Scientists from the University of Colorado Boulder conducted an analysis of 759 dolphins stranded on the shores of the Bay of Biscay from 1997 to 2019. By determining the age of the individuals through growth layers in their teeth, the researchers found that the average lifespan of females declined from 24 to 17 years over the specified period.
According to Étienne Ruby, a postdoctoral researcher at the Institute of Arctic and Alpine Research, “there is an urgent need to improve dolphin population management; otherwise, we risk facing a decline in numbers and even the extinction of these animals.”
The main factor contributing to dolphin deaths is incidental catch in fishing nets. In the Bay of Biscay, about 6,900 dolphins from the winter population of 180,000 individuals died in 2021. The reduction in lifespan has also led to decreased birth rates and a slowdown in population growth of 2.4% since 1997.
Starting in 2024, French authorities have implemented an annual fishing ban in the bay in January to protect dolphins. Scientists suggest adjusting this restriction based on the migration routes of dolphins.
Ruby emphasized the importance of dolphins as top predators in the Bay of Biscay, highlighting their significance for the ecosystem: “Without these predators, fish populations can grow to threatening sizes, leading to excessive consumption of plankton and vegetation, which in turn threatens the stability of the entire ecosystem.”
