Population health monitoring of California sea lions through stranding data, satellite telemetry, and haul-out surveys provides welfare-relevant information about population-level challenges.
Sea lion welfare monitoring at the population level reveals welfare threats that would not be detectable through individual animal observation alone. The temporal patterns of stranding causes — peaks of domoic acid poisoning during algal blooms, leptospirosis cycles following El Nino warm water events, and entanglement surges with fishing season — provide early warning of welfare events requiring enhanced rescue capacity. Body condition trends across haul-out surveys reveal whether prey availability is supporting adequate nutrition across the population. This population-level welfare surveillance enables proactive response planning rather than purely reactive rescue operations, with the potential to reduce total welfare impact through better-resourced early intervention.