Michigan Department of Conservation
Institute for Fisheries Research Report No.1746, 1968
Some Factors Affecting Survival of Young-of-the-Year Brook Trout, Salvelinus fontinalis (Mitchill), in Streams
W. C. Latta
Abstract.-Survival of brook trout during the first year of life was considered in relation to (1) territorial behavior, (2) other segments of the trout population, (3) starvation and (4) the amount of groundwater entering the stream. No relationship was found between abundance of fingerling progeny and the number of spawners. Survival of eggs in the reads is usually high. Although little is known about losses of fry during emergence from the reads, it is presumed that most of the mortality occurs shortly after emergence. Territories are most likely formed upon emergence. Fry that have less desirable territories, or no territories at all, are less likely to survive. It has not been shown that predation by either brook trout or other vertebrates accounts for loss of fry. It was demonstrated that brook trout fry are relatively long-lived in the face of starvation, but the possibility exists that a rather short period of starvation may deter them from feeding effectively or assimilating the food that they do obtain. Death rate of trout fry from starvation increases with a rise in water temperature. Groundwater levels probably act as a physical factor of the environment to regulate the number of trout in the stream.