Trott had largely served the yellow and navy as an understudy to Danny Vukovic since first joining the club as a short-term injury replacement for John Crawley in December 2005.
Aside from the Hyundai A-League, Trott had made several appearances in friendlies and Pre-Season Cup matches for the Mariners, including a cornerstone role at the Philips Lighting Soccer 7?s in Hong Kong in 2007.
“By virtue of the unique situation regarding our goalkeeping stocks for next season, with Danny Vukovic set to miss a significant part of the campaign through suspension, we have been somewhat forced to make this very difficult decision,” said Mariners Executive Chairman Lyall Gorman.
“Matthew has been a model professional during his time at the Mariners and we are very thankful for his contribution to our club on and off the pitch since he first joined us.
“We wish him well with his future endeavours and we will keenly monitor his future progress.”