Reporting back on the Whales in a Changing Ocean Conference

Solène Derville, Entropie Lab, Institute of Research for Development, Nouméa, New Caledonia (Ph.D. student under the co-supervision of Dr. Leigh Torres)

My flight back to New Caledonia gives me time to think and process all that I have experienced in the last few days. From April 4th to 6th, I had the great opportunity to attend the “Whales in a Changing Ocean” conference held in Nuku’alofa, in the Kingdom of Tonga. This conference organized by SPREP (Secretariat of the Pacific Regional Environment Programme) as part of the “Protect Pacific Whales – Ocean Voyagers” campaign brought together members of the Pacific Island governments, whale-watching operators, NGOs, IGOS and scientists.

Opening ceremony

As a relatively novice PhD student studying humpback whale spatial ecology in New Caledonia this was my first experience attending a conservation and management focused conference. To be completely honest, when I was asked to attend the conference as part of the work I am conducting on the effect of environmental changes on humpbacks of the South Pacific breeding grounds, I gladly accepted the offer, as an opportunity for me to learn more about the political mechanisms underlying international conservation plans. However, I was a little sceptical as to what tangible outputs could come out of such event. How would the science be integrated into this rather political event? How many delegations would be able to make it? Would they manage to agree on strong objectives regarding the conservation of cetaceans in the region?

Leena Riekkola, a PhD student at University of Auckland, and I with traditional flower necklaces offered by the organizers

On the first day of the conference, we sat through several hours of formal opening ceremony and comments from the governmental delegations that had travelled to Tonga from all over the Pacific: Samoa, Papua New Guinea, Tuvalu, Niue, French Polynesia, New Zealand, Australia, the Cook Islands, Palau, Fiji and many others. These comments mainly consisted of a succession of (well deserved) acknowledgments to the Tongan government for hosting the event and the enumeration of the endless list of threats faced by cetaceans in the region. Despite the tedious nature of this inevitable display of etiquette, I was impressed by the sight of all these governmental and non-governmental delegations sitting around the same table to discuss the future of whales. I was surprised to hear a note of emotion in several of the speeches that day. I clearly had not realized how valuable whales are to the Pacific islanders. Valuable economically of course, as whale watching is one of the most important drivers of tourism to several of these islands, most of all to Tonga. But also importantly, whales and dolphins bear a strong cultural value to the people of the Pacific. Many of the attendees shared stories and legends about whales, and I quickly realized that these animals were indeed a “cultural heritage” that people were eager to protect and preserve.

The next two days of the conference were built around a series of plenaries and workshops surrounding 3 themes: sustainable whale-watching, scientific research and emerging threats. While I was initially a bit lost and did not quite understand where all of this was going, I progressively saw several recommendations and objectives emerging from the discussions. By the end of the conference, I realized how much had been accomplished in only three days and that these achievements were more than just words. Four main outcomes resulted from this conference:

  • The commitment to adopt and sign a Pacific Island Year of the Whale Declaration by 11 nations/territories of the region (out of 21), namely: Australia, the Cook Islands, Fiji, New Caledonia, New Zealand, Palau, Papua New Guinea, Samoa, Tonga, Tokelau and Tuvalu. Not all of the governmental representatives were able to sign but it is likely that some will join later.

  • The agreement to a voluntary commitment to “Protect, conserve and restore whale populations in the Pacific islands, which will be presented at the UN Oceans conference in June 2017.
  • A technical and scientific input from international working groups to help establish the next SPREP Whale and Dolphin Action Plan for 2018-2023

  • Tonga’s announcement of a whale sanctuary in their waters.

    Governmental representatives group photo after signing the Pacific Island Year of the Whale Declaration

Whether these declarations of intentions and recommendations will actually lead to tangible actions in the short term, I could not tell. But I am glad I got the opportunity to witness the very first regional conference on whales in the Pacific Islands, and the celebration of these beautiful creatures and their place in Pacific cultures.

The seamounts are calling and I must go: a humpback’s landscape

Solène Derville, Entropie Lab, Institute of Research for Development, Nouméa, New Caledonia (Ph.D. student under the co-supervision of Dr. Leigh Torres)

The deep ocean is awe-inspiring: vast, mysterious, and complex… I can find many adjectives to describe it, yet the immensity of it prevents me from picturing it in my mind. Landscapes are easy to imagine because we see them all the time, but their hidden ocean counterparts of seascapes with several kilometer-high seamounts and abyssal trenches are hard to visualize.

