Environmental Impact of Aquaculture

1
Environmental Impact of Aquaculture
2
Aquaculture Production

• World production doubled since 1984
• - 20,900,00 mt of fish and
• shellfish in 1995
• U.S. production has grown by 5-10
• each year over the past decade
• - 400,000 mt of fish and shellfish
• worth 729 million in 1997
• U.S. aquaculture production is expected
• to continue to increase steadily

3
Aquaculture wastes

• Wastes consist primarily of uneaten fish feed
  and fecal and other
• excretory wastes
• - Source of nutrient pollution
  algal blooms
• oxygen depletion fish
  kills
• - Source of nutrient pollution
  toxic algae (Pfiesteria)
• fish kills, contaminate shellfish and pose a
  health
• hazard to humans

4
Aquaculture wastes (continue)

• Fish feces can carry pathogens which can infect
  humans
• - Example Streptococcus bacteria
• Wastes can carry chemicals such as antibiotics
  to control disease
• and pesticides to control weeds, algae, and
  parasites
• - Copper-based algae-killers harm or
  kill shellfish
• - Aquaculture chemicals in food
  harm humans

5
Biological Pollution

• Introduction of unwanted non-native species to
  natural
• ecosystems
• - alter species composition
• - reduce biodiversity
• - introduce diseases and parasites

6
Reducing Nutrient and Chemical Pollution

• Use feed designed to protect the
• environment
• - low fishmeal content
• - minimize fish wastes
• Raise fish together with mollusks or
• hydroponic vegetables
• - make optimum use of water
• and nutrients
• - minimize farm wastes

7
Reducing nutrient.(continue)

• Closed aquaculture systems can
• treat wastes with mechanical
• chemical and biological filters
• Open aquaculture systems can
• place their cages and netpens in
• areas with strong currents or tides
• - flash waters avoiding waste
• accumulation

8
Reducing nutrient.(continue)

• Chemical pollution can be minimized by practicing
  preventive
• medicine
• - stock fish free of pathogens and parasites
• - minimize stresses on fish
• - vaccinate fish against disease

9
Reducing Biological Pollution

• Carefully choose the species or strains for
  farming
• - use only native species
• - use strains of non-native species that cannot
  survive and
• reproduce outside captivity
• Take measures to minimize escapes of cultivated
  fish into natural
• waters
• Grow reproductively sterile species

10
Conclusion

• Aquaculture facilities constructed without
  environmental
• protection in mind can cause serious
  environmental degradation
• A variety of strategies and technologies are
  now available to
• make fish farming environmentally sound
• The use of these strategies can make
  aquaculture more
• acceptable by the wider public and more
  productive