Cal. Fish & Game Code § 8601

Any net or line used to take fish that is anchored to the bottom on each end and is not free to drift with the tide or current is a set net or set line. Any net so placed that it will catch or impound fish within a bight, bay, or estuary, or against the shore upon the receding of the tide is a set net. Fyke nets, shrimp nets, or crab nets are not set nets.