The Case against Marine Mammals in Captivity - The Humane ...

Mortality and Birth RatesAnimals die, in captivity and in the wild. The simplefact that an animal dies in a zoo or aquariumis not notable in itself. The questions to ask are:What was the cause of death? How old was he or she?Many animal protection advocates who oppose captivitybelieve every death demonstrates that captivity kills,but this is overly simplistic. On the opposite end of thespectrum, zoo officials usually label every death “natural.”The truth is obviously somewhere in between, but thepublic display industry, with its proprietary access tothe relevant data, has been lax in defining where thattruth lies. Veterinary record-keeping and research intocauses of death have lagged behind the public’s interestin the welfare of captive wildlife. 285PINNIPEDS AND OTHER NON-CETACEANSThe annual mortality rates of seals and sea lions in captivity rangefrom 2.23 percent for Steller sea lions (Eumetopias jubatus) to 11.6percent for northern fur seals (Callorhinus ursinus). 286 There is littleinformation from the wild with which to compare the mortalityrates of captive seals and sea lions, but from limited data, captiveSteller sea lions seem to show mortality rates similar to or lowerthan their wild counterparts. 287 Mortality rates of captive-born pupsfor some species, such as the California sea lion, are lower than inthe wild, 288 but for others, captive pup mortality rates are relativelyhigh. Two-thirds of captive South American sea lions (Otaria byronia)and northern fur seals die in their first year, 289 a rate that maybe higher than experienced in the wild. Comparatively, captive seaotters appear to fare better in terms of life expectancy, althoughhow this compares to wild populations is unknown. 290Few, if any, of the pinniped species typically held in dolphinaria,aquaria, and zoos (notably harbor seals and California sea lions)are captured from the wild anymore. Surplus captive-bred animals,in fact, have now become a problem in many cases, and facilitiesare concerned with reducing the fecundity of these species. 291Few of the California sea lions now held in dolphinaria andzoos were captured from the wild.Many of the currently available methods used to control reproductionmay have long-term detrimental effects, and further researchis needed to develop less-harmful contraceptive methods. 292As noted earlier, most aquaria and zoos currently obtain polarbears from captive-bred stock. However, sea otters, walruses (asnoted earlier), manatees, and a handful of other pinniped species,Surplus captive-bred animals have now become a problem in manycases, and facilities are concerned with reducing the fecundity ofthese species. Many of the currently available methods used tocontrol reproduction may have long-term detrimental effects, andfurther research is needed to develop less-harmful contraceptivemethods.such as northern elephant seals (Mirounga angustirostris) andSteller sea lions, are still acquired from the wild for the mostpart. All of these species have had relatively small populationsin captivity, and data on their life history parameters are limited.