Steller sea lions form massive breeding rookeries where intense competition, pup crushing, and entanglement in marine debris create significant welfare challenges for both adults and pups.
Sea lion breeding rookeries combine natural social intensity with human-caused welfare pressures. Natural competition and combat cause injuries that would normally be the cost of reproduction in an uncrowded environment. Marine debris — particularly discarded plastic packing bands — causes severe progressive wounds as young animals grow into material caught around their necks. Declining prey availability forces nursing mothers to extend foraging trips, leaving pups to fast for longer periods and reducing milk quality. The combination of natural stressors and human-caused pressures creates a population welfare deficit that is measurable in reproductive rates and pup survival.