Welfare Assessment: Southern Resident Killer Whale

Read WELFARE.md and ETHICS.md before writing. Center the animal's interests, not its feelings. Every welfare claim is cited and confidence-tagged.

Summary

The Southern Resident killer whale (Orcinus orca) population of the Salish Sea is in a critical welfare state driven by three interacting stressors — Chinook-salmon scarcity, vessel noise and disturbance, and persistent contaminant loads — with prey depletion identified as the primary constraining force [NOAA Fisheries; Wasser et al. 2017]. The population has declined from 98 animals in 1995 to the low-70s in recent counts despite births [NOAA Fisheries; Marine Mammal Commission]. The confidence basis is measured: a peer-reviewed study links reproductive failure to a quantified nutritional-stress hormone signature, and the three-threat framework is the documented government consensus.

Five Domains

• Nutrition — Diet is dominated by Chinook salmon; Fraser River Chinook account for roughly 80% of the summer diet in the Salish Sea, and Chinook abundance has fallen from historical levels, directly limiting energy intake (Hanson et al.; NOAA Fisheries) — measured.
• Environment — Vessel presence and underwater noise in core summer habitat reduce foraging efficiency, while persistent organic pollutants (including PCBs) accumulate in blubber and mobilize during nutritional stress (NOAA Fisheries; US EPA) — measured / modeled.
• Health — A peer-reviewed study detected high pregnancy failure across 2007-2014, with failure linked to nutritional stress; contaminant burdens add an immuno-suppressive load that compounds the nutritional one (Wasser et al. 2017; NOAA Fisheries) — measured.
• Behaviour — Vessel traffic interrupts foraging behaviour, and reduced prey density lengthens search effort, so disturbance and scarcity compound rather than add (NOAA Fisheries) — measured / modeled.
• Mental state (inferred) — Not narrated. Inferred only from a validated proxy: among studied females, failed pregnancies showed thyroid-hormone-to-glucocorticoid ratios nearly seven times lower than successful pregnancies — an established nutritional-stress signature, not an emotion claim (Wasser et al. 2017) — measured.

Cumulative pressure (disturbance budget)

This population is a textbook case for the disturbance-budget model in WELFARE.md, because the stressors are multiplicative, not independent. Vessel noise degrades echolocation and foraging efficiency at exactly the times prey is scarce, so the same noise costs more energy than it would in a prey-rich system; and nutritional stress mobilizes stored contaminants, so the toxic load peaks when the animal is already compromised (NOAA Fisheries; Wasser et al. 2017). On the budget framing, utilization is high: the combined human pressure across the Salish Sea core habitat sits above what the prey base can support, which is why the trend is decreasing despite individual protections and births.

What supports recovery

Cited, concrete interventions that would move the welfare state toward recovering:

• Chinook-salmon abundance recovery across the major contributing river systems, addressing the primary constraint on reproduction (Wasser et al. 2017; NOAA Fisheries) — measured / expert-opinion.
• Vessel-noise and approach-distance management in core foraging habitat to restore foraging efficiency precisely where it is most degraded (NOAA Fisheries) — expert-opinion.
• Reduction of persistent-organic-pollutant inputs to the Salish Sea to lower the immuno-suppressive load that compounds nutritional stress (US EPA; NOAA Fisheries) — modeled / expert-opinion.

No advocacy beyond the evidence: each measure maps to one of the three documented, interacting stressors.