The only thing that I could find was
"Fish That May Not be Filleted, Steaked or Chunked: No person shall llet, steak or cut into chunks on any boat or bring ashore as llets, steaks or chunks the following: any species with a size limit unless a llet size is otherwise speci- ed in these regulations."
I am still not exactly sure in the case of eating. @tanner.s
On the fish and wildlife website in FAQ a galley chef asked if he could on the sport boat and they responded with,
"Yes, galley cooks can prepare a fisherman’s sport-caught fish as long as the fisherman is aboard, the fish fillets meet any size requirements (California Code of Regulations Title14, section 27.65) and the fish is not prepared until ready for immediate consumption (Fish and Game Code, section 2015). According to California Department of Fish and Wildlife (CDFW) Lt. Eric Kord, “It would not be legal for the partyboat to hold a bunch of unidentifiable fillets in the galley fridge or an ice chest even if the plan is to cook them for the passengers. That won’t fly. As soon as the skin patch comes off or the fish gets chunked up, it must go onto a frying pan immediately and not be stored elsewhere.”
All bag limits and boat limits continue to apply even if some people’s fish are consumed. This means that those fish removed from people’s possession for preparation and consumption cannot then be replaced that day. Cooked fish still count toward the fisherman’s bag limit and the overall boat limit. Just because the fish was consumed does not mean passengers can then start fishing again to replace the fish if the boat limit has already been reached. If the bag limit is 10 for a fish, and the passenger catches 10, but eats one, the passenger cannot go take an 11th fish that day to replace the one he ate.
This is just CDFW’s part of the answer. The city/county might have their own take on it since you are probably operating under a business license that might have some restrictions regarding food storage and preparation.
Bottom line … you can cook sport caught fish for your passengers as long as the fish is counted toward the angler’s individual bag limit and the boat’s boat limit. The fish must also meet the fillet length requirements and any skin patches must be left on until the fish is prepared for immediate consumption."
A lot of that is up for interpretation it seems like. I'm sure if you cut up a fish and threw it on the pan or grill, you'd be just fine. Whether it is legal, I'm not too concerned. Once it's being cooked, there's no way of knowing what size it was or if it even came from the Pacific Ocean really haha.