Licensing fewer vessels to operate in a fishery may increase the stock of the by-catch species, at least in the short-term, by reducing the fishing effort. Setting a minimum size for the fish caught can increase the discards unless enforcement is carried out at the point of capture, which is not always practical. Setting such limits, especially if combined with a ban on discards, encourages fishers to operate on grounds where there are fewer undersized fish and to employ more selective gears and practices.
Restricting the number of days that fishing vessels can spend at sea can lead to less discarding. This may be simply a consequence - just as in licensing fewer fishing vessels - of reducing the fishing effort. In other instances, there may be insufficient fishing time to fill the storage space with the higher value components of the catch, encouraging the retention of the less valuable ones that would otherwise be discarded.
A wide range of regulatory measures have been introduced in response to individual transferable quotas (ITQs) as more and more fisheries switch to them. (ITQs are a management tool used to allocate the Total Allowable Catch (TAC) to individual fishers or companies. They are usually granted as a form of long-term fishing right and are tradable.) Regulatory measures include allowing catches above the quota to be traded (sold to those with unfilled quotas) as an alternative to discarding. Allowing the quota to be exceeded up to a set amount in one year in return for a reduction in the quota the following year is one way of giving flexibility to such schemes.
Economic measures include taxes, subsidies and quota substitution. The voluntary surrender of above-quota catch without penalty is another option. Here the fisher may sell the catch as usual, but must pay the "deemed" value (the value realized in excess of the cost of landing) to the management authority. Such policies have been employed with some success in world fisheries, but arriving at an appropriate incentive to reduce by-catches and discarding is difficult because the costs of fishing differ from fisher to fisher.