Speaking at a hearing into Victoria's native bird hunting arrangements, Electrical Trades Union state secretary Troy Gray said seven unions and member organisations would demonstrate against a ban.
"If there is a decision to ban duck hunting - the day that that decision is made or the day after - the major infrastructure projects in this state will shut down," Mr Gray said.
In March, about 800 ETU members walked off the job at Victoria's Metro Tunnel project in defence of outdoor activities, after the duck shooting season was shortened in February.
"It is not a message, it is not a threat," Mr Gray said.
"Whether we like it or not, it is going to happen."
He said the CFMMEU, the Transport Workers Union and the Australian Workers Union were among the organisations supporting the ETU's stance.
Mr Gray said outdoor recreation was crucial to construction workers, who often worked 10 or more hours a day, six days a week.
"In the construction industry ... the suicide rate is eight times the national average," he said.
"You go to Swanston Street, you drop 80 metres into the ground and you live six days a week underground.
"What they look forward to is getting out ... to the outdoors, whether it be the fishing, hunting ducks, deer, whatever it may be."
Mr Gray said members had complained that state-owned areas for camping, horse riding, rock climbing, gold prospecting and camping had been reduced in recent years.
Animal Justice Party upper house MP Georgie Purcell questioned how a duck shooting ban would stop people from enjoying other activities in the great outdoors.
"You're talking about four-wheel-driving, camping, fishing, none of that has been banned or is in any way under threat," Ms Purcell said.
Mr Gray said there was a public sentiment that the government had taken a heavy hand in regulating public recreation in Victoria.
"We're gating the bush, we're gating the coastlines, and working-class people are not falling for it anymore," he said.
