Here's what anglers were catching off fishing piers in the area in August, 1907 (and I doubt that mercury levels were a concern):
In Redondo Beach:
"After several weeks of catches of mackerel, small fry, occasional yellowtail and halibut, Redondo boasts the latest sensation in catching barracuda from a wharf...Half a hundred fine fish were taken.
"A school of sardines and a number of small mackerel were playing about the wharf when a school of barracuda rushed up, snapping hooked fish from the leaders and playing havoc with tackle generally. The barracuda turned back and continued their depredations. Jig lines and jigs soon were in operation, and fresh bait was at a premium. One after another the barracuda came streaming up to the wharf. It was literaly (sic) wriggling with them."
The above picture, btw, is of Redondo's Wharf #1 in 1908. Brazenly copied from the library resource page of Redondo.org.
"Anglers casting from the beach between Del Rey and Manhattan have made some good catches of corbina, but the yellowfins seem rather scarce for the season, and fishers are at a loss to account for it. As a rule, they are very plentiful during this month and September."
In Venice, a ten-and-a-half pound croaker was caught, with the help of the wharf policeman!
In San Pedro, croakers are reported, and "the trolling outside from Point Fermin to Portuguese Bend is improving steadily, and yellowtail are striking the spoons better every day."
"Long Beach is infected with what Sherman Baker calls 'critters'." Turned out to be stingrays.
In Balboa, "J. Frank Jones ... hooked a good-sized sea trout, and was playing him when along came a big yellowtail and engulfed trout, tackle and all at one fell swoop."
At the mouth of Newport Bay, "Bass are biting well in the bay, and a few goodly strings of croakers are on record ... Some big corbina are caught every Sunday from the Del Mar wharf.""The trolling off Newport, Laguna, and Arch Beach is excellent just now, and plenty of fist are being caught."
Don't know too much about fishing, but croakers and corbinas are in the same family. This picture of a California corbina is from Wiki.