Abstract

The Alaska SeaLife Center Rescue and Rehabilitation Program (ASLC) is a volunteer under the Alaska Region Stranding Network and the only active marine mammal stranding facility in Alaska. The Center rescues, treats and releases stranded or injured marine mammals and birds. This program is an important part of the Center's commitment to understand and maintain the integrity of the marine ecosystem of Alaska through research, rehabilitation and public education.

On May 31st, 2002, the stranding hotline received a call regarding a lone Steller sea lion neonatal pup that was observed by Alaska Department of Fish and Game field researchers on a beach near Lowrie Island rookery in Southeast Alaska. Severe storms had occurred over the previous three days. Many pup carcasses were found in the waters near the rookery. Due to the fact that the pup was still bright, alert and vocal, the decision was made to continue to observe the pup in hopes that the mother would locate it. After five days, the pup was still alone on the beach and had become increasingly lethargic and less vocal.

Steller sea lion pups have never been rehabilitated in Alaska for many reasons. The most obvious is that they are born and live on remote rookeries with other sea lions and neither the rookeries nor pups in distress are easily accessible. In the past 25 years, there has been a dramatic decline in the western U.S. stock of Steller sea lions due to a number of hypothesized causes that include lack of prey availability, pollution, commercial fisheries, or other long-term environmental changes.⁸ The U.S. stock of Steller sea lions west of longitude 144° is currently listed as endangered under the Endangered Species Act and the eastern stock is listed as threatened. The most vulnerable age group appears to be the juveniles. Rehabilitation of young Steller sea lions can provide a unique opportunity in to gather information, which could assist in the future research and management of this species.⁷

After receiving authorization from the National Marine Fisheries Service (NMFS) national and regional stranding coordinators, the ASLC arranged for the Steller pup to be picked up and flown by helicopter to Ketchikan, then by commercial air cargo to Anchorage, and finally delivered by truck to the Center. Physical exam of the pup on arrival revealed moderate dehydration, emaciation and severe lethargy. All lung lobes ausculted clear, but she was tachycardic. She had greenish brown diarrhea. Age was determined to be approximately seven days old from size, dentition, status of umbilicus and known stranding date. Initial blood work and urinalysis revealed dehydration, hypoglycemia, leukocytosis and an elevated LDH. Supportive care with subcutaneous fluids, oral electrolytes, umbilical flushing, injectable antibiotics, and injectable vitamin B were instituted. Initial fecal parasite tests and culture were negative. Serum was tested for antibodies to toxoplasmosis, brucellosis, leptospirosis, morbillivirus and seal herpes virus I and II. All tests were interpreted as negative titers. She responded to initial treatment within eight hours and became more vocal and active and began suckling on her flippers.

Several different formulas have been tried with Steller sea lion pups and most offer less than ideal nutrition. Many formulas have led to gastrointestinal problems and even severe impactions.^4,5 A sea lion formula which had been successfully employed at the Vancouver Aquarium was slowly introduced over 36 hours.¹ Within two days, she was suckling from a bottle.

Sea lion milk formula (initial).

For the next two weeks, the pup, nicknamed "Faith," progressed fairly well, continued to suckle well and gained about 0.12 kg/day. She developed a mild upper respiratory infection so oral antibiotics were continued. Her stool was still soft and only somewhat formed, but normal in color and odor. In the second week, she began to regurgitate occasionally after feeds and seemed to have increased gas, but still had a good appetite. Over the next two days, she began vomiting after feeds and became more lethargic. She had soft, unformed stools that were small in size. Her physical exam revealed mild distension of abdomen, jaundice, and decreased production of urine and feces. CBC, serum chemistry, electrolytes and urinalysis were unremarkable. Supportive care was begun with oral fluids and electrolytes and the milk formula feeds were discontinued. She then began vomiting up curdled formula with coagulated blood. Abdominal radiographs revealed a large, ingesta filled stomach with gas present in the middle and distal GI tract. Despite medical treatment, her condition worsened. She was anesthetized with isoflurane for endoscopy and gastric lavage. Endoscopy revealed a large inspissated mass of curdled formula obstructing the outflow near the pylorus. Saline lavage was attempted for close to three hours with minimal retrieval of the pieces of the mass. Post-lavage radiographs revealed some breakup of the ingesta in the stomach.

