Harbor porpoise in the Salish Sea

Harbor porpoises declined dramatically in the Salish Sea in the 1970s but their populations have since rebounded, increasing by more than 10% per year in recent decades. A 2020 report for the Encyclopedia of Puget Sound examines harbor porpoise status and trends, natural history and recent policy considerations for the species.

With a population growth of about 10 percent per year in inland waters, harbor porpoises are having an undetermined but growing effect on food dynamics in Puget Sound.

After an almost complete collapse in the 1970s, harbor porpoise populations in Puget Sound have rebounded. Scientists are celebrating the recovery of the species sometimes known as the "puffing pig." 

The mysterious practice of killing porpoises may have a useful function, but it has yet to be fully explained, according to orca researcher Deborah Giles.

A 2016 technical report from the Washington Department of Fish and Wildlife and the Cascadia Research Collective details the decline of the harbor porpoise in Puget Sound in the 1970s and reports that species numbers have increased over the past twenty years likely due to outside immigration.

Harbor porpoises were once common in Puget Sound, but had all but disappeared from local waters by the 1970s. Regular and numerous anecdotal sightings in recent years show that populations of these cetaceans are now increasing and may be approaching their former status. The attached document from NOAA Fisheries describes harbor porpoise numbers and their geographic range in Puget Sound as of 2011. 

HARBOR PORPOISE (Phocoena phocoena vomerina): Washington Inland Waters Stock (NOAA Fisheries 2011)

Puzzling encounters between endangered killer whales and harbor porpoises point to questions about prey availability and whale culture, scientists say. Are the whales playing, practicing their hunting skills, or is something else going on? 

Harbor seals and harbor porpoises in the Salish Sea are showing a relatively high presence of antibiotic-resistant bacteria. A 2021 paper in the journal Oceans suggests that these findings may indicate a wider problem among other species in the region.

A paper published in the journal Oceans in 2020 describes cases of prey-related asphyxiation in harbor porpoises along the U.S. West Coast. The findings suggest that a majority of cases involve non-native American shad and that asphyxiation tends to occur more with reproductively active females than other age and sex classes.

A 2020 paper published in Frontiers in Marine Science describes details of the fungal disease Mucormycosis which has caused the death of harbor porpoises, harbor seals and one orca in Puget Sound in recent years. The authors discuss the implications for local marine mammals, specifically the endangered southern resident killer whale population.

A 2017 paper in the journal Marine Mammal Science examines harbor porpoise group structure and site fidelity in the Salish Sea. 

The Puget Sound Ecosystem Monitoring Program released its fifth annual Marine Waters Overview this week. The report provides an assessment of marine conditions for the year 2015 and includes updates on water quality as well as status reports for select plankton, seabirds, fish and marine mammals.

A 2015 paper in the journal Diseases of Aquatic Organisms examines potential causes of increased harbor porpoise strandings in Washington and Oregon.  

A study in the Journal of Comparative Physiology shows that muscle development necessary for diving can take several years to mature in harbor porpoises. Scientists argue that this may make immature harbor porpoises more vulnerable than adults to impacts from boat traffic or other disturbances. 

A 2014 paper in Endangered Species Research suggests that harbour porpoises inhabiting coastal waters of southern British Columbia constitute a single genetic population, which should be reflected in management decisions.

A report from the Puget Sound Ecosystem Monitoring Program provides an overview of 2013 marine water quality and conditions in Puget Sound from comprehensive monitoring and observing programs.

Harbor porpoise (Phocoena phocoena) are one of the most frequently sighted cetaceans in the Salish Sea. Anecdotal information, possibly supported with stranding encounter rate data, suggests that harbor porpoise may have increased in Puget Sound, or have shifted their distribution back to Puget Sound relative to earlier decades.