Effect of Ration Size on Water Quality and Culture Performance of Pacific Lamprey Ammocoetes Entosphenus tridentatus

The Pacific lamprey was once found throughout the Pacific Northwest, and is of critical importance to the ecosystem and the indigenous cultures of the region. As these lamprey have declined across large parts of their historic range, effective culture techniques for the species are needed to assist restoration efforts. This study was conducted to refine feeding methods, specifically the ration size, for larval stage (ammocoete) lamprey under intensive culture conditions. Food densities of 250, 500, 750 and 1000 mg/L were offered twice per week during a 12 week trial. Each ration was randomly assigned to three replicate tanks, each containing 10 fish. Ammocoetes began the trial measuring 27.1 ± 3.1 mm (Mean ± SD; n=120) in total length and weighed 32.7 ± 12.5 mg.  Initially, and every 4 weeks during the trial, weight, length, survival and water quality was measured, and relative condition factor was determined. Results from this project will provide needed insight regarding how ration affects water quality and the growth, condition and survival of the ammocoetes.