If they're calling it flounder, it's probably flounder. There are many species of flounder, some of which are abundant on the west coast.
For example (per NOAA Fisheries):
Arrowtooth flounder: Abundant from Alaska to West Coast. Not overfished. Good choice for sustainable seafood harvest. Harvest includes commercial trawl.
https://www.fisheries.noaa.gov/species/arrowtooth-flounder