Integrating agriculture and aquaculture in Arizona.

Abstract

This research project was designed to test the feasibility of growing catfish (Ictalurus punctatus) in cages at two densities in three types of irrigation waters in Arizona in 1989 and 1990. The types of waters studied were a pre-irrigation flowing water ditch, an irrigation return water sump and a pre-irrigation stationary water reservoir. Cages were designed for each type of water. The duration of the experiment was 76 days in 1989 and 117 days in 1990. Growth of fish was poor at both densities in pre-irrigation flowing water in 1989. Poor growth was probably due to the velocity of water and size variability of fish at stocking (coefficient of variability = 48%). Hand grading and the addition of baffles to cages resulted in increased growth and decreased size variability (25%) in 1990. Poor growth and low food conversion (5.2) were seen at both densities in irrigation return waters in 1989. Reduced growth and poor feed conversion were due in part, to wild fish bumping cages until food was lost. High variability in final weight (48.9%) was due to stocking of ungraded fish. In 1990, wild fish were removed from the pond and catfish were handgraded at stocking. These procedures resulted in higher final weights (660 g), lower conversion ratios (1.3) and lower size variability (31%). In 1989, poor growth and high size variation (55.4%) also occurred at both densities in pre-irrigation standing water. In 1990, grading fish at stocking and lowering stocking densities resulted in increased growth (570.6 g) and a lower coefficient of variability (28.7%). However, the food conversion ratio (2.6) was still high, due to food loss from cages, a disease outbreak and the associated mortality. Growing fish in all three types of irrigation waters appears to be biologically feasible. Fish in irrigation return flow waters had better growth rates than fish in flowing pre-irrigation water or in stationary pre-irrigation water. However, questions concerning the possible addition of contaminants to the system from agriculture effluent and the economics of integrating aquaculture into agriculture requires further study.