US scientists say they have found the first direct evidence that female lemon sharks return to the same locations of their birth in order to release their own young. This is the first time this behaviour, known to occur in sea turtles and salmon, has been documented in sharks.
The team, lead by Kevin Felheim of the Field Museum of Natural History in Chicago, have been tagging lemon sharks at the Bimini Biological Field Station in the Bahamas since 1993. Very soon they began to notice that the females were returning to the same lagoon every two years to give birth which lead to the idea that they were returning to where they were born themselves.
The long term nature of the study was necessary since sharks are slow to mature. Over the study around 2,000 sharks were tagged with DNA and measurements taken from all. The research was published on December the 5th and shows that at least six females returned to their birth place 15-17 years later. While the sample is small, it is estimated that these six represent between 24% and 75% of surviving females in the studied group.
It is thought that the research may strengthen the conservation of Bimini lagoons since the sharks may not easily adapt if their birth place is damaged.