Table 5.—
Kaplan–Meier survival analysis results for captive (SEA, SeaWorld Parks and Entertainment) and free-ranging (NR, northern residents; SR southern residents) killer whale (Orcinus orca) populations. CB = captive-born.
| Group | Age (years) at 75% survival probability (± SEM, 95% CI) | Age (years) at 50% survival probability (± SEM, 95% CI) | Observed deaths | Expected deaths |
|---|---|---|---|---|
| SEA 2000–2015 (n = 39) | 15.6±2.2, 0.9 to 24.9 | 24.8±1.1, 14.1 to --- | 9a–g | 9.5 |
| SEA captive-born (CB) (n = 31) | 14.1±1.9, 2.7 to 25.0 | 25.0±1.3, 14.1 to --- | 120a–d,f | 136.2 |
| NR 1975–2014 (n = 358) | 14.0±1.9, 11.0 to 19.0 | 29.0±1.3, 28.0 to 35.0 | 71a | 52.9 |
| SR 1975–2015 (n = 144) | 3.0±1.7, 1.0 to 14.0 | 23.0±1.1, 16.4 to 26.0 | 8b–f | 9.5 |
| Groups modeled with neonatal loss (NL) included in analysis.i | ||||
|---|---|---|---|---|
| SEA 2000 to 2015 (n = 39)j | 15.6±2.2, 0.9 to 24.9 | 24.8±1.1, 14.1 to --- | 9a–g | 11.3 |
| SEA CB + NL (2 animals, n = 33) | 12.3±2.1, 0.9 to 25.0 | 25.0±1.1, 14.1 to --- | 10a–f | 12.7 |
| NR (10% NL, n = 397) | 6.3±2.0, 2.9 to 12.0 | 28.0±1.5, 23.0 to 35.0 | 87c | 67 |
| NR (20% NL, n = 443) | 1.0±0, 0.5 to 3.0 | 23.0±2.1, 18.0 to 30.1 | 106d | 87 |
| NR (30% NL, n = 465) | 0.5±0, 0.1 to 1.0 | 21.0±2.7, 14.0 to 26.0 | 227e | 222 |
| SR (10% NL, n = 160) | 1.0±0.5, 0.5 to 3.0 | 20.0±2.3, 12.0 to 24.0 | 159f–h | 174 |
| SR (20% NL, n = 179) | 0.5±0.1, 0.1 to 0.5 | 14.0±4.1, 6.0 to 23.0 | 205g | 224 |
| SR (30% NL, n = 189) | 0.1±0.1, 0.05 to 0.5 | 10.0±4.2, 3.0 to 20.0 | 116h | 96 |
a–hSignificant differences between rows within the same column were determined by log-rank test with significance set at P < 0.05.
iNeonatal loss (NL, loss prior to 6 months of age) has been estimated to be ~40% in free-ranging killer whale populations (Olesiuk et al. 1990, 2005). NL in free-ranging animals was modeled as follows: total estimated calves (TEC) born were first determined by dividing the total observed calves (LC) for the population across the time period by 1 minus the % NL. For example, a 10% NL was determined as follows: NL = (LC/1 − 0.1) − LC.
jNo neonatal loss was experienced for this group.
“---” represents values that cannot be determined owing to the fact that no animals in the upper age groups (> 30 years) have died.