The news brought little comfort to anxious family members back home, since the new charges still carry stiff prison sentences of up to seven years.
But Patti Ruzycki Stirling, whose brother Paul Ruzycki was serving as first mate aboard the Greenpeace ship "Arctic Sunrise" when it was seized last month, said the decision still represents progress from the Russian government.
Ruzycki, fellow Canadian Alexandre Paul and 28 other activists were originally facing prison terms of up to 15 years under the original piracy charges.
"It's the first step in the right direction, the fact that they've come to their senses and realized that piracy is lunacy, that they had no grounds for that," she said in a telephone interview from her home in Port Colborne, Ont.
Greenpeace took a harder line, saying their crew members were arrested while travelling in international waters and should not be behind bars at all.
Christy Ferguson, Arctic Campaign Co-ordinator with Greenpeace Canada, called the new charges "wildly disproportionate."
"Hooliganism carries up to seven years in prison for what was still a peaceful protest being made in the public interest," she said. "These were people who were protesting dangerous Arctic drilling and trying to shine a light on what's happening in the Arctic."
She added the situation could get worse if Russia's Investigative Committee follows through on a warning that it could file additional charges against the activists, including violence against authorities — a charge punishable by up to 10 years in prison.
Vladimir Chuprov of Greenpeace Russia said the activists "are no more hooligans than they were pirates" and should be freed immediately.
"We will contest the trumped-up charge of hooliganism as strongly as we contested the piracy allegations. They are both fantasy charges that bear no relation to reality," he said in a statement.
Ruzycki Stirling said the prospect of seeing her brother spend years behind bars is alarming, particularly after learning details of his incarceration.
She said her brother has been able to make one 20-minute phone call to his family, in which he reported cold, noisy conditions that prevent him and his fellow crew members from sleeping.
All told, however, she said her brother was in good spirits and reasonable health.
Word of the reduced charges follows a comment by Russian President Vladimir Putin, who said last month that he doesn't think that the Greenpeace activists were pirates.
The group of 28 Greenpeace activists, a Russian photographer and a British videographer have been held since their ship was seized by the Russian coast guard after protesting outside a Gazprom-owned oil rig on Sept. 18.
The Investigative Committee said that the detainees' refusal to testify has impeded the investigation.
"That prompts the investigators to thoroughly check all possible versions, including the seizure of the platform for financial benefit, terrorist motives, the conduct of illegal scientific research and espionage," the agency added.
_ With files from Michelle McQuigge in Toronto.