When I started a PhD on the spatial ecology of humpback whales, a species typically known for its coastal distributions, I never imagined my research would lead me to seamounts. Lesson of the day: you never know where research will lead you… So here is how it happened.

About twenty years ago when my supervisor, Dr Claire Garrigue, started working on humpback whales in New Caledonia, she was told by fishermen that humpbacks were often observed in prime fishing locations, about 170 km south of the mainland. After a little more investigation into this claim, it was discovered that these fishing spots corresponded with two seafloor topographic features: the Antigonia seamount and Torch Bank (Fig. 1), These features rise from the seafloor to depths of 30 m and 60 m respectively and are surrounded by waters about 1500 m deep. This led Dr. Garrigue to implement an ARGOS-satellite tagging program to follow the movements of humpbacks leaving the South Lagoon (one of the main breeding area in New Caledonia, Fig. 1). Sure enough, most of the tagged whales (61%) visited the Antigonia seamount (Fig. 2; Garrigue et al. 2015)⁠.

Map of New Caledonia and our study areas: the South Lagoon and the Southern Seamounts. Light grey lines represent 200m isobaths. Land is shown in black and reefs in grey.
Figure 1: Map of New Caledonia and our study areas: the South Lagoon and the “Southern Seamounts”. Light grey lines represent 200m isobaths. Land is shown in black and reefs in grey.
Figure 2: ARGOS tracking of 34 humpback whales tagged between 2007 and 2012 in the South Lagoon. The Antigonia seamount and Torch Bank are completely covered by tracklines.
Figure 2: ARGOS tracking of 34 humpback whales tagged between 2007 and 2012 in the South Lagoon. The Antigonia seamount and Torch Bank are completely covered by tracklines.

 

Seamounts are defined as “undersea mountains rising at least 100m from the ocean seafloor” (Staudigel et al. 2010). Most of them have a volcanic origin and the majority of them are located in the Pacific Ocean (Wessel 2001). But what is the link between these structures and marine life? The physical and biological mechanisms by which seamounts attract marine wildlife are diverse (for a review see: Pitcher et al. 2008)⁠. In a nutshell, topography of the ocean floor influences water circulation and isolated seabed features such as seamounts affect vertical mixing and create turbulences, consequently resulting in higher productivity.

For instance, have you ever heard of internal waves? Contrary to the surface waves people play in at the beach, internal waves propagate in three dimensions within the water column and can reach heights superior to a 100m! When these waves encounter steep topography, they break, similar to what a “normal” wave would do when reaching shore. This creates complex turbulence, which in turn may attract megafauna such as cetaceans (see com. by Hans van Haren).

The importance of seamounts for cetaceans is often referenced in the literature, however, few studies have tried to quantify this preference (one of which was recently published by our labmate Courtney Hann, see Hann et al. 2016 for details). So what importance do these seamounts serve for humpback whales in New Caledonia? Are they breeding grounds, do they serve as a navigation cue, a resting area, or even a foraging spot (the latter being the less likely hypothesis given that humpback whales have never been observed feeding in tropical waters)?

To answer this question, an expedition to Antigonia was organized in 2008 and about 40 groups of whales were observed in only 7 days! The density of this aggregation, the high occurrence of groups with calves and the consistent singing of males suggested that this area may be associated with breeding or calving behavior. Several other missions followed, confirming the importance of this offshore habitat for humpbacks.

Looking through all this data I was struck by two things: 1) whales were densely aggregated on top of these seamounts but were rarely found in the surrounding area (Fig. 3), and 2) other seamounts with similar characteristics are only a few kilometers from Antigonia, but seem to be rarely visited by tagged whales.

What is so special about these seamounts? Why would energetically depleted females with calves choose to aggregate in these off-shore, densely occupied and unsheltered waters?

