Abstract

Within the Northeastern Pacific, there are a number of stranding networks that coordinate recovery and post mortem examination of beach-cast marine mammals. In Washington State, primary responders include the National Marine Fisheries Service, Washington Department of Fish and Wildlife, Cascadia Research, Friday Harbor Marine Mammal Museum, SeaDoc Society-UC Davis, and Central Puget Sound Marine Mammal Stranding Network. In British Columbia, the Department of Fisheries and Oceans, Vancouver Aquarium, Saltspring Island Wildlife Rescue and Animal Health Center attend strandings and where licensed, assist with rehabilitation. Over the course of the last 7 years, whole animal carcasses, fresh and fixed tissues and swabs have been submitted to the Animal Health Center for diagnostic evaluation from 747 harbor seals (Phoca vitulina), 301 cetaceans, 100 Steller sea lions (Eumetopias jubatus), 98 sea otters (Enhydra lutris), 17 California sea lions (Zalophus californianus), 9 northern fur seals (Callorhinus urninus), 1 Guadulape fur seal (Arctocephalus townsendii) and 5 elephant seals (Mirounga angustrirostris).

As a component of the clinical and pathologic investigation of stranded marine mammals within the Northeastern Pacific region, routine samples of intestinal contents have been inoculated into selenite broth for selective isolation of Salmonella spp. Isolates recovered include: 7 S. Typhimurium from 5 harbor seals and 2 harbor porpoises; 4 S. Hadar from harbor seals; 3 S. Arizonae from California sea lions; 2 S. Reading from California sea lions; 2 S. Javiana from harbor porpoises; 1 S. Newport from a harbor porpoise; 2 S. Kentucky, 1 from a harbor seal and 1 from a Steller sea lion; 1 S. Heidelberg from a harbor seal; 3 S. Enterica-1 rough isolate from a harbor porpoise, 1 isolate from a Steller sea lion, and a 0 4,12:i: from a harbor seal; and 1 S. Enteriditis from a harbor seal. In most cases, there are no overt pathological lesions associated with recovery of bacteria. In rare outbreaks in captive facilities, particularly with concurrent seal herpesvirus infection, evidence of septicemia was apparent in harbor seals. With the exception of 1 harbor porpoise with transmural enteritis and fibrinous peritonitis, most cetaceans lack overt lesions. Interestingly, S. Newport was recovered from a neonatal offshore killer whale (Orcinus orca) that recently succumbed to omphalitis with secondary septicemia in California. The potential transfer of these bacteria from terrestrial environments or cycling within marine environments is unknown.

To place these isolates in context of terrestrial wildlife, production livestock and avian species, case records for British Columbia were reviewed for the last 7 years and the number of cases of Salmonella spp isolates identified. The most frequently recovered Salmonella spp was S. Typhimurium. There were 192 cow isolates, 48 pigs, 41 chicken, 44 pigeon, 11 pine siskin, 2 seagulls, 2 house sparrows, and 2 finches with individual isolates involving a llama, sheep, rabbit, raccoon, hummingbird and an unspecified psittacine. S. Enteritica was most often recovered from pigs (21 cases) with individual isolates from a cow, deer and capybara. S. Enteritides was recovered from 8 chicken, 4 pig and 2 cow cases. There were 29 cases of Salmonella hadar in chickens with 2 isolates from raccoons and individual cases involving a seagull, cow, dog, mink and raccoons. There were 59 isolates of S. heidelberg from chickens, 36 from turkeys, 4 cows, 3 dogs, and 2 farmed mink. There was a solitary case of S. newport from a turkey and 3 cases of S. arizonae from farmed mink.

Sixty nine serovars of Salmonella spp were recovered from terrestrial and avian species in British Columbia with only ten Salmonella spp serovars recovered from marine mammals within the Northwestern North America. The limited sample size precludes a thorough evaluation of the linkages between terrestrial and marine wildlife for these bacteria and their role in observed pathologies. However, our results underscore the potential for inter-species bacterial transmissions of concern and point to the need for further research.