CPlay-Tuna-Resource-250217.pdf
Tuna is a generic Māori word for freshwater eels. Māori have over 100 names for eels.
I LIVE: lakes and rivers connected to the sea.
I EAT: Small insects larvae, snails, midges and crustaceans. As our mouths get bigger, we can eat kōura (freshwater crayfish), fish, small birds and rats. When scared I bite!
Did you know: I’m the largest fish in Aotearoa freshwaters
There are three tuna species in NZ: The longfin eel, known as tuna, are unique to NZ, and are one of the largest eels in the world.
LONGFIN EEL
(Anguilla dieffenbachii) Max size: 2m, 25kg
SHORTFIN EEL
(Anguilla australis) Max size: 1.1 metre, 3kg
AUSTRALIAN LONGFIN EEL
(Anguilla reinhardtii), Max size: 2 metres, 21kg
At the end of their lives, eels leave NZ to spawn near Tonga, Samoa, and Fiji. Their fertilised eggs grow into larvae, which drift thousands of kilometers on ocean currents, eventually becoming 6–8 cm glass eels. Near the shore, these glass eels grow into 10–15 cm elvers and move into streams, wetlands, and rivers, often returning to the very places where their mothers lived. Eels can grow up to 1-2 meters long and live for over 100 years! They then return to the sea as migrant Tuna Heke to begin the life cycle again.
My super power is:
- I can swim 1000s km in the sea or fresh water.
- Near the end of my life, I swim from NZ to the deep trenches near Tonga.
- This is where I release eggs/sperm to spawn.
- Over 10 months, my tiny larvae follow the ocean currents back to NZ.
- They develop into transparent glass eels, and swim to rivers.
- They turn greyish-brown and become elvers, to grow into strong adults in fresh water (rivers, lakes, wetlands). Then the swim back to sea and repeat our life cycle.
I help the eco system as a top predator and food source in the marine food chain and help balance the ocean environment.
I am a Taonga species central to the identity and well being of many Māori and are a significant mahinga kai (food).
Treasured & Mysterious
Eels (Tuna) are seen by Māori as taonga (treasures) and ancestors, reminding us of our connection to nature and the importance of caring for it. “Tuna" is the general Māori name for eels. There are three types of eels in Aotearoa New Zealand (NZ): longfin, shortfin, and Australian longfin. Eels are often called "living fossils" because their body structure has remained largely unchanged for millions of years. We still don’t fully understand their evolution.
Incredible Adaptations
- Eels are born without a gender. They grow faster in areas with fewer eels and become females, while those in crowded, competitive environments grow slower and become males.
- Eels are carnivores and use their teeth to eat insects, worms, fish, small birds, and even mice.
- Although they rarely bite humans,if they do, it can result in a painful graze.
- Before starting their long journey to the ocean to spawn, eels undergo dramatic body changes. Their heads flatten, and their eyes enlarge.
Mysterious Migration
- Eels don’t rely on sight; instead, they follow invisible paths using environmental cues such as the Earth's magnetic field, temperature, and salinity.
- During their journey, they cannot feed and rely solely on stored body fat for energy.
- No one has ever seen eels reproduce in the wild. Scientists believe instinct guides longfin eels to the Tongan Trench and shortfin eels to waters near Samoa and Fiji.
- They pass through the deep Kermadec and Tongan Trenches, where the Pacific Plate is sliding under the Australian Plate, creating the ideal deep-sea condi