Internationally, the demand and resulting value of glass eels has increased tremendously in recent years. Live glass eels are now selling for over $15,000 per kilo. This international demand results from over-fishing of adult and glass eels in Asia, North America and Europe. This world experience indicates that recruitment over-fishing of long-lived freshwater eels can be catastrophic. Because of the increasing significance of adult eels in the estuarine fisheries of NSW, decreased catches in recent years and the prospect of increased future catches of glass eels for aquaculture, it is important to undertake research which will lead to an understanding of the current status of adult eel stocks in NSW. Stocks of adult eels must be managed properly to ensure continued production of the commercial fishery for adult eels, continued recruitment of glass eels and elvers for aquaculture and stability of coastal catchment ecosystems.

Limited research into the basic biology and ecology of longfinned eels has been carried out in Victoria and Tasmania, but there have been no biological studies conducted in NSW. The only published age and growth information for this species comes from one catchment in Tasmania and indicates that they are relatively long-lived (40 years), but this age data has not been validated. The available literature indicates that growth rates of freshwater eel species are highly variable among habitats and distributional ranges. Therefore, there is a need to determine the basic biological parameters of NSW longfinned eel stocks, including validated age structure, growth and mortality rates, and reproductive characteristics for use in stock assessment modelling.

Since there is a significant commercial fishery for adult eels in NSW, fishery-dependent techniques based on sampling of commercial catches represent the most cost effective stock assessment and monitoring methodology. Age and growth monitoring of many commercial finfish species in NSW is currently carried out by sampling fish at the Sydney Fish Markets and regional fishermen’s co-operatives. Most of the commercial eel catch in NSW is exported live through a few (currently four) specialised processors. Therefore, it will be necessary to establish a specialised monitoring regime and fishery-dependent model which will provide data on which to base advice for the future sustainable management of exploitation of the resource.