A string of unexplained great white shark deaths along the North American Atlantic Coast has raised concerns among marine scientists. The first known case was recorded in August 2023, when a juvenile male shark, weighing 500 pounds and measuring 8 feet 9 inches, was found dead on a beach in Prince Edward Island, Canada. The carcass was taken to the Atlantic Veterinary College at the University of Prince Edward Island for examination. Initial observations showed no external injuries, and starvation was ruled out due to the presence of a healthy liver. A necropsy later revealed meningoencephalitis, an inflammation of the brain tissue, as the cause of death. The findings prompted further investigations when additional cases surfaced across the region.

Study Identifies Possible Pattern in Shark Deaths

As reported by The New York Times, in a study by the Canadian Wildlife Health Cooperative (C.W.H.C.), tissue samples from four more great white sharks found in eastern Canada showed similar brain inflammation. Dr. Megan Jones, a veterinary pathologist and regional director of C.W.H.C., stated to The New York Times that three of the five sharks examined displayed signs of a potentially infectious disease affecting the brain. In total, nine cases of dead white sharks with brain swelling have been recorded since July 2022. While brain inflammation has been detected in other shark species, its cause was usually linked to bacterial infections. In these great whites, no such clear cause has been identified.

Lack of Baseline Data Poses Challenges

Dr Alisa Newton, chief veterinarian for OCEARCH, a Florida-based shark research organisation, noted that while the deaths appear concerning, a lack of baseline mortality data for white sharks in the western North Atlantic makes it difficult to determine if this is an anomaly or a natural occurrence. She first identified meningoencephalitis in a white shark in 2022 from a brain tissue sample collected from Long Island, New York. The condition was also found in sharks from South Carolina and Massachusetts, with additional cases under review.

Investigations Continue Amid Uncertainty

Efforts to understand the root cause of the inflammation are ongoing. Genetic sequencing of brain tissue from a South Carolina shark has been initiated at the Washington Animal Disease Diagnostic Laboratory to identify potential viral or bacterial pathogens. Meanwhile, some experts, including Tonya Wimmer, executive director of the Marine Animal Response Society (MARS), believe the increased number of beached sharks could be linked to population growth rather than an emerging disease. Until more evidence is gathered, the mystery behind these deaths remains unsolved.