New Zealand longfin eel
| New Zealand longfin eel | ||||||||||||
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New Zealand longfin eel in a crevice of a waterfall near Piha Beach |
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| Anguilla dieffenbachii | ||||||||||||
| JE Gray , 1842 |
The New Zealand long- fin eel ( Anguilla dieffenbachii ), English: Longfinned Eel, is one of the three major eel species that live in New Zealand . The other two species are the short-fin eel ( Anguilla australis ) and the recently introduced Australian long -fin eel ( Anguilla reinhardtii ). The New Zealand longfin eel is one of the longest and, with a maximum age of 100 years, one of the longest-lived eel species in the world.
Occurrence
In contrast to the European eel, the New Zealand long-fin eel prefers fast-flowing clear brooks with a stone bottom. Anguilla dieffenbachii is endemic only to New Zealand and the Chatham Islands between the latitudes 34 ° S - 47 ° S. New Zealand long-fin eels cover large distances from lowland waters to highland lakes on their spawning migrations.
description
The New Zealand longfin eel can weigh up to 180 cm and over 25 kilograms. There are also unconfirmed reports of 2 meter long animals with a live weight of over 50 kilograms. The heaviest New Zealand longfin eel ever caught with a fishing rod was from 1981, weighed 15 kilograms and was caught in the Selwyn River. The eels have a dark gray to black body color. They differ from other eel species in the length and arrangement of their dorsal and anal fins. The sexing of the animals can only be carried out from a length of 450 millimeters.
Way of life
Anguilla dieffenbachii lives catadromously like many other eel species . The fish live in fresh water and migrate into the sea to spawn. From a population-genetic point of view, this type of reproduction leads to panmixia and random allele distribution . New Zealand long fin eels grow very slowly and can live for 106 years in captivity. Male and female animals differ in length and age once they start migrating to the sea. Male animals begin the migration with an average age of 23 years (12–35 years) and an average length of 666 millimeters. Females aged 20 to 60 years and 1156 millimeters in length. The average migration age of the animals varies between the North and South Island . The population of the North Island reaches a faster generation time due to the younger average age of the fish. The migration of eels is influenced by temperature, water flow and lighting conditions. Climate phenomena such as El Niño also play a role. There are four phases in the life cycle of the New Zealand longfin eel, which is not yet fully understood. Adult specimens often hide under bank cavities, crevices or rotted plant material. New Zealand long fin eels are food gathering opportunists. They eat insect larvae and small eels, among other things. As they grow, they also feed on galaxies and trout . They mainly eat fish, small water birds and animal carcasses. They show an omnivorous diet and locate their prey with the help of their highly developed sense of smell.
Economical meaning
The New Zealand longfin eel is an important source of protein for the Māori . Nowadays it is consumed fresh or smoked. The commercial use of Anguilla dieffenbachii began in the 1960s, reaching an annual output of 2,000 tons. Since 2000, a catch limit quota with a certain permitted catch has been introduced on the South Island and in 2004 on the North Island. The catching and export of glass eels was banned. For a long time, attempts were unsuccessful to keep A. dieffenbachii in aquaculture . The last farm had to close in 1982. The reasons for the failure were economic problems (a low market price did not justify the high production costs for eel rearing), an uneven supply of glass eels and high animal mortality. In the 21st century, with a better understanding of the biology of A. dieffenbachii and the dwindling populations of the European eel ( Anguilla anguilla ), breeding efforts have resumed.
Relationship with people
Anguilla dieffenbachii was first described by the Europeans by James Cook . The Māori , who call the fish Tuna or Taniwha, revere the New Zealand long-fin eel in numerous myths. In their mythology it has various meanings as a phallic symbol or in a heroic saga as an antagonist to Māui . Legend has it that Māui found Tuna in bed with his wife while he was sleeping. Other stories tell of a girl who was raped in a spring well by Tuna, who was once her pet. A villager caught Tuna and chopped off his head, and a girl buried him in the sand. A short time later, a coconut palm grew exactly at this point . Māui would have cut Tuna in half. One half became freshwater eels and the other half became saltwater eels. Taniwha means "water monster" or "powerful person" in the Maori language. According to their ideas, killing a Taniwha is a taboo break at certain times that is cursed. Some of the fish are kept in isolated ponds by the natives of New Zealand, where they are fed daily and can reach old age. The Maori treat the animals with respect and admiration. Other animals are kept in freely accessible pools of a stream or river, where they can begin their spawning migration unhindered. Due to the regular feeding, the eels are very used to humans and have lost their shyness. They are not aggressive towards humans, but only hand feeding can lead to unintentional bite injuries.
Web links
- Importance of Tuna to Maori.
- Maori Eels.
- Potangaroa: The Longfin Eel Tuna Kuwharuwharu - Facts, threats and how to help.
- Distribution map of the New Zealand longfin eel near Waitakere.
literature
- AMR Burnett: Studies on the Ecology of the New Zealand Long-finned Eel, Anguilla dieffenbachii Gray, Australian Journal of Marine and Freshwater Research 3 (1) 32-63, CSIRO Publishing.
Notes and individual references
- ↑ E. Watene: Potential for Commercial Eel aquaculture in Northland. Auckland: National Institute of Water and Atmospheric Research, 2003
- ↑ DJJellyman: Status of New Zealand fresh-water eel stocks and management initiatives. ICES J. Mar. Sci., 2007
- ↑ GJ Glova, D. Jellyman and ML Bonnett: Factors associated with the distribution and habitat of eels (Anguilla spp.) In three New Zealand lowland streams. New Zealand Journal of Marine and Freshwater Research, 1989, 32 (2), 255-269
- ↑ a b c d e New Zealand Longfin Eel on Fishbase.org (English)
- ^ PR Todd: Size and age of migrating New Zealand freshwater eels ( Anguilla spp .), NZJ Mar. Freshwat. Res., 1980, 14 (3): 283-293
- ^ Fishing World Records
- ↑ Archived copy ( memento of the original from February 9, 2013 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
- ↑ PJ Smit, P. Benson, C. Stanger, B. Chisnall, C Stanger and BL Chisnall: Genetic structure of New Zealand eels Anguilla dieffenbachii and A. australis with allozyme markers, Ecology of Freshwater Fish, 2001, Volume: 10, Issue : 3, Pages: 132-137
- ↑ Chisnall, B. Hicks: Age and growth of longfinned eels (Anguilla dieffenbachii) in pastoral and forested streams in the Waikato River basin, and in two hydro-electric lakes in the North Island, New Zealand ( page no longer available , search in Web archives ) Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice.
- ↑ of Fisheries: Longfin Eels and Shortfin
- ↑ Doole: Optimal management of the New Zealand longfin eel ( Anguilla dieffenbachii ), The Australian Journal of Agriculture and Resource Economics 2005 .
- ↑ Maori Eels
- ↑ http://www.longfineel.co.nz/longfin-tuna/importance-of-tuna-to-maori/
