Seafood, like produce, has seasons - see what they are on the West Coast of the U.S. with this Guide to West Coast Seafood Seasons. Peak seasons are noted for the entire West Coast, regions may have shorter seasons.
Note: Modern flash-freeze methods make most of these fish available at high quality year-round.
Abalone, year-round. Only farmed abalone is available commercially and it is available year-round.
The season for diving for your own wild abalone is tightly regulated - see your state's department of fish and game for specifics, including season, size limits, catch limits, and harvest areas.
Albacore tuna, June through August. Look for line-caught or pole-caught tuna and you'll end up with a sustainably caught tuna, as well as one naturally lower in mercury than other choices (such caught tuna tend to be juveniles and their shorter lifespan means less time to have developed a heavy mercury load).
Anchovies, May through October
Clams, year-round for farmers, October through June for various wild species. There are lots of types of clams available on the West Coast, including razor clams and geoducks. See state-specific fish regulations if you want to harvest your own.
Dungeness Crab, November through February southern area and June through August north. This highly and well managed fishery spans the coast from just south of San Francisco up into Canada.
The opening of Dungeness crab season coincides with Thanksgiving in the San Francisco Bay Area, where crab holds a place on many Thanksgiving tables.
Halibut, March through November
Mussels (farmed), year-round
Oregon Pink Shrimp, May through September
Oysters (farmed), year-round
Rainbow Trout (farmed), year-round
Sablefish (a.k.a. black cod or butterfish), March through November
Salmon, May through September. High-quality frozen wild-caught salmon is available year-round; thanks to modern flash-freezing techniques, it is the far superior choice to fresh farmed salmon for both flavor and sustainability.
Sardines, availability varies season to season as their population fluctuates and catch rates are regulated, but they are in season all year
Spiny Lobster, October through December
Spot Prawns, February through December. These are tricky to find commercially in the contiguous U.S. since restaurants tend to buy up any local catch before they make it to markets for the rest of us, but are more widely available in British Columbia and Alaska.
Squid, April through February