Typically, in early spring when the water temperature rises above about 62 degrees, Yellowtail arrive in Southern California from Mexico in search of schools of squid. They winter far down the Baja coast in deep reefs. They feed throughout the summer as far North as the Santa Barbara coastline but seem to prefer the offshore islands. By October, they begin working themselves South and usually seem to disappear during the winter. However, there are home guard Yellowtail who chose to spend the entire year in California, presumably to take advantage of the winter squid spawn, as evidenced by catches all winter.

Yellowtail are hands down a favorite fish for eating when fresh (best consumed within the first three days of being caught) otherwise the fish can taste “gamey”. Yellowtail may be prepared in a variety of ways. Filleting is probably the best, though some like to steak the fish. The collar and bellies are great eating too. They are also excellent when served fresh as Hamachi (Sashimi with a cocktail sauce). Yellowtail are great prepared and eaten just about any way – grilled over the BBQ, baked in the oven wrapped in foil with your favorite peppers, onions, tomatoe & vegetables. Yellowtail are an oily white meat fish that may be grilled, broiled, baked, sauted poached, or smoked, all with exceptional results. It’s not ideal for frying, though, since it tends to trap in the fish’s own oil. As with most fish, yellowtail are best when very fresh. Yellowtail keep well frozen, too, especially when vacuum packed.

Yellowtail are caught all over Southern California. Mossback yellows hang around structure and the heavier tackle makes it easier to “turn” the fish and keep it away from structure thus less chance of breaking an angler off.  
The most common way of fishing for “Yellow’s” when live bait is available is fly-lining live Anchovy, Sardine or even small Mackerel with little or no sinker, carolina-rigged or similar using small hooks and light line or a couple feet of fluorocarbon leader tied to braid or common mono-filament line. If the fish are biting on the surface, it is usually evident by a lot of bird activity diving the surface feeding on bait being pushed up by fish below feeding then fly-lining using just a small #2 – #4/0 live bait hook with little or no weight is best. A small cramp-on split shot, rubber core or sliding egg Carolina style works.
For deeper fish a Dropper Loop is most common or San Diego knot with the weight on the bottom and hook looped through the upper loop. Select the liveliest bait in the well – the bait that is hardest to catch. Avoid bloody or red-nose bait and if you see a small brownish-colored bait called “Brown Bait” or a small Mackerel and the deeper Yellow’s are biting try those baits. Listen to the deckhands on what to use. Watch what other anglers are fishing and what fish are being caught. You’d be surprised sometimes it’s the smallest lively pinhead Anchovies that the biggest fish are eating. If you are new to casting conventional reels, don’t get tempted to use big Sardine just so you have some weight for better casting – instead go with the smaller Anchovies, Brown Bait or Small Mackerel and pinch a small split-shot to the line about a foot above the bait. If Barracuda and Mackerel are thick and you notice everyone catching only these fish and you are targeting a nice Yellow, the extra weight sometimes helps drag the bait a little deeper past the thick Mackerel schools where the Yellows are hangin’.

Yellows are not very line shy so a typical rent rod with a Penn Jigmaster 500 and is usually fine. Straight mono instead of all the various braid line and fluro combos being used although newer reels are more designed for what is called braid line with a flurocarbon leader. 
For fishing light or heavy iron “yo-yo” technique any reel with a high ratio cranking in line fast is perfect for yo-yo or fast retrieve surface iron casting. Jig color, you can start by matching the bait and/or water color in the area being fished. Anything scrambled egg, green or chrome/mackerel Tady, Salas, Sumo are all popular brand iron that work great for yo-yo fishing deep water fish. A easier to use and better casting star drag reel is suggested for Southern California-style stand-up jig fishing. Put this reel on a CalStar Graphighter 800M or L (medium or light) or similar jig stick and you have a premium tackle setup for fishing yellows. This rod/reel combo is perfect for throwing (casting) light surface iron jigs for when the fish are closer to the surface. I use this setup for both styles of fishing taught in this how-to.
Yellowtail are a blast to catch and eat or release. Hopefully using some of the info here will help put you on one of these popular Southern California gamefish.