Storing and Cooking Shellfish
For live product, the temperature should ideally be close to that of the fish's natural environment at the time, so will vary according to the year. For practical purposes, the typical home fridge is going to be fine, even though it might be a few degrees cooler. Overly cold temperatures can actually kill the shellfish (not a good thing). Definitely don't freeze them. They should also be kept moist, yet well drained. The best way to do this is to place them in a colander and cover them with a wet cloth. You might need to re-soak the cloth occasionally to keep it nice and wet.
Our blanched clams are frozen at the factory, so can be kept in the freezer for months (the expiration date is around a year after production). Before use, it's best to take the pack out of the freezer the day before and let it defrost in the refrigerator. If the pack is unopened, it can safely stay in the fridge for up to a week.
The key is to be vigilant and prevent the rubbery texture that comes from overcooking. Remove each piece as soon as its shell pops open. At the end if there are some stubborn specimens, you can use a knife to prise them open. Contrary to popular belief, unopened shellfish aren't inedible. The danger is actually when cooking with live shellfish that are already opened, and hence dead. Since you don't know how long they've been in that state it's best to be on the safe side and throw those away.