Large quantities are smoked, others are jellied or marinated. Tanned eel skins have also been used in high quality leather products . Unfortunately, few eels stocks receive the attention necessary for effective management and the large body of data required to devise good regulations is usually unavailable. Periodic sampling of the commercial catch and information on the total catch and fishing effort would be most valuable. The regulations governing the fishing season and types of gear permitted vary between provinces, but all have a minimum size limit of 20 cm.
Catch quotas are uncommon.
The eel's complex life cycle contributes to the difficulties of effective fishery regulation. Mathematical models of fish populations have proved very useful for many fish species but have not, so far, been successfully applied to eel populations for the reasons just given. Clearly, much work remains to be done before all of the mysteries associated with the eel have been resolved. The worldwide demand for eels is greater than can be supplied by natural means and eel culture has become a major source of marketable eels. Eel farming is widespread in Japan and Taiwan and, to a lesser extent, in France and Italy.