Spill definitely makes the pie bigger.

Reclamation of unused habitat or restoration of degraded habitat also makes the pie bigger.

Harvest can only make the pie smaller. The ESA's harvest mandate of a 15% cap on exploitation just reigns in the harvest to an "acceptable" level that does not impede recovery. I believe what's deemed acceptable is still open to debate.

But regardless of how big the pie, the managers currently make sure the allowable impact is maximally consumed. At least for now, 15% will die no matter how big the pie gets.

In fact, if wild run-sizes ever do recover, becoming bigger and bigger over time, managers could only be expected to raise the exploitation rate higher and higher, eventually ratcheting it up to MSY levels as the end-game.