Guido Pavez

In the Eastern South Pacific (ESP), blue whale ( Balaenoptera musculus subsp.) aggregations have been described for two feeding areas (in northern and southern Chile) and in the Eastern Tropical Pacific (ETP). However, despite the knowledge of these areas, little is known about the seasonal movements of blue whales between them. Comparisons of 1074 individual blue whales, photographed across these regions from 1992 to 2019, resulted in re‐sightings of 107 individuals. Photo‐identification comparisons were conducted using the Southern Hemisphere Blue Whale Catalog, a collaborative platform for sharing photo‐identification data among 21 research groups from 7 nations. A total of 92 matches were found within the southern Chile feeding area and 13 matches within the northern Chile feeding area. High site fidelity was found for the southern Chile feeding area (return rates ≥ 43%). The longest interval between the first and last sighting was 17 years. There was no exchange between northern and southern Chile feeding areas. Two matches revealed long‐distance connectivity and migration of blue whales from southern Chile to the Galápagos Islands in the southern ETP. There were no matches between Chile and the Costa Rica Dome, farther north in the ETP, a location known for the year‐round presence of blue whales. The results highlight the importance of collaboration to understand blue whale movements and migration patterns. Our results provide valuable ESP and ETP region‐wide data toward understanding population structure and informing conservation and management strategies, population assessments, and/or delineating biologically important areas.

Anthropogenic activities can alter the occurrence of many animal species, and marine mammals, in particular, may be impacted by coastal development. The marine otter, Lontra felina , inhabits the coasts of southern South America, where increasing urban encroachment and extractive activities are progressively altering its habitat. We estimated the abundance of L. felina at six study sites (with similar habitat structure) in northern Chile over three years, relating this to the presence of people, boats, and pets. We also calculated a human disturbance index using these human presence variables. Our findings indicated that marine otter abundance was negatively associated with the number of people, while boats and pets showed no significant associations with otter abundance. The human disturbance index, which integrates these variables, was also negatively related to otter abundance. Although marine otters are generally considered tolerant to human presence in coastal environments, our results show a consistent pattern of lower otter abundance at sites with greater human presence, particularly where people directly accessed shoreline habitats. This pattern is not explained by habitat structure, which was similar across sites, and suggests that local human activity may contribute to shaping spatial variation in abundance. This multi‐year assessment raises a warning about human influence on native species in coastal areas, which can inform evidence‐based conservation decisions.