international collaboration Archives - Geospatial Ecology of Marine Megafauna Laboratory

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 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!

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.

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.

New Zealand’s mega-fauna come to Newport, Oregon.

By Olivia Hamilton, PhD Candidate, University of Auckland, New Zealand.

The week leading up to my departure from New Zealand was an emotional rollercoaster. Excited, nervous, eager, reluctant… I did not feel like the fearless adventurer that I thought I was. D-day arrived and I said my final goodbyes to my boyfriend and mother at the departure gate. Off I went on my three-month research stint at the Hatfield Marine Science Center.

Some thirty hours later I touched down in Portland. I collected my bags and headed towards the public transport area at the airport. A young man greeted me, “Would you like to catch a taxi or a shuttle, ma’am?” “A taxi please! I have no idea where I am”, I responded. He nodded and smiled. I could see the confusion all over his face… My thick kiwi accent was going to make for some challenging conversations.

After a few days in Portland acclimatizing to the different way of life in Oregon, it was time to push on to Newport. I hit a stroke of luck and was able take the scenic route with one of the girls in the GEMM lab, Rachael Orben. With only one wrong turn we made it to the Oregon coast. I was instantly hit with a sense of familiarity. The rugged coastline and temperate coastal forest resembled that of the west coast of New Zealand. However, America was not shy in reminding me of where I was with its big cars, drive-through everything, and RVs larger than some small kiwi houses.

The Oregon Coast. Photo by Olivia Hamilton.

We arrived at Hatfield Marine Science Center: the place I was to call home for the next quarter of a year.

So, what am I doing here?

In short, I have come to do computer work on the other side of the world.

Dr. Leigh Torres is on my PhD committee and I am lucky enough to have been given the opportunity to come to Newport and analyze my data under her guidance.

My PhD has a broad interest in the spatial ecology of mega-fauna in the Hauraki Gulf, New Zealand. For my study, megafauna includes whales, dolphins, sharks, rays, and seabirds. The Hauraki Gulf is adjacent to Auckland, New Zealand’s most populated city and home to one of our largest commercial ports. The Hauraki Gulf is a highly productive area, providing an ideal habitat for a number of fish species, thus supporting a number of top marine predators. As with many coastal areas, anthropogenic activities have degraded the health of the Gulf’s ecosystem. Commercial and recreational fishing, run-off from surrounding urban and rural land, boat traffic, pollution, dredging, and aquaculture are some of the main activities that threaten the Gulf and the species that inhabit it. For instance, the Nationally Endangered Bryde’s whale is a year-round resident in the Hauraki Gulf and these whales spend much of their time close to the surface, making them highly vulnerable to injury or death from ship-strikes. In spite of these threats, the Gulf supports a number of top marine predators. Therefore it is important that we uncover how these top predators are using the Gulf, in both space and time, to identify ecologically important parts of their habitat. Moreover, this study presents a unique opportunity to look at the relationships between top marine predators and their prey inhabiting a common area.

The Hauraki Gulf, New Zealand. The purple lines represent the track lines that aerial surveys were conducted along.

Common dolphins in the Hauraki Gulf. Photo by Olivia Hamilton

A Bryde’s whale, common dolphins, and some opportunistic seabirds foraging in the Hauraki Gulf. Photo by Isabella Tortora Brayda di Belvedere.

Australisian Gannets and shearwaters foraging on a bait ball in the Hauraki Gulf. Photo by Olivia Hamilton.

To collect the data needed to understand the spatial ecology of these megafauna, we conducted 22 aerial surveys over a year-long period along pre-determined track lines within the Hauraki Gulf. On each flight we had four observers that collected sightings data for cetaceans, sharks, predatory fish, prey balls, plankton, and other rare species such as manta ray. An experienced seabird observer joined us approximately once a month to identify seabirds. We collected environmental data for each sighting including Beaufort Sea State, glare, and water color.

The summary of our sightings show that common dolphins were indeed common, being the most frequent species we observed. The most frequently encountered sharks were bronze whalers, smooth hammerhead sharks, and blue sharks. Sightings of Bryde’s whales were lower than we had hoped, most likely an artifact of our survey design relative to their distribution patterns. In addition, we counted a cumulative total of 11,172 individual seabirds representing 16 species.

Summary of sightings of megafauna in the Hauraki Gulf.

My goal while here at OSU is to develop habitat models for the megafauna species to compare the drivers of their distribution patterns. But, at the moment I am in the less glamorous, but highly important, data processing and decision-making stage. I am grappling with questions like: What environmental variables affected our ability to detect which species on surveys? How do we account for this? Can we clump species that are functionally similar to increase our sample size? These questions are important to address in order to produce reliable results that reflect the megafauna species true distribution patterns.

