In October and November DoC spent $295,000 on a co-ordinated incident management (CIM) plan in response to an increase in threats and abuse, which culminated in an anti-1080 hikoi to Parliament.
DOC spokesman Nic John said the department had been working with police, resulting so far in four warnings, four arrests and one conviction, adding that it was unfortunate that money was being spent on security when DoC staff were operating legally and in the interests of promoting conservation for all New Zealanders.
"I don't think anybody should be subjected to the harassment and threats that our staff have — not many workplaces would tolerate this, and we've done so for far too long," he said.
Mr Hague said it was infuriating that DoC had had to shift money away from conservation.
"This is money that should have been available for the vital task of protecting our nature, and to have it diverted, in order that DoC staff and contractors can be safe from these awful people, is just absolutely frustrating," he said.
The "irrational" behaviour of the anti-1080 protesters had been highlighted when autopsy results revealed that a weka, which was used during a protest, had likely been shot with a .22 rifle, despite claims it had been poisoned with 1080.
"These extremist anti-1080 protesters are just completely beyond reason. They don't use actual evidence in anything they say, and their arguments are immune to the rules of logic that most people would apply," Mr Hague said.
Roger Lorigan, who runs the pest control company Epro, said his staff had been the target of many threats and vandalism, including the Far North incident. Anti-1080 sentiment had ramped up over the past 18 months, but he remained committed to the cause.
"I've been dealing with 1080 for a long time, and I'm a mad keen hunter as well, so I sort of see it from both sides," he said.
"When you look at New Zealand's threatened species, and you look at its bush, it's a pretty spectacular thing to try and save; 1080 works, there's no ifs, buts or maybes, and it doesn't do all the damage people try and say it does."