Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Radiocarbon dating suggests white sharks can live 70 years and longer

Adult white sharks, also known as great whites, may live far longer than previously thought, according to a new study that used radiocarbon dating to determine age estimates for white sharks in the Northwest Atlantic Ocean.

Sharks are typically aged by counting alternating opaque and translucent band pairs deposited in sequence in their vertebrae. It is unclear whether these band pairs are deposited annually, making it difficult to accurately estimate age or provide estimates for longevity for many shark species.

The goal of the white shark ageing study, published January 8 in PLOS ONE, was to determine the periodicity of band pair deposition in vertebrae of white sharks from the Northwest Atlantic Ocean using radiocarbon dating. Once validated, the band pair counts can provide a method for determining minimum estimates of longevity in white shark populations.

This first successful radiocarbon age-validation study analyzed vertebrae from four male and four female white sharks (Carcharodon carcharias) caught between 1967 and 2010 in the Northwest Atlantic Ocean.

"Ageing sharks has traditionally relied on counting growth band pairs, like tree rings, in vertebrae with the assumption that band pairs are deposited annually and are related to age," said Lisa Natanson, a fisheries biologist in the Apex Predators Program at NOAA's Northeast Fisheries Science Center (NEFSC) and a co-author of the study. "In many cases, this is true for part or all of a species' life, but at some point growth rates and age are not necessarily in sync. Growth rates slow as sharks' age. Deposition rates in vertebrae can change once the sharks reach sexual maturity, resulting in band pairs that are so thin they are unreadable. Age is therefore frequently underestimated. "

Bomb radiocarbon dating is one of the best techniques for age validation in long-lived species like sharks. The technique uses the discrete radiocarbon pulse in the environment caused by the detonation of nuclear bombs in the 1950s and 1960s as a "time stamp". Radiocarbon levels incorporated into the band pairs are measured and related to a reference chronology to determine the absolute age of a fish and can also be used to confirm or refute annual age in a species.

In this study, researchers from NOAA's Northeast Fisheries Science Center (NEFSC) and the Woods Hole Oceanographic Institution (WHOI) compared radiocarbon values from the shark vertebrae with reference chronologies documenting the marine uptake of carbon 14 produced by the atmospheric bomb testing. Samples were dated at the National Ocean Sciences Accelerator Mass Spectrometry Facility at WHOI. The result was the first radiocarbon age estimates for adult white sharks.

Estimated bomb radiocarbon dating age of the oldest female white shark sampled was 40, and for the oldest male 73. Ages for the three other males were 9, 14, and 44, while the other females sampled had estimated ages of 6, 21, and 32.

Previous studies of white sharks from the Pacific and Indian Oceans suggested that none of the examined specimens were older than 23 years. Also, none of these earlier studies were able to document annual periodicity of the band pairs used to assign age.

Natanson and colleagues suggest that either white sharks are living significantly longer and growing slower in the Northwest Atlantic than either the Pacific or Indian Oceans, or longevity has been underestimated in previous studies.

Knowledge is limited about the age and growth rates of white sharks, apex predators that live in coastal and offshore waters throughout the world. White sharks are considered vulnerable under the International Union for Conservation of Nature (IUCN) Red List of Threatened Species and are protected via international trade agreements and conventions.

Sharks are long-lived animals that grow slowly and do not produce many young. In many parts of the world they are fished commercially, requiring age and growth data for conservation and management efforts. Validation of age in shark species is also critical in understanding their longevity as well as in estimating vital rates such as age at maturity, lifetime fecundity or fertility, growth rates, and differences in growth between males and females.

The shark vertebral samples for this study were provided by Natanson from the Apex Predators Program, which maintains one of the largest collections of North Atlantic white shark vertebrae. The Apex Predators Program, located at the NEFSC's Narragansett Laboratory in Rhode Island, collects basic demographic information about sharks and their life histories by conducting research on their distribution and migration patterns, age and growth, reproductive biology, and feeding ecology.

