overfished

The word is narrower in fisheries law than in ordinary speech. Under the Magnuson-Stevens Act, the United States law governing marine fishing, a stock is declared overfished when its population has dropped below a defined threshold, whatever the current level of fishing. A separate term, overfishing, describes the fishing itself: a harvest rate higher than the stock can bear. A population can be overfished without any overfishing going on, which is the usual case for a run held down by drought, disease or blocked habitat rather than by boats.

For West Coast salmon the threshold is written in terms of escapement. The Pacific Fishery Management Council declares a stock overfished when the geometric mean of its spawning escapement across the three most recent years falls below what it calls the minimum stock size threshold. Rising back above that line moves the stock to a middle status, not overfished and rebuilding. It counts as fully rebuilt only when the same three year average clears a higher bar, the escapement associated with the largest catch the run could sustain year after year.