Mote study reveals migration of sharks

The largest-ever scientific study of whale sharks, which are the world’s biggest fish, was published in the journal PLOS ONE Wednesday, Aug. 21 by Mote Marine Laboratory scientists and collaborators from Mexico. The study reveals the sharks’ international journeys and their relationship to the largest whale shark feeding hotspot known to science.

The nine-year study, entitled “Horizontal Movements, Migration Patterns, and Population Structure of Whale Sharks in the Gulf of Mexico and Northwestern Caribbean Sea,” is now available online in the peer-reviewed journal PLOS ONE. To view the paper online, visit: http://dx.plos.org/10.1371/journal.pone.0071883

This Mote-led study shows that whale sharks found at a major feeding hotspot near Mexico’s Yucatan Peninsula travel to many places throughout the Gulf of Mexico, the northwestern Caribbean Sea and the Straits of Florida. These findings highlight why the Mexican feeding site is a vital fueling station for whale sharks throughout the region and suggest that these wide-ranging fish need international protection. The study also documented the second-longest whale shark migration ever confirmed, a trail that may help researchers discover where the sharks give birth.


Great whites tagged by Mote on Cape Cod expedition

Mote scientists report that as of Aug. 22 two great white sharks of have been tagged and released during “Expedition Cape Cod.”

“Betsy” and “Katharine” were each fitted with multiple scientific tags by a team that included Dr. Nick Whitney and Dr. Robert Hueter of Mote Marine Laboratory’s nationally designated Center for Shark Research. Mote scientists have been invited to participate in the research trip led by the nonprofit organization OCEARCH.

OCEARCH helps leading scientists obtain groundbreaking data on the biology and health of sharks, supporting research on sharks’ life history and migration. Their research ship, the M/V OCEARCH, is a 126-foot vessel equipped with a custom 75,000-pound hydraulic lift and research platform. It serves as both mother ship and at-sea laboratory.

Betsy, the first shark of the expedition, was tagged on Aug. 15. She is an immature female measuring 12.5 feet long and weighing in at 1,400 pounds. Whitney had the opportunity to tag Betsy with an accelerometer, a tag that monitors the fine-scale movements of the shark following its release. Katharine, the second shark of this expedition, was tagged on Aug. 20.  She is a 14-foot, 2-inch female shark weighing about 2,300 pounds, and she appears to be nearly mature. She was also tagged by Whitney with an accelerometer.

The accelerometer tags that Whitney attached to Betsy and Katharine’s fins are designed to stay on for two weeks, then release from the sharks and float to the surface so he can retrieve them and collect their data. Leaving the accelerometers on for so long is a bold move because there’s no telling where the sharks will travel and whether the scientists will be able to retrieve the tags once they pop off the fish. Each shark was also sampled for blood to learn more about their physiology and tagged with a satellite tag that lets the scientists follow their real-time movements. The public can also follow their travels through the Atlantic Ocean online through the Global Shark Tracker at http://sharks-ocearch.verite.com/.

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