Natanson has studied sharks for years and has authored or co-authored numerous studies to determine age and growth estimates for tiger, sandbar, mako and other shark species. She has published many reports on general life history aspects of various shark species, routinely collects samples from fishermen and at tournaments, and heads the program's coastal shark survey, which was most recently conducted in 2012. The survey is the oldest continuing survey of large coastal sharks in the U.S. Atlantic Ocean.

With lifespan estimates of 70 years and more, white sharks may be among the longest-lived fishes. Sharks that mature late, have long life spans and produce small litters have the lowest population growth rates and the longest generation times. Increased age at maturity would make white sharks more sensitive to fishing pressure than previously thought, given the longer time needed to rebuild white shark populations.

Study authors, in addition to Lisa Natanson from NOAA, included Li Ling Hamady and Simon Thorrold from WHOI and Greg Skomal from the Massachusetts Division of Marine Fisheries. Hamady is a Ph.D. candidate in the MIT/WHOI Joint Program in Oceanography.

Shelley Dawicki | EurekAlert!
Further information:

More articles from Life Sciences:

nachricht Tissue-engineered colon from human cells develop different types of neurons
02.10.2015 | Children's Hospital Los Angeles

nachricht Big eyes! – MDC Researchers Identify Cause of Inherited Form of Extreme Nearsightedness
02.10.2015 | Max-Delbrück-Centrum für Molekulare Medizin in der Helmholtz-Gemeinschaft

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: New Sinumerik features improve productivity and precision

EMO 2015, Hall 3, Booth E06/F03

  • Drive optimization called automatically by the part program boosts productivity
  • Automatically switching the dynamic values to rapid traverse and interpolation...

Im Focus: LZH presents additive manufacturing at the LABVOLUTION

The Laser Zentrum Hannover e.V. (LZH) will present how laser-based technologies can contribute to the laboratory of the future at the LABVOLUTION in Hannover in Hall 9, Stand E67/09, from October 6th to 8th, 2015. As a part of the model lab smartLAB, the LZH is showing how additive manufacturing, better known as 3-D printing, can make experimental setups more flexible.

Twelve partners from science and industry are presenting an intelligent and innovative model lab at the special display smartLAB. A part of this intelligent...

Im Focus: New polymer creates safer fuels

Before embarking on a transcontinental journey, jet airplanes fill up with tens of thousands of gallons of fuel. In the event of a crash, such large quantities of fuel increase the severity of an explosion upon impact.

Researchers at Caltech and JPL have discovered a polymeric fuel additive that can reduce the intensity of postimpact explosions that occur during accidents and...

Im Focus: 3-D printing techniques help surgeons carve new ears

When surgical residents need to practice a complicated procedure to fashion a new ear for children without one, they typically get a bar of soap, carrot or an apple.

To treat children with a missing or under-developed ear, experienced surgeons harvest pieces of rib cartilage from the child and carve them into the framework...

Im Focus: Walk the line

NASA studies physical performance after spaceflight

Walking an obstacle course on Earth is relatively easy. Walking an obstacle course on Earth after being in space for six months is not quite as simple. The...

All Focus news of the innovation-report >>>



Event News

EHFG 2015: Securing healthcare and sustainably strengthening healthcare systems

01.10.2015 | Event News

Conference in Brussels: Tracking and Tracing the Smallest Marine Life Forms

30.09.2015 | Event News

World Alzheimer`s Day – Professor Willnow: Clearer Insights into the Development of the Disease

17.09.2015 | Event News

Latest News

Infrared thermography can detect joint inflammation and help improving work ergonomics

02.10.2015 | Medical Engineering

Semiconductor nanoparticles show high luminescence in a polymer matrix

02.10.2015 | Materials Sciences

New Sinumerik features improve productivity and precision

02.10.2015 | Trade Fair News

More VideoLinks >>>