Cooperative Fish and Wildlife Research Units Program: Washington
Education, Research and Technical Assistance for Managing Our Natural Resources

Knowledge about the demographic and environmental factors underlying population dynamics is fundamental to designing effective conservation measures to recover depleted wildlife populations. However, sparse monitoring data or persistent knowledge gaps about threats make it difficult to identify the drivers of population dynamics. In situations where small, depleted populations show continued evidence of decline for unknown reasons, integrated population models can improve our understanding of demography, provide fundamental insights into factors that may be limiting recovery, and support conservation decisions. We used mark-resight and aerial survey data from 2004-2018 to build an integrated population model for the Cook Inlet population of beluga whales (Delphinapterus leucas), which is listed as endangered under the U.S. Endangered Species Act. We examined the relationships between beluga vital rates and prey availability and environmental conditions and conducted a population viability analysis to predict extinction risk across a range of hypothetical changes in beluga survival and reproduction. Our results indicated that while survival of breeding females (0.97; 95% CrI 0.95-0.99) and young calves (0.92; 0.80-0.98) was relatively high, survival of non-breeders (0.94; 0.91-0.97) and fecundity (0.27; 0.21-0.35) may be depressed. Furthermore, our analysis indicates that if vital rates and environmental variability remain similar to estimates from the latter part of the study period, the population will likely continue to decline, with a 19-32% probability of extinction in 150 years. Our model framework highlights the utility of integrated population modeling for identifying factors contributing to the failure of protected populations to recover.