The blue whale is the largest animal species ever to have inhabited the Earth. The global population prior to human predation has been estimated at 350,000. Today that number is around 10,000.
Blue whales inhabit every ocean, but one of their largest subpopulations is the Northeast Pacific group, which transits the California Bight every summer south of Point Conception. These whales transit four favored areas: the California Bight (south of Point Conception,) the west coast of Baja California, the Sea of Cortez, and the Costa Rica Dome. By far the largest number of blue whales congregates in the California Bight between June and October because food is abundant there during that time. This area is also one of the world’s busiest shipping lanes, with over 6,000 cargo ships/year transiting the Santa Barbara Channel between the ports of Los Angeles and Long Beach.
Blue whales are extremely vulnerable to strikes by cargo ships, cruise ships and other vessels at night while feeding on krill, transiting or resting. During the day krill descend hundreds of feet into the water column, but every evening the whales’ photosensitive prey re-concentrate near the surface. Following the krill back to the surface, the whales may not react quickly enough to avoid the large ships, which cannot see them on the dark surface.
Ship collisions usually end in injury or death for these giants of the seas. The documented number of blue whales killed by ships along the coast of California has been as high as five in a year. The actual number of mortalities is unknown, but is suspected to be many times higher because blue whales are negatively buoyant, which means they sink when they die. Ship strikes represent a survival threat to this subgroup and to the worldwide population.
GWC staff give educational presentations, develop public actions, and produce web-based videos to educate and inform the public about the dangers faced by the North Pacific group of blue whales. Focusing attention on State and federal regulatory agencies and on ship owners, they work to strengthen the rules and operational policies for vessels transiting critical blue whale habitat.