|It is generally accepted by fisheries biologists that annual natural mortality
rates for wild trout in streams range from 30% to around 65%. For hatchery trout, mortality rates are
considerably greater. For example: A study was conducted by Commission staff to evaluate the survival of
stocked brown trout (planted during the fall) from October until the opening of the angling season during the following
April. As part of the study, four streams were evaluated. At the time that this study was conducted, the streams were
closed to angling during the fall. As a result the study served as an evaluation of the survival of hatchery brown
trout from fall to spring without the influence of angling pressure during this time period.
For evaluation purposes, all of the fall stocked trout were tagged with a small plastic tag. Return to the creel
rates were determined by a combination of creel census and volunteer angler tag returns. Survival rates were determined
by population estimates via electro-fishing surveys. The results of this study indicated that return to the creel
rates of the fall stocked brown trout were very low, as only 4.6% of the fall stocked trout were caught by anglers
the following spring. In addition, only 20% of the fall stocked brown trout were estimated to have survived the winter
to become available to the angler at the beginning of the next season. Based on the results of this study, over winter
mortality of fall stocked brown trout was approximately 80%.
Adult trout stocked during the fall and winter are intended to expand fishing opportunities beyond the traditional
spring and summer time frame. By extending trout stockings throughout the year, we are able to provide greater variety
for Pennsylvania's anglers. It is not likely that the adult trout we stock will reproduce in the streams, nor is that
our goal. Adult trout stockings are designed primarily to support "put and take" trout fisheries in waters
that otherwise could not provide much recreational sport-fishing without plantings. Those waters with viable naturally
reproducing populations are managed specifically for wild trout.