[MARMAM] New Publiication: Where humpback whales and vessel traffic coincide, a Colombian Pacific case study

Isabel Cristina Ávila Jiménez isabelc.avila at gmail.com
Mon Apr 3 00:07:37 PDT 2017

My coauthors and I announce the publication of the following article:

Avila, I.C., L. M. Correa & K. Van Waerebeek. Where humpback whales and
vessel traffic coincide, a Colombian Pacific case study. Boletín del Museo
Nacional de Historia Natural, Chile 66: 85-99.


During the austral winter, G-stock humpback whales immigrate and occupy the
Bahía Málaga area, Colombian Pacific, to breed and calve. However, due to
fishing and whale-watching activities, and proximity to the major
Buenaventura seaport, significant vessel traffic transits the Bahía Málaga.
We counted the number of whales and boats present h-1 in a 14 km2 area,
from a 20 m high shore platform. During 312 daytime hours of observations
over 52 days in August-September 2008, we recorded 770 sightings of whale
pods (many resampled), 0-15 humpback whales h-1 (mean 4.0 whales h-1) and
0-17 vessel trips h-1 (mean 4.5 trips h-1). Each additional day in the
breeding season showed an 1.0% increase in the mean number of sighted
whales, due to still arriving whales and new calves. The majority of trips
(96%) consisted of small vessels, the rest were medium vessels. Most
(71.1%) transited at fast speed (≥16 knots). To evaluate whether the
vessels affected the density of whales per hour in the study area, we
fitted a Generalized Linear Model with number of whales as dependent
variable and vessel size and speed as factors. Number of vessel trips did
not have a significant impact on the number of whales sighted h-1. Over the
short term (hours), the whales remained in the same area despite the
shipping. The evident risk of vessel-whale collisions and potential
long-term impact are discussed. To mitigate risk of ship strikes, several
measures are recommended, such as a vessel speed below 10 knots in the
vicinity of whales.

The publication is available at
https://issuu.com/mnhn_cl/docs/tr7_avila_et_al or by email to

isabelc.avila at gmail.com

Isabel Cristina Avila
Biologist Msc
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