For the first time in Israel, researchers have performed an ultrasound examination on a sandbar shark, (Carcharhinus plumbeus), revealing an advanced stage of pregnancy. The breakthrough discovery was made as part of a long-term study on local shark populations, conducted by the Apex Predator Lab at the Morris Kahn Marine Research Station of the University of Haifa.
The ultrasound was carried out this week on a shark named Romi off the coast of Hadera. It provided valuable data on the reproductive habits of sandbar sharks in the Mediterranean. This marks the first time a reproductive scan has been successfully conducted on this species in the region.Simultaneously, researchers encountered another pregnant shark, Emily, a dusky shark (Carcharhinus obscurus), who had been found with a fishing hook lodged near her gills.
The hook was safely removed, and subsequent examinations confirmed she was also expecting.The ongoing study, now in its tenth year, focuses on reproductive indicators among shark populations in the eastern Mediterranean. The waters off Hadera serve as a seasonal aggregation site for sharks, though the precise reasons remain under investigation. "Our research provides crucial insights into the reproductive behavior of sharks in the region," said Dr. Aviad Scheinin, head of the Apex Predator research division at the Morris Kahn Marine Research Station.
"We aim to determine whether this site serves as a permanent birthing ground or a temporary transit area for pregnant sharks. The data we collect through tagging, hormone testing, and ultrasound scans help us piece together a more complete understanding of shark reproduction in the Mediterranean."
During routine tagging and medical assessments, researchers found that Emily had sustained an injury from a fishing hook. While the injury was treated successfully, it highlighted the impact of human activities on shark populations."This case further illustrates the link between fishing activities and shark conservation," Dr. Scheinin noted. "The more we understand their movements and reproductive cycles, the better we can implement protective measures for these species. Our ability to access sharks in this study also enables us to provide immediate care when necessary, as in Emily’s case."
Healing capabilities
Sharks are known for their remarkable healing capabilities, but researchers stress the importance of continued monitoring to assess the long-term effects of interactions with fishing gear.
Romi’s ultrasound results also contributed new insights into the reproductive cycle of sandbar sharks. "The embryos observed in the scan measured between 50 and 77 centimeters, aligning with the known 12-month gestation period of the species," explained Dr. Lee Livne, a postdoctoral researcher at the Apex Predator Lab specializing in shark reproduction. "Our encounter with Romi was particularly significant, as only five sandbar sharks have been documented in our region. This was the first time we’ve conducted an in-depth reproductive examination on this species."
Romi and Emily were named in honor of hostages Romi Gonen and Emily Damari. They are the seventh and eighth sharks tagged this season. Since the study’s launch in 2016, a total of 123 sharks have been tagged in the region. Researchers hope that continued tracking of these tagged sharks will provide a deeper understanding of their migration and reproductive behaviors, ultimately aiding in the conservation of these vital marine predators in the Mediterranean Sea.