Feeding protocols vary for every animal at The Marine Mammal Center.
The type, amount, and frequency of food each animal receives varies depending on species, age, body condition, and specific medical problem.
Often, when an animal is first admitted to the Center, they are suffering from dehydration. To rehydrate an animal we give them an electrolyte solution either orally or subcutaneously (under the skin). Some animals require intravenous fluid therapy. Once the animal has been rehydrated, we begin the feeding regimen.
Our goal is to feed young or emaciated pinnipeds (seals and sea lions) the equivalent of 10% of their body weight in whole fish (mostly herring) every day. This ensures that they are getting adequate nutrition and are putting on weight. Once an animal is healthier, we reduce them to a maintenance diet, which means we feed them 5% of their body weight each day.
Pups
Pups are prescribed feeding regimes depending on their age and species. Pacific harbor seal pups that are not yet weaned are generally started on Formula 99. This formula is designed to simulate their mother's milk, which can be up to 50% fat. The formula is comprised of a commercially available soy-based milk replacer, water, and fish oil (for fat). The addition of fish oil increased weights rapidly in 1999, allowing for earlier release of harbor seal pups, and decreased incidence of herpesvirus-associated disease. Pups at this stage are fed every four hours from 8am to midnight.
Northern elephant seal pups that are not yet weaned are generally started on ES Formula. The formula is comprised of ground up herring, whipping cream, water, fish oil and lactase. Elephant seal pups are fed this mixture every four hours from 8am to midnight.
Pups that are getting formula (Formula 99 or ES Formula) or electrolytes are fed using a method called tube-feeding. One person restrains the animal while another inserts a soft, flexible feeding tube down the animal's esophagus and into its stomach. A volunteer then uses one of several methods to pump formula down the tube into the animal's stomach. The entire process takes about five minutes.
We do not bottle-feed pups for several reasons. First, bottle-feeding increases the amount of time volunteers must spend with the animals, increasing the likelihood that an animal will bond with humans. Second, tube-feeding allows us to better monitor the amount of food each animal is receiving. Third, most harbor and elephant seal pups only nurse from their mother for twenty-eight days before being weaned. It can often take us this long just to get an animal interested in the bottle.
Once pups have been stabilized and their teeth have erupted, they graduate from tube-feedings to what we call fish-school, which is a series of exercises designed to stimulate the animal's interest in fish. Volunteers initiate an animal's interest with easy to "catch" thawed frozen fish. The fish may be dragged through the pool on a string or while being held with forceps. Later the pup moves on to competing for fish with other animals and eating fish on its own, "free-feeding."
Before pups are released, they must be able to forage for food on their own. One of the techniques used to ensure this is offering live fish to make certain the animal can track, catch and eat on its own.
Free-Feeding Animals
Free-feeding is how we feed most of the animals at The Center, including weaned pups, California sea lions, northern and Guadalupe fur seals, and adult harbor seals. Animals that are free-feeding are generally fed two or three times per day. During the busy seasons, volunteer animal crews may work 12 hour days in order to accommodate all of hte patients' needs.
Once an animal is free-feeding, we dump the fish (usually herring) in the pool and let the animal eat on its own. One important component of this free-feeding is competition with other animals. We try to keep animals together in pens so that they will socialize with one another and not bond with humans, and so that they will have to compete for their food just as they would in the wild.
