Environmental Impacts of Aquaculture Effluents

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Environmental Impacts of Aquaculture Effluents

• Josh Vinson

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Aquaculture Industry

• Increase in seafood demand due to
• 1. Increased per capita consumption
• 2. Increased global population
• Wild food fish populations currently being over
  fished
• Wild caught fish production has remained steady
  at 60-70 mT /yr since early 1980s
• Wild caught fish production cant be increased
• Increased seafood demand must be met with
  increase in cultured seafood
• -rapid industry growth environmental concern?

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Aquaculture Effluent

• Effluents refers to either a continuous or
  intermittent discharge of a liquid from an
  aquaculture facility
• Effluent composition
• Dissolved compounds
• 1. Phosphorus
• 2. Nitrogen
• Sludge
• Fecal material and uneaten feed

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Dissolved Compounds

• Phosphorus and Nitrogen
• Cause eutrophication
• Algal blooms
• Kills fish and other benthic organism
• alterations in food chains
• removal of oxygen
• Organic matter
• Increased BOD
• Decreases DO in water column and sediments
• Alters benthic food chains and ecology
• Can kill higher life

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Sludge

• Sludge refers to the solid particulate portion
  of aquaculture effluents.
• Composed primarily of fecal material and uneaten
  feed.
• Volume directly related to feeding rates.
• Nutrients (P, N), and organic matter leaches out
  or is broken down and ultimately becomes
  dissolved compounds.
• Impacts are the same as those for dissolved
  compounds, but management and treatment differs.
• End product of sludge treatment is typically used
  as agricultural fertilizer.

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Aquaculture Methods And Associated Degree of
Environmental Impact

• 3 Broad categories of aquaculture
• Extensive
• Deals primarily with shellfish
• slow, low-volume, dilute continuous waste
• Semi-intensive
• Cages
• High stocking densities
• large volume of continuous, untreated waste
  released
• Raceways
• large volume of continuous, treated waste.
• Ponds
• Intermittent release of, treated waste.
• Intensive
• Closed recirculating systems (CRSs)

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Aquaculture Methods
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Management Strategies

• Goal Reduce environmental impact of aquaculture
  without decreasing production
• Funding for research
• Improve feed conversion ratios (FCR) ratio of
  gain in wet body weight to the amount of feed fed
  
• Improve organism-specific feeds to increase
  nutrient retention.
• Improve waste treatment methods
• Educate Farmers on
• Method benefits and drawbacks
• Integrated aquaculture techniques
• Ex Waste-water-fed mollusk farming can be used to
  recover excess nutrients
• Best Management Practices (BMP) plans
• Encourage communication between researchers and
  commercial facilities via conferences and meetings