Gray Whale Numbers Continue Decline
Published:24 Oct.2022 Source:ScienceDaily
Gray whales that migrate along the West Coast of North America continued to decline in number over the last 2 years, according to a new NOAA Fisheries assessment. The population also produced the fewest calves on record this year since counts began in 1994, an accompanying report explains.
These include ecological changes in the Arctic affecting the seafloor and the amphipods and other invertebrates living in and above the sediment and in the water column that gray whales feed on each summer, according to new research published earlier this year.Some gray whales may have struggled to find food amid those shifts, gray whales feed on a wide variety of prey over an enormous range, so there could be many variables affecting how, when, and where they find food.But, some stranded whales had clearly died of other causes such as getting hit by ships or predation by killer whales.
The same factors that affect gray whale survival likely also affect their reproduction, the report on calf numbers concludes. Depending upon the age of the whales, this lower body condition may have led to delayed reproduction and lower calf counts, and/or reduced survival in thin whales.