So you can keep them alive, but only one daily limit.
Assuming that alive falls under the "fresh" description which is my understanding. But the possession limit is a bit murky.
The definition for possession limit (reg pamphlet pg 11) is "The number of daily limits allowed to be kept
in the field or in transit." (emphasis added) There is nothing in that which addresses fresh or processed.
Under the specific Shellfish/Seaweed Rules (pg 125) the Possession Limit is further defined as "One daily limit in fresh form. Additional shellfish may be possessed in frozen or processed form."
So, can one be in the field or in transit with a limit of fresh crab as well as additional crab which has been processed? Seems so. But the murk doesn't end there.
If one goes to the WAC the following will be found:
WAC 220-56-312
Shellfish—Possession limits.
It is unlawful for any one person to possess
at any time (emphasis added) more than one daily limit of fresh shellfish. Additional shellfish may be possessed in a frozen or processed form.
The "at any time" is a much broader coverage than the "in the field or in transit" language in the pamphlet and, according to a senior WDFW LE officer, includes at an ordinary residence. So, if one were to harvest a limit of crab and keep them at home in a fresh form and then go out the next day and retain any additional crab they would be in violation of the above cited WAC.