A short, sourced guide to the difference between introduced species, stocked fish and natural reproduction.
A managed fishery can also produce wild fish
The modern Great Lakes salmon fishery grew from deliberate introductions, but its story does not stop at the hatchery gate. Michigan DNR dates its Lake Michigan coho initiative to April 2, 1966. The program responded to declining lake trout and abundant alewife. Michigan's Chinook establishment followed stocking in 1967; earlier introductions had already been attempted. These are milestones of the modern Michigan program, not the first fish introductions anywhere in the basin.
Three terms worth separating
- Introduced: moved beyond a species' native range.
- Stocked: deliberately released by a fishery program.
- Wild-origin: produced by natural reproduction, even when the species was introduced.
NYSDEC documents substantial natural reproduction in the Salmon River. That makes “all Lake Ontario salmon come from hatcheries” an inaccurate shortcut. It does not make stocking unnecessary, and a historical study's wild percentage should not be presented as today's figure for every river. Stocking decisions and monitoring remain lake- and program-specific.
Read the biology alongside the history
Compare the steelhead, Chinook and coho life cycles. Steelhead's repeat-spawning potential and the salmon species' differing juvenile schedules help explain why one simple stocking or run calendar cannot describe every fishery.
Reviewed October 26, 2026. This introductory chapter covers selected agency-documented milestones, not a complete basin history or a review of every existing archive chapter.
