Birch Bay is one of the most popular destinations in all of Washington State for crabbing Dungeness crab. Harvest season normally begins mid-August and seasoned veterans will regularly catch their quota each day.
The park is popular because of its boat launch and large beach area where many people will launch smaller boats and kayaks to drop their crab pots. There are even some people who will go crabbing by walking out in the shallows with a rake and bucket.
Fishing in Birch Bay is popular as well but most visitors will find they need to get into the deeper areas of the bay by boat to catch larger fish. The bay has salmon runs (you're most likely to catch a Chum or Coho) and Trout. There's flounder and other bottom fish and you're very likely to hook a Dogfish in Birch Bay as it is one of the most common fish in the bay and surrounding area.