Listening to the Sea

Listening to the Sea

The ocean is full of sound – from snapping shrimp, to fishes to whales, nearly everyone underwater is talking with one another.   Acoustic communication is particularly important for whales and dolphins, as sound travels much further underwater than light, and different species use sounds to coordinate foraging activity, mating, or other social interactions.

In 2013, we discovered that Omura's whales produce low-frequency, pulsive sounds, at least some of which seem to be used as a breeding display!  So we have been conducting a study using acoustic recorders to learn more about the presence and distribution of Omura's whales around the northwest of Madagascar. 

In December 2015 we placed four underwater microphones (hydrophones) at various sites around our study area. Each of these hydrophones recorded all underwater noises, or the “soundscape” for the past 12 months. 

Sal and Loic just did a dive to 35m to recover our recorder. It's got a little bit of growth on it, but otherwise looks good!

In the last couple of weeks, we've been diving at each of the sites to recover the recorders, and we're glad to report that we got them all back!!  This is actually great news, because it is not always guaranteed that you will find and recover remotely deployed instruments like this.  As an oceanographer once told me as a student, when you put something over the side of your boat and into the ocean, be prepared to kiss it good-bye, and feel lucky if you get it back….!

The next step is to download all the data, and then we'll spend the next few months combing through the recordings, looking for Omura's whales vocalizations and other species who are also in the area.  These data will help us to understand the seasonal habitat use of Omura's whales in Madagascar.

Sal and Boris looking over the first of the acoustic data they just downloaded!

An example of the new acoustic data, showing the songs of multiple Omura's whales.  You read this like you would sheet music - time is across the x-axis and frequency (or pitch) on the y-axis.  The data look clean and beautiful!

Before we leave the field this season, the recorders will be redeployed to record over the next year, this time in deep water off the shelf of Madagascar. Can't wait to see what we find!

November 1st - Field Season Started

Field Site 206

November in Nosy Be, Madagascar, means the Omura's whales are making their presence known again, and it is time for the 2016 field research for the "O-whale" team! And the field season has been off to a busy start!  This year we chose a different base for our field camp, working from Ambondrona beach, off the southwest side of the island of Nosy Be.

We were lucky enough to find a house to rent that could hold the whole team, so we are all together in one place. Right now there are 6 of us - 4 members of the science team and 2 boat pilots. We have the luxury of electricity and running water, which makes life pretty comfortable for everyone here. The main work area of the house is a lovely, covered open-air patio on the second story, where we eat all of our meals and spend every evening working up data.

There is a local troop of black lemurs that live in the trees on the property - 2 males, 3 females and 2 babies.  We watch them from our patio every day, as they play and the babies clamber up and down tree trunks and branches. They are very sweet until they start screaming, and they can be quite uproarious, sometimes in the middle of the night. The resident rooster also likes to establish his presence regularly, starting at about 3:00am. So, needless to say, we have been adapting to the nightly noises in our surroundings.

There is also a crocodile on the premises, and several Madagscar radiated tortoises, and every once in a while, a stray zebu (the local breed of cattle) wanders through. Sunbirds and drongos complete the picture, visiting the trees around the house.

We have a busy season planned, we'll post updates when we can!

- The O-whale Team

New Field Season Begins Now!

New Field Season Begins Now!

It's been a while since we've posted... and a lot has been going on behind the scenes. Our field season last spring was really successful, and we spent the summer and fall going through data and fundraising to get back to Madagascar for another field season.  So we are excited to report that the Omura's Whale Team is back in the field and on the water, as of this past week!  We've got a lot planned this field season, and have high hopes to find and learn more about this incredible species.  Stay tuned for regular updates!

The Omura's Whale Project Team

Week 2 – First week on the Water!

Week 2 – First week on the Water!

Now that we are at our field base and have the “lab” set up in one of our bungalows, we are ready to start field work.  With each year that I return to Madagascar to study Omura’s whales, I am never quite sure what we will find… this is because we know so little about this species, that we don’t yet know how reliably and consistently we will be able to find animals.  Is this population here all year round?  Do the same individuals use this habitat around Nosy Be from year to year?  Do they range much farther in Madagascar than this immediate region and will they sometimes be very far from Nosy Be? 

Prior to my arrival this year, I heard numerous reports from friends and local tourist operators that there were many whales sighted in early and mid-October, in conjunction with swarms of what people referred to as “tiny shrimp”.  This was very encouraging, however, they seemed to thin out right before I got here and were nearly absent during our set-up week.  This made the team a bit nervous…

...and then our first day on the water proved to be momentous...

Omura's whale surfaces after feeding lunge.

Out on the water by 7:50 and within one hour we find our first Omura’s whale of the season quite close to Sakatia!  These whales are relatively small, show very little of themselves at the surface, and don’t put up a prominent blow like larger whales, so can be a bit tough to find.  But this first morning the sea is very calm, making it easier to find them.  And as soon as we sight our first animal we see at least two others in the vicinity – we have found an aggregation!

A series of images showing side lunges.

And what’s more, they are feeding!  This is fantastic, because we really hoped to focus more on feeding behavior this year, particularly to document what they are feeding on.  So the previous reports of “tiny shrimp” were indeed tantalizing – and it seems that the swarms of these zooplankton, what we believe to be a tropical species of krill, or euphausiids, have returned. 

By the end of the nearly 10 hour day we have worked with four different Omura’s whales, done two plankton tows in the vicinity of feeding whales collecting good samples from the krill swarms, and collected a “poop” sample from the fecal plume of a nearby whale.  Truly a remarkable first day!!

Collecting a fecal sample.

