Research on blue whales and ship strikes
Cascadia Research has been
conducting work to better understand the causes and potential solutions to the
mortality of blue and other large whales due to ship strikes. This
issue became a priority after at least five blue whales were killed in fall 2007 as
a result
of ship strikes in the southern California area
(see publication
on blue whale ship strike mortality off California, March 2010). Three of these animals were
discovered in the vicinity of the Santa Barbara Channel. This level of mortality
was far higher than had been seen in any previous year and if there were
additional deaths of animals that did not wash up, could be significant to this
endangered species. Only a small proportion of large whale mortality is
documented as strandings because most large whales sink or do not wash ashore.
True mortality could be ten times or more higher than suggested by the
documented strandings and could be a significant factor preventing the recovery
of blue whales. This species has not shown the type of recovery that other
species like gray, humpback, and fin whales have shown since the end of large
scale commercial whaling. In the eastern North Pacific, blue whale numbers have
not increased and by some measures have decreased. Cascadia Research in collaboration with Scripps Institution
of Oceanography and with the support of the Channel Islands National Marine
Sanctuary and National Marine Fisheries Service initiated research in 2008 on
some of the factors possibly responsible for this mortality.
Our
observations and the data from these tags will help us address several of our
key objectives:
Determine how animals are distributed in relation to shipping routes and what shifts in shipping lanes might reduce the incidence of ship strikes
Examine
the behavior of blue whales in the shipping lanes
including documenting their specific feeding and diving pattern in this
area.
Use GPS tags to provide detailed movement patterns of the whales in and around the shipping lanes in the day and throughout the night (something we could not do before).
Monitor whale reaction to ship close approaches (less than 1nmi) including to <200m of our tagged whales to determine how whales react to ships and gain insights into how different strategies like slowing ships would alter the incidence of ship strikes.
Most recently we have worked to apply our research finding to management solutions (see for example Joint Working Group report below).
More detailed descriptions of Cascadia's work on ship strikes:
Joint Working group recommendations on ship strikes and acoustics (June 2012)
Associated Press story on Joint Working Group proposal to reduce ship strikes off San Francisco (July 2012)
New York Times article on increasing threat of ship strikes to blue whales (July 2012)
Review of ship strike issue for ACS newsletter by John Calambokidis (2011)
Update of ship strike research off S California in 2011 (24 October 2011)
New publication on baleen whale feeding (13 October 2011)
LA Times story on Cascadia and blue whales (7 October 2011)
Publication on blue whale ship strike mortality off California, March 2010
Links to photographs:
