2020 harvest advice for northern Hudson Bay narwhal

Abstract

To estimate current abundance and determine trends in population dynamics of Northern Hudson Bay (NHB) narwhal, a population model was fit to four survey estimates from 1982– 2018 and a series of reported annual harvests from 1951–2018. Earlier surveys in the series (1982 and 2000) were conducted and analysed using different protocols than the more recent surveys in 2011 and 2018. The estimates from these earlier surveys were adjusted to account for different analyses and survey methods to make them comparable. The model was robust to input parameters, and estimated a 2019 abundance of 14,400 (95% CI 10,300–20,400 [rounded to the nearest hundred]) narwhal. Based on the model trajectories, a total landed catch of 0, 63, 83, 93, 108, 173, and 450 narwhal per year would result in a 0%, 20%, 40%, 50%, 60%, 80%, and 100% probability of decline, respectively, in this NHB narwhal population in ten years. Potential Biological Removal (PBR) from the modelled 2019 abundance estimate was calculated to be 188, resulting in a landed catch of 151 to account for whales killed but not landed