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Estuary origins
In comparison to the vast span of geological time, the estuaries that we see today are very recent coastal features. -
Tuna - identification
There are several ways to tell the three New Zealand eel species apart. -
Climate Change Vulnerability Assessment (CCVA)
ServiceTo prepare for changes in climate, our freshwater and oceans decision-makers need information on species vulnerability to climate change. -
Tuna - life cycle and leptocephalii
Freshwater eels have an unusual life cycle which sees them travelling between the ocean, estuaries and freshwaters. -
Taonga Species Series: Kākahi
Feature story06 June 2017What does science tell us about New Zealand freshwater mussels? -
Tuna - habitat
Tuna are found in all sorts of habitats (places), including coastal estuaries, lakes, wetlands, rivers, mountain streams and even alpine tarns. -
Taonga Species Series: Pātiki
Feature story06 June 2017What does science tell us about New Zealand flounder? -
Tuna - diet
Longfin eels are the largest and longest-lived fish in New Zealand's freshwaters, and where they are present they are the top predator. -
Tuna - maturation and identifying sex
The sex of tuna is not determined genetically, as in some other organisms. -
Tuna - age and methods of ageing
Knowing the age (i.e. proportion of young vs. old) of eels in an eel population provides an understanding of how fast they grow and may give an indication of the pressures faced by tuna in a particular environment or habitat. -
Tuna - tuna heke (downstream migrants)
Every year, a proportion of eels mature and migrate to sea to spawn. Once eels become migrants (also known as tuna heke or tuna whakaheke) they stop feeding, and progressively develop the external features that clearly distinguish them from 'feeders'. -
Tuna - spawning grounds
All species of freshwater tuna spawn at sea, although the spawning grounds of only four species are known with certainty worldwide.