Hey Jester..............
Welcome aboard!
You might start out with this site right here. Just go to the first message of almost 11,000 in the FISHING forum and start reading and dreaming. Another good site for the Sea of Cortez fishing facts is MEXFISH.COM. You might spend several days perusing that stuff.
Around Puerto Penasco and without a boat you have three choices for shore fishing: the esteros, the open sandy beaches and the rocky shorelines of Whale Hill and La Cholla. There are plenty of locals that can take you out for a fee and guarantee a load of fish. Most of them even supply all of the gear and bait.
If you have your own boat or fishing kayak the whole scene will change along with a whole new list of fish species available. Just a hundred feet out from shore you can get good sized Groupers, Yellowtail, Sierra the local King Mackerel, Corvinas, Flounder, Triggerfish and at least a dozen more.
Watch out when catching "Sea Trout" as there are none here and it's kind of a catch-all word for a half dozen species of juvenile croakers to include the endangered giant Totoaba and baby White Sea Bass that should not be taken under three feet in length.
The fish charts published online showing what you can catch in what month are total tourist BS with no factual knowledge what-so-ever. Plan on being flexible and prepared for anything at any time. I always carry four spinning outfits on my Jeep as well as some fresh shrimp and a handfull of lures like Castmasters, Spoons and Diamond Jigs as you never know when a feeding frenzy might appear right in the surf with big Pinto Bass, Sierras and Corvinas chasing sardines or smelt in just two feet of water!
You don't need a Mexican Fishing License to fish from shore or from a local charter boat, but the LAW down there is DEAD SERIOUS when fishing from a private boat. Most seem to think they can just gaff it off, but when the Mexican Navy boards your boat you had better have every document for your boat and a current fishing license for every person on board at you fingertips.
Tight Lines,
JJ