Eels - Description

Two species of eel native to Australia have been assessed as commercially applicable for aquaculture ventures. Longfin eel (Anguilla reinhardtii) is a subtropical species that is distributed from northern Queensland down through to the northeastern tip of Tasmania.

Shortfin eel (Anguilla australis) is a more temperate species that is distributed from southern Queensland to Tasmania.

The life cycles for the two species are very similar. Both are catadromous (that is, they live in freshwater but migrate to saltwater for reproduction) and spawn in the Coral Sea waters at depths greater than 300 metres. Each female can produce 5-10 million pelagic eggs, which are carried to the continental shelf by ocean currents where they develop into -glass eels?, which are toothless and unpigmented. The glass eels move into estuaries with the assistance of currents and tides and after one to three years grow into elvers as they develop pigmentation.

As elvers they then continue the migration into lakes and rivers and other accessible water bodies. It is thought that mature (or silver) eels die after spawning.

Farming Production

Aquaculture of eels occurs in New South Wales, Victoria, Queensland and Tasmania.
Total Australian production in 2001-02 was 124 tonnes. Victoria is traditionally the largest aquaculture producer of eels, although Queensland was the largest eel producer in 2001-02.
At prices of around $11.60 a kilogram, the aquaculture eel industry was valued at $1.44 million in 2001-02. This compares with wild eel production in New South Wales, Victorian and Commonwealth waters of around 346 tonnes in 2001-02, valued at $1.91 million (beach value). Total Australian wild eel production, including Queensland production, would be in excess of 400 tonnes.

In Victoria, the productive inland natural lake systems have been used for thirty years for the extensive growout of shortfin eel.

In recent years, eel production has increased and is beginning to expand into the harvest and ongrowing of both shortfin and longfin glass eels under intensive enclosed farming systems.

Eels have a high stocking density tolerance, which means that a large number can be produced in a relatively small area. Semi-intensive culture of eels is also conducted in earthen ponds, while extensive growout generally occurs in public and private lakes, swamps, wetlands and farm dams.

Production in Queensland comes from both pond based farms (two farms with 39 ponds) and tank based systems (four farms with 30 tanks). In 2001-02 the eel aquaculture industry continued its strong growth, with production nearly doubling over that of the previous year. Queensland produced 72 tonnes of eels valued at $893 000 at the farm gate.

Production from the eel aquaculture industry in Queensland has continued to decrease steadily since reaching 71.8 tonnes in 2001–02 to 43 tonnes in 2004-05.  Due to the very low number of producing farms in 2005–06 no production data from the eel farming sector can be reported as it would compromise client confidentiality. The two species of eels that are being cultured are the long-finned eel (Anguilla reinhardtii) and the short-finned eel (Anguilla australis).

The industry in New South Wales and Tasmania is small, and constrained for the most part by the limited availability of wild stocks.

Juvenile glass eels or elvers for growout are harvested from the wild by licensed fishers. In order to conserve uncertain wild stocks, quota limitations to harvest and therefore production have been set. Once harvested, juveniles are stocked in nursery tanks before being moved to growout facilities (earthen ponds, or flow through or circulating intensive tank systems.
Recirculation systems are becoming increasingly popular as a means of providing controlled environment conditions for year-round production, as they reduce the demand for fresh water and discharge of nutrient rich effluent, and for ensuring minimal escape of stocks and pathogens.

Eels prefer temperatures between 23 and 28¨C and under ideal conditions grow to a marketable size of 150-200 grams in twelve to eighteen months.

( REF. Australian Aquaculture. Industry profiles for selected species)

CLICK HERE FOR MORE INFORMATION

CLICK HERE FOR RELEVANT ASSOCIATIONS