Shark Cruising!

05/04/2012 13:01

I feel very privileged to have been able to take part in several NOAA Juvenile Shark Surveys.  During the summers of 2004, 2005, and 2007 I spent 7-10 days on board the RV David Starr Jordan, met wonderful people, watched a ton of movies, perfected ship-board yoga, and of course got up close and personal with blue and mako sharks and pelagic stingrays.  I loved being out on the water, watching incredible sunsets (and sunrises on the early sets!) and seeing a range of amazing wildlife including ocean sunfish, jumbo squid, diving birds, sea lions, dolphins and more!  See more photos in Adventure.

My purpose on these expeditions was to collect pelagic stingrays, Pteroplatytrygon violacea, to study their feeding behavior and sensory biology.  Pelagic stingrays are somewhat of an anomoly in the stingray world.  Rays in general are well suited to life at the bottom of the ocean with their flat body shape and mouth on the bottom.  Some ray species, such as the Manta and devil rays, have successfully made the water column their home, and their body design reflects adaptations for this habitat change.  Their wings are pointier and flap like a bird's wings for more efficient and faster swimming, and their mouths have shifted toward the front of their body instead of underneath it.  Pelagic stingrays are the only stingray to make this same habitat shift, however, their body shape has not changed to the same extent as their filter feeding cousins.  Pelagic stingrays have what is known as an intermediate wing shape and swimming style, somewhere in between flapping and undulating, and their mouth is still underneath!  So how do they compete with the blue and mako sharks for their fish and squid prey?  The answer lies in their versitile wings!  They actually use their wings to surround and trap prey so that they can maneuver them into their mouth!  As a result, we frequently caught rays on our longline surveys with hooks lodged in their wings instead of in their jaws.

By collecting these stingrays I was able to take them back to labs at Scripps Institution of Oceanography (SIO, La Jolla) and at the Wrigley Marine Science Center (WMSC, Santa Catalina Island) to study their sensory anatomy and detection capabilities and also take a closer look at their unique prey capture strategy.  For more on their sensory biology see Making sense of stingray sensory anatomy.

Don't worry, I didn't forget about the sharks!  On the shark cruises we surveyed the sharks we caught on longline sets, documenting the species, size, gender, and location.  This information is part of a long term data set to look for trends and changes to shark catch and composition.  We also took a variety of biological samples (muscle tissue, fin clips, blood), for various genetic and physiological studies.  Finally, we fitted the sharks with a variety of tags to be able to track their movements and learn more about their behavior.  Learn more about the sharks and cruises here

Return to Research