I fish the South Jetty a few times every year. I've never caught a rockfish or ling, but I have caught lots of Kelp Greenling, Sculpin, Redtail, Calico, and Striped Surfperch. You also get the occasional sanddab or crab. I've seen people catch Ling and California Halibut from there, but that is pretty rare.
I was just there this weekend, and in about an hour we had one sanddab between us, and that's it. Fishing the outlying areas will be more productive. I got two Lingcod, 3 Black Rockfish, 1 Grass Rockfish, 3 Kelp Greenling, and 3 Calico Surfperch fishing from shore more towards Gold Beach. Biggest Lingcod was 26" and an ounce shy of 6 pounds.
All that to say, it is doable, if the conditions are right. Use fish bait for rockfish and lings, or try artificial lures.
I've caught small lings off the beach at night near the Winchuck River Mouth, which is pretty awesome to experience. It just takes patience and a lot of legwork to find the honeyholes. Good luck!