Ancient DNA suggests a historical demographic decline and genetic erosion in the Atlantic bluefin tuna

Abstract

Achieving the aim of the current UN Ocean Decade to “protect and restore ecosystems and biodiversity” is stymied by a lack of historical knowledge on how human exploitation has impacted and therefore what should be restored. Here, we sequence DNA in ancient fish bones to evaluate the historical diversity of the Atlantic bluefin tuna, which has been of great commercial importance for centuries. We find that bluefin tuna began to undergo demographic decline by 1900, 70 y earlier than currently recognized. Correspondingly, we find that modern bluefin tuna had lower levels of genetic diversity than historical ones. This suggests that human impacts on the diversity of marine fishes are likely to have begun earlier and be more complex than previously thought.