How large was the western gray whale population around Sakhalin Island in 2010?
The “best” estimate of the population in 2010 is 136 animals (not counting calves of the year). The population is not known exactly but was estimated to be in the range of 125-156 animals in 2010 with 90% probability.
How do you survey western gray whales?
Western gray whales have been studied using photo-identification methods since 1994. The whales have distinctive patterns of markings on their bodies, such that individuals are easily recognizable from photos. By recording which animals are re-sighted each year and which animals are new, the total population number can be estimated, even though not all the population is present off Sakhalin each year. The photos are taken by researchers in zodiacs.
How has the population changed over the past few years?
The population has been increasing in recent years. Since studies began in 1994, the population has approximately doubled. Provided that conditions on its feeding ground do not deteriorate, the population is projected to continue to increase. It will be necessary to continue to monitor the population so that steps can be taken if problems develop.
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