Oops! The book I have that is so, so good about Gray whales was written by
another “ich”: Not another Smith. James Sumich! Sorry colleagues! Paul
Sent from my iPhone
On May 5, 2020, at 6:45 PM, Paul Petrich <ppetrich39@xxxxxx> wrote:
Hi Robert and Michael,
I had the good fortune to catch a lecture by Jim Smith who teaches at Oregon
State University’s Hatfield Marine Center. I also bought his book “E.
Robustus”. printed 2014. His extensive research over the years led to
classifying four distinct populations of Gray whales.
True Easterners: Arctic summer bottom feeders migrating to Baja i winter
PCFG ( Pacific Coast Foraging Whales ): Foraging along the west coast of N
America where he estimated about 200 foraged off Oregon on mostly zooplankton
there!
Trans-Pacifics’: Summer bottom feeders from Sakhalin Is & Kamchatka that join
the True Easterners migration to Baja in winter!
True Westerners: Sakhalin Is and Kamchatka in summer and warm SE Asia coastal
waters in winter
Complete title of his book includes : “ The biology and human history of gray
whales.” May be of use?? Cheers, Stay well!
Paul Petrich Jr
ppetrich39@xxxxxx
“In the end it is not the years in your life that count. It’s the life in
your years.”…Anonymous
On May 5, 2020, at 1:40 PM, Robert Warner <robert.warner@xxxxxxxxxxxxxxxx>
wrote:
Interesting article of variation in gray whale condition differences between
groups (lactating females in poorer condition) and between years (low
productivity years associated with poor condition and subsequent mortality).
The only part that's confusing to me is that they refer to gray whale prey
as zooplankton, primarily mysids, and what I've read is that they are
primarily benthic feeders. But low productivity would also affect benthic
creatures, so the conclusions are still OK.
Lemos et al., 2020. Intra‐ and inter‐annual variation in gray whale body
condition on a foraging ground. Ecosphere 11: e03094
Baleen whales store energy gained on foraging grounds to support
reproduction and other metabolic needs while fasting for long periods during
migration. Whale body condition can be used to monitor foraging success, and
thus better understand and anticipate individual‐ and population‐level
trends in reproduction and survival. We assessed the body condition of
eastern North Pacific gray whales (Eschrichtius robustus) on their foraging
grounds along the Oregon coast, USA, from June to October of three
consecutive years (2016–2018). We used drone photogrammetry and applied the
body area index (BAI) to measure and compare whale body condition, which is
a continuous, unitless metric similar to the body mass index in humans. A
total of 289 drone flights were carried out over 106 photo‐identified
whales, which were grouped into demographic units by sex, maturity, and
female reproductive status. Calves and pregnant females displayed the
highest BAIs, followed by resting females, mature males, and, finally,
lactating females, reflecting the significant energetic demands on
reproductive females. In all three years, gray whale body condition improved
with the progression of feeding seasons, demonstrating the accumulation of
body energy reserves on the foraging grounds. Yet, body condition was
significantly better in 2016 than in 2017 and 2018 when overall body
depletion was observed, indicating a difference in prey availability and/or
quality between years. We analyzed local upwelling patterns between 2013 and
2018 as an oceanographic proxy for prey and determined significantly greater
upwelling between 2013 and 2015 than low upwelling years between 2016 and
2018. We hypothesize that these upwelling patterns created ecosystem shifts
in primary productivity and zooplankton prey of gray whales, causing
carry‐over effects between foraging success and body condition in subsequent
years. This study demonstrates the value of monitoring whale body condition
to better understand temporal variation in foraging success, and potentially
detect and describe the causes of anomalous changes in whale population
health, such as the 2019 gray whale mortality event.
Here's the link:
https://esajournals.onlinelibrary.wiley.com/doi/full/10.1002/ecs2.3094#.XrHLMPWdmt8.email
Cheers,
Bob Warner
Robert Warner
Dept. Ecology, Evolution, and Marine Biology
University of California, Santa Barbara
USA 93106
+1 805 2528433
robert.warner@xxxxxxxxxxxxxxxx
