A large, healthy-looking great white shark that washed up dead on a beach in Canada is the latest in a string of mystery strandings in the region.
The 14-foot-long (4.3 meters) male adult shark was seen thrashing in the water near North Bay Wharf in Nova Scotia before stranding on Broad Cove Beach in Cape Breton on Oct. 5. The carcass then washed back out to sea, but a team with the animal conservation organization Marine Animal Response Society (MARS) managed to recover it a week later for analysis.
Pathologists performed a necropsy on the great white shark (Carcharodon carcharias), but the examination yielded no clues about the cause of death.
“Right now it does not look nutritional (the liver was large and full of lipids), nor does it look like trauma,” Laura Bourque, a wildlife pathologist with the Canadian Wildlife Health Cooperative who conducted the necropsy, told Live Science in an email.
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While the shark’s dorsal fin was missing a chunk, the necropsy revealed this was the result of an old, healed injury and probably didn’t contribute to the animal’s death. The shark was otherwise “in good overall body condition,” MARS staff wrote in a Facebook post.
The stranding is the latest in a series of similar incidents that have left scientists floundering. The shark is the fifth great white found beached on the Canadian coast and registered with MARS since last October — a record number when compared to the last 20 years, which saw just one or two such strandings in total, Live Science previously reported.
Scientists haven’t got to the bottom of the previous four strandings yet, but they are “in the process of finalizing those cases,” Bourque said.
Adult great white sharks rarely wash ashore, Tonya Wimmer, the executive director of MARS, told Live Science in an email. Three of the five dead sharks were juveniles. “This last year has been an anomaly in terms of the number of white sharks reported to us in distress or dead,” Wimmer said.
Very little is known about what causes sharks to become stranded, Wimmer said. While marine mammals can wash up for various reasons — including ingestion of plastics, entanglement in fishing gear, vessel strikes, disease and injury — it’s unclear whether the same factors are at play with sharks, she added.
Scientists kept samples of the shark’s tissues and are performing additional tests, as “any infectious, toxic or metabolic disease may potentially not be apparent at necropsy,” Bourque said.
The team also collected additional samples in the hope they might “support several research projects on these magnificent animals,” the Facebook post said.