Divers catch 2605 catfish in southern Lake Taupō.

Cressi Great Lake Taupō Catfish Cull organiser Aaron Dowman with some of the 2605 catfish speared during the competition last Saturday. Photo / Supplied

Most people like cats. Most people like fish. But nobody — nobody — likes catfish.
Except perhaps divers armed with pole spears, who like catching catfish.

And plenty of the slimy critters were caught last Saturday during the annual Cressi Great Lake Taupō Catfish Cull on southern Lake Taupō.

Organiser Aaron Dowman says the competition was based at Motuoapa and covered an area of Lake Taupō from Bulli Point south to the Tokaanu tailrace. In all, 274 divers speared 2605 catfish.

The annual competition is run by Spearfishing New Zealand and is the only freshwater spearfishing competition in New Zealand. While other New Zealand spearfishing competitions allow the use of spearguns, in the Lake Taupō one competitors use a spear known as a Hawaiian sling, or pole spear.

The divers came from all over New Zealand and some even from overseas, Aaron said.
During the competition divers were in water between 1m and 15m deep. Aaron says the majority of the catfish were caught at the lower end alongside the coastline, from Motuoapa Bay to the Tokaanu tailrace.

The winners were Pat Swanson and Rowan Virbickas who got 119 fish between them. The smallest catfish caught was 3 grams and the largest more than 500g, Aaron says. In past years the biggest catfish has been up to 700g.

At the end of the competition the catfish were loaded onto a lined trailer and transported to Awhi Farm near Turangi where they will be turned into compost.

Aaron says the number of catfish caught varies from year to year. Last year there was a storm a few days beforehand which pushed the fish into deeper water, and the year before that there were fewer fish in the Motuoapa Marina because the marina was being redeveloped.

DoC freshwater threats ranger Brenda Lawson, who attended the competition, says it's been scientifically proven that catfish don't have an effect on the trout population in the lake. However, the main problem with catfish was that they were bottom feeders and stirred up mud and silt, making the water murky.

They also ate snails and New Zealand native fish like bullies. Larger catfish were also known to eat koura (freshwater crayfish).

"Once [catfish] get to 25 to 30cm and above, they actually do feed on the koura and once when I was hunting for a red-eared slider turtle I caught a catfish which obviously had been eating koura. It had pink flesh and eight reasonable-size koura in its stomach," Brenda says.

"We don't want catfish in the lake but they're not a huge problem, they don't seem to have enough habitat to become hugely overpopulated. They prefer the warm shallow waters around the raupo swamps in the Tokaanu-Motuoapa area."

However in areas that suit catfish, they can proliferate.

"When they did the Motuoapa Marina refurbishment and had to empty out the old marina and release any native species, in one little area which they thought must have been a breeding ground, they caught 6000 juvenile catfish.

"Every month the DoC fishery team set fyke nets to study them and they regularly catch 300 at a time from the Tokaanu area."

Catfish, which were thought to have been eradicated from Lake Rotoiti, have recently been rediscovered there and that means the message of Check Clean Dry to reduce the spread of freshwater pests is more important than ever.

"We want people to be aware that catfish can be spread by people moving boats and boat trailers and there's also the possibility of the eggs being moved. Catfish can last a long time out of water and even one you think is dead on board could be released into another lake and still live."

The pressure's not over for Lake Taupō's catfish yet — the World Freshwater Spearfishing Champs runs on Lake Taupō on March 9 and 10.