Sea ranching or artificial recruitment of aquatic organisms into their natural habitat for stock improvement or enhancing the production or for conservation of resources, though practised intensely only in recent years, is an age old practice. It is said to have been originated in USA as early as 1870. Ranching of red and . Pacific salmons was being carried out since 1964 in the Far East, and at the present level of ranching, it was estimated that an additional production of 10,000 - 20,000 tonnes/year was realised. In Japan, besides abalone and "kuruma" shrimp (Pellaeus japonicus), the ranching of which started in 1975, about 45 species are ranched to supplement the natural stock.