[MARMAM] New Publication: Humpback whale calf vulnerability to small-vessel collisions; assessment from underwater videography in Hawaiian waters

Kate Lomac-MacNair klomacmacnair at gmail.com
Thu Nov 8 05:05:04 PST 2018

Dear colleagues,

Cetos Research Organization is pleased to announce the publication of a new

Lomac-MacNair, K., Zoidis, A.M., Anderson, M., Blees, M. (2018). Humpback
whale calf vulnerability to small-vessel collisions; assessment from
underwater videography in Hawaiian waters. *Journal of Coastal Sciences *5(2),


Using underwater videography, we developed a subsurface ethogram of
humpback whale (*Megaptera novaeangliae*) calf behavior among mother/calf
resting groups in their Hawaiian Islands birthing/breeding grounds. Data
collected from 2001 to 2018 in waters between the islands of Maui,
Moloka’i, Lana’i, and Kaho’olawe (the Four-Island area), support the
assumption that humpback whales are more vulnerable to small-vessel
collision during their first year(s) of life. This, along with four
incidents of first-hand observation of calves with significant wounds
likely resulting from propellers were the impetus for further investigation
into calf vulnerability to vessel collision in Hawaiian waters. We examined
underwater video footage of mother/calf groups to investigate
calf-surfacing events with or without the mother, as well as the calf
behavior displayed while at or near the surface. We defined three depth
zones: Depth A (<5 meters [m]), Depth B (5-10 m), and Depth C (>10 m). We
considered Depth A the small-vessel collision vulnerability zone based on
the approximate body length of a calf, and the depth at which a
small-vessel draft (i.e., hull or propeller) could make contact with the
calf at or below the surface. We analyzed 3,022 30-second samples of
underwater video footage from 226 mother/calf resting groups. It was
possible for the calf to be in more than one Depth Zone during an interval
when moving from deeper water to surface water or surface water to deeper
water which resulted in a total of 3,499 samples of which 1,422 (40.6%) the
calf was in Depth A, 592 (17.0%) the calf was in Depth B and 1485 (42.4%)
the calf was in Depth C. Of the samples having calves in Depth A, there
were 509 samples (36%) of calves surfacing alone, 532 samples (37%) of
calves surfacing with the mother and 381 samples (27%) where calves did not
break the surface. In Depth A, calves were found to exhibit rest behavior
significantly more than other behaviors (χ2 = 1,430.1, df = 3, p < 0.001, n
= 1,422). Our results provide insight into the vulnerability of humpback
whale calves to small-vessel collisions in the coastal waters of Hawaiian
Island birthing grounds.

Our paper is available online at:


Or via e-mail request to *klomacmacnair at gmail.com <klomacmacnair at gmail.com>*
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