Results
Overall, 198 Southern resident, 568 Northern resident and 510 Bigg’s
killer whales were observed in these populations over the
>40 year period of observations (Table 1) and included in
the analysis. The adult sex ratio for all datasets was female-biased
(Table 2). There was a substantial number of individuals, where the sex
had not been determined with 202 in Northern residents and 209 in Bigg’s
killer whales (Table 2).
Age-specific survival
The model (Gompertz with bathtub shape) reveals a clear age- and
sex-specific pattern of survival for all three populations (Fig. 2). We
assessed the fit of the model by plotting the estimated survival
probability together with the observed survival probability of
individuals of known age (Supplementary Fig. S1). The models predict
that 95% of the female lifespan on average has occurred (age where lx =
0.05) after a median±standard deviation of 59±0.5 years (credible
interval: 52±0.5 - 65±0.7 years) for Southern residents, 59±0.6 years
(credible interval: 54±0.6 - 65±1 years) for Northern residents and 66±2
years (credible interval: 56±1 - 77±3 years) for Bigg’s. For males, the
model predicts that 95% of the male lifespan has occurred after a
median of 37±0.1 years (credible interval: 33±0.2 - 41±0.5 years) for
Southern residents, 38±0.3 (credible interval: 36±0.4 - 41±0.5) for
Northern residents and 49±1 (credible intervals: 43±1 - 56±1) for Bigg’s
killer whales. The variation arises from the permutations.
Post-reproductive representation
All three populations had a post-reproductive representation that was
significantly greater than zero (p < 0.05), with
estimated PrR values above 0.3 for all three populations (Fig. 3). For
all three populations, median expected female lifespan as
post-reproductive was >20 years (Table 4) and the
probability of surviving until age M (the age when 95% of female
fecundity has occurred) was median >40%.