How Rainfall In Australia Helped Scientists Crack The Mystery Of Shark Aging

InnovationScienceHow Rainfall In Australia Helped Scientists Crack The Mystery Of Shark AgingByMelissa Cristina Márquez,Contributor.Forbes contributors publish independent expert analyses and insights. Márquez is a marine scientist and science communicatorFollow AuthorJun 10, 2026, 08:45am EDTIt is estimated that fewer than 2,500 mature Speartoothed sharks remain in the wild. Julia ConstanceThe first time I held a shark vertebra in my hand, I was surprised by how small and delicate it looked. People tend to imagine sharks as all teeth and muscle, but hidden inside their bodies are fragile structures that literally hold them together. For decades, scientists have tried aging sharks the same way dendrochronologists read tree rings: by counting bands in calcified tissue. One pair of bands, one year of life. Simple enough, right?Well, maybe not.A new study on the critically understudied speartooth shark, Glyphis glyphis, suggests that scientists may need to rethink how we estimate age in at least some sharks and rays. And considering that more than one-third of all chondrichthyans, the group that includes sharks, rays and chimaeras, are threatened with extinction, getting age right is kind of a big deal! Age estimates influence conservation status assessments, estimates of population recovery and fisheries management decisions. If you do not know how quickly an animal grows or how long it lives, you cannot accurately predict how vulnerable it is to overfishing.Traditionally, as was said above, shark age estimation relies on counting visible bands in vertebrae. These bands are usually viewed under transmitted light optical microscopy, or TLOM. Basically, researchers are looking for alternating opaque and translucent zones that are thought to represent annual growth cycles. The problem is that these bands are not always easy to interpret; in tropical species, where environmental seasonality is less dramatic than in temperate waters, the bands can be faint, compressed or i...