Endangered orca population in
Washington acts genetically smaller than it really is
Date: April 24, 2018
Source: NOAA Fisheries West Coast Region
A new genetic analysis of
Southern Resident killer whales found that two male whales fathered more than
half of the calves born since 1990 that scientists have samples from, a sign of
inbreeding in the small killer whale population that frequents Washington's
Salish Sea and Puget Sound.
Only about 26 of the 76
endangered whales in the Southern Resident population are currently breeding,
according to the analysis published this week in Animal Conservation. The
limited number of breeding whales reduces the effective size of the population,
leaving it less resilient to change and possibly compromising the survival of
individual animals, said lead author Michael Ford, a conservation biologist at
NOAA Fisheries Northwest Fisheries Science Center in Seattle.
"The effective size of this
population is really small," he said. "It's acting like a population
of only 20-30 individuals."
Authors of the research also
include scientists from the North Gulf Oceanic Society and Center for Whale
Research. While the new paper builds on earlier genetic studies, it also raises
new questions about whether inbreeding may be contributing to the population's
struggles. Southern Resident numbers have fallen to their lowest point in 30
years.
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