It is illegal to whitebait after 9pm, but Doc has been receiving more and more reports about up to a dozen people a night fishing on the river.
So on Thursday night a 12-person enforcement party, including Police and the Inland Revenue Department, headed to the Koau (south) branch of the Clutha, intent on catching any offenders.
However, the three vehicles carrying the team were spotted and lights were flashed from a nearby crib warning the whitebaiters.
When the team arrived on the beach it found only a few whitebaiters leaving the beach.
None had nets in the water or whitebait on them.
Doc area compliance manager Bill Wheeler said it was disappointing that the raid had not found "anyone to make an example of" but the operation would still show the whitebaiting community that Doc was serious about catching those who flouted the rules.
"They'll now be on edge. They won't know when we'll come back.
"Seeing three Doc trucks packed full with rangers sends a big message about how serious we are."
A search showed one fisherman had taken off on a quad bike, discarding his fluorescent jacket along the way.
Further down the beach the quad bike was found abandoned in scrub.
Doc took the serial number and planned to follow it up.
Whitebaiter Malcolm Hay, who was spoken to by Doc on the beach, said he was only out fixing his net, but Doc's raid might give his fellow whitebaiters a bit of a shake-up.
Showing his empty bucket, he said while the fish were not running last night, the season had been a good one thanks to high rivers and creeks.
"It's good fun."
Mr Wheeler said reports had indicated people were fishing at the mouth of the river, 24-hours a day whenever the tide was right, essentially fishing commercially and exploiting the resource.
It was believed the whitebaiters were taking 30-40kg each a night.
Whitebait could wholesale from $40 a kg on the riverbank to $120 a kg in the supermarket, Mr Wheeler said.
There were no regulations around the sale of whitebait, apart from the need to declare income from its sale.
The regulations, under the Conservation Act, banned whitebaiting from 9pm to 6am, as some species were threatened, he said.
"The poor little wriggly things are fighting for a chance to breed next year. This denies them a fighting chance."
Fishing outside regulation hours had been an ongoing problem on the Clutha and "a low-key approach" taken by Doc in the past had not been successful.
It was hoped the operation would send a message that people could not do this with impunity, Mr Wheeler said.
Further raids were planned.
Whitebaiters breaking the regulations faced a fine of up to $5000 and the possible loss of their nets.
Whitebait facts
- Native fish that spend six months at sea before making their way up rivers
- Inanga most common species, shortjaw kokopu and giant kokopu threatened species
- Major threat destruction of egg-laying habitat
- Regulations designed so enough young fish mature and produce new whitebait.
- Fishing permitted between 5am and 8pm (or 6am and 9pm daylight saving time)
- Regulations provide for fines of up to $5000
