Salmon eggs are the migratory angler's universal bait. During and after spawning runs, trout and steelhead key on loose eggs drifting downstream from upstream nests — and a properly drifted egg presentation is the closest thing to a guaranteed eat.
Three forms cover most water. Single eggs (sold in jars, cured pink or red) hook directly through the membrane and drift one at a time. Roe sacks are a small wad of eggs tied into a square of mesh, fished on a snelled egg-loop hook. Cured cluster bait is roe still in its natural skein, cut into chunks and either snelled or hooked through the skin.
Drift them dead, on light leader, with just enough split shot to bump bottom. Don't overweight — eggs ride near bottom naturally and a leaden drift screams "fake" to a pressured fish.