and overfishing

Benthic habitats the combined size of India and Brazil

are being disturbed or destroyed by trawling and dredging every year (150 times larger than annual forest clearout)

60% of the worlds large rivers

are strongly or moderately fragmented by dams, diversions or canals

Overfishing is a result of 3 items

Tragedy of the commons, bycatch, destructive fishing methods

Bycatch

unintentionally caught species

Destructive fishing methods

trawling, drift nets, longlines

Nonnative species

displacement of native species by exotic species

80% of marine pollution

comes from land runoff

Ocean Acidification

as a result of CO2 absorbtion

Florida Everglades biodiversity loss

due to water diversion, development, agricultural runoff and introduced species (burmese python)

The Great Lakes biodiversity loss

due to invasive species (zebra mussel and sea lamprey)

Lake Victoria biodiversity loss

due to invasive species (Nile Perch), agricultural runoff and overfishing

1st strategy to protect and sustain waterways

use comprehensive land-use planning

2nd strategy to protect and sustain waterways

prevent and control invasion of exotic species

3rd strategy to protect and sustain waterways

minimize disruption of water flow

4th strategy to protect and sustain waterways

protecting and creating spawning sites

Fishery regulation (1st method for using fisheries more sustainably)

set, monitor and enforce quotas

Economic approaches (2nd method for using fisheries more sustainably)

reduce or eliminate subsidies

Bycatch (3rd method for using fisheries more sustainably)

reduce bycatch

Protected areas (4th method for using fisheries more sustainably)

establish no-fishing marine areas (MPA)

Nonnative invasions (5th method for using fisheries more sustainably)

reduce invasions by exotic species

Consumer Information (6th method for using fisheries more sustainably)

use labels that allow consumer to identify fish that have been harvested sustainably

Aquaculture (7th method for using fisheries more sustainably)

restrict location of fish farms to reduce damage to coastal environments

Major fisheries are located in the neritic zone for 3 reasons

inshore waters have more productivity, inshore waters are more accessible to humans, deep waters cannot sustain large fish populations

Largest catches of fish occur here

Continental shelves of northwest Europe, western South America and Japan

Maximum sustainable yield

largest number of fishes that can be harvested year after year without diminishing the stocks

Over 80%

world fishery overexploitation rate

250% larger than necessary

global fishing fleet is ___ than need to catch what oceans can sustainably produce

Magnuson-Stevens Fishery Conservation and Management Act of 1976

govern US fisheries

“Conservation and management measures shall prevent over fishing while delivering optimum yield from each fishery on a continuing basis.”

Optimum Yield

maximum sustainable yield modified by any relevant economic, social or ecological factors

Bycatch

non-target organisms and undersized target organisms that are captured by the fishing year

Shrimp Industry bycatch

10 lbs of bycatch for every lb of shrimp

Ghost fishing

lost nets or traps continue to trap organisms contributing to huge numbers of death

North Pacific example - 30,000 to 40,000 km (20,000 miles) of nets are set per day with a daily loss rate of 20%

Aquaculture

rearing of select aquatic plants and animals under controlled conditions to increase the amount of food available to humans. Is effective and efficient but can lead to water pollution and increase in disease

Marine aquaculture

mariculture

Fish farming

cultivating fish in a controlled environment (to eat)

Fish ranching

holding anadromous species in captivity for the first few year, releasing them, and then harvesting them as adults.

anadromous

(live part of their lives in freshwater and part in salt)