Mortality, Rate of Growth, and Fin Regeneration of Marked and Unmarked Lake Trout Fingerlings at the Provincial Fish Hatchery, Port Arthur, Ontario

The experiment was initiated in an attempt to determine the effect resulting from the excision of the adipose fin of lake trout (Cristivomer namaycush). The experimental fish (500 marked and 500 unmarked) taken at random from fish handled during the daily clipping operations were weighed and measured and placed in two troughs allocated for the experiment. In June 1948 after a lapse of 10 months the fish were counted and examined. The aggregate loss was 13 or 2.6 percent of the marked fish and 20 or 4.0 percent of the unmarked fish. Measurements indicated no appreciable difference in the length and weight. The growth increments were 4.59 centimeters and 6.79 grams in marked fish and 4.56 centimeters and 6.77 grams in the unmarked fish. A total of 24 or 4.9 percent of marked fish exhibited varying degrees of regeneration. Of this total, 17 fish or 3.47 percent could be identified as marked fish.