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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 - habitat
Tuna are found in all sorts of habitats (places), including coastal estuaries, lakes, wetlands, rivers, mountain streams and even alpine tarns. -
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
Currently, the most reliable method to estimate the age of tuna is by examination of their otoliths or "ear bones" -
Tuna - tuna heke (downstream migrants)
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. -
Tuna aquaculture - New Zealand
New Zealand's first eel farm was established in 1971. Despite other farms opening in later years, no eel farms remained by the start of the 1980s. -
Instream barriers and altered water flow
Instream barriers and diversions alter the natural flow of rivers, streams, and lakes. -
Tuna - glass eels
Glass eels (about 5.5 to 7.0 cm) arrive in fresh water during spring, especially during September and October, although they may be present from July to December. -
Mitigation and best practice options
Some simple steps to minimise the effects of wastewater on water quality and mahinga kai.