1. 1980 6 million metric tons is less than 10% world fish catch, rapid growth. 1993 10.7 million metric tons
   
2. popular species (60% total yield)-rainbow trout, salmon, channel catfish, mullet, milkfish, carp, tilapia
   
3. 75% from eastern Asia and Pacific –China fish ponds 1/3 global yield
   
4. 3 main strategies (Gomiero et al.)

1) Extensive-lightly stocked with no magt. & low yields.

2) Semi-intensive-Grow fish with low trophic position (low market value) in small confined areas. Optimize for quantities of animal protein, not economic gain. Add fertilizer/manure. Mostly areas with high pop. and little animal protein. Fish biomass yield/feed input > 1.

3) Intensive- High yields, high costs, high density, high quality, expensive products such as trout or shrimp. Relies on feed input and high water cylcing. Usually in more ‘developed’ countries. Fish biomass yield/feed input < 1.

• Ideal Organisms-
• Feed Efficiency-
• Why? High feed efficiency
• Low trophic fish--net energy gain

• Goal of course: To use "waste" in productive manner. Treating wastewater in aquaculture ponds: "transformation of environmental contaminant into useful resource."
  
• Problems-consumer acceptance, ineffective treatment
  
• Fish often increase concentrations of phytoplankton, and TSS-how?
  
• No single species can consume all sizes of suspended solids—need combination like zooplankton and silver carp.
  
• Zooplankton eat particles smaller than 25um, and carp consume particles > 25 um, but they don’t live well together.
  
• Zooplankton-pelagic animals unable to maintain position by swimming against physical movement of water. Usually most of secondary aquatic production attributed to zooplankton (herbivorous and carnivorous)(they eat phytoplankton). Holoplankton—spend whole life as zooplankton, Meroplankton spend only part of life as zooplankton i.e. larval stage.

• 3 treatments tested; catfish, catfish/carp, catfish/carp/zooplankton refuge. 1000 liter tanks (4x our tanks).
  
• Tested for phytoplankton and zooplankton

• Refuge tanks had large zooplankton, non-refuge only small zooplankton
  
• Large zooplankton (refuge tanks) filtered more than twice the water of small zooplankton (without refuge) Figure 2
  
• Great reductions in phytoplankton and chlorophyll values with refuge and catfish tanks (figure 3, Table2)
  
• Carp grew faster in refuge tanks

• Phytoplankton make-up almost all Suspended Solids in stabilization ponds-technique also reduced suspended solids. Possibly better than sand filtration or coagulation with alum. (overhead of stab. Pond). Can also grow fish (40% more with refuge)!
  
• In stabilization ponds phytoplankton produce the oxygen that bacteria need to reduce BOD. To produce maximum oxygen phytoplankton need to be at intermediate levels—use zooplankton to control.
  
• Proposed system: 2 initial ponds reduce ammonia and BOD to acceptable fish levels. (fig. 4)
  
• What ecological engineering principles are demonstrated by this system?
  
• How would you change the design of our system based on this article?

I.     History of Aqauculture in China and Italy

• China and Italy several centuries BC

• 600 AD polyculture system developed in China

• 1960’s intensive aquaculture started in Italy

II.      Biodiversity China vs. Italy

• Diversity of species is complex system of natural controls.
  
• Balanced polycultural system may reach full resource exploitation
  
• China 8-9 different species, usually 1-4 species of carp most
  abundant (Table 2). Different feeding habits-no piscivores.
  
• Polyculture takes advantage of natural food chain dynamics-use sun and nutrients to stimulate primary productivity.
  
• Enhance utilization of biological resources by keeping food chain short (only 90% of energy dissipated between trophic levels). (fig. 4)
  
• Italy most fish are piscivores feed industrial pellets (Table 3) (Fig. 3)

III.      Technical Characteristics

• Table 4
  
• Italian system relies on outside energy and material inputs to have concentrated, "intensive" production. Relies on productivity of distant systems (marine, industry). Results in greater outputs from system.
  
• Ecological footprint?

IV.      Socioeconomic Context

• Table 5

• Higher standard of living in Italy (GDP/capita), must have high yield and economic return to make viable. Presently, semi-intensive does not work in italy—what could change this? Farm subsidies.
  
• In China protein from fish ponds is essential for food supply
  
• Population pressure in China forces utilization of all resources (i.e. wastes). Goal of fish ponds "establish human managed, self-sufficient ecosystem where waste are recycled to increase the food supply for people."
  
• 8.3 kg of dry manure to 1 kg wet fish

V.      Conclusions

• Slow throughput-China-recover ag. waste as low quality resources and produce animal protein
  
• Large throughput-Italy-many high quality resources to produce highly valued species.
  
• Analogy to general agricultural production.