New Clues Reveal Genetic Diversity among Alaska’s Harbor Porpoises

Powerful tools reveal hidden structure of harbor porpoise population.

Harbor porpoises are shy, elusive creatures that live in Alaska’s coastal waters and are vital parts of the marine ecosystem. But how these animals are distributed and connected across the vast Alaskan waters remains a mystery. A new study published in the scientific journal Molecular Ecology sheds light on the hidden structure of Alaska’s harbor porpoise populations, using the powerful tools of environmental DNA (eDNA) and molecular genetic analyses.

Research Challenges

Studying harbor porpoises can be tricky. Their shy nature and preference for nearshore habitats make them difficult to approach and collect tissue samples from directly. Previous research relied on samples gathered opportunistically from beach strandings and fisheries bycatch, which limited the complete picture.

This new NOAA Fisheries-led study tackled these challenges with a two-pronged approach. First, researchers utilized the existing collection of tissue samples, spanning decades of dedicated effort. Second, they harnessed the power of eDNA, a revolutionary approach that detects tiny traces of genetic material left in the water behind passing animals. By strategically collecting eDNA samples from key areas where harbor porpoises occur, scientists were able to glean valuable genetic information from these elusive creatures without needing to collect tissue samples from every individual.

Unveiling Hidden Populations with eDNA

Traditionally, information on the genetic structure of animal populations was based on the analysis of tissue samples. The need for large numbers of tissue samples is incredibly time-consuming and can be very challenging for elusive species like harbor porpoises. Thankfully, science has a new tool in its toolbox: environmental DNA (eDNA).

eDNA consists of tiny fragments of genetic material shed by animals in their environment, like skin flakes or bits of scat. By collecting and analyzing eDNA from water samples, scientists can indirectly detect the presence of species, even in areas where direct tissue sampling is difficult.