Failure, Defeat
A shellfish that can't live through winter is a failure. Any proper shellfish would survive through the winter, so this is quite an embarrassing defeat.
Imagine you're a shellfish in the cold, cold winter. The water is freezing but you must tough it out so no one will say you're a failure in spring when they find your dead, defeated shellfish body.
はい
やぶ
None
The best way to avoid failure is to say a little haiku (はい) to distract you from the cold. In fact, this can work in any situation where you're afraid of defeat. Say a haiku aloud, it will calm your nerves and warm you from the inside.
Imagine being a shellfish freezing in the cold winter water, but you avoid failure by muttering haiku over and over to keep you warm and determined.