It was the best season Department of Conservation freshwater ranger Pete Ravenscroft could recall, with the last good season four or five years ago a "shadow" of this one, he said.
"It's one out of the blue."
Taieri River whitebaiter Walter Gibson (78) returned home empty-handed only two days this season.
"It's been very good compared to last season, which was very poor."
Catching more than a pound (500g) each session was not unusual, but he tried to let plenty go past so there were more whitebait next year, he said.
Mr Ravenscroft said the Clutha River was a prime example of a waterway that fished really well, although the amount caught was hard to quantify as whitebaiters were notoriously cagey about their catches.
Rumours abounded of people catching a couple of hundred kilo a season or even in a weekend.
The reason for the good season was not known, but factors could be Doc's work with Contact Energy to try to regulate flow levels to achieve optimum spawning conditions for the whitebait.
"It's the first time Contact has been able to achieve it."
More than 40km of spawning sites along Otago rivers had been fenced off in recent years, as well.
"We really don't know what the reasons are.
It could be a combination of a number of things."
Whitebait species inanga, which made up 95% of the Otago whitebait catch, was listed as at risk and declining, so a good season could only be positive.
As only a small percentage of whitebait were caught by fishermen, it was retaining habitat that made the most impact on its numbers, he said.
While it could not control whitebait's time at sea, Doc did its best to maintain its habitat in freshwater.
