Sharks off the coast of Israel travel regularly between Hadera and Ashdod
The sharks, which are tracked using satellite tagging and acoustic telemetry, are an interesting sight in the area, considering the desert conditions of the water.
By OMRI RONDusky Shark swiming in the sea(photo credit: HAGAI NETIV/MORRIS KHAN STATION FOR SEA EXPLORATION IN HAIFA UNIVERSITY)
New research from the University of Haifa has revealed that Israel’s sharks travel about 50 kilometers (30 miles) between human-altered habitats along the shores of Hadera and Ashdod from season to season, in a single-day commute.Scientists at University of Haifa’s Morris Kahn Marine Research Station have tagged a total of 62 sandbar and dusky sharks and taken fin-clip, muscle and blood samples to understand their biology. They also followed their movement using satellite tagging and acoustic telemetry, and found that the sharks appear to remain in Hadera from December to June.Previously, it was believed that the sharks migrated away from the area in March, leading researchers to suggest that the sharks' route may have changed over the years due to human influence to the environment.“This doesn’t happen anywhere else,” Eyal Bigal, Manager of the station’s Apex Predator Laboratory, led by Dr Aviad Scheinin said. “There’s something about this water off Israel’s coast that attracts apex predators that are, in the case of sharks, already endangered in the Mediterranean Sea. Here, we see large numbers of sharks in human-altered habitats like power stations, gas platforms, and fish cages. They’re not anywhere in the open sea,”“For some of the sharks that we tagged in Hadera, on the same day they leave that city they go to the other hot spot in Ashdod, even if it’s quite far away," Bigal said. "A few of our sharks disappeared from Hadera and on the same day they showed up at the fish cages in Ashdod, just a few hours later. Then they stayed there for a few months and moved back to Hadera, so they hopped between hot spots. And the same sharks are coming back every year,”“They might be diverted from their natural routes where they’re supposed to be swimming and reproducing and playing their role as apex predators,” he said. “Instead, they linger at these hot spots. It might function as what we call an ‘ecological trap.’ It’s good for them at the individual level; they’re comfortable and it’s nice for them temperature-wise. But at the population level, they might be diverted from functioning as apex predators and maintaining their role in the environment,”Bigal also noted that outside of the sandbar and dusky sharks that are being tracked along Israel's shores, researchers are seeing fewer sharks in the greater region this year, including blue sharks, mako sharks, and thresher sharks. It is unclear if and how this development is related to COVID-19 causing the waters of the Mediterranean to be less in human use during this time.
