New Zealand is a dream country for all trout bums. I was lucky enough to spend more than a year there on working, holiday, and tourist visas. During my stay, I saw a few giant eels following the trout I hooked. I also landed a couple of trout with apparent marks of eel jaws. COVID stopped all traveling for a while; however, in November 2022, I finally returned to the North Island for some fishing.
Returning to this river, it’s just like I remembered. I had a short walk to the river, prepared my nymphing setup, and started working water in the upstream direction. After approximately 2 hours of fishing, I landed five nice rainbows and reached some hefty rapids. Only a few people fish through these rapids, so there was an excellent opportunity to get into some bigger fish. After a few casts, I hooked another beautiful rainbow.
The fight took a few minutes, and I was able to get it in the net! After successfully landing, I decided to take some pictures. I prepared a tripod with my phone, and when I put my hand into the net to grab the trout, I almost shit my waders. A long black shape came quickly from the side and tried to catch my rainbow. Not one but two eels together were chasing this fish while I had it in the net. I moved toward the Eels trying to scare them away. The Eels moved a bit back but started to chase again. I’ve never seen Eels so aggressive before. Suddenly I lifted the net from the water, but the Eels continued to pursue, with one of them biting the trout in my net.
I finally tried kicking the Eels away to try and get them to stop harassing my nice rainbow. The Eels were crazy-it seemed as if they wanted a good meal from the trout I landed.
I didn’t want to torture the trout more with photo shooting, so I released him, hoping he would escape the jaws of the Eels. By the end of the day, I saw three more eels, something I had never seen nor experienced when fishing this majestic river.
Fish: Native vs. “Invasive”
It’s pretty well known that trout are not the native fish of New Zealand. On the other hand, Eels are native, so let’s look closer.
Longfin Eel (Anguilla dieffenbachii) are locally known as “tuna.” Endemic to New Zealand, the longfin eel, so named because its dorsal (top) fin is longer than its bottom fin, is one of the most giant Eels in the world. Some females can reach up to 2 meters long and weigh up to 40kg.
During the day, Eels are secretive, hiding under logs and boulders or undercut riverbanks. They hunt primarily at night, using their excellent sense of smell. Juvenile Longfin Eels feed on insect larvae, worms, and water snails. As they get bigger, they begin to feed on fish. They will also eat freshwater crayfish and even small birds like ducklings.
When Eels begin life, they are microscopic, only reaching one millimeter in length. Eels are slow growing compared to many other fish – a longfin may grow only between 15-25mm a year. They can also live for many years. Large longfins have been estimated to be at least 60 years old.
Longfin Eels have a unique life cycle. They live in rivers, lakes, and wetlands for most of their lives. Then, after 25-80 years, they travel 5000km to the South Pacific near Tonga to breed. After laying their eggs, they die. The tiny fertilized eggs float on ocean currents for about 15 months until they reach New Zealand. They then journey inland, swimming up rivers and waterfalls and even crawling over dams! They transform into glass eels and then elvers before becoming adults. However, Longfin Eels are now considered at risk, and their numbers are still declining.
Angler Story of the Week from Martin Dvořák, be sure to follow his fly fishing adventures on Instagram @mdx_flyfishing.