title: Comparisons of life-history parameters between free-ranging and captive killer whale (Orcinus orca) populations for application toward species management.
abstract: Data collected on life-history parameters of known-age animals from the northern (NR) and southern resident (SR) killer whales (Orcinus orca) of the eastern North Pacific were compared with life-history traits of killer whales located at SeaWorld (SEA) facilities. For captive-born SEA animals, mean age and body length at 1st estrus was 7.5 years and 483.7cm, respectively. Estimated mean age at 1st conception was different (P< 0.001) for the combined data from both northern and southern resident (NSR) free-ranging populations (12.1 years) compared to SEA (9.8 years), as was the estimated mean age at 1st observed calf (SEA: 11.1 years, NSR: 14.2 years,P< 0.001). Average calf survival rate to 2 years of age for SEA animals (0.966) was significantly greater (P= 0.04) than that for SR (0.799). Annual survival rate (ASR) for SEA increased over approximately 15-year increments with rates in the most recent period (2000-2015 ASR: 0.976) improved (P< 0.05) over the first 2 periods of captivity (1965-1985: 0.906; 1985-2000: 0.941). The SR (0.966) and NR ASR (0.977) were higher (P≤ 0.05) than that of SEA until 2000, after which there were no inter-population differences. Based on ASR, median and average life expectancy were 28.8 and 41.6 years (SEA: 2000-2015), 20.1 and 29.0 years (SR), and 29.3 and 42.3 years (NR), respectively. The ASR for animals born at SEA (0.979) was higher (P= 0.02) than that of wild-caught SEA animals (0.944) with a median and average life expectancy of 33.1 and 47.7 years, respectively. These data present evidence for similar life-history parameters of free-ranging and captive killer whale populations and the reproductive potential and survivorship patterns established herein have application for use in future research concerning the overall health of both populations.
authors.affiliation: SeaWorld and Busch Gardens Reproductive Research Center, SeaWorld Parks and Entertainment , 2595 Ingraham Road, San Diego, CA 92019 , USA (TRR, JKO).
authors.forename: Todd R
authors.initials: TR
authors.lastname: Robeck
authors.affiliation: SeaWorld and Busch Gardens Reproductive Research Center, SeaWorld Parks and Entertainment , 2595 Ingraham Road, San Diego, CA 92019 , USA (TRR, JKO).
authors.forename: Kevin
authors.initials: K
authors.lastname: Willis
authors.affiliation: SeaWorld and Busch Gardens Reproductive Research Center, SeaWorld Parks and Entertainment , 2595 Ingraham Road, San Diego, CA 92019 , USA (TRR, JKO).
authors.forename: Michael R
authors.initials: MR
authors.lastname: Scarpuzzi
authors.affiliation: SeaWorld and Busch Gardens Reproductive Research Center, SeaWorld Parks and Entertainment , 2595 Ingraham Road, San Diego, CA 92019 , USA (TRR, JKO).
authors.forename: Justine K
authors.initials: JK
authors.lastname: O'Brien
keywords: fecundity; gestation; longevity; mortality; orca; reproductive maturity; survivorship