Insights Into Anthropogenic Threats and Early Mortality in the Guadalupe Fur Seal From a Mixed Colony on the San Benito Archipelago, Mexico

The study on the Guadalupe fur seal (GFS) at the San Benito Archipelago (SBA) during the 2024 breeding season revealed a neonatal mortality rate of 29.52%, with deaths attributed equally to trauma and emaciation/infectious disease. Alopecia syndrome was prevalent in 21% to 26% of non-pup GFSs, particularly affecting yearlings and juvenile males. Entanglement incidents, entirely due to marine debris, primarily impacted juveniles. The marine debris on SBA beaches was 92% plastic, mainly bottles and fishing gear, suggesting local pollution sources. Mortality and alopecia rates were higher than on Guadalupe Island, indicating significant health challenges for GFSs at SBA. The study highlights the need for further research to understand the factors affecting the establishment of a breeding colony at SBA.