Female common dolphins in the North Atlantic now live, on average, seven years less than in the 1990s, threatening their population growth. Researchers link this decline to bycatch in fishing nets and worsening environmental stresses.
October 22, 2025
Source:
SciTechDaily
Dramatic Drop in Dolphin Longevity
The average lifespan of female common dolphins in the North Atlantic has plunged from 24 years in the late 1990s to just 17 years by 2019. This alarming decline is the focus of new research published in Conservation Letters by University of Colorado Boulder scientists. Their analysis centred on 759 stranded dolphins found in the Bay of Biscay between 1997 and 2019.
This is a significant setback for a species that relies on slow reproduction rates. The team determined dolphin ages by examining tooth growth layers, a reliable biological aging method.
The study highlights a 2.4% drop in annual population growth for North Atlantic common dolphins—a direct impact of this shortened lifespan.
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Source:
Leader Publications
Bycatch and Environmental Pressures Under Scrutiny
One major factor fueling the crisis is bycatch—the unintentional entanglement of dolphins in fishing nets. In the Bay of Biscay alone, around 6,900 dolphins died from bycatch in 2021, representing a substantial loss for the estimated winter population of 180,000 animals in the region (BBC News).
Additional environmental pressures include prey depletion, likely linked to overfishing and ecosystem disruption, as well as possible climate change effects. These stressors reduce reproductive success and increase mortality rates, creating a compounding threat to population stability.
Traditional monitoring relies on boat and aerial surveys, which often fail to capture early warning signs of population decline—especially in slow-reproducing species like common dolphins.
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Source:
Leader Publications
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