Escapement in plain English

Escapement is the count of salmon that get past the fishery and up the river to spawn. Managers set escapement goals, the spawning numbers a run needs to replace itself, and they open and close fishing in season to hit those goals before anything else. Escapement plus harvest is the total run, and the escapement half is the part managers protect first.

The fish that get away, on purpose

The word sounds like a loss, but escapement is the plan. These are the fish that escape the nets and continue upriver to spawn, seeding the run that comes back in future years. ADF&G counts them at weirs, towers and sonar stations set on the rivers, tallying fish as they pass. Add that escapement to the commercial harvest, plus the sport, subsistence and personal-use catch, and you have the total run. Manage the escapement well and the run sustains itself. Manage it badly and it does not.

Escapement goals: BEG, SEG and OEG

An escapement goal is the target range of spawners for a stock, and Alaska uses a few kinds. A biological escapement goal, or BEG, is the spawning range ADF&G sets to produce the maximum sustainable yield from a stock, built from the biological data and expressed as a range. A sustainable escapement goal, or SEG, is used where the data will not support a full BEG and is based on the stock's historical performance. An optimal escapement goal, or OEG, is set by the Alaska Board of Fisheries and can weigh other uses and concerns on top of the biology. Whatever the label, the goal is a range, not a single number, and hitting it is the manager's first job. ADF&G reviews and updates these goals on a regular cycle as new data comes in.

Why the fishery opens and closes on short notice

Escapement is why an Alaska salmon fishery can open and close in a matter of days. Managers watch the fish crossing the counting projects in close to real time. If escapement is running behind the goal, they cut fishing time by emergency order to let more fish upriver, even in a season that looks strong at the docks. If escapement is running ahead, they add time so the fleet can take the surplus. The harvest swings a permit holder lives with in July are the visible side of managers steering escapement toward the goal. Conservation comes first, and the fishing is what is left after the river gets its share.

See it against a managed run

The Bristol Bay page above shows harvest against forecast for the world's largest sockeye fishery, where five districts are opened and closed through June and July to move fish onto the spawning grounds and onto the tenders at the same time. The harvest you see is what the fleet landed after managers accounted for escapement. A strong percent of forecast and a well-seeded set of rivers are not in conflict, they are the same management working.

The Run reports management actions as ADF&G announces them, with no comment on the disputes that sometimes surround them. For how a run gets projected before any of this plays out, see how ADF&G forecasts salmon runs, and for how escapement turns into the openings and closures the Bristol Bay fleet fishes by, see Bristol Bay commercial fishing announcements, explained.