 

Figure 3: 3D surface plot of the seabed in the Southern seamount area. Humpback whale groups observed in-situ during the boat-based surveys conducted between 2001 and 2011 are projected at the surface of the seabed: blue points represent groups without calf and white points represent groups with calf. Antigonia and Torch Bank have a clear flat-top shaped which classifies them in the “guyot” seamount type. Most whale groups aggregated on top of these guyots.
Figure 3: 3D surface plot of the seabed in the Southern Seamounts area. Humpback whale groups observed during the boat-based surveys (2001-2011) are projected at the surface of the seabed: blue points represent groups without calf and white points represent groups with calf. Antigonia and Torch Bank have a clear flat-top shaped and are called “guyots” seamounts. Most whale groups aggregated on top of these guyots. For 3D interactive plot: click here.

I will spend the next two months at the GEMM lab in Newport, OR, trying to answer these questions using ocean models developed by New Caledonian local research teams (at IRD and Ifremer). I will be comparing maps of local currents and topography of several seabed features located south of the New Caledonia main island. The oceanographic model used for this study will allow me to analyze a great number of environmental variables (temperature, salinity, vertical mixing, vorticity etc.) through the water column (one layer every 10m, from 0 to 500m deep) and at a very fine spatio-temporal scale (1km and 1day, even 1 hour at specific discrete locations) to better understand humpback whale habitat preferences.

Figure 4: Modeled Sea Surface Temperature for July 15th 2013 (model in progress, based on MARS3D, development by Romain Legendre). A temperature front occurs in the middle of the study area, along the Norfolk ridge. On this image, a cold eddy is forming right on top of the Antigonia seamount.
Figure 4: Modeled Sea Surface Temperature for July 15th 2013 (model in progress, based on MARS3D, development by Romain Le Gendre). A temperature front occurs in the middle of the study area, along the Norfolk ridge. On this image, a cold eddy is forming right on top of the Antigonia seamount.

 

Looking forward to uncovering the mysteries of seamounts and sharing the results in December!

Literature Cited

Garrigue C, Clapham PJ, Geyer Y, Kennedy AS, Zerbini AN (2015) Satellite tracking reveals novel migratory patterns and the importance of seamounts for endangered South Pacific Humpback Whales. R Soc Open Sci

Hann CH, Smith TD, Torres LG (2016) A sperm whale’s perspective: The importance of seasonality and seamount depth. Mar Mammal Sci:1–12

Pitcher TJ, Morato T, Hart PJ, Clark MR, Haggan N, Santos RS (2008) Seamounts: ecology, fisheries & conservation. Oxford, UK: Blackwell Publishing Ltd.

Wessel P (2001) Global distribution of seamounts inferred from gridded Geosat/ERS-1 altimetry. J Geophys Res 106:19431–19441

Staudigel H, Koppers AP, Lavelle JW, Pitcer TJ, Shank TM (2010) Defining the word ‘seamount’. Oceanography 23,20–21.

Looking back on a busy field season

Solène Derville, EnTroPie Lab, Institute of Research for Development, Nouméa, New Caledonia (Ph.D. student under the co-supervision of Dr. Leigh Torres)

After one month and a half in the field, I am now comfortably sitting at my desk in the Institute of Research for Development (IRD) in Nouméa and I am finally finding the time to look back on my first marine mammal field experience.

The New Caledonian South Lagoon is certainly not the worst place on earth to study whales. While some people spend hours trying to spot extremely rare and shy species living in freezing cold polar waters, I have to endure a 25°C temperature, turquoise waters and a study species desperate for attention (series of a dozen breaches are not uncommon). As with all field work, there were ups and downs but following humpback whales during the 2015 breeding season was by far the most exhilarating field experience I’ve ever had.

During the austral winter, humpback whales are thought to travel and stay in different areas of the New Caledonian Economic Exclusive Zone. Using satellite telemetry, several seamounts (e.g. Antigonia), banks (e.g. Torche bank) and shallow areas have been shown to play an important role for breeding and migrating humpback whales (Garrigue et al. In Press). However, as much as we would like to study whales in these areas, offshore field missions are logistically and financially hard to conduct. This is why most of the data on humpback whales in New Caledonian waters have been collected in coastal waters, and more specifically in the South Lagoon. Opération Cétacés, a local NGO, has been studying whales in this area for about two decades and I was lucky to participate in this year’s field season with their experienced team.

