The move was due to a combination of geographical and cultural reasons, he said.
Poverty Bay will not follow their neighbours in moving to the Chiefs jurisdiction.
“We are committed to the Hurricanes,” Poverty Bay Rugby Football Union chairman Hayden Swann said.
“We receive good support from their coaching development and representative programmes.”
Chiefs chairman and former All Black Bill Osborne said there were rich cultural links shared by the Chiefs and Ngāti Porou East Coast.
“This is a marriage steeped in cultural understanding.
“We share the same values when it comes to culture, te ao Māori principles and spirituality.
“Our focus on people, as opposed to things, is also common.
“I also want to take this time to thank the Hurricanes and New Zealand Rugby for their support on this endeavour.”
Morrison said Ngāti Porou had whakapapa links to Tainui.
“In many ways this is where we belong.”
Morrison said talks had been held with the Chiefs about how the partnership might develop.
Coaches had been sent to Hamilton to assist in their development.
It was possible the Chiefs could some day have a training camp on the Coast, he said.
Ngāti Porou East Coast’s move to the Chiefs was approved by the New Zealand Rugby Board late last year.
The union was formally welcomed to the Chiefs last month at a pōwhiri held under the carved Whatanoa gateway at the entrance to Waikato Stadium.
The Chiefs' affiliated provincial unions are Counties Manukau, who moved from the Blues in 1999, Thames Valley, Waikato, Bay of Plenty, Taranaki, who moved from the Hurricanes in 2013, King Country and East Coast.