I have seen anchovies, often huge schools of anchovies, at virtually every saltwater pier in the state, from San Diego to Crescent City. Visit places like the Santa Cruz Wharf, Humboldt Bay, Crescent City, and the San Francisco waterfront (some years) and you will find the waters saturated with anchovies during summer months. But, it’s the same at many piers, just not as often or as steady.
But, it must be remembered that the bait schools like anchovies move around, they travel to where their planktonic food (a variety of small organisms) is found. In response, the larger fish like mackerel and bonito follow their food—whether it be anchovies, sardines or other bait.
It also must be remembered that both anchovies and sardines see wide swings in population based upon water temperatures. The water temperature plays a role in the survival of the larvae and quite often you see swings where anchovy numbers go up and sardine numbers go down or anchovy numbers go down and sardine numbers go up. You may see both fish at the piers but usually one species or another is predominant.
Unfortunately, I have not fished enough this year to have a good feel for what’s going on statewide. I know when I was in the southland earlier in the year (especially during visits in July) that there were a lot of sardines at the piers I was visiting (Oceanside to Malibu). I don’t remember if anchovies were also present. Central Cal piers I visited in August, Santa Cruz to Monterey, had a lot of anchovies.
As for bait, both have long been considered prime bait. Anchovies due to their smaller size are one of the go to baits for many gamefish, everything from mackerel to bass to halibut and even larger species. Sadines are often considered better for larger species like yellowtail although small sardines will also work for the somewhat smaller gamefish. The bottom line is that both, depending upon their size, (since there are large anchovies and small sardines) are used on a wide variety of species.
As far as catching them from a pier, one does need to remember that anchovies are far more delicate than sardines. Those who use a Sabiki-type bait rig to catch them will find that many of the anchovies they catch, mostly snagged, will show injury and often will not last long as live bait. It’s far better to catch anchovies with a drop net. The sardines are less fragile, typically caught by the mouth, and will last as live bait far longer than anchovies. It's the same with small smelt, they are tough and can survive being caught on a snag line far better than anchovies.
As far as freezing, I freeze both and indeed freeze whatever left over bait I have. I sprinkle the bait with a fair amount of salt and find both will continue to be effective bait for months as cut bait.