In commercial fishing it's gear restrictions. There's also season restrictions on the west coast. Salmon commercial fishing is regulated literally by the minute as to when the season opens, when the season closes. Strong law enforcement is certainly necessary, and I think somebody has spoken to that. On the recreational fishing side, it's the length of seasons, closures during spawning times in certain sensitive areas, gear restrictions on the number of rods that someone can use, harvest limits of how many you're allowed to keep. Catch and release has certainly become the North American method of allowing fishing to continue but the fish are put back. Those other methods have been proven very successful in many cases.
On May 2nd, 2017. See this statement in context.