Long-term Photo-Identification Studies of Gray Whales (Eschrichtius robustus) offshore Northeast Sakhalin Island, Russia, 2002-2017
Olga Yu. Tyurneva, Yuri M. Yakovlev, Vladimir V. Vertyankin, Peter van der Wolf, and Michael J. Scott
International Whaling Commission
Photo-ID studies of the Sakhalin feeding aggregation of North Pacific gray whales (Eschrichtius robustus) have been conducted annually since 2002 offshore northeast Sakhalin Island as part of an industry-sponsored monitoring program jointly funded by the Sakhalin-1 (operated by Exxon Neftegas Limited) and Sakhalin II (operated by Sakhalin Energy) oil and gas development projects. With the addition of nine calves in 2017, the Sakhalin gray whale catalog now contains 283 identified individual gray whales. Of the nine new calves, six cow/calf pairs and three calves without mothers were recorded off Sakhalin. One of the identified mothers was sighted for the first time as a nursing cow, bringing the total identified numbers of cows in the database since 2003 to 29.
The photo-ID catalog compiled over the last 16 years provides strong evidence of the steady increase in the number of gray whales observed off Sakhalin Island each year. For incorporation into gray whale population modeling, the annual effort and observations of the studies are detailed in the paper and the results are compared with the other long-term gray whale photo-ID studies of the area.