Evidence of copulation in an anthropogenic colony of the South American sea lion, Otaria byronia (De Blainville, 1820) in Río Valdivia, Valdivia, Chile

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Abstract

In Chile, the South American sea lion Otaria byronia forms colonies on exposed rocky coasts. Since the mid-1970s, a group of individuals has become established around the Valdivia fish market (VFM) (ca. 39S), southern Chile, where they regularly obtain food from fish discards provided by the fish market's sellers. Given their regular presence in the area and the lack of breeding activity, this group has been considered a non-breeding aggregation. From 2019 to 2025, researchers conducted 168 bimonthly censuses around the VFM as part of a long-term monitoring program; however, no mating events were recorded during those censuses. In December 2025, outside of census days, a copulatory event was observed in front of the VFM, indicating previously unreported reproductive behavior within this anthropogenic colony. Additionally, in April 2022, a dead pup was recorded within the Cruces River wetland, nearly 25 km north of the VFM. Together, these two reproductive-related records suggest that this anthropogenic colony may be transitioning toward a breeding structure.

Jaramillo, E., Oliva, D., Sepúlveda, M., Navarro, F., & Barrales, C. (2026). Evidence of copulation in an anthropogenic colony of the South American sea lion, Otaria byronia (De Blainville, 1820) in Río Valdivia, Valdivia, Chile. Latin American Journal of Aquatic Research, 54(5), 874-880. doi:http://dx.doi.org/10.3856/vol54-issue5-fulltext-3639

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