Once these questions are addressed, we can get on to the fun stuff – the habitat modeling and interpretation of the results. I will hopefully be able to start addressing these questions soon: What environmental and biological variables are important predictors of habitat use for different taxa? Are there interactions (attraction or repulsion) between these top predators? What is driving these patterns? Predator avoidance? Competition? So many questions to ask! I am looking forward to answering these questions and reporting back.

International Collaborations: What do the Oregon Coast and Maui’s dolphins have in common?

My name is Solène Derville and I am a master’s student in the Department of Biology at the Ecole Normale Supérieure of Lyon, France. As part of my master’s, I am spending a few months in Newport, where I am working under Dr Leigh Torres’s supervision in the GEMM Lab. Hopefully, this will be the starting point for a longer term collaboration, for a PhD project about the spatial ecology of humpback whales in New-Caledonia (South Western Pacific Ocean) which I am currently preparing.

On an early morning of February 2015, I am waiting at the airport for my flight to PORTLAND/PDX. I’ve had only one day to pack but I feel confident that I’ve made the right choices as my 23kg luggage contains mainly jumpers, sweatshirts, thick socks, and a brand new umbrella. I’ve got everything I need to face my four months internship in rainy Newport, Oregon.

A few disillusionments await me when I finally land: 1) my “saucisson” (fancy sausage) can’t pass customs and ends up in a bin despite my attempts to negotiate with the customs official, and 2) as soon as I am out of the airport, it starts raining. At first sight this looks like the harmless kind of drizzle I’ve experienced in England, until I realize it’s raining sideways! So much for buying a new umbrella…

Luckily, these small inconveniences don’t affect my spirits for long as I get to discover the richnesses Oregon has to offer.

My mouth drops open the first time someone tells me that I can see elk around Newport and that gray whales are commonly observed next to the jetty at this time of year. It’s difficult to describe to someone who’s always been living in this environment how exciting it is to me. I am not used to all this wilderness and certainly not to living so close to it. It’s a thrill to think that I only need to ride my bike for a few miles to meet the amazing local fauna.

Of course, the beauty of Oregon’s landscapes and the richness of its wildlife is not the only thing that catches my attention. I am immediately touched by the kindness of people, the sense of sharing and the deeply rooted sense of community. I feel welcomed at HMSC, and by my colleagues in the GEMM lab and I am eager to start my internship.

So what is my work here exactly?

Well, believe it or not, I’ve crossed the Atlantic Ocean and came to the US to actually work on a species of dolphins endemic to New-Zealand! Dr Leigh Torres, and I are investigating the fine-scale distribution and habitat selection patterns of Maui’s dolphin (Cephalorhyncus hectori maui). This subspecies of the more common Hector’s dolphin (Cephalorhyncus hectori, also endemic to New-Zealand) is the smallest dolphin in the world and unfortunately among the most endangered (listed as “critically endangered” by the IUCN). The Maui’s dolphin population is thought to have decreased to under 100 individuals in the past decades.

Maui's dolphin credit: Will Rayment — Maui’s dolphin credit: Will Rayment

In practice, this means I am doing data analysis so I spend my days in front of my computer. This may sound a bit dull, but computer work is actually a great part of research in ecology (apart from awesome field work stage, but this is only the tip of the iceberg). Speaking for myself, I’ve always found it very exciting to put together all this hard-won data to answer important questions, especially when the conservation of species as emblematic as the Maui’s dolphin is at stake. To tell the truth, the nerdy code writing work is also a lot of fun!

My data set consists of boat-based observations of Maui dolphin groups made during the 2010, 2011, 2013 and 2015 summer surveys. Overall about a hundred groups were observed. Based on these observations we would like to know: WHERE are the Maui dolphins (distribution pattern)? And WHY (habitat preferences)?

My job is first to describe the spatial distribution patterns of these observations given the year, composition of groups, or group behaviour (whether animals were feeding, resting etc.). This can be done using kernel density estimates: a very good method for “smoothing” a distribution in 2 dimensions and highlighting its main characteristics (extent, core areas etc.). This allows us to answer (or try to answer) the “WHERE” question.

The second stage of my analysis is to describe the environmental conditions at each of the dolphin group locations and compare them with the environmental conditions in surveyed areas where Maui dolphins where not observed. This allows us to better understand the environmental cues that Maui dolphins might be following to find “suitable” places for their every-day activities and therefore try answer the “WHY” question. In statistical jargon, we are exploring the relationship between probability of presence of Maui dolphins and environmental predictors such as: sea surface temperature, turbidity of the water, distance to closest river mouths, distance to the coast and depth.

The resulting models will be used to predict seasonal variations in Maui’s dolphin distribution, notably in winter when direct surveying is difficult because of weather conditions. Based on the resulting dynamic distribution models, we finally aim to predict how Maui’s dolphins might interact with anthropogenic activities or react to changes in their environment.

So far, preliminary results are very promising and I am hoping to share these soon!

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