CAUSES AND TRENDS OF HARBOR SEAL (PHOCA VITULINA) MORTALITY ALONG THE BRITISH COLUMBIA COAST, CANADA, 2012-2020.

A retrospective study was conducted to categorize and describe the causes of mortality in harbor seals (Phoca vitulina) along the British Columbia coast that presented to the Vancouver Aquarium Marine Mammal Rescue Centre (MMR) for rehabilitation from 2012 to 2020. Medical records for 1,279 predominantly perinatal live-stranded harbor seals recovered in this region were reviewed. Approximately 20.0% (256 individuals; 137 males, 118 females, 1 unknown) of these animals died while at MMR. Infectious disease was the most common cause of death, accounting for 60.5% of mortality across all age classes. This was followed by nonanthropogenic trauma (7.1%), metabolic illness (5.4%), nutritional deficiency (5.0%), parasitic illness (5.0%), congenital disorders (2.5%), and human-associated trauma (0.4%). Pups were the most common age class (87.4%) amongst mortalities and predominantly died of an infectious process (62.5%). Phocid herpesvirus-1 infection was identified in 18.9% of the mortalities, with the highest prevalence occurring in 2019 (30.8%). Fungal disease was detected in six seals: three cases of pulmonary mycosis due to Cryptococcus gattii and three cases consistent with mucormycosis. In six cases, mortality was attributed to congenital disorders. Two of these cases involved axial skeletal malformities that are not currently described in the literature. This is the first study to describe the causes of mortality in harbor seals undergoing rehabilitation in British Columbia.

HISTOLOGIC ANALYSIS OF TESTICULAR DEVELOPMENT AND SEXUAL MATURATION IN REHABILITATED NORTHERN SEA OTTERS (ENHYDRA LUTRIS KENYONI).

As part of routine captive management of the species, sea otter (Enhydra lutris) males are often castrated to prevent reproduction, to preserve limited spaces for future nonreleasable stranded individuals, and to minimize potential aggression among cohorts. To determine the relative stage of testicular development, testicles from 14 castrated, rehabilitated northern sea otters (Enhydra lutris kenyoni) were submitted for histologic examination. Eight of the otters (aged 201, 304, 344, 352, 360, 373, 401, and 1,423 d old) had evidence of varying degrees of sexual maturity. Histologic grading of maturity of individual testicles showed inactive testes, spermatocytes with some maturation of spermatogenic precursors, and fully active spermatogenesis. Spermatozoa were seen in the otters that were 401 and 1,423 d old (1.1 and 3.9 yr old). Sexual maturity for wild male sea otters in Alaska has been previously reported to occur from 3 to 5-6 yr. Social maturity, or the ability to breed and reproduce, may occur a few years later than the onset of physiologic maturity; age, weight, territory quality, and the length of time holding a territory may influence a male otter's mating success. Early testicular development in rehabilitated sea otters may be related to abundant resources, lack of competition, and decreased environmental pressures. Additionally, these findings have implications for husbandry and management practices in short- and long-term care facilities.

A REVIEW OF NEOPLASMS IN A POPULATION OF JAMAICAN FRUIT BATS (ARTIBEUS JAMAICENSIS) UNDER HUMAN CARE.

Although reports of tumors in chiropteran species are rare, postmortem examinations conducted on aging captive populations suggest that neoplasia may be more prevalent and clinically more significant contributors to morbidity and mortality than previously appreciated in these animals. A retrospective study was conducted to describe cases of neoplasia identified in Jamaican fruit bats (Artibeus jamaicensis) under human care at the Vancouver Aquarium between 01 January 2013 and 31 March 2021. Approximately 13.2% (N = 47/355) of the bat population died within this time span, and gross and histologic postmortem examinations were performed on 28 of 47 individuals. There were eight malignant and three benign neoplasms detected in 10 cases (eight females, two males), including: malignant histiocytoma, esophageal adenocarcinoma, two squamous cell carcinomas, spindle cell sarcoma, periosteal chondrosarcoma, uncharacterized uterine neoplasia with unrelated multicentric pulmonary carcinoma, and cholangiocarcinoma. Benign variants included three suspected uterine leiomyomas. A wide variety of tumor types and tissue predilections were identified, suggesting a complex and perhaps multifactorial pathogenesis in neoplastic transformation in microchiropterans. To the authors' knowledge, these tumor types have not been previously described in Artibeus sp., and some of these neoplasms have not previously been reported in chiropterans.