California Code, Fish and Game Code - FGC § 2361

It is unlawful to import into this state for commercial purposes any salmon of smaller size than can be legally taken under regulations of either the Pacific Fishery Management Council or the state of landing.  Such prohibition does not apply to domestically reared salmon as defined by commission regulations to include salmon which have returned to a hatchery or licensed artificial collection facility.  Such domestically reared salmon may be imported under regulations established by the commission.