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Nutria's Return: Human Reintroduction Suspected
28 Jul
Summary
- Nutria, invasive rodents, returned to California via human reintroduction.
- Genetic study shows current nutria population is not native descendants.
- Eradication efforts cost California $5 million annually since 2017.
California officials now suspect that the reappearance of invasive nutria in the Central Valley was the result of human reintroduction, not natural survival. A recent genetic study compared modern DNA samples with historical specimens.
The findings revealed that the current nutria population is most closely related to a group in central Oregon, not to the animals previously eradicated in California by the late 1970s. This genetic evidence strongly suggests a deliberate or accidental reintroduction by people.
Nutria, large semi-aquatic rodents, pose significant ecological and agricultural threats. They damage wetlands by eating plant roots, weakening soil and creating open water, and can undermine levees and flood-control structures. Since 2017, California has spent about $5 million annually on eradication efforts.
More than 7,800 nutria have been removed since 2017 through extensive trapping and removal operations across the Sacramento-San Joaquin Delta and Central Valley. Understanding the human role in this invasion is crucial for future prevention strategies, emphasizing biosecurity alongside removal efforts.
