Objectives:

1. Characterize nineteen environmentally sensitive parameters of the effluent produced from a recirculating production system stocked with yellow perch and operated under common commercial production strategies.

2. Determine trends in effluent characteristics when compared feed input rates, system biomass, and volume of water added to the system.

Methodology: Five hundred yellow perch fingerlings will be stocked into each of two independent recirculating aquaculture systems. Each system consists of a 3780 liter (1000 gallon) production tank, a settling tank particle filter and a trickling biofilter. Oxygenation will be accomplished with aeration rather than oxygen injection. The diet fed will be the practical perch diets studied by Paul Brown which yield the best cost-of-gain. Two type of effluent will be analyzed. The primary effluent will result from the siphoning of the settling tank. Settleable solids will be siphoned off the bottom of the settling tank and then discharged twice daily. The second type of effluent will result from a weekly cleaning and subsequent draining of the settling tank. The effluent samples to be analyzed will be collected on a weekly basis in either plastic or borosilicate glass. Sample portions that do not pertain to solids analyses will be filtered through a 75 micron filter to remove settleable matter since settleable matter may interfere with several chemical analyses. After filtration is complete, all of the samples will be stored according to Standard Methods until analyses are performed. Effluent samples will be analyzed once per week during the perch grow-out trial. Levels of these nineteen environmentally sensitive parameters will be determined: alkalinity, total and nonionized ammonia, biological oxygen demand, dissolved carbon dioxide, dissolved oxygen, feed added to the system, fish biomass in the system, hardness, nitrate, nitrite, particle size distribution, pH, total and reactive phosphorus, settleable matter, temperature, total dried solids, and total effluent volume. All analyses will be performed using APHA Standard Methods.

Rationale: Yellow perch as recognized as a species with considerable commercial culture potential in the North Central US. This project is part of a joint effort to analyze several important perch culture components.

Accomplishments: ISU has extensive experience in intensive Tilapia culture and in effluent characterization.

Benefits: Knowledge of effluent characteristics will allow perch culturists and regulatory agencies to maintain a proactive approach to perch culture pollution abatement.