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| Grundarfjörður |
Iceland - Orca 2014
Iceland - a change of scene and most definitely a change in
temperature since Tanzania! I have spent
the last couple of weeks working with the University of St Andrews Sea Mammal
Research Unit (SMRU) on a project led by Dr Patrick Millar investigating methods for measuring and monitoring the health/body condition of
cetaceans, in this case, orca.
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| Orca off the bow |
Our part of the project will be testing sonar as a tool for
specifically measuring body condition from body measurements. This might seem like a far cry from mapping
seabed or reconstructing palaeo-landscapes, the more usual deployment of sonar
in my work, but really it’s not such a far cry.
The idea is to use a new generation of very high resolution sonar to map
in real time the acoustic reflections from the body surfaces of whales as they swim
past the boat or as we can manoeuvre the boat into a position to observe their
habits such as feeding. Ultimately, if
we can obtain consistent and representative measures of body dimensions then
SMRU might be able to observe aspects of body condition change during a season.
The sonar we are working with is the latest 3D sonar from
CodaOctopus the Echoscope. This sonar
sends out a broad spectrum of acoustic energy about two, main frequencies, namely
375kHz and 610kHz. The energy is recorded
on an array in 3D that allows the reflected signal to be correctly positioned
within a cone of insonification that is about 50degree in width and height. With the addition of positioning and motion
reference to the sonar, together with an insonification rate of up to 10 pings
per second it should be possible to track the whales in real time. What we are up here determining is if we can
not only track them and thus ascertain their behavioural characteristics but if
the sonar will also give us the resolution to be able to make precise body
measurements. This will require quite a
bit of processing to first remove any noise in the data such as the fish
schools that the whales are often hunting, the clutter from wave action at the
surface and the seafloor.
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| SMRU boat Tango with Echocope fitted to starboard |
So here we are in Grundarfjordur, on the Snefels peninsular
with the team (Filipa Samarra, Sara Tauares, Miguel Neves, Fedutin Ivan, Olga
Filatora, Sebastien Houillier, Paul Wensveen, Kagari Aoki, Julie Becsau, Jose
Guilabert, Melanie Chocholek and Luke O’Connor) that will also be making a
record of photo ID, sound recordings, tagging whales with motion sensors and
taking samples for biopsy. Why
Grudarfjordur? Well over the last few years there have been large number of
orca that visit the fjords in winter to feed on the vast stocks of herring that
congregate in the still, cold and somewhat protected waters.
The setting is spectacular with snow-capped mountains of
layered basalts surrounding the fjord. Sure, its cold with frozen ground and
even the snow at sealevel with an icy crust but that does not seem to daunt the
Icelandic horses with their heads bowed to the constant north-easterly
winds.
Our mornings start with a check for orca in the fjord. If there, and this is usually given away by
the flocks of gulls and the odd eagle that flock above the feeding whales, then
we launch the boat. The sonar is
deployed after making observations of behaviour in order that we can determine
if the sonar is having a detrimental effect on the orca and then it’s a gentle
approach to groups where they are feeding in order to obtain data. On a good day we will get sonar data, photo
ID of the whales and if lucky some biopsy samples.
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| Image from Echoscope showing large male orca and young orca in background |
Processing is going to take some weeks to obtain
quantitative information but at the end of the trip we have managed to record
some great data showing behaviour including groups working the herring schools
up to the surface for feeding.
There is a great team here and it’s a real privilege to work
on this project and in this part of the world – well worth a visit if you are
interested in whales, outdoor scenery or of course for views of the northern
lights! Next time I must remember to
bring my ice climbing and skiing gear for those days that the whales do not
turn up!
