Working with one of the world’s smallest and rarest dolphins

Hector’s Dolphins. Photo: NZ Whale and Dolphin Trust

I do science outside because it is all I ever wanted to do. When I was three years old, my family and I were sailing somewhere in the south of Chile and we saw some orca (Orcinus orca). It was a mother and calf, and seeing them amazed me to a level I can’t describe. That image got branded in my brain forever and I remember it as if it was yesterday. I guess I wanted to become a marine biologist even before I knew what marine biology was! To follow my passion, I moved to New Zealand, where world famous marine mammal scientists accepted me as one of their PhD students and I got the chance to work with Hector’s dolphins, a very unique species.

My name is Maria Jesus Valdes, and I am a marine biologist from Chile currently doing my PhD in New Zealand. I study the effect of mussel farming on Hector’s dolphins (Cephalorhynchus hectori hectori), which involves looking at changes in the water, the sediment in the bottom, the fish and marine invertebrates that coexist with the dolphins and of course: the dolphins. I am trying to see if the presence of this industry in the dolphin’s habitat is having an effect, either positive or negative, on this important species.

With the fast growth of the human population, there is increased demand for food. With so many fisheries declining (or collapsing!) aquaculture appeared as a way to provide sea food farmed in a similar way to crops on land. From 2000 to 2012, the world’s fish production via aquaculture has doubled! This increase has also taken place in New Zealand, where aquaculture has grown to a significant primary industry. Although the global growth in aquaculture means that cetaceans (whales, dolphins and porpoises) and aquaculture projects share the same coastal areas, there has been little research on the industry’s potential effects on these majestic marine mammals. The few studies there are, suggest that dolphins are being displaced from areas with intensive aquaculture. For example, Chilean dolphins (Cephalorhynchus eutropia) in Chiloé Island were absent from areas with high mussel farm coverage and bottlenose dolphins (Tursiops truncatus) decreased the use of important habitat in Shark Bay, Australia, after an oyster farm was established. In New Zealand, studies on dusky dolphins (Lagenorhynchus obscurus) in Admiralty Bay showed that they rarely use the areas occupied by mussel farms.

Mussel farms in New Zealand. Photo: NZ Whale and Dolphin Trust

Hector’s dolphins are very special as they are the only cetacean species endemic to New Zealand, which means they are only found there and nowhere else in the world! Unfortunately, they are not doing so well and are classified as an endangered species. They were named after Sir James Hector who examined and described one of them for the first time. There is a population of these dolphins in the Banks Peninsula, where a Marine Mammal Sanctuary (BPMMS) was established in 1988 to protect them. Though strict regulations were established to prevent their accidental entanglement in fishing nets and to regulate tourism in the area, no studies have been conducted to evaluate the effects that additional coastal development, such as aquaculture, may have on this endangered cetacean species. For this reason, it is important to assess the impacts mussel farming has on Hector’s dolphins’ habitat use. And that is where I fit in the puzzle!

To investigate this, I am studying six bays on the northern side of Banks Peninsula; three with and three without mussel farms. At each bay I am applying different methods (including land-based and boat-based) in order to assess the effect of mussel farming in the ecosystem. Just to name a few: I am sampling the sediment to analyze the benthic macrofauna (the animals that live on and in the mud) along with the sediment’s particle size and organic matter content.  I am also taking water samples for dissolved nutrient content analysis, using fish traps to assess the potential prey species for the dolphins, measuring oceanographic variables such as temperature, salinity, oxygen and chlorophyll throughout the water column. To understand the dolphins’ habitat use I am doing some land-based tracking using an electronic theodolite (a survey instrument that allows me to collect angle data of the dolphin’s positions which I can then transform to coordinates and reconstruct their movements), passive acoustic devices (called “TPODs”) moored in the ocean that can detect the echolocation clicks of the dolphins. I will also analyze over 30 years of data from my laboratory’s sightings database.

The author with Hector’s Dolphins in the background. Photo: NZ Whale and Dolphin Trust

The first year of my PhD was very hard. Though I was very confident in my fieldwork skills and I had worked with marine mammals (whales, dolphins and sea otters) in different parts of the world, I struggled (a lot!) with things like driving a big manual truck to tow a trailer with our 6 m research vessel. We don’t leave the boat in the water, which means that every day I have to drive it up and down narrow, winding rural roads and back it up into the boat ramp for launching. I had to learn about engines, electrics and even mixing concrete! It sometimes seemed that it would never get easier, but here I am! Now I’m halfway through my research project, more than 9000 km away from home, and I feel confident doing things that scared me so much at first. So, my message is:  if I did it anyone can do it!

I am in beautiful Banks Peninsula for two months for my summer fieldwork. The best thing about this field season is that I was able to bring along undergrad students from my University from Chile as assistants! I am so happy to be able to share this experience with younger scientists and inspire them to dare to dream big. Also, this is the first time it is an “all women crew” with currently four women, from three different countries. It is very intense work, with the day beginning at 5:30 am. My PhD journey has had lots of sweat and tears (and swearing in Spanish) but it has been worth it. I can’t put into words how much I have learned and how empowering it feels each time I, with the help of my team, overcome another challenge, sort out another “crisis” or break gender stereotypes. I hope I can contribute to making aquaculture more sustainable and to the conservation of this endemic endangered dolphin species. The data obtained so far looks very promising and I look forward to sharing it with all of you!


The author and her research team while out doing research. Photo: Tony Muir

Bio: Maria Jesus Valdes (aka “Jesu”) is currently based in New Zealand, alternating between beautiful Banks Peninsula and Dunedin, for her PhD research on Hector’s dolphins. She was born and raised in Santiago, Chile, but always knew she had to travel the world to pursue her dream of learning about marine mammal conservation. She has worked in her home country, USA, Australia and New Zealand with species that include Chilean dolphins, Peale’s dolphins, sea otters, blue whales, sperm whales, bottlenose dolphins and Hector’s dolphins. When she is not doing fieldwork or lab work she enjoys dancing, hiking, surfing, mountain biking snorkeling and scuba diving. She also loves music and puppies (who doesn’t?). Her research is supported by the New Zealand Whale and Dolphin Trust and University of Otago. To learn more about the Trust’s work for the conservation of whales and dolphins in New Zealand check out the website, and Instagram @nzwhaledolphin (she manages the latter).

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