[MARMAM] New paper: "Whale wave": shifting strategies structure the complex use of fjord critical habitat by humpback whales

Eric Keen ericmkeen at gmail.com
Mon Mar 13 18:46:21 PDT 2017


Dear colleagues,



We are pleased to announce the release of the following publication in
Marine Ecology Progress Series:



Keen EM, Wray J, Meuter H, Thompson KL, Barlow JP, Picard CR (2017) ‘Whale
wave’: shifting strategies structure the complex use of critical fjord
habitat by humpbacks. Mar Ecol Prog Ser 567:211-233.
https://doi.org/10.3354/meps12012  <https://doi.org/10.3354/meps12012>



Journal access is available at:
http://www.int-res.com/abstracts/meps/v567/p211-233/

PDF copies are also available upon request to: ekeen at ucsd.edu



Best wishes,

Eric Keen


Abstract:
A decade of visual surveys (2005-2014) revealed that humpbacks *Megaptera
novaeangliae* occupy a temperate fjord system in British Columbia, Canada,
in a wave pattern that propagates from outer channels in the summer to deep
inland channels in late fall. Monte Carlo randomization confirmed this
apparent pattern statistically. ‘Before’ and ‘after’ shift phases were most
evident in July and October, respectively. We hypothesized that the ‘whale
wave’ was being driven by (1) prey following, (2) the tracking of
environmental proxies, (3) fine-scale philopatry, or some combination of
these three factors. To evaluate these hypotheses, we collected new data in
2015, including visual and hydroacoustic surveys and oceanographic
sampling. To both full-season and monthly datasets, we fit generalized
additive models (GAMs) in a stepwise procedure, using variable sets that
represent our hypotheses. Prey models were generally the worst predictors
of humpback distribution, while the most complex habitat models were the
best. The Prey model performed best in June but increasingly poorly in
remaining months. The performance of all models declined throughout the
season, suggesting not only that this whale wave is being driven by needs
other than food, but also that untested variable(s) inform late-season
distribution. Alternative explanations of the wave include physiological
maintenance and social habitat partitioning. Our findings demonstrate that
marine predators can use complex spatial strategies not only to navigate
vast areas of ocean but also to exploit specific habitats thoroughly.
Though annually persistent and specific in structure, the whale wave would
go (and has gone) unnoticed in typical marine mammal surveys.


-- 
Eric M Keen <http://www.emkeen.org>
PhD student, Scripps Institution of Oceanography

Captain, *RV Bangarang <http://www.rvbangarang.org>*
Instagram: @rvbangarang
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