The good weather holds out for the rest of the week and we are treated to full days of work with whales, more feeding, and more plankton and poop samples.  Two major highlights to mention.  First our first mother-calf pair of the season, first seen deep in the bay to the south on our second day out, and then again three days later.  The mom was feeding at the surface, making several rolling lunges in which her pectoral fin and fluke came out of the water, while the calf meandered around nearby.  Very mellow and tolerant, she gave us some great opportunities for underwater video to document her feeding behavior. 

The second exciting moment came when we recognized a whale while on the water from previous years.  Upon return to base that night, a check of photos verified that this was in fact a female that we first photographed in 2012 within an aggregation of four whales, and then in 2013 with a calf, and now in 2015 again without a calf.  This female clearly considers Nosy Be her home! 

Finally, to close out the first week, we deploy our four SoundTrap recorders, in a relatively tight diamond-shaped cluster about 2km apart from each, outside of Sakatia.  This first deployment will be for two weeks, in part to test the new units, and in part to use the close spacing as an “array” and attempt to locate singing whales through an acoustic triangulation technique.

All in all, an amazingly successful first week for a field season!  An excellent start!

- Sal Cerchio

Week 1: Getting to Nosy Sakatia

Week 1: Getting to Nosy Sakatia

Week 1 - first week of November 2015

 Beautiful scenery in Madagascar: view of Nosy Be outside Hellville

Beautiful scenery in Madagascar: view of Nosy Be outside Hellville

Getting to Madagascar from Cape Cod (my home) was a bit of a process.  After a 4am wake up, 3 flights, 4 airports and 28 mostly sleepless hours, one finally arrives in Antananarivo (more commonly referred to as simply “Tana”), and with any luck in possession of all of one’s luggage.  This was not one of my lucky trips… the Rubbermaid crate with most of my equipment appears to have been left in Johannesburg.  In fact, during the 11 years I have worked in Mada, I think about 1 or 2 in every 10 bags gets lost in transport!  So far they have always turned up in Tana later, and on this occasion I was pleased to be able to return to the airport and pick up the crate the very next day.  And an added bonus – with all of the equipment still in it!!  That was a great relief, because this year I was carrying four precious remote acoustic recorders, each about the size of a soda can, cutting edge technology called SoundTraps manufactured by Ocean Instruments New Zealand.

Next, onto Nosy Be after a couple days in Tana.  Nosy Be is an island located on the northwest coast of Madagascar, and means literally Big (Be) Island (Nosy).  A spectacular setting, lush and green in the wet tropical belt that includes the northwest and east coast rain forests, with dramatic mountains and rocky coasts, white beaches and various small islands scattered about the region.  It is one of the few infrastructure centers in Madagascar, and a center of the tourism industry due to its beauty, accessibility and relatively modern conveniences.  I have worked here since 2007, and know the area well, so always greeted by familiar faces in a hotel I stay at each year in the working town of Hellville.  Ah, Hellville…  in some ways aptly named, in other ways an exhilarating center of culture and real people, with an energetic central open-air market, a main strip with a litany of small, overstuffed and random shops, two small harbors and a variety of low to mid-range hotels, all amid the dusty streets and acrid smells typical of a least developed country .

Sal and Boris on Sakaia - with a chameleon friend!

Bringing gasoline to fuel the field research

Here I meet my team, headed by Boris Andrianantenaina.  I have worked with Boris since 2010, and last year he just completed his Masters degree (DEA in the Malagasy system) on coastal dolphins of Nosy Be at the Institute of Fisheries and Marine Science (IHSM ), University of Toliara.  Boris is a brilliant and highly motivated young man, and manages the field work we do in Madagascar.  Also based in Nosy Be, in the beachside town of Madirokely, are partners Les Baleines Ass’eau, a Malagasy NGO formed by brothers Tanguy and Arthur Guillemain, who we began to work with in 2014 and have become essential support for our research.  From Madirokely and Hellville, we spend a week setting up for the coming field season, buying necessary supplies, arranging for our boat rental, building moorings for our acoustic recorders, and meeting with our regional partners at the National Center for Oceanographic Research (CNRO).  After a week of preparations, we make our way aboard our 8m fiberglass boat to our field site on Nosy Sakatia, with all of our equipment and 1000L of gas in tow. 

Humpback dolphins | Photo: S. Cerchio

Base camp for the field season!

Sakatia is a small island off the west coast of Nosy Be, and a new base of operations this year chosen to be closer to the concentration of Omura’s whale sightings identified in the last 2 years.  On the way we have a brief encounter with a pod of Indian Ocean humpback dolphins, the previous focus of our work from 2007 to 2012, so kind of like a welcoming party from old friends!  We have a pretty nice setup Nosy Sakatia, renting two bungalows at a tourist lodge on the beach that is undergoing renovations; this means there are no tourists right now and we were able to get a discounted price. The accommodations are a little rustic for some tastes (no hot water, for example), but actually quite luxurious for a field camp, with electricity and running water full time (really unusual), great food, and a somewhat finicky internet connection.  It's a slice of tropical paradise and I feel really lucky to be here for a little while!

Now that we are set up and ready to go, next week we start the field work!!

Sal Cerchio

Welcome to our blog!

Welcome to our blog!

12 February 2016

We had a great field season in November-December 2015!  We put in a lot of effort on the water, and found Omura's whales nearly every day.  We worked hard on documenting feeding behavior and figuring out what these guys are eating, and we also deployed new long-term acoustic recorders to start monitoring the region for year-round activity. 

We'll be posting blogs about the 5 weeks spent in the field. Check back for updates!