A second senior gang member, usually based in Mataura, was arrested in Gisborne and police are still looking for a third "key member" of the Dunedin gang.
The arrests were the culmination of a six-month-long electronic surveillance operation targeting the hierarchy of the gang in the South.
Southern police district crime services manager Detective Inspector Steve McGregor said 35 police staff took part in raids at properties across the city early yesterday.
The eight people arrested face a wide variety of charges, including participation in an organised crime enterprise, conspiracy to supply cannabis, possessing cannabis for supply and more than 50 charges of selling cannabis.
The alleged crimes took place in Dunedin and Mataura.
Cannabis was located at several of the properties and a caravan and three motorcycles, one a Harley-Davidson, suspected to be linked to the organised crime enterprise, were seized.
One of those arrested, a male, appeared in court in Gisborne yesterday, but is expected to make further appearances in Dunedin.
Another male was in police custody last night, and is expected to appear in the Dunedin District Court today.
The others are expected to appear in Dunedin this week and next week.
Det Insp McGregor said electronic-based surveillance was used during the operation, which was named Rocket, but declined to elaborate.
Late last year, new cyber-monitoring measures were introduced giving police the power to monitor all mobile calls and texts, email, internet surfing and online shopping, chatting and social networking.
Police believed the cannabis was sourced from within the Southern Police District, which includes Otago and Southland, and their evidence so far suggested most of it was sold locally, Det Insp McGregor said.
He declined to say to whom police believed the drugs were sold.
The operation's aim was to infiltrate local Mongrel Mob hierarchy and this was the "first step" to achieving that, he said.
"But that does not mean to say we are finished."
