sea robin invasion?

what is up with all the sea robins? i was fishing last nite before dark and saw them rising feeding on smaller bait? are they eating spearing or something? Spawning? thanks

Getting ready to spawn and putting on the feed bag. They are all over. Got one that must of been 3 pounds last night. On a bunker chunk. Crazy

Probably feeding on grass shrimp/rainfish. Saw them this morning in the surf zone.

Thanks guys. Thought it was a little strange.