Nicolas Lubitz
Who I am
Originally from Germany, I always knew I wanted to study biology and I thought the best strategy to do that would be to get out into the world and work and study in as many places as possible. So I did my undergraduate degree at the University of Miami in Florida. During this time I worked for Neil Hammerschlag’s shark lab, where I gained my first experience of catching and tagging sharks. I also spent a semester in the Galápagos Islands studying scalloped hammerheads and horn sharks. Then I went to South Africa to work with great white sharks for a few months, after which I spent six months at the Bimini Shark Lab conducting personality research on juvenile lemon sharks. All this led me to James Cook University in Australia, where I am now conducting my PhD on movement drivers in sharks and rays. My particular focus is bull sharks and great hammerheads, two incredible species that are the perfect model organisms to answer important ‘bigger picture’ questions about animal movement ecology and conservation. To this day, I am driven by the many questions that pop into my head when I observe things in nature and I try to find new ways to answer them. I enjoy nothing more than being outdoors and experiencing what nature has to offer!
Where I work
My research project basically takes place along the entire east coast of Australia. I am lucky in that bull sharks, my main study animals, sometimes move between Sydney and Cairns, so I get to work in a lot of places. An extensive acoustic receiver array set up along the coast between Sydney and Cairns provides unprecedented coverage and enables us to locate tagged bull sharks that have been fitted with internal acoustic tags. Thus I know when and where they passed one of those receivers. Most of the animals I follow were tagged off Cairns, the Palm Islands, the Whitsunday Islands, the Capricorn Bunker Reefs and Sydney, so they provide a representative sample from the east coast’s bull shark population.
In addition, Australia’s east coast is made up of many different eco-regions, including the Wet Tropics, with heavy rainfall and freshwater output, and the Dry Tropics, with little rainfall and periods of little freshwater output. Thus, as bull sharks rely on freshwater rivers for nursery habitat, this coast provides a dynamic landscape to study bull shark population connectivity and nursery use. In order to link the tagged adult female sharks and their movement patterns to nursery rivers along the coast, I also need juvenile bull shark tissue samples for genetic analysis. Since the juveniles spend their first three years of life in rivers, my study area also includes a variety of river systems between Sydney and Cairns.
What I do
My primary focus is shark movement ecology, with my research aiming to address knowledge gaps concerning what drives shark movement. Often movement patterns relate to life-history requirements, such as feeding, reproduction or remaining within suitable environmental conditions. However, in my tracking data I see an incredible amount of variability in movement behaviour and thus a lot of complexity. I like to find new methods and approaches to breaking down this complexity and use it to my advantage to reveal why sharks migrate (or don’t) to certain places at certain times. In an applied sense, a thorough understanding of movement dynamics in sharks is essential for management and conservation, as it sheds light on seasonally critical habitats and the linkages between them. Bull sharks roam widely along Australia’s east coast and show high variability in their movement patterns. Females are believed to consistently return to specific river systems to give birth to their young. For this particular project I am using genetics and acoustic tracking to tackle a large-scale ecological question from multiple angles. I want to determine if female bull sharks are strictly pupping in their natal rivers or if there is some flexibility, which would increase connectivity and potential for the recovery of the population as a whole. To achieve this, I spend many days out on the ocean catching adult female bull sharks and tagging them internally with an acoustic transmitter to track their movements. But I also spend a lot of time on river banks along the east coast, trying to avoid crocodiles – with varying success – while catching and releasing juvenile bull sharks to collect a little fin clip. Genetic analysis of these fin clips enables me to identify rivers where juveniles and females are most closely related. Subsequently, I want to match the genetics with the tracking data to find out to what extent females return to their natal rivers to pup.