The 33-year-old defensive end failed to keep a morning appointment with head coach Lary Kuharich. He cleared CFL waivers after none of the other seven teams claimed him.
"I don't know where he is," Kuharich said after practice. "It's over, I guess."
Gastineau played 10 seasons with the New York Jets and played in five Pro Bowls before walking out on the NFL team during the 1988 season.
The Lions signed Gastineau before the 1990 CFL season at the insistence of owner Murray Pezim, the Vancouver stock promoter who backed Gastineau's bid to become a pro boxer. Gastineau played four league games for the Lions before going on the injured list in early August with a rib cartilage problem.