1. Definition
Artificial recruitment to existing fish stocks and transplantation of species to newer areas in open waters (lakes, reservoirs, rivers, irrigation canals, seas and oceans), and stocking of newly-formed reservoirs.
2. Objectives
(a) To increase the stocks of selected species;
(b) To resuscitate the stocks of overfished or environmentally altered water bodies;
(c) To fill ecological niches;
(d) To utilize more fully certain biological resources, and
(e) To compensate the effects of barriers on the migratory routes to spawning grounds.
3. Methods
3.1 Artificial propagation of seed and their release into open waters.
3.2 Stocking of adults into open waters and spawning streams.
3.3 Construction of fishways and artificial spawning channels.
4. General considerations
4.1 Concept of "ocean ranching" - making use of homing behaviour of anadromous fishes (salmon, sturgeon, shad, striped bass, etc.).
4.2 Assessment of the status of fisheries based on natural stocks.
4.3 Assessment of carrying capacity of the receiving waters.
4.4 Selection of suitable species based on the need to utilize available food or the objectives of culture (omnivorous, plankton-feeding, herbivorous or predator species).
4.5 Rates of stocking; size at stocking; frequency of stocking based on the extent of establishment of the introduced species - once only, occasionally or continuously.
4.6 Factors determining the success of transplantation and artificial recruitment.
4.7 Possible effects of transplantation on the indigenous fauna and general ecology of the receiving waters - rapid increase of introduced species and possible elimination of indigenous species, destructive effects of transplanted fish, introduction of new pests, etc.
5. Seed production
Techniques of hatchery production (see also Chapter IV - Seed Production).
6. Stock evaluation
Methods of stock evaluation to assess the success of artificial recruitment.
7. Management measures
7.1 Lakes and reservoirs
Clearance of shallow waters; predator control; installation and proper maintenance of inlets, drainage outlets and spillways; fertilizing and supplementary feeding; introduction of fish food organisms, etc.
7.2 All open waters
Protection against pollution from pesticides and domestic or industrial effluents; maintenance of a balanced population through manipulation of stocking and harvesting; supplementary transplantation with continued artificial recruitment where necessary; methods of harvest, particularly in reservoirs with highly uneven bottoms (special gill nets, seines, cast nets, long lines, traps, light fishing, electrical fishing, etc.).
8. Benefits from artificial recruitment and transplantation
(a) Non-dependence on natural spawning areas;
(b) Increased harvest;
(c) Increased survival rate;
(d) Greater utilization of natural food;
(e) Establishment of productive fisheries in new areas, and
(f) Resuscitation of depleted stocks, etc.
9. Species currently used and indigenous species that could be profitably used in inland and marine waters - fishes, crustaceans and molluscs
10. Economics of artificial recruitments and transplantation
Practicals
Visits to selected artificially stocked reservoirs/lakes and preparation of a report on the status of their fisheries and management measures.
