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Trout fishermen are reeling in their best catches ever as shoals of fish migrate to escape the soaring temperatures.
The latest heat wave, posting temperatures of up to 28C last week, has forced massive shoals of trout to abandon sweltering Lake Rotorua in search of colder water in the streams, where there is more oxygen.
And it's good news for hordes of fishermen, who are experiencing a fly-fishing bonanza.
Eastern Fish and Game staff described the fishing conditions as "pretty exceptional" and told of chaotic scenes on the riverbanks at Awahou as crowds of fly fishermen try their luck.
The fish are so numerous that anglers have been catching them just metres away from children swimming and jumping in the water, with the trout seemingly oblivious to the noise and splashing.
The most popular locations have been the Awahou, Ngongotaha, Waiteti and Hamurana streams.
One local fishing shop admitted they had so many customers that they ran out of trout flies last week and had to reorder more stock.
"Things are happening which haven't happened here for a number of years," said Eastern Fish and Game regional manager Rob Pitkethley.
"Lake Rotorua is very warm and when the conditions are like this the fish ... are moving into a cold water stream mouth and even into the lower reaches of the streams.
"So there's a lot of fish there and they are highly visible.
"I was at the Awahou stream and it was chaos. On Thursday night there were more than 50 and less than 100 people all milling around swimming and fishing. It is a bit of a carnival atmosphere going on at the moment, kids jumping out of willow trees, people catching fish. It's just bedlam.
"It really highlights the importance of the cold water to sustain the Rotorua fishery and it's a good message to get out there.
"We have concerns about those cold water sources being threatened by various things such as increased water extraction, or diverting more of the cold water away. If it was all diverted directly down into the Kaituna River you would expect to see some impact."
Fish and Game staff have increased their patrols in the area to ensure the large number of anglers are obeying the rules. Mr Pitkethley said there had been a good level of compliance with just a few people fined for using the wrong methods such as spinning where only fly fishing is allowed, "mainly through ignorance".
Trout fishing tutor Harvey Clark, who lives in Ngongotaha, said the deluge of fish meant he had complete beginners hauling out five-pound fish within a few hours of being taught how to cast.
"I have seen women of 60 down there for the first time hooking fish - but not necessarily landing them - and I have seen tiny children of six or seven catching fish that are damn near as big as they are. It's very amusing."
