Eels
Poor eels! They are ugly, slimy and snake-like. Lots of people don’t like them. But eels are actually fantastic creatures. They make amazing journeys and they’re not stupid – they are easily tamed and people can have ‘pet’ eels in their streams.
The eel’s story
Hey good looking. Photo: Mike JoyEels live in swamps, rivers, lakes and estuaries. They eat small fish, insects, worms and snails. Shortfin eels prefer the lowland waters. Longfin eels are good at climbing and often live far up rocky mountain streams.
Female eels grow bigger, become adult later and live longer than male eels. A female longfin eel will become an adult and ready to produce eggs when she is about 60 years old (!!!)and a female shortfin eel when she is about 40. Some females don't breed until they are 100 years old. Male eels are younger when they mature.
When the adult eels are becoming ready to migrate, their guts shrivel and they stop eating. They will never eat again. Their eyes become very big to help them see their way through the ocean.
Fact box
• Eels are long, skinny fish
• They swim by wriggling their sinuous body
• Both the longfin and the shortfin eels are native but the longfin is also endemic. It is only found in New Zealand.
• They date back 100 million years in New Zealand
• They live to a great age, up to 100!
• Small long-fin eels eat on insect larvae, worms and water snails. Once they get older they snack on fish, freshwater crays and even ducks
• They migrate between freshwater and the sea
• They need protection urgently! Their numbers are plummeting!
A migration is a long journey and the eel’s migration is amazing. In the autumn, the phase of the moon and heavy rain tell the eels when it is time to set off. Down the streams they go, out of the harbours and across the ocean – 2500 kilometres to their breeding place.
It takes them about five months to make this journey.
Paris maybe the love capital for humans, for our eels it’s Tonga. It's here that they all meet up and make their babies.
In the inky depths of the sea the eels spawn, producing their eggs and sperm. The fertilised eggs drift up into the plankton and away in the ocean currents. The parent eels die.
The eggs hatch into leaf-shaped larvae, so clear you can see right through them.
For nearly a year they drift across the Pacific and past Australia. As they approach the coast of New Zealand they turn into tiny eels called elvers.
Elvers climbing up a rock faceThe elvers swim up the rivers to find their homes where they will live and grow until, one day, they set out again on their own migration.
Eels are in trouble!
• Too many eels are being caught by commercial fishermen. The endemic longfin eel is now classed as a threatened species, in danger of extinction.
• Eels are losing their homes. Most of the wetlands have been drained and turned into paddocks. Many streams are blocked by culverts. Many rivers are blocked by dams.
• Hydrodams are too high for elvers and native fish to climb and, even if they can, when it is time to migrate, they can’t swim down over the dam. They are killed in the turbines.
Helping eels
• Some lakes and the rivers in National Parks are closed to fishing and safe for eels to live in.
• Passages and fish ladders can be made to let eels and other native fish swim upstream through culverts and up dams.
• Big dams can let water spill over at times when eels are migrating downstream (wouldn’t that help them?)
What you can do
• If you live on a farm with a pond or streams or rivers, protect your eels. Don’t let commercial fishermen catch them.
• If you catch a black eel and see its skin wrinkle, put it back. It is one of our special longfin eels.
• Culverts are little dams that we use to channel water under roads. Eels can climb wet rocks but they can’t jump up into culverts high above the water. Look at the culverts near you. Will they let fish swim up them? They can be modified to let fish through.
