The short-finned eel (Anguilla australis), also known as the shortfin eel, is one of the 15 species of eel in the family Anguillidae. It is native to the lakes, dams and coastal rivers of south-eastern Australia, New Zealand, and much of the South Pacific, including New Caledonia, Norfolk Island, Lord Howe Island, Tahiti, and Fiji.
Description
thumb|right|The dorsal and anal fins are similar in length
The body of the adult short-finned eel is long and snakelike, roughly tubular and the head is small, with the jaws reaching back to below the eye or further. The dorsal (top) and anal (bottom) fins are of roughly equal length. The colour varies considerably from one individual to another; a deep olive-green is typical but it can be much lighter; golden or even (rarely) yellowish. There are no markings of note, but the underside is pale, often silvery, and the fins greenish. When full grown, they reach about . The short-finned eel has a typical regeneration time of 15 to 30 years for females and it reaches a maximum size of about and . Males tend to be slower growing and reach a smaller adult size.
Anguillid eels are undifferentiated gonochoristic fish.
During their life cycle however, eels migrate over huge distances to spawn.
Diet
thumb|An 1888 illustration of a short-finned eel attacking a [[kelp gull|black-backed gull in New Zealand]]
A. australis are carnivorous, ferocious ambush predators, feeding on crustaceans, fish, frogs, snakes, and even waterbirds and aquatic mammals such as rakali. Recent evidence that has utilised analytical microchemical techniques in eel otoliths has suggested that eels are facultatively catadromous rather than obligatory. Discrete populations of ocean and estuarine residents exist, that very rarely enter freshwater. Research done in 2008 identified that tropical species such as A. reinhardtii (Australian long-finned eels]]
Short-finned eels make excellent eating and have long been esteemed as an important food. The consumption of short-finned eels is a longstanding tradition in many Pacific nations, including Japan, Australia and New Zealand.
Prior to European settlement at least two Aboriginal Australian nations, the Gunditjmara and the Djab wurrung from Western Victoria, farmed eels on a large scale, trading smoked eel with distant communities in return for other goods.
For the Māori people of New Zealand, starved of protein after the extinction of New Zealand megafauna, the short-finned eel was a significant food resource. The short-finned eel is known to Māori as , alongside the endemic New Zealand longfin eel. One traditional method of preparing eels was to cook them in an umu bound in rangiora or kanono leaves. They had a highly developed fishery for freshwater eels before the arrival of Europeans, and an extensive knowledge of the ecology of eels, harvesting them through a variety of techniques. Present-day recreational anglers catch and eat them regularly, and New Zealand has a well-established commercial eel fishery. Māori are now concerned that the commercial fishery is compromising their ability to harvest short-finned eels for ceremonial purposes. The increasing pressure on eels has led to reduced recruitment of juveniles of anguilid species which limits the industry and potentially leads to ecological impacts. The eel was known as kooyang in the Gunditjmara language.
Current industry
Since short-finned eels make excellent eating, there is global demand for them. The major market is Japan with smaller markets in other parts of Asia and in Europe. Aquaculture is the single fastest growing animal food producing sector in the world, having an annual growth rate of 6.9%. The worldwide production of Anguillid eels from aquaculture is estimated to be 242 000 t per annum with a value of $US 1 billion. Chinese eel aquaculture production has increased dramatically over the last 10 years, now accounting for 75% of the total annual world production, and relies on the demand of the Japanese market.
Techniques for artificial breeding of the Japanese eel "A. japonica" have been studied intensively since the 1960s. It is difficult to rear these animals in captivity, the main problem being incomplete techniques for inducing sexual maturation and incomplete rearing techniques of larvae.
However the main way that full growth of oocytes is achieved is by repeated injections of salmon pituitary extracts,
Most eel culture facilities utilise freshwater. However a saltwater eel farm operated in Bristol in the United Kingdom for 15 years, using warm seawater growing eels to a marketable size in 18–24 months (it was shut down for economic reasons.)