Treatment was continued with subcutaneous fluids, oral fluids and electrolytes, antibiotics, anti-gas medication and lactulose.³ The pup began to pass formed chunks of the formula and her abdominal distension began to subside. The formula was changed to a fish based formula and she began suckling again. After losing weight for two weeks, she began to suckle eagerly again and started gaining weight.

One-week post lavage, the pup showed worsening clinical signs included hypothermia, anorexia, polydipsia, abdominal cramping, and lethargy. A fecal culture was positive for Salmonella (Group D not typhimurium). Antibiotics and supportive care were continued. The formula contents, food fish, housing area and all other animals in the rehabilitation facility were tested for Salmonella spp., but were negative. Whether this infection was acquired in the wild or after admission into rehabilitation is still unknown. It is not uncommon for an animal to be asymptomatic and intermittently shed Salmonella. When concurrent disease or stress occurs, this may increase the susceptibility of animals to infection.^2,6 One study found that four percent (9/212 individuals) of the animals tested from rehabilitation centers were positive for Salmonella spp. These included a variety of wildlife such as raptors, marine mammals and marine birds.⁹

Faith remained fairly healthy with occasional bouts of gastrointestinal illness. Weekly fecal pathogen cultures revealed persistent shedding of Salmonella for 12 weeks before three sequential negative fecal pathogen cultures were obtained. During this time, "fish schooling" was begun and, at four months of age, she quickly weaned herself onto a whole fish diet.

Most otariids are highly social creatures. Pups have a long period of maternal dependence and need to learn appropriate behavior for survival and reproduction. A great challenge in rehabilitation and hand raising pinnipeds is to release pups that are able to socialize and function within a group of their own species. Proper feeding and good health are prerequisites for adequate physical development in a young pup. However, there are additional factors that can positively influence a pup's social development. The pup needs ample opportunity to acquire and perfect swimming and social skills, and human contact must be limited before release can be considered.

Due to the fact that Faith would be in captivity for an extended period of time, a socialization plan was instituted as soon as she was in good health and free of communicable disease. The plan consists of introducing Faith to the ASLC's two resident Steller sea lion females in a progressive, controlled, and positive setting. The females have been exposed to young pups previously at the Vancouver Aquarium and their behavior was acceptable. For Faith, this socialization plan has helped develop appropriate interactions and behaviors with other sea lions and has provided basic skills that she will need to survive in the wild. The interactions have also provided enrichment to the captive Steller sea lion as a husbandry practice.

The goal of the ASLC is to release Faith back into the wild in Southeast Alaska this spring. Until then, we will continue to try to increase her survival skills so that she may meet release criteria.

Acknowledgements

We would like to thank our veterinary technicians Millie Gray and Tim Lebling and our many Rehabilitation Department interns and volunteers for their efforts, and Dr. Marty Haulena and Dr. Dave Huff for their input and advice. Thanks also to Lee Keller, Husbandry Director at the Alaska SeaLife Center, and the ASLC Mammal Staff for their suggestions and for their collaboration in the socialization of this pup.

References

1.  Christen DR. 1997. Overview of the hand rearing of four neonatal Steller sea lions (Eumetopias jubatus) at the Vancouver Aquarium. Unpublished data: 4-7.

2.  Clegg FG, SN Cheijina, AL Duncan. 1983. Outbreaks of Salmonella Newport infection in dairy herds and their relationship to management and contamination of the environment. Vet. Rec. 112: 580-584.

3.  Dierauf LA, FMD Gulland. 2001. CRC Handbook of Marine Mammal Medicine. 41: 916-917.

4.  Haulena M, personal communication, Suasilito, CA, 2002.

5.  Huff D, personal communication, Vancouver, B.C. 2002.

6.  Jahraus CD, HL Philips. 1999. Clinical presentation and treatment of a Salmonella Bredeney epidemic in Shelby County, Alabama South. Med. J. 92: 700-801.

7.  Mellish JA, personal communication, Seward, AK, 2002.

8.  Pascual MA, MD Adkison. 1994. The decline of the Steller sea lion in the northeast Pacific: demography, harvest or environment. Ecological Applications 4(2): 393-403.

9.  Smith WA, JAK Mazet, DC Hirsh. 2002. Salmonella in California wildlife species: Prevalence in rehabilitation Centers and characterization in isolates. J. Zoo Wildl. Med. 33(3):228-235.