Music Industry Piracy Investigations general manager Michael Speck said a survey carried out by the anti-piracy unit's computer forensic experts revealed a dramatic reduction in the number of active file-sharing hubs.
Speck said 50 of the 63 Web sites which fell within MIPI's "investigative threshold" had shuttered.
In addition, there was a noticeable decline in the number of Australian users accessing the allegedly illegal hubs, he said.
Speck added that comments now appearing on major file-sharing Web sites suggested that hub owners were aware of the legal action against Swiftel and have decided to act by shutting their file exchanges.
He said one of the sites under surveillance recorded 1,606 users on a particular day shortly after the raids, but had become completely inactive within a week.
"The knock-on effect of last week's raid represents an important development in the fight against Internet piracy in Australia and proves that the Internet service provider industry is prepared to take copyright issues seriously," Speck said.
MIPI expects more hubs to cease operations next week. The 13 remaining hubs have been warned to comply with copyright legislation or risk court action.
"They will continue to be targets. We will get to them in due course if they don't shut themselves down. We take the view that the raid on Swiftel was sufficient warning for the 63 targets. The remaining [active hubs] don't get further warning," Speck told ZDNet Australia .