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| The most common eel encountered in the headwaters of small streams, these endemic fish may live for over 60 years, and grow to 2 m in length. They penetrate far up waterways to their sources, and are only found in New Zealand. No doubt large aggressive individuals of this species were taken to be the mythical beast; the 'Taniwha'. They are typically the top level predator in their habitat, feeding largely opportunistically on whatever they happen to come across in their foraging. Larger adults may take large insects and spiders, koura, small rodents, and even fish including their smaller cousins the shortfin eels (A. australis). They are largely active at night, finding their food chiefly through their excellent sense of smell. Conservation status: Although fishing pressure and loss of preferred upper forested stream habitat has certainly reduced historic population sizes, longfin eels are still common. This is undoubtedly through their high tolerances to water pollution and habitat modification. |
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More commonly found in wetlands and rivers, the shortfin eel is an opportunistic feeder, making use of any small animals (dead or alive) which they happen upon with their excellent sense of smell. Food items include snails, small fish, and insects. They are found through New Zealand, often penetrating deep inland but being more common near the coast. This species is also found in Australia and grows to a length of around 1 m. They are most active at night, and are often readily seen under torchlight hunting along the edges of stream banks and under rocks and sunken logs. Conservation status: One of the few native freshwater fish species likely to have benefited from human impacts, increased nutrient inputs and warmer water temperatures such as those found in many pasture streams cause greatly increased growth rates in shortfin eels. Their major threat is through commercial fishing taking adults before they are able to reproduce, and dams acting as migration barriers. |
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| The common smelt is frequently abundant in the open waterways such as the Waikato River and many of its lakes. It is also sometimes found in large streams where temperatures are cool, and the current relatively swift. Their food in streams is largely terrestrial insects caught at the surface, whilst in lakes they feed on the large zooplankton crustacea. Populations may be either migratory or not, and are often of mixed life-strategies. The upstream migrating young of migratory populations are often caught and sold as second-class whitebait, and the adults are traditionally dried for later eating. They have, however, a very distinctive cucumber smell. Smelt only live for around 2 years. Conservation status: As their name suggests, common smelt are not significantly threatened in most parts of New Zealand, often surviving well in modified water bodies. |
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| The torrentfish is the only freshwater member of the “blue cod” family. Well named for its preference for fast turbulent waters, at night they move to pools to feed. They are well adapted to fast water life with their low-profile body, and sharply pointed head. This is also a migratory species, only existing where there is easy access to the sea. Males predominate in the lower reaches closer to the sea, whilst the females are more abundant at higher elevations further inland. Typical food items include worms and aquatic insect larvae; with a predominance of slower moving species in their diet taken with their downward pointing mouth. Lengths are to around 110 mm and they probably live for 5 or more years. Conservation status: Mostly found in open-bedded rivers, the torrentfish does not seem to have been seriously affected by the removal of native forest cover as have other species. It remains relatively common. |