A lake stocking formula for rainbow trout (Salmo gairdneri) in British Columbia was developed from early studies of the ecology, production and sport fishery of rainbow trout which were conducted by Mottley on Paul Lake. The lake carrying capacity, catch per unit effort, as well as other factors were used to alter the basic stocking density which was calculated in terms of numbers of fry per mile of shoreline. It became necessary under some circumstances (e.g. in the presence of competitors, or predators) to plant fish larger than fry. A method was developed to convert numbers of fry to equivalent numbers of larger trout and conversely, from large to small.
A field experiment was designed to test the accuracy of conversion factors. Domestic stocks of rainbow trout of four size classes (fry, about 3,000 per pound; 500 per pound; 100 per pound; 50 per pound) were planted in each of four lakes. Numbers of each size class were determined by the stocking formula and the conversion factors. The observed ratio at age 1+, of the four sizes in three of the lakes differed significantly from the expected 1:1:1:1 ratio, which indicated an error in conversion factors. However, inspection of relative survival of individual size classes indicated that there were no gross errors in the conversion factors.
Smith, S. B., Halsey, T. G.; Stringer, G. E.; Sparrow, R. A. H.. 1969. The Development and Initial Testing of a Rainbow Trout Stocking Formula in British Columbia Lakes. BC Ministry of Environment. Fisheries Management Report. 60