The South Lagoon of New Caledonia
The South Lagoon of New Caledonia

The usual day in Prony (the village that we live in during the whale season) usually starts early. We get up at about 5:30, and start by engulfing a bowl of porridge (nicknamed “globi” and considered as a highly exotic dish). By 6:30 everyone is standing in our rigid-hulled inflatable boat, listening to the weather forecast on the radio. After a 15 minute trip across the bay of Prony, two people disembark and climb to a land-based lookout, the N’Doua Cape, where they will spend the day trying to spot humpback whales and guiding the boat towards their location via VHF radio communication. The vessel-based team slowly approaches the whale groups to do photo-identification (using the unique marks on the ventral surface of the tail flukes), biopsy collection, and behavioral activity monitoring. The particular coastal geography of this study area (see previous post: Crossing Latitudes) allows us to uniquely combine land-based and boat-based surveying. These methods increase our encounter rate and allow us to collect more individual-based data. Yet, compared to a standardized boat-based surveys, our survey effort is much more complex to estimate and account for in a spatial distribution model.

This season, the number of whale encounters was particularly high. We spent 31 days at sea and observed a total of 99 groups. Using photo-identification, we documented 113 different individuals, some of which were first observed more than 15 years ago! Biopsy samples were collected from 139 different individuals and we managed to record 4h of songs performed by six different whales. Given that the size of the New Caledonian population is currently thought to be less than 1000 individuals, our sampling is not too bad!

A calf breaching out of the water on a late afternoon. No wonder humpback whales are favored by whale-watching companies, they can be very active at the surface!
A calf breaching out of the water on a late afternoon. No wonder humpback whales are favored by whale-watching companies, they can be very active at the surface!
These two adult whales were part of a very active competitive group of eight individuals and displayed a peculiar behavior that included gently rolling and rubbing themselves against each other.
These two adult whales were part of a very active competitive group of eight individuals and displayed a peculiar behavior that included gently rolling and rubbing themselves against each other.

Another great achievement of this season was the tagging of two adult humpback whales with ARGOS satellite-tracking devices. It was a thrilling experience to be part of this procedure and witness the level of concentration and experience required to place a tag on a whale. Our two individuals, one a presumed male and the other a female with calf, were respectively baptized Lutèce (the name Romans gave to Paris) and Ovalie (an old fashioned way to call rugby in France). Their tags transmitted for 15 and 20 days respectively, which was not long enough to follow their migration south towards Antarctica. Yet, both whales spent time on seamounts that are known to play an important role for humpback whales in the region. We were very interested in Ovalie’s track (map given below), as she travelled along the Loyalty ridge, a seafloor structure of great interest to us. We suspect that whales could be using this ridge as a navigational aid and/or using shallow areas (seamounts and banks) along the ridge as resting or breeding habitats. The amount of humpback whales present in this area and the eventual role played by oceanic features along the Loyalty ridge will be the subject of my future research.

Raw ARGOS track: Ovalie visiting seamounts south of New Caledonia and then travelling towards the Loyalty ridge (Don’t worry whales didn’t start walking on land since you saw your last National Geographic documentary; the accuracy of the satellite transmitter is to blame. For some of these points accuracy simply can’t be estimated –classes A and B- and unrealistic locations will have to be removed before performing analysis. In general, accuracy of ARGOS locations ranges between 250 and 1500m).
Raw ARGOS track: Ovalie visiting seamounts south of New Caledonia and then travelling towards the Loyalty ridge (Don’t worry whales didn’t start walking on land since you saw your last National Geographic documentary; the accuracy of the satellite transmitter is to blame. For some of these points accuracy simply can’t be estimated –classes A and B- and unrealistic locations will have to be removed before performing analysis. In general, accuracy of ARGOS locations ranges between 250 and 1500m).

 

But now that we have all this data, let’s get back to work! As much as I love being in the field, there comes a time when you have to sit in front of your computer and try to make sense of all this information you collected.

And that is where my collaboration with the GEMM Lab comes in! I am looking forward to visiting Newport once again in December and to start shedding a light on the ‘How’s and ‘Why’s of New Caledonian humpback whales’ space use.

Literature cited:

Garrigue, C., Clapham, P. J., Geyer, Y., Kennedy, A. S., & Zerbini, A. N. (In Press). Satellite tracking reveals novel migratory patterns and the importance of seamounts for endangered South Pacific Humpback Whales. Royal Society Open Science.

