Whale sharks in Gulf of Mexico swim near the surface, take deep dives

November 18, 2015

Tracking whale sharks in the Gulf of Mexico revealed their use of near-surface waters, as expected, but also their use of deeper water off the continental shelf, including remaining at depth greater than 50 meters continuously for more than three days, according to a study published November 18, 2015 in the open-access journal PLOS ONE by John Tyminski from Mote Marine Laboratory, Florida, and colleagues from the US and Mexico.

Whale sharks are a wide-ranging, filter-feeding species typically observed at or near the surface, but little is known about their sub-surface habits. To examine whale sharks' long-term movement patterns, including near and offshore movements, the authors of this study attached pop-up satellite archival transmitting tags to 35 whale sharks in the southeastern Gulf of Mexico off the Yucatan Peninsula from 2003-2012 and three tags to whale sharks in the northeastern Gulf off Florida in 2010. They received data from 31 tags and 9 tags that were physically recovered provided high resolution data on vertical movement.

They found that whale sharks feeding inshore on fish eggs off the northeast Yucatan Peninsula spent extended periods surface swimming beginning at sunrise followed by an abrupt change in the mid-afternoon to regular vertical oscillations, a pattern that continued overnight. In oceanic waters, sharks spent about 95% of their time within epipelagic depths (<200 m) but regularly dove deep (>500 m) usually during daytime or twilight hours (max. depth recorded 1,928 m). Nearly half of these "extreme" dives had descent profiles with brief "stutter steps" around 475 m deep. The authors posit that these stutter steps represent foraging events. They also found that whale sharks can remain continuously at depth (>50 m) for more than three days, suggesting they are not obligate surface feeders. Overall, the results demonstrate complex and dynamic patterns of whale shark habitat utilization, likely in response to shifting ocean conditions influencing the distribution and abundance of their prey.

Dr Tyminski notes: "As the world's largest fish, the filter-feeding whale shark does not blindly vacuum the sea for food. On the contrary, these sharks show dynamic vertical movements patterns that likely evolved as an efficient means of getting the most out of planktonic prey patches both near surface and at great depths."
In your coverage please use this URL to provide access to the freely available paper: http://dx.plos.org/10.1371/journal.pone.0142156

Citation: Tyminski JP, de la Parra-Venegas R, González Cano J, Hueter RE (2015) Vertical Movements and Patterns in Diving Behavior of Whale Sharks as Revealed by Pop-Up Satellite Tags in the Eastern Gulf of Mexico. PLoS ONE 10(11): e0142156. doi:10.1371/journal.pone.0142156

Funding: This research was supported by funding from Georgia Aquarium, Christopher Reynolds Foundation, National Geographic Society, Mote Marine Laboratory and an anonymous private foundation. The Natural Protected Areas National Commission of Mexico (SEMARNAT/CONANP) provided personnel, biological station facilities, boats, fuel and conventional tags during the early stages of the work (2003-2009). Those stages also were supported in part by a Mexico Small Grants Program funded by the UNDP/Global Environment Facility, as provided by the Mexican NGO SER de Quintana Roo A.C. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Competing Interests: The authors have declared that no competing interests exist.


Related Whale Sharks Articles from Brightsurf:

Reef sharks in decline
Though many people find them intimidating, menacing or just plain scary, sharks are vital to the health of the world's oceans.

Sharks almost gone from many reefs
A massive global study of the world's reefs has found sharks are 'functionally extinct' on nearly one in five of the reefs surveyed.

Plastics found in sea-bed sharks
Microplastics have been found in the guts of sharks that live near the seabed off the UK coast.

Life in the shallows becomes a trap for baby sharks
Baby reef sharks tolerate living in the sometimes-extreme environments of their nurseries -- but these habitats face an uncertain future which may leave newborn sharks 'trapped'.

How old are whale sharks? Nuclear bomb legacy reveals their age
Nuclear bomb tests during the Cold War in the 1950s and 1960s have helped scientists accurately estimate the age of whale sharks, the biggest fish in the seas, according to a Rutgers-led study.

Cold War nuclear bomb tests reveal true age of whale sharks
Atomic bomb tests conducted during the Cold War have helped scientists for the first time correctly determine the age of whale sharks.

Caribbean sharks in need of large marine protected areas
Governments must provide larger spatial protections in the Greater Caribbean for threatened, highly migratory species such as sharks, is the call from a diverse group of marine scientists including Stony Brook University School of Marine and Atmospheric Sciences (SoMAS) PhD Candidate, Oliver Shipley.

Recreational fishers catching more sharks and rays
Recreational fishers are increasingly targeting sharks and rays, a situation that is causing concern among researchers.

Walking sharks discovered in the tropics
Four new species of tropical sharks that use their fins to walk are causing a stir in waters off northern Australia and New Guinea.

Lonesome no more: White sharks hang with buddies
White sharks form communities, researchers have revealed. Although normally solitary predators, white sharks (Carcharodon carcharias) gather in large numbers at certain times of year in order to feast on baby seals.

Read More: Whale Sharks News and Whale Sharks Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.