The quantification of all ecological effects of stocking is impossible on the basis of present knowledge. Therefore the possible hazards should be carefully considered and evaluated separately in each case. Fisheries authorities should inspect all major stocking programs and reject those in which the risks involved are too high or the fisheries management objectives will probably not be achieved.
The prerequisite for all stocking activities is that the water quality requirements of the species of concern are met.
It is recommended that no stocking should be carried out in the situations listed in Table 2.
It is generally accepted that stocking practices are economically profitable when the cost/benefit ratio is greater than unity. New stocking schemes are likely to have a higher level of uncertainty and therefore as a safeguard it is sensible to plan them with an initially higher cost benefit ratio. On the other hand most stocking programmes generate social benefits and these can smooth out the possible errors in economic evaluation. In some cases stocking has been justified purely from a social point of view but it is not recommended that long term stocking programmes are undertaken without a more complete evaluation of all the factors involved.
