CONCLUSION

This study provides the first integrated comparison of the morphometric, biochemical, and hematological characteristics of GSL and sympatric GFS pups during an active ENSO event. Despite reduced marine productivity associated with the weak-to-moderate 2024 El Niño conditions, GSL pups maintained favorable body condition and exhibited clinical profiles that largely fell within the physiological ranges reported for other otariid species. Interspecific comparisons revealed consistently higher body condition, GLOB, and TP concentrations in GSL pups, whereas most hematological variables showed broad overlap between species, suggesting largely comparable health status with some species-specific physiological differences.

A major strength of this study lies in its integrated approach, combining morphometric measurements with serum biochemical and hematological assessments under naturally occurring ENSO conditions. Furthermore, the direct comparison of sympatric GSL and GFS pups sampled during the same period provides valuable insights into species-specific responses to reduced marine productivity and establishes clinically relevant baseline information for both species. The incorporation of environmental indicators, including ONI and chlorophyll-a concentrations, further strengthens the ecological interpretation of the findings.

Overall, the results indicate that GSL pups exhibited apparent physiological resilience during the 2024 El Niño event despite evidence of reduced ocean productivity. The baseline data generated in this study contribute to a better understanding of the health status of Galapagos pinnipeds and provide an important foundation for long-term health surveillance and conservation programs. Continued multidisciplinary monitoring across ENSO and non-ENSO periods will be essential for detecting early signs of nutritional or physiological stress and for improving conservation strategies for these endemic marine predators in the face of increasing environmental variability and climate change.