Mr Lenton said T&G prioritised recruiting locals - but added that as a group, they tended to be less productive.
"In terms of the ability to earn high wages [local and RSE] workers were capable of the same result. But when you look at the overall spread the result was completely different. Most of our RSE workers are in that top group of producers. The local labour was spread much more diversely."
Mr Lenton said many Northland unemployed people were not living anywhere near where seasonal work took place. RSE workers generally paid for accommodation at local motels, lodges and holiday parks.
"But if you take a person say, in Dargaville, for them to travel back and forth to Kerikeri is a big ask," he said.
Melanie Chandler-Winters, Northland regional seasonal labour co-ordinator for PickNZ, said there was a lot of work going on to promote horticulture to the Kiwi workforce, including through schools and trade academies. Her organisation had worked with Corrections placing people coming out of prison into work, as well as with Maori trusts.
Mr Lenton said the money RSE workers earned had an "unbelievable" effect in their home countries.
He travelled to the Pacific Islands twice a year on recruitment missions and described how the standard of living had been lifted in one Vanuatuan village.
"First time we went out there [in 2007] there was one light. When we went out there last time it was lit up like the North Shore ... We're starting to see some of the workers who have been here six, eight or 10 seasons. They've got basic needs sorted and looking at setting up businesses there."
The Ministry for Social Development said at the end of September there were 7910 people receiving a jobseeker benefit in Northland.