[MARMAM] Updated info on the interactions between killer whales and sailing boats in the Iberian Peninsula

Ruth Esteban ruthesteban at gmail.com
Tue Oct 6 02:09:05 PDT 2020

Dear all,

Since July, thirty-three interactions of killer whales with sailing boats
have been registered: six in the Strait of Gibraltar, then five on the
Portuguese coast and finally twenty-two since mid-August, in Galicia,
northern Spain.

The boats that were targeted by the killer whales during the interactions
were later inspected to better understand how the interactions occurred and
what type of contacts took place. The interactions were mostly limited to
the rudder of the boat, with marks found on the hull or signs of physical
contact of the animals with the structure of the vessel.

Only 15% of the encounters with the killer whales were classified as
interactions which resulted in some kind of damage to the sailboats. In any
of the interactions, people were never endangered by the direct activity of
the killer whales. However, there were some risky situations during
night-time and long-lasting interactions, due to abrupt movement of the
steering wheel or turns of the boat, which caused distress to the crew
members due to their lack of experience with killer whales and their

*International Working GroupA Group of Experts thoroughly investigates the
trail of orca interactions*
An international Working Group (WG) of cetacean experts and competent
administrations has been set up, with great knowledge of the casuistry and
behaviour of orcas. The WG has been analysing each and all cases in great
detail and is in permanent contact with SOS-Galicia, Salvamento Marítimo
(Spanish Lifeboats), the Spanish Ministry of Ecological Transition and the
Demographic Challenge (MITECO) and the Xunta de Galicia (Regional
Government of Galicia) to compile all the available information. The
scientific group is made up of Dr. Alfredo López from the Universidade de
Aveiro-CESAM, Mr. Jose Cedeira from CEMMA; Mrs. Cristina Martín from
TURMARES Tarifa, Mr. Ezequiel Andréu Cazalla from the Garum Tarifa
Association, Mrs. Rocío Espada from Ecolocaliza and LBMarina from the
University of Seville, Mr. Francisco Martinho from ECCO Ocean, Dr. Marisa
Ferreira from SPVS and Dr. Ruth Esteban from the Museu da Baleia da Madeira
and Ocean Sea. Institutional members include Mrs. Elvira García Bellido
from the Spanish Ministry for Ecological Transition and the Demographic
Challenge and Mrs. Marina Sequeira from the Instituto da Conservação da
Natureza e das Florestas de Portugal.

The information used by the WG is based on more than 700 records of killer
whales on the Iberian coast in the last 20 years compiled by CEMMA, Dr.
Ruth Esteban, Mr. Francisco Martinho, SPVS and especially Turmares Tarifa.

*IdentificationThe GLADIS, involved in the interactions, are young killer
whales known in the Strait*
During the different interactions, up to 3 different individual killer
whales have been identified as directly involved in the events. These
animals were observed near the sailboats, and were identified in 61% of the
interactions thanks to photos and videos taken by the crew that were sent
to the working group. In addition, in some interactions, two other adult
individuals were observed further away from the ship, and have not been
identified so far, but are considered as most likely not involved in the

The three interacting killer whales have been named the GLADIS (BLACK,
WHITE and GRAY) and all were observed from June to August of this year in
the Strait of Gibraltar. Additionally, two of them (BLACK and WHITE GLADIS)
had already been observed in previous years in the area.

In the Strait of Gibraltar, individuals have been observed relatively
frequently with injuries caused by the friction with fishing lines when
they try to “steal” tuna already hooked on the longlines.
The two GLADIS (BLACK AND WHITE) observed in the Strait of Gibraltar this
year presented injuries consisting in marks appearing successively on their
bodies and more intensively between the 20th of June and 3rd of August.

The WG has mapped and described the injuries on a representation of the
body of each specimen, to try to clarify their origin, hoping they can
offer clues towards an explanation for the interacting behaviours. All
marks identified as of anthropogenic origin or open wounds with doubtful
origin were systematically registered.

The observed marks were meticulously detailed based on the underwater
photographic series provided by the Scientific Department of Turmares
Tarifa. The photographs of the orcas located by Francisco Gil were taken by
photographer Rafael Fernández Caballero, with the permission of MITECO.

*CausesThe trigger for this behaviour could have been an adverse incident*
In the Strait of Gibraltar, juvenile killer whales are commonly observed
approaching boats of various kinds, likely due to their curiosity. The
stern is especially as there are mobile and noisy structures. However, the
interactions with sailboats detected since July in the Strait, Portugal and
Galicia are considered unprecedented due to the repeated physical contact
of the specimens with the structure of the ships.

Although the approach and beginning of the interaction are similar to other
previously observed encounters with boats, the GLADIS showed an
unprecedented novel behaviour consisting in physical contact with the
weakest structure of the ship, the rudder, which sometimes led to breaking
partly or completely the rudder.

The trigger for this strange and novel behaviour could have been an adverse
incident between these killer whales and a boat. At the moment there is
still no clear evidence of when or if it actually happened, and the WG
cannot confirm what type of ship could be involved, or if the incident was
accidental or intentional.

However, given the lack of evidence, the WG cannot rule out either that the
novel behaviour could be induced by the juvenile orcas’ own interest and
curiosity, since by touching moving parts of the boat they can move or even
stop a large moving object.

Kind Regards,


Ruth Esteban, PhD.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.uvic.ca/pipermail/marmam/attachments/20201006/acadeef0/attachment.html>

More information about the MARMAM mailing list