October 11th, 2016 — With a quick jab, Greg Skomal reached a milestone last week. The detachable stainless steel tip on his harpoon penetrated the skin of a 14-foot male great white shark hunting seals just 20 feet off Nauset Beach. The dart lodged between the tendons at the base of the shark’s dorsal fin, tethered to a pencil-size acoustic tag that will broadcast a signal identifying the shark for the next decade.
Skomal had tagged his 100th great white, dating back to 2009 when the massive predators began showing up in appreciable numbers off Chatham. He named the shark Casey after shark tagging pioneer Jack Casey, who founded the National Marine Fisheries Service Cooperative Shark Tagging Program in 1962 and developed many of the techniques still in use today.
As the number of sharks coming to the Cape seems to grow every year, so has Skomal’s appreciation of the unique situation he finds himself in: a shark researcher caught in a real-life “Sharknado.”
“If you told me 10 years ago we’d hit a hundred, I’d say, ‘You’re crazy,’” he said.
The number of sharks ranging along the Cape’s shoreline, many passing near surfers and swimmers, is sobering. Skomal, a senior fisheries biologist with the state Division of Marine Fisheries, is finishing the third year of a five-year population study and has identified more than 200 individual sharks through tagging and underwater videos that find unique scars and coloration on each animal.
“Frankly, I was surprised nobody got bit this summer,” said Chris Lowe, a professor at California State University, Long Beach, noting that seals and sharks have modified their behavior to the point where the sharks must hunt in increasingly shallow waters, including the popular beaches where millions swim every summer.
A soon-to-be published study of seven adult gray seals, captured and tagged on the Cape three years ago by a team led by Duke University professor David Johnston, showed them leaving the shore to feed at all times of day and night, and taking multiday trips, when sharks are not around in the winter. But the summer is a different story. Johnston said the study found seals have adapted their behavior to better avoid white sharks. Since great whites rely heavily on their eyesight to hunt, tagged seals were leaving at twilight and taking only single day trips in summer, he said.