"[I'm] not sure why WEG was disestablished, no reasons were given to me.
"I believe the demise of WEG has left a void. We were highly respected overseas and the WEG example was held up as a best practice model for other countries to consider following."
Williamson said the group hadn't been replaced with anything similar.
"I was very proud of WEG and I think we did do pretty good work around profiling and interdicting persons involved in smuggling endemic wildlife out of New Zealand."
Williamson said New Zealand was particularly vulnerable to wildlife trafficking, as bringing in foreign invasive species and pathogens could cause our own native species to become extinct.
"Conversely the trafficking of our endemics out, we risk losing something of our identity.
"We have an extremely high rate of endemism [species found only in New Zealand] unlike countries like the UK for example.
"In fact, they were able to reintroduce species such as the sea eagle from Scandinavia when they lost their own species.
"We simply can't do that."
An expert source, who asked not to be named, said a lot of what made WEG successful was lost when the group was disbanded, such as their shared location.
They said the current system, based on the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), wasn't stopping smugglers.
"The permit system is the way of monitoring and regulating legal trade in CITES-listed specimens," the source said.
"Plenty of illegal trade happens outside of the permitting system.
"The wildlife crime and trafficking issues that predominate in New Zealand are related to smuggling, the perpetrators of which cannot be caught via the permit system."
When contacted for comment, a Ministry for Primary Industries spokesman said there were still people working on the problem, but not as a dedicated task force.
Communications adviser Nick Hirst said New Zealand had made a commitment to stop smuggling, by passing the Trade in Endangered Species Act in 1989, and signing up to CITES.
"The aim of CITES is to ensure international trade in specimens of wild animals and plants does not threaten their survival.
"Around 6000 species of endangered animals and 30,000 species of endangered plants are protected under CITES.
"This act has been administered by the Department of Conservation [DoC] since it came into force on June 1, 1989," he said.
DoC has rangers that manage and investigate under the CITES permit system to identify people trying to illegally import or export protected species.
Customs spokesman Martin Mere agreed with MPI that although the groups no longer operated under the WEG title, MPI, DoC, and Customs continued to work together.