Abstract
The morphometric and dietary data collected over the past 50 years from the marine mammals housed at the SeaWorld parks provide a unique opportunity for a comprehensive look at the growth patterns of different marine mammal species. Body mass measurements and demographic data were compiled for the cetaceans and walruses of known age at the SeaWorld parks. The species in this dataset include Orcinus orca (Oo) (n=30), Delphinapterus leucas (Dl) (n=18), Tursiops truncatus truncatus (Ttt) (n=130), Cephalorhynchus commersonii (Cc) (n=7), and Odobenus rosmarus divergens (Ord) (n=17). For each species, we used historical weight records to model growth using Gompertz models for the entire lifespan and linear models for selected age ranges. Cc and Ttt grew fastest in the first year of life, Dl from years two to four, Ord and Oo females in year four, and Oo males in year nine, with an max growth rates of 6, 16, 60, 82, 148, and 184 kg/year, respectively. All species except for Ttt exhibited sexual dimorphism, contradictory to what has been previously recorded for wild Atlantic bottlenose populations.1 In species Dl and Oo, males grew more slowly, reaching mature body weight ten and fifteen years after females, respectively. Ord males grew more quickly, reaching mature weight 7.5 years before females. Both males and females of Ttt reached mature weight at age 17.5. Dl individuals grew faster than what has been reported for wild populations, reaching adult size 5 years earlier.2 Females of Ttt and Ord grew more slowly, reaching mature size 10 years later than the wild populations in both species.1,3 Growth curves for Commerson’s dolphins have not been previously described. Predictive equations were generated that allow the establishment of yearly growth targets for different sex and species classes in managed care. This data provides the basis for evaluating growth, energetic, and nutritional requirements of captive and wild animals, for establishing body mass targets, and for understanding the impact of age, sex, and species on growth rates.
Acknowledgements
We would like to thank Kaylin Ackerson for her contribution to compiling and cleaning up the raw demographic data. Thanks to Jeff Kaeffaber for his invaluable advice on statistical analysis. Thanks to Laura Stalter for exchanging R coding tips, and for daily support in general as my co-intern.
* Presenting author
Literature Cited
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2. Suydam RS. Age, Growth, Reproduction, and Movements of Beluga Whales (Delphinapterus leucas) from the Eastern Chukchi Sea. Ph.D. Thesis. University of Washington, Seattle, WA; 2009:152.
3. Fay FH. Ecology and Biology of the Pacific Walrus, Odobenus rosmarus divergens illiger. North American Fauna. 1982;74:1–279.