A groundbreaking genomic study of great white sharks in the Western North Atlantic has revealed the existence of sibling pairs among tagged individuals, a discovery that scientists believe could significantly enhance understanding of these apex predators.
The research, conducted by OCEARCH using genetic samples, identified three pairs of full siblings and seven likely half-sibling pairs. One full sibling pair is believed to have originated from the same litter, while the other two full sibling pairs are estimated to be five and 19 years apart.
This genetic insight marks a new phase in studying white shark biology and ecology, shifting focus from their solitary reputation to exploring potential familial influences on their behavior, such as their tendency to return to specific habitats annually. "This research changes the questions we can ask," said Chris Fischer, founder and expedition leader of OCEARCH. "For most people, white sharks are the ultimate lone predator. But every expedition reminds us the ocean is more complex than we imagine."
One notable finding involved tagged sharks Jekyll and Olympia. While scientists initially observed similar migration patterns between Jekyll and another shark, Simon, DNA analysis confirmed Jekyll and Olympia share the same parents, born five years apart. Olympia was tagged in 2021 off Cape Cod as a juvenile, and her tracking data ceased in 2022. Jekyll, also a juvenile at tagging in 2022, was tagged off Jekyll Island, Georgia, with his tracking data stopping in 2024.
Researchers also observed a pattern among the full sibling pairs: one sibling was typically found in southeastern U.S. habitats during winter or spring, while the other was located in New England or New York during summer or fall. However, scientists emphasize that this does not imply conscious recognition, intentional group travel, or the inheritance of migration routes among these sharks.
Dr. David Portnoy, a collaborating scientist with OCEARCH, noted that the study is just the beginning. "We’ve identified close family relationships among Western North Atlantic white sharks, but we’ve only scratched the surface of what those relationships may tell us," he stated. Future research aims to integrate genomics with tracking data to explore whether related sharks exhibit similar habitat use or migration patterns.
The findings also raise questions about the population size of white sharks in the Western North Atlantic. The identification of multiple sibling pairs from a limited sample could suggest a smaller population, which, if further confirmed, could have significant implications for conservation strategies.