Pregnant hammerhead shark migrates over 4,000 km
For the first time, researchers have succeeded in documenting the migration of a pregnant scalloped hammerhead shark (Sphyrna lewini) from the Galápagos Islands to Cocos Island off Costa Rica.
The 2.5-meter-long animal was christened Cassiopeia and fitted with a satellite transmitter off Darwin Island in February 2021. Over the next 14 days, the hammerhead shark then swam over 700 km to Cocos Island. Because female hammerhead sharks give birth to their 20-30 young in the mangrove-covered bays of mainland South America, Cocos Island was only the first part of the journey. In total, Cassiopeia covered more than 1,700 km until she gave birth to her young in the Gulf of Panama, a well-known nursery of the scalloped hammerhead sharks. She then returned to the Galápagos Islands. And for the first time, the migration could be documented over an entire distance of more than 4,000 kilometers.
Complete migration of the pregnant Cassiopeia from Galápagos to the coast of Panama and back © CDF
Scalloped hammerhead sharks are classified as endangered by the World Conservation Union (IUCN) because the migration routes of the females lie in the middle of international fishing zones. It is very much hoped that the data now collected will confirm the importance of a protected migration route for these impressive animals.
