Rotational line crossing: An approach to the reduction of inbreeding accumulation in trout brood stocks

A system is presented for maintaining trout brood stocks for long periods with levels of inbreeding accumulation lower than that experienced in random mating populations of equal size. The system requires the formation of three or more distinct breeding lines. Brood stock generations are advanced by a systematic mating scheme in which females of each line are mated to males of a different line. Eggs for hatchery production may be obtained from matings either within a single line or between lines. An opportunity for improving the breeding population is provided through selection of individual fish to be used in the production of the next brood stock generation. The requirement for increased handling of brood stock is not considered to be serious.