Clarifying mussel regulations

How was eating them on 4/28 any less risky? Or on 11/1? What will it take to close the season so they won't kill

I joked with another guy on here about last week. Are they going to kill you the day after? Probably not. But I think of it like a spring pollen bloom. Sometime around 5/1 flowers are going to bloom and I'm about to get itchy. It's not on the dot every year, but it's pretty consistent. I imagine algae is similar.

Once May hits I don't harvest Mussels anymore. the risk to reward is not worth it. If I really really have the urge to consume mussels i'll go buy them. since were are talking about PSP, what about gaper clams? are they at risk too this time of month? i'm not getting a clear definite answer.

Any info on how much of a risk other bivalve class of mollusks are subjected to, i.e clams, scallops, oysters, to name a few, wild or not? Why are mussles at higher risks?

Apprently the toxins are present at all times but the higher temps increase the risks which happens to be during the spring and fall. And the link above  specifically puts Humbolt Bay at higher risk, way up north. What about all commercial farms down south in higher temps waters? Or are the waters there not tested as much as they are up north?

Any biologist, feel free to shed some light on this.