Reducing the threat of ship strikes on large cetaceans in the Santa Barbara Channel Region and Channel Islands National Marine Sanctuary

During September of 2007, NOAA received reports of five blue whale carcasses between Santa Cruz Island and San Diego. Historically, the maximum number of blue whale documented fatalities in a single year in the region was three, occurring in both 1988 and 2002. NOAA’s National Marine Fisheries Service (NMFS) designated the blue whale mortalities as an “Unusual Mortality Event” (UME) on October 11, 2007, recognizing that the observed mortalities had met one or more criteria for the declaration of an UME (Hogarth 2007). The first animal was brought into port on the bow of a large ship, and necropsies on two of the other whales found floating in the Santa Barbara Channel appeared to confirm ship strike as the cause of death. Two additional blue whale carcasses, an adult female and a very young individual (believed to be a fetus expelled after stranding of the adult) were discovered on San Miguel Island on November 29, 2007. Though the San Miguel carcasses were several weeks old, it was determined that the adult had injuries consistent with those sustained in a collision with a large vessel, and that the calf likely died as a consequence of its mother being struck and killed (Lecky 2008). In response to these events, the Channel Islands National Marine Sanctuary (CINMS) and its Sanctuary Advisory Council (SAC) have been working to develop both short and long-term management measures to reduce the ship strike threat to Endangered Species Act (ESA) listed large whales in CINMS and the Santa Barbara Channel region. Information gathering through case studies and stakeholder engagement are the first steps towards a long-term plan.