Causes of Mortality in a Harbor Seal (Phoca vitulina) Population at Equilibrium

Sink or swim: Risk stratification of preweaning mortality in harbor seal pups (Phoca vitulina richardii) admitted for rehabilitation

“…Nutritional factors, primarily emaciation and malnutrition, were the second most commonly reported condition contributing to mortality. Previous research has suggested an interaction between poor nutritional status and increased susceptibility to infection, possibly as a result of immunosuppression and/or metabolic derangements (Ashley et al, 2020; Greig et al, 2010). PHV‐1, an alpha herpes virus primarily identified postmortem by adrenal and hepatic lesions with intranuclear viral inclusions (Gulland et al, 1997; Osterhaus et al, 1985) is also likely to further compound the effects of inadequate nutrition and prior infection on pups undergoing rehabilitation.…”

“…This source of error was, however, minimized by developing a simple scoring system that allowed detailed descriptions of injuries to be quantified into a single score, thereby enabling comparison between pups. While the sources of injury can rarely be identified on admission, possible causes include storms or harsh sea conditions (Baker et al, 1998; Osinga, Shahi Ferdous, et al, 2012), collisions with recreational or commercial vessels (Ashley et al, 2020; Barcenas‐De la Cruz et al, 2018), attempted predation (Gaydos et al, 2005; Hayward, 2009; Lucas & Stobo, 2000; Steiger et al, 1989), intraspecific aggression (Sullivan, 1982), entanglement (Bjorge et al, 2002; Colegrove et al, 2005) or conflict with humans (Ashley et al, 2020; Barcenas‐De la Cruz et al, 2018; Colegrove et al, 2005).…”

Trends in Propeller Strike-Induced Mortality in Harbor Seals (Phoca vitulina) of the Salish Sea

“…We evaluated harbor seal stranding and necropsy records from 2002 through 2019 in well-covered stranding-response areas of the Salish Sea: San Juan County (SJC) and South Puget Sound (SPS), in which consistent funding since the early 2000s (Ashley et al 2020) has facilitated stable marine mammal stranding response and necropsy (Fig. 1).…”

“…Data evaluated included stranding date, location, level of decomposition, age class, sex, length, weight, and findings of human interaction (National Oceanic and Atmospheric Administration 2020). In addition, we reviewed necropsy reports and analyzed gross findings, histopathology, and ancillary test results (Ashley et al 2020).…”

Streptococcal Infections in Marine Mammals

“…Between 2010 to 2017 the health of captive and stranded Alaskan ice seals were investigated and S. phocae isolates were obtained from blood, abscess, and lymph node samples from ringed seals [ 152 ]. Harbor seals stranded at the coast of San Juan County, Washington, USA between 2002 to 2018 were examined and from one adult female animal a fatal septicemia caused by S. phocae was reported [ 153 ].…”