Scientists are putting radio transmitters in young fish to find out who or what is killing them.
The missing fish leave home as young juveniles and are failing to return on schedule a couple of years later.
More so than their cousins, the salmon, these hard-headed fish travel alone, frequent rougher neighborhoods near the ocean surface, and wander further from home. Speculating that predators might be to blame, biologist Brodie Antipa said "we just don't know what's going on out there.
The transmitters are expected to show when and where these young fish are running into trouble.