Land locked is a term used to describe a population of what were once anadromous fish that has been confined to freshwater body by either natural or artificial barriers. Instead of dying off, these land locked fish complete their adult years in the lake and spawn in creeks that feed into the lake. Natural barriers can be a gradual formation due to landscape changes or a sudden change such as a land slide. Artificial barriers can be the construction of a dam.
Classic examples of land locked species include kokanee, which are sockeye salmon that only live in lakes. Residents rainbow trout are land locked versions of steelhead. Both land locked and anadromous varieties are classified as the same species because they can still interbreed and produce fertile offsprings.
Because lakes do not have as food as the ocean, land locked fish are usually much smaller than their anadromous cousins. The average size of kokanee is between 1 and 3lb, while sockeye salmon usually reach 6 to 10lb.