The fur seal was first sighted on 9 June 2016 at the Barra El Jiote community, Jutiapa (13° 47’ 29.19″ N, 90° 14’ 29.59″ W; Fig. 1). Members of the community attempted to push the fur seal back into the ocean on several occasions but each time it returned to shore a few hours later and a couple of kilometers further north, moving a total distance of about 6.5–8 km. In the last attempt, members of the community reported that stray dogs harassed the fur seal and that in response the fur seal attacked and wounded one of the dogs, likely in self-defense. To prevent further harassment, members of the community enclosed the pinniped in a large industrial cooler (180 × 70 cm) with approximately 20 cm of seawater. The fur seal spent the night and the following morning in those conditions.
On 10 June, a team of biologists and a veterinarian visited the location and observed the behavior of the fur seal and performed a visual external examination. Morphological characteristics were used to identify the species of fur seal, its gender, and estimate the age class according to Clark (1975), Reeves et al. (1992) and Jefferson et al. (1993, 2007). Furthermore, multiple photographs of the fur seal were sent to five independent pinniped specialists including a specialist on Galapagos fur seals (D. Bárcenas, Universidad Autónoma de Baja California Sur, Mexico; F. Elorriaga-Verplancken, Centro Interdisciplinario de Ciencias Marinas, Mexico; D. Páez-Rosas, Universidad San Francisco de Quito, Ecuador; S. Villegas, University of California, Santa Cruz, U.S.; C. Yaipén-Llanos, Organización Científica para la Conservación de Animales Acuáticos, Peru) to confirm the initial identification.
The four species of Arctocephalus found in the Americas are morphologically different. A. galapagoensis is the smallest otariid species; it has a compact body and adult males are stocky in build. Additionally, the size and shape of the muzzle are key taxonomical characteristics use in dichotomous keys to distinguish A. galapagoensis from the other three species (see taxonomical key by Jefferson et al. 1993). A. galapagoensis has a short and straight muzzle that rapidly tapers in width and thickness to the small nose. Also, the muzzle is pale tan and the color extends onto the face and forehead over the eyes, forming a small pale mask. In contrast, the other three species do not have a short muzzle. Instead, they have either 1) a moderately long muzzle that tapers in width and thickness to the nose, slightly enlarged rhinarium and upward-angled nostrils (e.g. A. australis) or 2) a long muzzle with a bulbous, enlarged rhinarium and significantly downward-angled nares (e.g. A. philippii or A. townsendi). Further, A. philippii and A. townsendi have a variable amount of buff to reddish-brown color on the muzzle that may extend into the face. In A. australis, the face is dark and the sides of the muzzle may be gray to yellow (Reeves et al. 1992; Jefferson et al. 1993, 2007).
There are also some differences in the head’s shape and fur coloration, especially among males. In A. galapagoensis, males have a slightly rounded crown and a short sloping forehead. They do not have the characteristic sagittal crest of other male otariids. Nevertheless, males of A. australis have a rounded crown and prominent forehead, of A. philippi have a rounded crown with the apex above the ear pinnae and a slight rounded forehead, and of A. townsendi have a long, narrow and fairly flat head. Males of A. galapagoensis are dark brown on the back and sides, with pale tan heads and bellies. Yet, in A. australis and A. philippii, males are dark brown to black and in A. townsendi, both sexes can be uniform dark brown to black (Reeves et al. 1992; Jefferson et al. 2007).
The fur seal did not have any apparent wounds, nasal or ocular secretions, was calm and exhibited regular breathing patterns; however, the fur seal was emaciated and some bone structures (e.g., vertebral spine, hips, pelvic and scapular bones) were visible during the external examination of the animal in situ. A release was attempted near the shoreline but the fur seal did not move. Because of the animal’s behavior and thin body condition, it was decided that the fur seal needed to be taken to a rehabilitation center and with authorization from the Guatemalan Commission of Protected Areas (Consejo Nacional de Areas Protegidas), the seal was transported to the Wildlife Rescue and Conservation Association (Asociación de Rescate de Vida Silvestre, ARCAS) located in Hawaii, Santa Rosa (Fig. 1).
Reports of pinnipeds ranging far in search of more favorable conditions have been documented during ENSO events (Trillmich and Limberger 1985; Capella et al. 2001; Aurioles-Gamboa et al. 2004; Alava and Salazar 2006; Elorriaga-Verplancken et al. 2016a,b; Villegas-Zurita et al. 2016; Alava and Aurioles-Gamboa 2017). Thus, to investigate the potential correlation of the stranding of the fur seal with the 2014–2016 ENSO event, the average anomalous sea surface temperature (SST) was examined for the day of the stranding and on the three consecutive months prior to the event in the eastern tropical Pacific including the Galapagos Islands following Villegas-Zurita et al. (2016).