Reading about turtles makes you a better shark researcher

It takes a lot of hard work to become a good ecologist. You need to take lots of classes to learn the background theory (I’m currently in the 23rd grade). You need to spend time in the field to collect samples and data, and then spend time in the lab analysing them. Once you’ve done that, you need to write up your results and publish them in scientific journals. You need to apply for grants to pay for your field and lab expenses. You need to teach classes and recruit and train volunteers and assistants. All these tasks are important, but you can do them more effectively if you take time off from them to read research papers published by other scientists.

Reading the most current scientific literature is, however, an open-ended task. For a given research speciality there can be hundreds of related scientific journals that publish tens of thousands of papers a year. Reading them all, or even skimming the titles of them all, is basically impossible. So how should scientists choose what keywords to search?

As a shark feeding ecologist, I use a non-invasive research technique known as stable isotope analysis to calculate what sharks are eating (this link explains how it works: http://www.southernfriedscience.com/ ). What current research papers should I read to gain a better understanding of my own speciality? Obviously, papers on the use of stable isotope analysis to study shark feeding ecology. And papers on other methods that can be used to examine the feeding ecology of my study species – and some of their related behaviours like migration and hunting. But should I also read about the feeding ecology (and related behaviours) of other land and sea animals? Doing this can greatly extend my already-long reading list, but it can also be very important.

For my Master’s research (published open-access here: http://www.tandfonline.com/doi/full/10.1080/19425120.2014.920742 ), I wanted to use non-lethal stable isotope analysis to study how the diets of sandbar sharks change over time as the animals grow, which is important information for ecosystem-based fisheries management. When I reviewed published papers about the use of stable isotope analysis to discover how shark diets change, I found studies that had analysed growth rings on vertebrae or compared the isotopic signature of liver tissue to that of muscle (different tissues take different lengths of time to incorporate the isotopic signature of the diet, so comparing two tissues can reveal change over time). Unfortunately, though, these studies required sacrificing the shark.

Photo © Elizabeth Mills

No-one had yet done what I wanted to do with sharks. So I changed the keywords in my literature search and found that it had been done with another study animal – sea turtles. I modelled my research on the sea turtle study and turned it into a novel contribution to the field of non-lethally determining the diet of sharks. In fact, there have been many other important contributions to the use of stable isotope analysis made with studies on marine mammals, bony fishes, seabirds and sea turtles that have not yet been applied to sharks (which I have reviewed here: http://rjd.miami.edu/assets/pdfs/pubs/Shiffman%20et%20al%20stable%20isotopes.pdf ).

It’s common for scientists to read only about their own study animal, but extending your reading to what other researchers are doing with completely different study animals can give you important new ideas and insights. This principle also helped me with my PhD research. For one of my dissertation chapters, I will be using a population genetics analysis previously applied only to whales to help answer a question that is important for the conservation of sharks. Stay tuned for a future Save Our Seas Foundation blog post to learn more!

David Shiffman is a PhD candidate at the University of Miami’s Abess Center for Ecosystem Science and Policy. You can follow him on twitter @WhySharksMatter