File Entry: Killer whale demography documentation

This documentation contains the tutorial to run the Killer whale demography workflows.

This tutorial explains the type of input data needed to run the workflow. The corresponding analysis use data from two distinct O. orca populations in Canada, Southern Resident Killer Whales (SRKW) and the Northern Resident Killer Whales (NRKW).

The Killer whale demography workflow performs the following analyses:

•      Vital rates estimation and probability distributions

•      Construction of Birth-flow Matrix Model

•      Eigen analysis

•      Elasticity analysis (deterministic and stochastic)

•      Damping time

Two distinct populations of resident killer whales (Orcinus orca) in the north-eastern Pacific Ocean have been identified in Canada and the U.S. as being of conservation concern. The Southern Resident Killer Whale (SRKW) population is currently listed as endangered under the U.S. Endangered Species Act on the grounds of its small population size and vulnerability to demographic stochasticity and catastrophic events such as oil spills (NMFS 2008). In Canada, under the Species At Risk Act (COSEWIC 2008), SRKW is listed as endangered due to its small and declining population size while the Northern Resident Killer Whale (NRKW) population is listed as threatened due to its small population size. The major threats identified for these two populations are nutritional stress associated with prey abundance levels and availability, particularly Chinook salmon (Oncorhynchus tshawytscha) (COSEWIC 2008, Ford et al. 2010a, 2010b), pollution and contaminants, and disturbances from vessels and sound (COSEWIC 2008, NMFS 2008). An important difference in the population-size trajectories of these two populations is that, in spite of their home range overlap and potential access to similar resources, SRKW has remained at a population size of less than 100 individuals for the last four decades with an average of 85 individuals in the last decade. NRKW population size has been generally increasing for the last four decades with 268 individuals at the end of 2011.