Effects of Temperature and Size on Ammonia Excretion by Fasted Golden Shiners

Abstract

The golden shiner Notemigonus crysoleucas is the major species of baitfish raised and sold in the United States. They are shipped in trucks from large farms to distributors up to 2,500 km distant. The costs associated with shipping could be greatly reduced if truck loading were increased, but higher densities of fish elevate ammonia concentrations to detrimental levels. In our work, we have simulated live hauling conditions to measure the ammonia excretion rates of golden shiners at 15, 20, and 25°C. The experiments were conducted for 24 h in three recirculating systems after fingerling golden shiners were fasted and acclimated for 2 d. The experiment was repeated four times using different lots and sizes of golden shiners. The results indicated that there were no significant differences in the hourly ammonia excretion rates (HER) between two lots of same-size golden shiners. The hourly ammonia excretion rates were inversely proportional to fish weight and increased with temperature. The average HER for all sizes of fish ranged from 2.9 to 7.4 g NH₃-N/kg fish/h at 15°C, 5.2–11.2 g NH₃-N/kg fish/h at 20°C, and 6.2–15.0 g NH₃-N/kg fish/h at 25°C. The results of this study will be used to design ammonia control systems to safely increase fish density on commercial fish hauling trucks.