"We fully understand and support him in this decision and wish him and his family all the best for the rest of the year here in New Zealand, and for their next adventure in France," Hansen said.
This year will be Ranger's second as captain after he co-captained the side last year along with lock Bryce Williams.
Northland's first match of the ITM Cup is a Ranfurly Shield clash against Waikato, which will be the first time Northland has opened its season with a Ranfurly Shield clash.
Last week, All Blacks coach Steve Hansen said he will continue to pick Ranger despite his impending departure to play club rugby in France.
Ranger played two sparkling cameos against France in June before earning a starting spot in the final test at New Plymouth.
Northland's ITM Cup squad is:
Robbie Abel, Derek Carpenter, Rupeni Caucau, Justin Davies, Warren Dunn, Latiume Fosita, Roy Griffin, Dan Hawkins, Willgriff John, Mateo Malupo, Whiria Meltzer, David Morgan, Matt Moulds, Tom Murday, Bronson Murray, Jake Paringatai, Owen Pihema, Dan Pryor, Jack Ram, Rene Ranger (c), Ben Seymour, Mac Sykes, Viliami Tahitu'a, Tane Takulua, Jone Tori, Scott Vessey, Will Whetton, Bryce Williams, Matt Wright, Ross Wright.