He said the policy of widely distributing caps had aided players in their bid to move to the northern hemisphere and Japan, adding to their value and easing the employment processes.
"I'm hugely concerned about New Zealand rugby, I'm really worried about it," Gatland told The Sunday News.
"If you're looking forward, you've got to make that All Blacks jersey incredibly elite, you can't give it away.
"This is reflected in the number of players we're losing.
You've got to think about who you're selecting as All Blacks and make it really hard to earn that jersey.
"That's going to help keep a number of players here, because if you've been an international in the last 18 months you qualify for a visa in the UK and that would cut off a number of players having an opportunity to go there."