Update on the status of gray whales since the 2020 Implementation Review

Abstract

The International Whaling Commission’s Scientific Committee conducts regular Implementation Reviews (IRs) of the biology, threats and status of whale species subject to aboriginal subsistence whaling. The last IR of plans for hunting eastern North Pacific (ENP) gray whales by the Chukotka Natives of the Russian Federation and the Makah Tribe of the United States of America occurred in 2020. This paper presents a review of new scientific findings on gray whales to assess whether the current status of the stock(s) is within the parameter space tested in the 2020 IR. Updated information on gray whale stock structure hypotheses, abundance and calf productivity, health and strandings, human removals by hunting and non-hunting sources, population growth rates, immigration into the Pacific Coast Feeding Group, parameterisation of the Makah hunt, and future episodic mortality events (EMEs) were reviewed for this assessment. For almost all factors, it appears that the current dynamics of the ENP gray whale population are within the parameter space evaluated in 2020 IR. The exception is that EMEs affecting whales in the ENP are occurring more frequently and at a greater magnitude than previously evaluated. However, preliminary evaluations suggest that the performances of the Gray Whale Strike Limit Algorithm (SLA) and Makah Management Plan are robust to recent and future EMEs of Northern Feeding Group gray whales and reductions of productivity of the Pacific Coast Feeding Group, at least under the initial parameterisations. We therefore conclude that there is no compelling need for a Special IR prior to the next scheduled IR in 2026, while noting that additional abundance data for 2022/23 and 2023/24 analysed after drafting this paper could strengthen or weaken the evidence for this conclusion.