In the wild, dolphins and whales obtain freshwater (a requirement for all mammals) from eating live food such as fish and squid (they do not drink). In captivity, they are fed dead fish that have lost a significant amount of water in the process of being frozen and thawed (Sikorski et al. 1976). If the whales are not provided sufficient hydration, they can develop significant health problems (Couquiaud 2005a). In order to counteract any dehydration suffered from eating only thawed frozen fish, captive orcas are frequently offered gelatin, which is mostly water, as an artificial way to provide them with sufficient freshwater. Many facilities also give ice to their captive cetaceans.
If captive whales and dolphins fail to get enough water via other means, a last resort is forcing them to swallow a gastric tube through which water is pumped directly into their stomachs1.
Fish that have been frozen and thawed also lose nutrients (Couquiaud 2005b), and the protein structure can change as well (Sikorski et al. 1976). Gelatin does contain protein in small amounts but these proteins may not be complete or available to whales and dolphins, as they are usually derived from beef and pork and undergo complex processing when rendered into gelatin2.
Couquiaud, L. 2005a. Whales, dolphins, and porpoises: Presentation of the cetaceans. Aquatic Mammals 31: 288-310.
Couquiaud, L. 2005b. Food and fish house. Aquatic Mammals 31: 364-370.
Sikorski, Z.E., Olley, J., Kostuch, S., and Olcott, H.S. 1976. Protein changes in frozen fish. CRC Critical Reviews in Food Science and Nutrition 8: 97-129.
Watch our killer whale trainer explain why we feed our killer whales gelatin — the same kind you and I would eat. It’s one of many sources of hydration for our whales and they seem to have as much fun with it as children do.