"It's with a heavy heart that I announce that my family and I will be leaving NZ at the end of the 2018 season," Sopoaga wrote in a post on Instagram.
"It was one of the hardest decisions I've ever had to make but is one I'm at peace with. I have loved every minute of being a professional footballer here in NZ, I've made life long friends and memories that I'll cherish forever.
"I'd like to thank the Highlanders, All Blacks, Southland and Wellington for the awesome experiences you have provided me with over the years. Thank you to all the fans for your support it's been one heck of a ride. To my team mates and coaches over the years thank you for everything, I've been blessed to have met so many top men.
"Last but not least to my family & friends you know who you are the ones who have stood by me through the lowest of lows and the highest of highs you have seen both the valleys and the peaks, THANK YOU will never be enough!
"So here's to 2018 one last roll of the dice before I head off to experience life on the other side of the world. I'm ready."
