The impacts of El Nino conditions on California sea lion (zalophus californianus) fisheries interactions: Predicting spatial and temporal hotspots along the California coast

TitleThe impacts of El Nino conditions on California sea lion (zalophus californianus) fisheries interactions: Predicting spatial and temporal hotspots along the California coast
Publication TypeJournal Article
Year of Publication2013
AuthorsKeledjian A.J, Mesnick S.
JournalAquatic Mammals
Volume39
Pagination221-232
Date Published2013/08
Type of ArticleArticle
ISBN Number0167-5427
Accession NumberWOS:000323549300002
Keywordscalifornia current; California sea lion; diet; ecosystem; El Nino Southern Oscillation; entanglement; Fisheries; foraging behavior; hotspots; interactions; island; marine mammal health; northern california; oceanographic conditions; pinnipeds; san-nicolas; stranding; variability; Zalophus californianus
Abstract

California sea lions (Zalophus californianus) are often viewed as a sentinel species whose health can be affected by prevailing oceanographic conditions and environmental quality. For this reason, it has become increasingly important to study natural stressors and anthropogenic impacts that can lead to diminished health and survival among individuals of this coastal species. In this study, Z. californianus stranding records spanning 1983 to 2010 were used to first identify regional and seasonal fisheries interaction hotspots in California, and second, to examine how these hotspots might change under additional environmental stress induced by El Nino oceanographic conditions that can affect prey availability. Analyzing mean monthly fisheries interaction cases as an example of human-related stranding revealed that (1) the number of monthly fisheries interaction cases has risen significantly over time proportional to statewide abundance estimates; (2) cases were significantly higher in Monterey, Los Angeles, and Orange Counties; (3) cases peaked May through August; and (4) fisheries interactions were significantly greater during El Nino conditions throughout the state. These results indicated that over a 27-y period, California sea lion health was affected by oceanographic conditions and that anthropogenic impacts may be heightened in early summer following the weaning period when young animals learning to forage may be less successful in El Nino conditions. Spatially and temporally explicit data such as these can be useful in mapping marine mammal health and understanding the dynamic natural and anthropogenic landscapes in which they are a part.

DOI10.1578/am.39.3.2013.221
Integrated Research Themes: 
Student Publication: 
No