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  • Writer's pictureChica Jo

What’s the big deal about a slimy fish?

The longfin eel (Anguilla dieffenbachii), the world’s largest and longest-lived freshwater eel, and a creature of great cultural and biological significance, is at risk of extinction.  These amazing and mysterious fish evolved 80 million years ago and are endemic to New Zealand. Longfin females often grow to two meters in length, have been reported to weigh up to 50 kilos, and can live over 100 years before migrating (like the smaller males) all the way downstream and then 6000 km farther to deep sea trenches to mate by releasing their up to 20 million eggs.  Soon, the tiny, transparent, leaf-shaped leptocephalli (baby eels) rely on ocean currents to drift back to their homeland where they are now small eels, called elvers, that spend their first years swimming back upstream to live in freshwater lakes and rivers.

The migrating adult eels as well as elvers face many human created challenges on their journeys.  Although they are resilient, determined creatures that are able to slither and climb out of water for two days, breathing through their skin, if it stays moist, New Zealand’s loss of 90% of its wetlands has caused a great decline in eel numbers since European settlers arrived and altered the landscape.  These settlers also encouraged eel eradication so as to promote introduced sport fish such as salmon and trout.  The tough longfin survived this purposeful, gross over-fishing, but now those introduced fish pose a threat, as do introduced mammals such as rats and house cats, all of

which feed on the young migrating eels.  Certainly, the effects of various water pollutants from farming, industry, and urbanization are obvious problems as are the many insurmountable dams and culverts that have been built in the last century.  However, in addition to the effects on these eels by global climate change (which is just beginning to be studied) there is one current, outstanding threat to their survival as a species:  commercial fishing!  The recent growth in unsustainable commercial eel fishing practices since the 1960’s (due to overseas demand where other eel fisheries were depleted) is the most clear and present danger to the survival of this eel, one of the world’s most awesome animals.

Called “tuna kuwharuwharu” by the Maori people, the longfins have long been a critical focus of Maori tradition and culture that continues today.  The Maori also historically relied on these eels for survival as a staple, dependable, year-round food source.  Ecologically the longfin eel plays a key role as the top predator in New Zealand’s struggling freshwater ecosystems.  Because of their unique life cycle, killing just a small number of Longfins now will likely mean a huge, sudden drop (possibly resulting in extinction) in these eel populations in the near future.


  1. Click here to sign the petition to ban commercial fishing of the longfin eel.

  2. Go find eels and watch them.  You may even be able to make an eel your friend by feeding it.  You can put dog food or pieces of meat in the water or even on the bank and pet your new friend as it comes out of the water to eat!

  3. If you catch an eel, admire its ancient strength and mystery; think of how long it has traveled, and then gently release it back into the water.

  4. Create fish passageways on your land if there are dams and/or culverts.

  5. Share what you have learned with everyone you meet and invite them to create part of the ‘Traveling Tuna Tapestry.

  6. Visit the Manaaki Tuna website, coming in 2011 to get more eel conservation information.

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