Humpback whale genomes reflect the increased efficiency of commercial whaling

Genetic diversity is declining globally, a trend that may particularly
impact exploited populations that must adapt to rapid environmental change
and other threats. Estimated genomic changes in effective population size
mirrored known whaling history and shifts in technology. In the Southern
Ocean, a comparison of genomes from historical and contemporary
populations indicated that the contemporary genomes have less diversity
and an elevated realised mutation load for moderately deleterious
mutations, likely due to the effects of whaling. Our results demonstrate
that the relatively recent, brief, and drastic depletion of humpback whale
populations by whaling likely had subtle but discernible, negative, and
lasting effects on the whales’ genomes. Thus, even as some humpback whale
populations are now recovering to pre-exploitation numbers, they likely do
so with a diminished adaptive capacity in the face of future conditions
and threats.