Environmental and Conservation Issues

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Environmental and Conservation Issues

• Kevin Fitzsimmons, Ph.D.
• Professor - University of ArizonaSec. / Tres. -
  American Tilapia Association
• President - US. Aquaculture Soc. Chapter of WAS
• May 30, 2001

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Environmental Impacts

• Impacts of feral tilapia on native fishes
• Effluents
• Eutrophication - effluents contributing to
  nutrient enrichment
• Drug residues
• Processing plant wastes

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Feral Tilapia

• Impacts of feral tilapia on native fishes
• Tilapia are pioneer species, they thrive in
  disturbed habitats
• Often introduced into areas that have severe
  environmental damage where natives are already at
  risk

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Feral Tilapia

• Tilapia have been introduced into 90 countries
• Many imported for weed or insect control
• Tilapia populations have escaped and fish have
  thrived in the wild
• Compete for food, nesting spots and other
  resources

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Feral Tilapia

• Colorado River case
• Dams, diversion of water, remove flood danger
• Natives were adapted to survive during flood
  events, flows changed algae and invertebrate
  communities
• Tilapia constitute 90 of the rivers biomass

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Solutions - Use all male tilapia

• All males, less likely to breed and become
  established
• Can be hormonally switched, genetically male, or
  triploids

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Use red skin varieties of tilapia

• Red tilapia are easier to find if escaped
• Survival is low in the wild
• Predation is high from birds, fish, humans

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Effluents

• Tilapia wastes rich in nitrogen, phosphorus,
  dissolved organic matter
• Increases Biological Oxygen Demand
• Increases dissolved carbon dioxide
• Nutrient enrichment and increased BOD contributes
  to eutrophication

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Effluents

• Pond effluents can pollute receiving streams
• Raceway and tank systems have concentrated wastes
  from filters
• Cages contribute waste load to lake
• Salt water culture can impact reefs or other
  marine ecosystems

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Solutions to eutrophication

• Use wastewater to irrigate field crops
• Good source of nitrogen, phosphorus and organic
  matter

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Solutions to eutrophication

• Add 8 kg/ha of nitrogen with pond water

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Solutions to eutrophication

• Add 2.5 kg/ha of phosphorus with pond water

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Solutions to eutrophication -Integrate with
shrimp culture

• Polyculture benefits
• Shrimp will graze on tilapia wastes

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Integrate with shrimp culture

• Polyculture benefits
• Production in low salinity, low impact

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• Photo of mangrove in Peru

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Mangrove farm in Peru

• Effluent from salt water tilapia can be used to
  irrigate and fertilize mangrove restoration
• Rich community is not good habitat for tilapia

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Conservation of genetic variability

• Breeding to native tilapias
• Inbreeding of farm stocks

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Conservation projects

• GIFT, and other breeding projects
• Domestication - Vests