Researchers from the University of Melbourne have developed an innovative method to study the speartooth sharks (Glyphis glyphis), an endangered species. The technique combines lasers and mass spectrometry to analyze the sharks’ vertebrae and obtain precise information about their age and the environments they have traversed throughout their lives.
Until now, biologists estimated the age of sharks by observing circular bands in their vertebrae, similar to tree rings. However, this criterion proved unreliable in rare species like the speartooth shark.
How the method works
The new technique uses laser ablation coupled with mass spectrometry with inductively coupled plasma (LA-MC-ICP-MS):
- The laser converts a tiny part of the vertebra into an aerosol.
- That material is analyzed to detect its chemical composition.
- Elements like strontium reflect the water conditions in which the shark lived, allowing researchers to reconstruct its environmental history.
By comparing the data with records of rainfall and wet or dry seasons, scientists were able to link the chemical signals with the aquatic environments inhabited by the species.
A unique and vulnerable species
The speartooth shark lives in rivers and estuaries of Australia and Papua New Guinea. Its adult population is estimated at just 2,500 individuals, making it one of the rarest and most threatened sharks in the world.
Critical conservation factors:
- Endangered: listed on the IUCN Red List.
- Apex predator: regulates populations of smaller fish and maintains trophic balance.
- Highly vulnerable: frequently dies as bycatch in fishing nets and crab traps.
- Restricted habitat: sensitive to degradation from pollution and human development.
- Unique biology: capable of living in both freshwater and saltwater, adapting to different salinities.
- Slow recovery: limited reproduction and few offspring, making population recovery difficult.
Impact of the research
Knowing the actual age and environments traversed by these sharks is essential for:
- Measuring the health of the population.
- Designing more precise conservation strategies.
- Avoiding erroneous diagnoses about their vulnerability status.
The study demonstrates that the combination of optics, geochemistry, and marine ecology can offer innovative tools to protect threatened species.
The Australian research breaks the traditional rules of biology and opens a path towards the conservation of one of the rarest and most endangered sharks on the planet. Each individual of this species is crucial for its survival, and the use of laser technology allows for obtaining unprecedented data that can make a difference in its protection.
