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So, here we are in July of 2015 and sharks are in the news. No, not the nation’s lawyers, the actual big predator fish that likes to hang out in REALLY salty water and eat flesh…any sort of flesh.
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Why are sharks in the news? Because they keep turning up where people are swimming and there are lots of pictures after the attacks. Not that sharks aren’t around the shore all the time – I mean, yours truly was on the beach in Daytona one day a couple decades ago and saw a blackfin shark pulled out of the ocean on the end of a fisherman’s pole – but that we’re actually seeing them go after humans on video. At least that’s what we think they are doing. Even if the sharks may think biting is self-defense. (Pure speculation, but it could be.)
At any rate, after the series of shark bites so close together in the Carolinas resulted in a number of people losing limbs, alarm bells kind of went off. Where are they coming from and WHY ARE THERE SO MANY? The short answer had to do with an increase in the saltiness of the water close to shore due to lack of rainfall and drought, and an increase in the critters that that particular variety of shark use as a food supply. The law of the jungle, ocean, and green spaces in the cities is that predators will show up where the food is.
What is interesting about this, in the case of sharks, is that some of the larger varieties, say the Great White, have a taste for animals that are on most conservation lists: seals, sea lions, otters – particularly the pups.
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What is even more interesting, is that 40 years after the release JAWS the movie, an adaptation of Peter Benchley’s best seller, and the shark killing frenzy that ensued in the late 1970s…scientific studies differ on whether or not sharks should be on endangered species lists. As in, the observational studies that estimate global numbers – at least the latest ones – do not agree at all. Just taking Great Whites (the big dudes, which all studies claim are “notoriously elusive”… kind of like the giant squid) for example:
January 2015 – An Australian lecturer in Marine Biology claims fewer sharks are being spotted around the continent. However, he claimed that younger individual sharks were spotted. Therefore, he concluded that the number of sharks in the ocean had dropped.
June 2014 – an American National Oceanic and Atmospheric Association study of the northwestern Atlantic suggested that numbers were on the increase since 1997 when hunting Great Whites was outlawed. “The species appears to be recovering,” said Cami McCandless, one of the authors. “This tells us the management tools appear to be working.” This particular study estimates the number in the northwestern Atlantic to be around 2,000 fish.
June 2014 – a sampling study by PLOS ONE, an open source science journal – indicates that numbers of Great Whites in the northern Pacific are on the rise. They tracked a couple hundred animals to the various gathering sites. The research presented suggests that previous studies underestimated the total number of the species in the northeastern Pacific by quite a bit.
Satellite tagging of white sharks at aggregation sites off central California has revealed clear seasonal movement patterns, with sharks present near coastal and insular pinniped rookeries during the fall and swimming to an offshore focal zone or Hawaii in the spring and summer. Of the sharks acoustically tagged in one of these studies, only 13 of 51 showed evidence of annual return to photographic sampling sites in central California. Only three sharks showed evidence of return each year for the three years of the study (2006–2008), although this figure no doubt underestimates the frequency of annual returns as not all sharks were tagged in year one. Yet Chapple et al. concluded that all mature and sub-adult white sharks return annually to these pinniped rookeries. While lack of detection does not prove absence and externally placed tags are known to shed from sharks, no convincing evidence for an annual return cycle of all sharks was provided, and none is available in the literature.
In other words, sharks don’t have clear cut hunting patterns. At least not the ones tagged and followed. And they head to the places sea lions, seals and walruses (pinnipeds) are known to give birth for easy pickings.
All this proves is that the number of the “notoriously elusive” Great White Shark is most likely on the rise off the American coasts. Why? That’s where the food supply is.
But, like a lot of estimations by scientists, no one knows for sure because the people doing the counting can’t always find the fish.
So, is it safe to go back in the water…good question.
P.s. From the size of the fin on this shark that checked out Australian surfer Mick Fanning off of South Africa on Sunday, one would guess that this might be one of those elusive creatures.
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