|
Stocking |
|
Although it is advantageous to standardize stocking densities, particularly beyond the level of extensive cultures, in practice variations may be necessary depending on
season and the availability of juveniles. Periodic review of yield levels, feed conversion ratios and the size range of harvested animals will indicate the most profitable density at which to operate. Since stocking density influences the size of animals at harvest, it can to a certain extent be adjusted so that the product meets the size requirements of the markets (Lee & Wickins, 1992). During the stocking process and the period directly afterwards, there is an enhanced risk of mortality due to predation and stress. When animals arrive for stocking they are usually weakened as a result of handling and transport and should be acclimatized gradually, minimising exposure to rapid changes in environmental conditions. Young post-larvae of hatchery origin are generally more delicate than larger nursery-reared or wild-caught juveniles. Requirements for acclimatization vary from one situation to the next, but in the tropics stocking during the heat of the day should be avoided (Lee & Wickins, 1992). | |