OceanSun-
Of the top of my head for Puget Sound recreational fisheries the release mortality is assumed to be 15% for adult fish encounters and 20% for "shaker" encounters. Those mortalities are used as part of the allowed ESA mortalities. Though it is important to remember for those ESA mortalities the calculation is for the number of adults that would not reach the spawning grounds because of those mortalities. In case of the "shaker" mortalities there are adjustments to determine the adult equivalence (AEQ) meaning what portion of the "shakers" mortality would have survived to reach adulthood; obviously there continues to be marine mortalities (your ling cod example) through out the fish's life. The smaller the fish the less likely it is that it would survive to adulthood.
Curt
That sounds like a reasonable and plausible mortality rate for shaker encounters - hook placement alone can take that many out with handling the rest well and not dragging them around. I was afraid they were using a much higher mortality. Calculating for AEQ is good to know as well -thanks!
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. . . and God said unto them, Be fruitful, and multiply, and have dominion over the fish of the sea . . .