Mortality in an off-shore predator critical habitat during the Northeast Pacific marine heatwave

Defining baseline mortality and trends in wildlife populations is imperative to understand natural anthropogenic threats overall population health improve conservation measures for species, particularly geographically confined habitats. The Guadalupe fur seal Arctocephalus townsendi (GFS) a threatened pinniped that ranges throughout the west coast of Mexico with sporadic dispersion higher latitudes. Their breeding habitat restricted Island, Mexico, which vulnerable periodic cyclic warming Northeast Pacific Ocean. impacts environmental change on GFS reproductive success at Island are poorly defined aim this study was establish pup (GFS n ) rates primary causes death during 2013-2016 seasons Island. Interannual were compared by year, geographic location. highest rate 2015 (14.7%), followed 2014 (8.2%), 2016 (6.7%) 2013 (5.6%). presumptive consistent other published long term otariids surveys included: emaciation (49%), trauma (24%), infectious disease (8%), drowning (4%) stillbirth/perinatal undetermined (11%). However, coinciding northeast marine heatwave 2014-2016, accounted 54% contrast 9% 2013. For , terrestrial may influence but like predators, features, such as an increase sea surface temperature associated changes maternal care, nutritional status pups survival. Monitoring crucial trends, document potential species demographics recruitment heatwaves consequences recovery.