 

From Oregon to New Caledonia: Crossing latitudes

**GUEST POST** written by Solène Derville from the Institute of Research for Development, Nouméa, New Caledonia. Entropie Lab

Last term I posted about the analysis of Maui dolphin habitat selection I have undergone under Dr Leigh Torres’ supervision at OSU. The results of this work are now compiled in a manuscript which I hope to submit for publication very soon.

Since I last posted on this blog, many things have changed for me: I went back to France at the end of May (with a heavy heart from leaving Newport and my dear lab mates) and I have graduated from the Ecole Normale Supérieure of Lyon and successfully completed my Biology Master’s degree. In September, I will start a PhD on the spatial ecology of Humpback Whales in New Caledonia. I will work at the French ‘Institut de Recherche pour le Développement’ in Nouméa, New Caledonia, under the co-supervision of Dr Claude Payri, Dr Claire Garrigue, Dr Corina Iovan (IRD) and Dr Leigh Torres (GEMM Lab, OSU).

Before telling you a bit more about my project and this summer field season, I would like to introduce the beautiful place where I will be spending the next 3 years. New Caledonia is an archipelago located in the southwest Pacific Ocean, east of Australia. This special overseas French collectivity includes a main island (Grande Terre) and several other islands such as the Loyalty Islands. New Caledonia’s lagoon is the largest in the world and was added to the list of the UNESCO world heritage sites in 2008, because of its exceptional biodiversity including many emblematic species such as humpback whales, dugongs, marine turtles, manta rays…and many others.

).new+caledonia+mapNew Caledonia location in South Pacific Ocean (map: http://springtimeofnations.blogspot.jp

map_of_new-caledonialonelyplanet

Map of the New Caledonian Archipelago (map: http://crosbiew.wordpress.com).

Moreover, the ‘Natural Park of the Coral Sea’ was established very recently by the New Caledonian to protect this biodiversity hotspot. This monumental marine park spans 1.3 million square kilometres and is, to date, the largest protected area on the planet. As the detailed management plan for this park will be progressively established in the coming years, there is a local need for more information about marine mega-fauna space use in order to define key areas for wildlife conservation. Thus, the description of the humpback whales ecological niche in New Caledonian waters is the next logical step to initiate conservation planning. The effect of human activities needs to be investigated as the New Caledonian humpback whales population forms an isolated breeding sub-stock and is exposed to mining industry intensification, shipping, harbour construction and boat recreation associated to tourism development.

The general aim of my project is to investigate how humpback whales are using their habitat within and between reproductive areas of Oceania in order to facilitate their conservation at the scale of giant marine reserves (new generation of marine protected areas over vast surfaces exceeding hundreds of thousands of square kilometres). I will therefore focus on the spatial ecology of humpback whales in the New Caledonian Exclusive Economic Zone, with several specific aims:

1/ to quantify the spatio-temporal patterns and dynamics of humpback whale distribution in New Caledonian waters in order to identify key areas for the species and determine if these areas change over time or depending on social context.

2/ to assess the connectivity and movement patterns between areas of interest at individual scale.

3/ to document humpback whale use of habitat in relation to environmental factors and include these results in the broader-context of the South Pacific Ocean breeding areas.

4/ to provide a spatial and temporal assessment of the anthropogenic activities risks to humpback whales in New Caledonia.

I will rely on a large amount of data collected between 1991 and present, and provided by Opération Cétacés (an NGO involved in scientific research on humpback whales and other marine mammals in Oceania since 1996), including boat-based, land-based and aerial observations, satellite tracking and individual-based information (via Photo-Identification and genotyping).

This year, I am taking part in the summer field mission undergone by Opération Cétacés in the South Lagoon. I am currently living in Prony, a little village located along the southern coast of Grande Terre. No electricity, no internet, whale watching from 7am to 4pm on a daily basis: the real life!

In my next post I will tell you a bit more about this field trip with Opération Cétacés but for now, I will let you enjoy these few pictures!

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Prony Bay (© S. Derville)

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Rémi, Claire and Daisy standing next to the “Cap N’Dua” lighthouse from which land observations are made. Whales can be spotted up to 20 nautical miles offshore (© S. Derville) 

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View to the East of Cap N’Dua (© S. Derville)

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Breach observed a few days ago in the South Lagoon (© C. Garrigue)

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Inverted peduncle slap (the whale is lying upside down in the water and energetically slapping the surface with its fluke) (© S. Derville).