Like most beach cutthroat fishing if you can't see them they aren't around. Good Luck.
True, sea runs do show themselves readily and visible fish are always a good sign for unfamiliar waters. Having said that, I've caught many cutthroat on my home beach before I even spot a jumper. This beach consistenly produces fish and I've fished it for so long I know that the fish are there even if I can't see them jumping at first.
Some anglers might conclude after a 5 or 10 minute cursory survey that the water is empty of cutts. Not so. That might be a fair conclusion after an hour of so of watching, but still always worth a cast or two.
An interesting thing about sea runs is that the jumpers are aggressive and catchable. On many occasions I've put my lure just feet from, or even within, the rings where the fish splashed down and hooked the fish immediately. This is such a truism for me that I'll even walk down the beach to stalk a jumper or quickly retrieve a cast to rifle a quick one in his direction. So if you are scouting a beach and see a cutt jump, cast to him as quick as you can while you still know where he is. You just might surprise him first and yourself second.