Hi joegreen,
For what it's worth spider crabs, (Maja squinado), undertake an autumn/winter migration from coastal nursery areas to offshore sites where they overwinter in depths of more than 50m. Adults return to the coastal nursery areas during the spring. I can understand you thinking them a pain in the thingy, but try landing the next one that grabs your bait - they're absolutely delicious to eat.
Cheers
Peter B