Causes of mortality in northern elephant seal pups on San Miguel Island, California

Abstract

In February 2015, we conducted a field study of causes of mortality of northern elephant seal ( Mirounga angustirostris) pups on San Miguel Island, California. Autopsies were performed on 18 freshly dead pups. Ages of pups ranged from stillborn to 6–8 wk. Gross and histologic lesions included trauma (9 of 18 pups), multifocal necrotizing myopathy (8 of 18), starvation with emaciation (7 of 18), congenital anomalies (3 of 18), bacterial infections (3 of 18), and perinatal mortality (stillbirths and neonates; 2 of 18). Trauma and emaciation or starvation were the most significant contributors to death. Bacterial infections included hemolytic Escherichia coli isolated from the lungs of 2 pups with pneumonia. Additionally, non-hemolytic Streptococcus sp. and hemolytic E. coli were isolated from the liver of an emaciated pup that had mild multifocal suppurative hepatitis. Other lesions, including a previously described necrotizing myopathy, congenital anomalies, and bacterial infections, were detected concurrently in cases with starvation and/or emaciation or trauma.

Streptococcus vicugnae sp. nov., isolated from faeces of alpacas (Vicugna pacos) and cattle (Bos taurus), Streptococcus zalophi sp. nov., and Streptococcus pacificus sp. nov., isolated from respiratory tract of California sea lions (Zalophus californianus)

“…halichoeri in grey seals and Stellar sea lions [8, 13], α- and β-hemolytic streptococci in Baltic Sea seals [14], non-hemolytic Streptococcus sp. was also isolated from the liver of a northern elephant seal pup ( Mirounga angustirostris ) in California [15], β-hemolytic and non-hemolytic Streptococcus spp. have been reported in California sea lions ( Zalophus californianus ), harbour seals, and northern elephant seals in California [16, 17].…”

“…zooepidemicus and S. marimammalium in harbour seals (Phoca vitulina), grey seals (Halichoerus grypus), and South American fur seals (Arctocephalus australis) [9][10][11], S. agalactiae in grey seals [12], S. halichoeri in grey seals and Stellar sea lions [8,13], α-and β-hemolytic streptococci in Baltic Sea seals [14], non-hemolytic Streptococcus sp. was also isolated from the liver of a northern elephant seal pup (Mirounga angustirostris) in California [15], β-hemolytic and non-hemolytic Streptococcus spp. have been reported in California sea lions (Zalophus californianus), harbour seals, and northern elephant seals in California [16,17].…”

Variation of blubber thickness for three marine mammal species in the southern Baltic Sea

“…The blubber layer is one of the main energy storage sites in marine mammals, additionally providing insulation, supposedly functioning as a phase change material and contributing to buoyancy and hydrodynamic shape ( Dunkin et al, 2005 ; Derous et al, 2020 ). Declines in blubber thickness have been associated with detrimental effects at the population level, such as reproductive failure and reduced survival rates ( Spraker et al, 2020 ; IJsseldijk et al, 2021 ).…”