The great white shark’s life span has recently been proven due to nuclear bomb residue. A new study has found that the amazing great white shark can live as long as humans, a finding that their age is much longer than researchers previously thought. Scientists thought the shark only lived about 23 years, but the species may actually be more prone to over fishing, being that they take longer to mature. Scientists usually look at bony rods, vertebrate, and teeth in order to determine the age of the sharks. These body appendages actually grow with the shark very similar to tree trunks rings, but it seems that this method is untrue due to how hard it is to distinguish the coloration of the rings. It was found that the residue from nuclear bombs, called Carbon-14 (a radioactive isotope), was absorbed by the sharks when nuclear testing was conducted.
During the 1950’s and 1960’s, huge amounts of the isotope fell into the ocean during nuclear testing. When the great white sharks absorbed the isotope, it created a type of time indicator. Four female and four male sharks were caught from the Atlantic Ocean and their vertebrae was studied with the radiocarbon from 1967 to 2010. The results showed that when the rings were counted on small to medium sharks before and after the isotope spike it was easier to figure out the ages in the same way tiger and sandbar sharks are studied. It eventually became apparent that after the initial isotope spike, the rings became much harder to find, so a closer inspection was obviously needed in order to determine the true age of the sharks. One male was found to be 73 years old and the largest female was 40, but the researchers could not conclude whether the female sharks had a different life span versus the males in the study. This data initially proves that the sharks develop at a slow pace very similar to humans, so reproduction is also slow to develop.
The great white sharks are considered a threatened species. Thus, this information is critical in understanding the lifespan and reproductive stance on the sharks in order to properly conserve the species. With the data now indicating the slow maturity of the sharks, conservation efforts may need to be strengthened in order to prevent over fishing and degradation of the species population as a whole.
Dr Thurrold mentions that the great white shark may be a famous species, but in reality we know very little about them. “Hopefully it isn’t too late to figure out more about them due to the drastic decreases in their populations over time due to commercial fishing,” says Dr. Thurrold. The study that was published in the PLOS ONE journal should help assist conservationists on the next steps that need to be taken. It just shows that the now illegal carbon nuclear bomb testing was good for something at least.
Biologists also believe the Sea of Cortez may be a nursery for the great white sharks. A 2,000 pound shark was accidentally caught by some commercial fishermen back in 2012. The shark was already dead and was just two feet shy of the length of the boat. It took about 50 men to drag it into shore. A month before that, a 990 pound great white shark was caught in the same location. This location was actually considered to be a rare location for white sharks, but obviously this may also be an important area that needs special attention to wildlife conservationists as well.
By Tina Elliott