Guy Harvey Magazine

WIN-SPR 2018

Guy Harvey Magazine is focused on fishing, boating, scuba diving, and marine conservation. Portfolios from the world's best fishing photographers, articles on gear, travel, tournaments, apparel, lifestyle, seafood recipes, sustainable fisheries.

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Page 13 of 83

14 | Stressed Out Seals If a sinking boat gets you jumpy, how would you feel about swimming among hungry great white sharks? Well, believe it or not, researchers have spent a lot of money and several years to prove the extremely obvious conclusion that seals get stressed out when great whites are nearby and attacking them. The study is titled, "Physiological stress responses to natural variation in predation risk: evidence from white sharks and seals." It was funded, in part, by Canon USA and the Herbert Hoover Foundation. The three-year study, led by the University of Miami (UM) Rosenstiel School of Marine and Atmospheric Science, looked at fur seals living among one of the densest populations of great white sharks off South Africa's Western Cape to test this predation-stress hypothesis in the wild. They discovered what anyone who has seen a cat chase a mouse might surmise: that the seals were, in fact, extremely freaked out when they were on the verge of being ripped apart by the jagged teeth of massive sharks. Even though the conclusion of the study was predictable, the methodology the researchers used to prove this phenomenon was biologically sound, if not Left: A great white shark attacks a decoy seal in Gansbaai, Western Cape, South Africa. Photo courtesy of Bernard Dupont. somewhat stinky. The team collected fecal samples of seals in areas where sharks were not present, as well as the poop of seals where shark attacks were frequent. They then measured and compared the levels of glucocorticoid metabolite concentrations, a cortisol stress hormone, in the fecal samples. The researchers found that seals exhibited high stress levels at locations where they were at risk of unpredictable and lethal attack from great whites, whereas seals that were lounging and sunning on rocks in areas without sharks were not stressed. According to the study's co-author Scott Creel, a professor at Montana State University, "Comparable stress responses were not detected in places and times where sharks were not hunting." So now we know. INTRODUCING THE NEW RAPALA COASTAL CATEGORY. A LINE-UP OF NEW INSHORE, NEAR-SHORE AND OFFSHORE LURES.

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