‘Killed in vast numbers’: horseshoe crabs under threat from overharvesting

Horseshoe crabs, known for their blue blood used in medical testing, are facing the threat of overharvesting, leading to population declines and ecological consequences.


Horseshoe crabs: Ancient species and medical heroes

Laurent Ballesta's award-winning photographs at the Wildlife Photographer of the Year exhibition showcase the fascinating horseshoe crabs, Earth's oldest species that thrive on the ocean floor.

The blue blood of horseshoe crabs has become a critical component in medical tests for assessing the safety of vaccines and other medical interventions.

Horseshoe crabs are facing declines in their numbers due to overharvesting, particularly along the eastern seaboard of America, where their blood is collected for medical purposes.

Ecological consequences and the decline of red knots

The decline in horseshoe crab populations has had wider ecological consequences, including major drops in bird populations such as the red knot.

Red knots rely on the millions of eggs laid by horseshoe crabs during the spawning seasons in Delaware Bay for their spring migration.

Recent declines in red knot numbers have been attributed to the decrease in horseshoe crab populations, highlighting the interconnectedness of species.

Alternatives and the need for change

While horseshoe crabs have been vital in medical testing, viable alternatives using synthetic ingredients have been available for over 15 years.

Some regulatory changes have been made to encourage the adoption of synthetic tests instead of horseshoe bleeding, but further actions are needed.

The hope is that companies will recognize the ecological consequences and adopt synthetic tests to save horseshoe crabs from overharvesting.