Numerous extinctions reveal species tipping points where multiple pressures converge to cause a cascade to demise. This paper examines how multiple pressures impacting Southern Resident Killer Whales (SRKW) could lead to their rapid downward spiral to extinction. The most commonly cited impacts to this population are historically low abundance of chinook salmon prey, vessel disturbance from ships and boats, toxicant loads above established health effects thresholds, and risk of oil spills from increased vessel and rail oil transport. Inbreeding and a heavily skewed male biased sex ratio at birth compound these problems. Lack of prey increases nutritional stress and dependence on fat reserves, while decreasing concentrations of bioactive thyroid hormone (T3). Fat metabolism increases circulating lipophilic toxins, which can further decrease T3 concentrations. Collectively, these impacts appear to increase rates of spontaneous abortion and neonatal loss. They may also lead to immunosuppression with a likely rise in incidence of disease and mortality. Associated population decline inherently increases inbreeding, which can increase male sex ratio bias at birth. Reduced T3 may also affect sex ratio at birth. SRKW seasonal presence in the Salish Sea is declining, attributed to declining prey and increased whale-watch vessels. Breeding events within and between pods are commonly observed during these visits to the inland waters. Their decline in visits may limit opportunities for breeding with a more diverse gene-pool, which could further increase inbreeding and associated potential for male-biased sex ratio bias at birth. Chinook remain at the epicenter of all this, indicating an increase in Chinook salmon abundance to be the single most effective mitigation we can do to recover SRKWs. Salmon are sentinels of ecosystem imbalance spanning from toxic contaminants to habitat destruction. Creative and immediate solutions are essential to expedite the process of recovery and ensure the survival of this iconic species
