Larry -
Thanks I suspect that folks are correct and we are looking at the result of the combination factors affecting crab survival. From the literature both higher acidic levels and temperatures have been shown to affect the survival/recruitment of Dungeness crabs.

Ph of 7.5/7.4 appears to be the threshold at which crab larva and molt survival is reduced. While the long term monitoring is hard to find those kinds of ph have been seen in deep south MA 12 and MA 13 for several years. Of additional concern is there may be an increase in those kinds of readings elsewhere in the Sound. All predicted changes associated with climate change.

Normal ocean ph is around 8.1 so I may not think a change to one of 7.4 is much of change but I would remind folks that the ph scale is logarithmic. That kind of change we are talking about is actually a 4 fold increase in acid levels.

Curt