[MARMAM] New publication: A case study of a near vessel strike of a blue whale: perceptual cues and fine-scale aspects of behavioral avoidance (Szesciorka, Angela)

Angela Szesciorka angela at szesciorka.com
Mon Dec 16 15:35:54 PST 2019

Dear colleagues,

My co-authors and I are pleased to share our recent publication in
Frontiers in Marine Science:

Szesciorka AR, Allen AN, Calambokidis J, Fahlbusch J, McKenna MF, Southall
BL. 2019. A case study of a near vessel strike of a blue whale: perceptual
cues and fine-scale aspects of behavioral avoidance. Front. Mar. Sci.
6:761. doi: 10.3389/fmars.2019.00761

Link to paper (full open-access):

Despite efforts to aid recovery, Eastern North Pacific blue whales faces
numerous anthropogenic threats. These include behavioral disturbances and
noise interference with communication, but also direct physical harm –
notably injury and mortality from ship strikes. Factors leading to ship
strikes are poorly understood, with virtually nothing known about the cues
available to blue whales from nearby vessels, behavioral responses during
close encounters, or how these events may contribute to subsequent
responses. At what distance and received levels (RLs) of noise whales
respond to potential collisions is difficult to observe. A unique case
study of a close passage between a commercial vessel and a blue whale off
Southern California is presented here. This whale was being closely
monitored as part of another experiment after two suction-cup archival tags
providing acoustic, depth, kinematic, and location data were attached to
the whale. The calibrated, high-resolution data provided an opportunity to
examine the sensory information available to the whale and its response
during the close encounter. Complementary data streams from the whale and
ship enabled a precise calculation of the distance and acoustic cues
recorded on the tag when the whale initiated a behavioral response and
shortly after at the closest point of approach (CPA). Immediately before
the CPA, the whale aborted its ascent and remained at a depth sufficient to
avoid being struck for ∼3 min until the ship passed. In this encounter, the
whale may have responded to a combination of cues associated with the close
proximity of the vessel to avoid a collision. Long-term
photo-identification records indicate that this whale has a long sighting
history in the region, with evidence of previous ship encounters.
Therefore, experiential factors may have facilitated the avoidance of a
collision. In some instances these factors may not be available, which may
make some blue whales particularly susceptible to deadly collisions,
rendering efforts for ship-strike reduction even more challenging. The
fine-scale information made available by the integration of these methods
and technologies demonstrates the capacity for detailed behavioral studies
of blue whales and other highly mobile marine megafauna, which will
contribute to more informed evaluation and mitigation strategies.

Keywords: ship strike, blue whale, near collision, active avoidance,
behavioral response, perceptual cues

Please contact me if you have any questions.




Angela R. Szesciorka, M.Sc.

Ph.D. Candidate, Dr. Nancy Foster Fellow

Scripps Institution of Oceanography

NOAA Southwest Fisheries Science Center

(c) 650-787-9462 | (w) 858-546-7066
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