How many times a year do pacific ocean botto fish spawn and for how long?

Fish like ling cod and rock fish.

Lingcod "Spawning occurs off British Columbia from February to April, off Puget Sound from December to April (perhaps to June), and off California from November to March, peaking from late December to early February."

With rockfish, it depends on the species when and how long they spawn (there are dozens of species, so I'm not going to list them all), but some are winter spawners, some are summer spawners.

This is from a book called "Probably More than you Want to Know about the Fishes of the Pacific Coast" by Robin Milton Love, a fisheries biologist at UC Santa Barbara, and one of the experts on rockfish. His website is below (it's kind of silly, but he knows his stuff).