Tolerance of Juvenile Lake Trout Exposed to Gas Supersaturation

Lake trout (Salvelinus namaycush) 2.9-3.9 cm long that were exposed to five gas supersaturation levels ranging from DELTA-P 9 to DELTA-P 159 mm Hg above saturation for 30 d grew at the same rates. Survival was also virtually equal in all treatments, ranging from 93% at DELTA-P 42 to 99% at DELTA-P 126. After 30 d, signs of gas bubble disease were evident at DELTA-P 126; 3% of fish had exopthalmia and 12% had bubbles in the nares. At DELTA-P 159, 20% had bubbles inside the mouth or on the conjunctiva, or rim of the orbit, plus 3% had exopthalmia. There were no signs of gas bubbles on fish at DELTA-P 75 or less.