Endangered
New Zealand longfin eel
Anguilla dieffenbachii
The New Zealand longfin eel is a freshwater eel that is endemic to New Zealand.
Appearance
The easiest way to identify the longfin eel is by the length of its fins: the dorsal (top) fin is about two-thirds the length of the body and starts significantly further towards the head than the anal (bottom) fin.
In the shortfin eel the fins are of similar length. Males average 66.6 cm but reach up to 73.5 cm in length, with an average age of 23 years (12–35 years).
Range and habitat
New Zealand longfin eel is endemic species to New Zealand, widely distributed through the country's lakes and rivers, among them the Chatham Islands. Longfin eels are often found great distances inland (up to 361 km) along fresh waterways and in high country lakes that are connected to the sea. As juveniles, they prefer shallow water (under 0.5 m deep) with coarse substratum and faster than average stream flow (such as that found in riffles).
Pins are Wikidata “endemic to” fields. Orange dots, when present, are GBIF occurrence tiles — survey bias included.
Breeding
Like other members of the Anguillidae, longfin eels have a rather unusual life cycle: they grow and mature into fertile adults in fresh water, then migrate to the sea to breed. This catadromous breeding system also ensures randomised mating, creating a panmictic population.
New Zealand longfins breed only once at the end of their lives, making a journey of thousands of kilometres from New Zealand to their spawning grounds near Tonga. Longfin eels are long-lived, migrating to the Pacific Ocean near Tonga to breed at the end of their lives.
In crisis
It is the largest freshwater eel in New Zealand and the only endemic species – the other eels found in New Zealand are the native shortfin eel (Anguilla australis), also found in Australia, and the naturally introduced Australian longfin eel (Anguilla reinhardtii). An important traditional food source for Māori (who name them ōrea), longfin eel numbers are declining and they are classified as endangered, but over one hundred tonnes are still commercially fished each year. The DOC panel concluded though that the commercial fishery of the species is stable or increasing, and noted "that public discourse on the longfin eel portrays the species as being severely threatened despite data that indicate otherwise." This conclusion has been seriously questioned, repeatedly, both before and since then, throwing its validity into doubt.
In June 2012 it was reported that some pet food companies use the nationally threatened eels in their products, sparking outrage by conservationists. The IUCN currently classes the species as "Endangered", making the following notes: "Population Severely Fragmented. Continued Reduction in Mature Individuals; continuing Decline in Area/Extent and/or Quality of Habitat" Despite this, the New Zealand government continues to allow its export and allows legal recreational killing of the fish.
New Zealand longfin eel is Endangered on this catalog because that is the IUCN category stored on Wikidata. Confirm the official criteria and any later count on iucnredlist.org.
Sources
Written for this catalog from the English Wikipedia article on New Zealand longfin eel, Wikidata item Q614800. Family and order context is original field-guide writing about the group, not a copied assessment of this one species. Wikipedia text is CC BY-SA. Not an IUCN assessment. Counts, when quoted, can change — confirm them on the recovery programme and on iucnredlist.org.
