Effects of rearing density on growth and survival of lake trout

Lake trout (Salvelinus namaycush) were reared at density indices (allowable density in pounds/cubic foot divided by fish length in inches) of 0.25, 0.50, 1.0, and 2.0 in cages suspended in circular tanks. Water flow rates were such that dissolved oxygen remained above 8 ppm within all the cages. Thus treatment effects were attributed to density and not influenced by water quality. Growth and condition were not affected by density, but survival was lower at the higher density than at the three lower densities. We conclude that lake trout may be successfully reared at a density index of at least 1.0 if the water requirements for respiration and waste dilution are met.