Insights on whale shark populations and evidence for their historic rise and recent decline

In the largest study on the genetics of whale sharks conducted to date, researchers found that the world's biggest fish likely exist in 2 distinct populations with minimal connectivity between the Indo-Pacific and the Atlantic Ocean. The findings suggest that mixing of whale sharks between the Indian and Atlantic was and is rare.

The Molecular Ecology investigators also found a significant and likely recent population expansion, but a very recent bottleneck might have gone undetected as genetic diversity at Ningaloo Reef in Australia has declined during 5 consecutive recent years.

In the future, genetic analyses can greatly increase researchers' still very limited understanding of whale shark ecology and the status of what appears for now to be at least 2 populations.