The major difficulty Mr McNeil said was they did not know who the Tapuika registered members of Te Arawa Fisheries Trust actually were.
"Te Kotahitanga are under no obligation to provide the information so they haven't." In all other respects, Te Kotahitanga had been co-operative and supportive.
Two other Te Arawa iwi, Ngati Rangitihi and Ngati Pikiao, are also considering withdrawing from the Te Arawa Fisheries Trust.
Mr McNeil said he had been a trustee since January 2008 and it was clear even then that Tapuika wanted to pull out.
"The trustees have been told from the floor to withdraw Tapuika from Te Kotahitanga. At the first meeting I thought it must have been a small disenchanted minority but it transpires that the disenchantment is endemic throughout the iwi."
He said one of the problems was there was little or no communication from Te Kotahitanga. The iwi also had concerns about the high administration costs.
"All those of Tapuika who are involved in iwi development thought the cost structures within Te Kotahitanga were relatively high."
Mr McNeil said the current process had provided a good opportunity to examine the costs and benefits of withdrawing and the iwi had commissioned independent analysis.
The benefits of being part of Te Kotahitanga were that it strengthened whakapapa links and unified Te Arawa waka, he said. The authority also had considerable experience in fisheries management and provided educational and iwi development funding benefits.
Members of his iwi had questioned whether they had sufficient experience to manage their own fisheries assets. However, they had already demonstrated commercial competency by retaining intact virtually all of a $2.5million pre-settlement payment from the Crown, Mr McNeil said. "The addition of $1million in fisheries assets will merely add to the kete and although there are unavoidable fixed costs in the industry, there is some advantage in being able to distribute the administrative and support costs for the fisheries assets over the iwi's wider asset base.
"Like virtually every other iwi in fisheries management, Tapuika will be looking to joint partnerships, if the fisheries assets are returned to the iwi," Mr McNeil said.
Te Kotahitanga chairman Ron Roberts has attended various hui and outlined the benefits of staying with Te Kotahitanga.
Part of those benefits were to do with overall benefits of scale.
"We might earn twice what these entities could if they withdraw."
He said the iwi's quota holdings would be so small, if they withdrew companies either wouldn't be interested in their quota or would pay very low lease prices on a take-it-or-leave-it basis.
"Commercially, withdrawal is pretty unwise."
Mr Roberts said his organisation was focused on distributing benefits and the organisation was well managed.
"Since we received the assets in 2006, our annual gross revenue has increased by 11.6 per cent to $1.3million.
"By staying together, Te Arawa has the ability to invest in high-revenue projects.
"At the moment, we are establishing a wholesale/retail/takeaways operation and investigating the acquisition of shares in a fishing/processing company and a quota company," Mr Roberts said.
"Withdrawing iwi will miss out on these types of opportunities."