Grandpa you should first of all realize that the 170 million pounds set aside for harvest is for long term sustained harvest. The remaining 510 million pounds is found in waters closed to commercial harvest due to pollution or is in waters to deep to safely harvest. Thus remaining to replace what is harvested. Annual harvest rates sre between 2 to 3% of that 170 million....which is what has been found to be their annual recruitment rate. Sorry but geoducks are not salmon as the bulk of the population will never be exposed to harvest whereas salmon are always exposed to someones ability to harvest.....hence always susceptiple to extinction. Apples and oranges. BTW there is a ton of scientific studies available on geoducks....take a look at some before assuming to much.