February 18, 2015 — The great white sharks that swim off Cape shores are not only older than we once thought, but also grow more slowly and become sexually mature at a much later date than previously believed. This makes their comeback story more remarkable, but also could mean that the Cape’s sharks are more experienced hunters, and less likely to mistake a human for a seal.
As recently as a couple of years ago, people were being told that the great white sharks swimming off Cape beaches were in their teens, and that a 20-year-old was a senior citizen. Sexual maturity was thought to occur at between 4 and 10 years of age for males and 7 to 13 years for females.
But last January, shark researchers revealed that the great white shark lifespan rivaled that of humans. Lisa Natanson from the National Oceanic and Atmospheric Administration’s Apex Predator Program in Narragansett, Rhode Island, Li Ling Hamady and Simon Thorrold of the Woods Hole Oceanographic Institution, and state Division of Marine Fisheries shark scientist Greg Skomal used radiocarbon dating to age four female and four male great white sharks. They found the oldest female was 40 and the oldest male 73 years old, far beyond the 20 to 24 years determined by earlier studies.
The latest research by Natanson and Skomal, published this week in the online journal Marine and Freshwater Research, found that these great whites reached sexual maturity at a much later age, two to three times what had been thought of as adult. Skomal and Natanson examined vertebral samples from 77 great whites caught by commercial and recreational fishermen and research vessels between 1963 and 2010. By counting the growth rings in the vertebra, and using the radiocarbon data from the longevity study, they were able to reconstruct what is being called the first reliable growth curve for western Atlantic white sharks.
Read the full story at the Cape Cod Times