Start Date: Jan 11, 2005
End Date: Dec 01, 2009
1. The minimum bottom-center drain surface loading rate and the water inlet structure design required to produce rapid solids flushing and safe fish swimming speeds will be identified using a 600 m3 experimental tank. Studies using oxygen and ph feedback control sytems will determine whether carbon dioxide gradients will induce fish to swim out of the culture tank during a harvest event. Sound levels and frequency ranges typically produced in the CIAS environment will be identified and analyzed to determine sound levels and frequencies that can cause hearing loss, damage fish ears and result in reduced growth rates. Controlled ozone and UV systems will be used to determine the combined ozone and UV irradiation dosages required to inactivate total heterotrophic bacteria and total coliform bacteria within a CIAS. Variable feeding rates per make-up water flow rates, fish health indicators and chemical analyses of organic carbon constituent will be used to determine whether advanced oxidation techniques can reduce accumulations of organic carbon constituents that impair fish health. Carbon dioxide removal across forced-ventilated cascade columns in a marine system will be characterized and modeled as a function of air: water loading, packing height, and salinity. Molecular techniques will be used to investigate reservoirs of infection for an emerging chlamydia-like bacterium that causes respiratory disease in Artic char. 2. The solids and nutrients capture and dewatering efficiency of a new bag filter system used to treat microscreen backwash will be determined. Biological nutrient removal will be evalutated within a commercial membrane biological reactor system using seperate stages for aerobic nitrification and anoxic denitrification. In conrolled, replicated feeding studies, the 'low fish meal and high grain proportion' feeds developed by ARS nutritionists at SGPGRU will be evaluated to determine differences in the amount of solid and nutrient waste excreted in comparison with standard fish meal and fish oil based diets, and determine if these grain-based feeds impact water quality in CIAS. 3. Growth and survival data on selected rainbow trout germplasm cohorts or families provided by NCCCWA will be collected. Replicated and commercial scale intensive recirculating aquaculture systems will be operated as performance trial platforms for the evaluation of singular and mixed stocks of trout. Aquaculture systems will simulate conditions found in commercial production environments or will be modified to create enhanced challenges. Trout will be tagged to allow either individual, family or cohort identification as appropriate. Linkage with specific research objectives at the NCCCWA will be maintained.