January 31, 2012 Featured Article Read More →

How Nuclear Bombs May Play a Role in Basking Shark Conservation

569px-Cetorhinus_maximus_by_greg_skomalA fascinating article by Li Ling Hamady of the MIT/WHOI Joint Program in Oceanography explains how scientists have found a “silver lining to mushroom clouds” by using the remnants of a past nuclear age to try and protect remaining populations of Basking Sharks which are considered vulnerable to critically endangered worldwide.

Though they are the world’s second largest fish behind whale sharks, basking sharks remain a closed book scientifically.

In the article, Li states “for conservation strategies to be effective, you first need basic knowledge of where marine animals live, mate, and give birth. But all of that remains largely unknown for basking sharks. Pregnant females and young juveniles have never been spotted.

Tags can remain on sharks only a year at the most, and basking sharks may live for more than 50 years. So to figure out shark migrations over their lifetimes, we use another technique.

Li takes vertebrae samples from stranded sharks collected over several years and then looks for a radioactive isotope 14C signature from nuclear bomb blasts in the 1950’s.

With an in depth knowledge of how such nuclear blasts react with the environment it is possible to detect if the deep-diving behaviour of sharks that seen in the short term using tags occurs over their lifetimes. Preliminary results from our vertebrae analyses indicate that Basking Sharks may make regular excursions into the deep.

By assessing different radioactive isotopes in the sharks vertebrae Li also hopes to establish where the sharks are going. Different areas of the ocean have different ratios of radioactive elements (this isotope landscape is referred to as an isoscape) which Basking Sharks ingest. She states “Since you are what you eat, by comparing the signatures in the vertebrae to isoscape maps of their zooplankton food sources in the Atlantic Ocean, we should be able to pinpoint the pathways of their migrations.

Basking Sharks travel far and wide, entering waters where they have different levels of protection. It is hoped that a greater understanding of their movements will pave the way for a multinational conservation plan.

Li concludes “the techniques we’re developing to study basking sharks will also be applicable to other highly mobile, understudied, endangered ocean species, such as whale sharks and great whites.”

Read this fascinating article in full here – http://www.whoi.edu/oceanus/viewArticle.do?id=125909&sectionid=1020

Posted in: Shark Bites
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