Freeze! New paper exploring benthic shark freezing behaviour
A introduction to Academy alumni, Daniel Rooth and his collaboration with the MDA & DICT to gain insight into the freezing behaviour of benthic sharks in response to predators within the Dyer Island ecosystem through underwater footage.
Written by Daniel Rooth, Ralph Watson, Jan 21 2025

Freeze! New paper exploring benthic shark freezing behaviour
My name is Daniel Rooth and I joined Marine Dynamics Academy and Dyer Island Conservation Trust for the first time in 2017 as a volunteer on board the shark cage diving and whale watching vessels. Since then, I have joined MDA and DICT four additional times, as a scientific intern, project intern and guest researcher. I would like to say that my time in Gansbaai has not only shaped my career as a researcher but also helped me envision and develop my passions and ambitions. A lot of the skills and methods I use in my research today I first tested and got familiar with during my scientific internship, such as deploying Baited Remote Underwater Video (BRUV) systems, scientific fishing, shark tagging, to name a few.
The opportunity to write my bachelor’s thesis with MDA was offered, which I gladly accepted. Under the supervision of Marine biologist, Toby Rogers, in 2018 I investigated the habitat utilisation and relative abundances of sharks using BRUVs, opening my eyes for the highly charismatic benthic catsharks and their preference for the kelp forest habitats around Dyer Island. In 2020 I returned as a project intern and together with my now former supervisor at MDA, Dr Ralph Watson, wrote my master’s thesis on interspecific interactions between the great white sharks, bronze whaler sharks, cape fur seals and short-tail stingray, around a shark cage diving vessel. In 2021 I graduated from Lund University in Sweden with a master’s in aquatic ecology, after which I landed a position as an environmental monitoring analyst in Sweden.
I am now a PhD student at the Technical University of Denmark, at the National Institute of Aquatic Resources. During my three years of PhD studies, I am going to study fish community dynamics in coastal marine habitats, with a strong emphasis on top- and mesopredatory fish species in transplanted eelgrass patches and artificial stony reef structures. Previous research has shown positive results from habitat restoration efforts by transplanting eelgrass, stony reefs and mussel beds to coastal ecosystems, increasing the biodiversity and abundances of invertebrate fauna. During my PhD studies I intent to investigate habitat utilisation and fish behaviour in these ecosystems and how to monitor them, with the hopes of increasing the success of future rewilding efforts.
In the following section below, I summarise and present a newly published scientific paper written by myself and my co-author Ralph, on predator avoidance behaviour displayed by some of the endemic benthic shark species I first encountered when writing my bachelor’s thesis in Gansbaai.
Some benthic elasmobranch mesopredators utilise crypsis to avoid predation by higher trophic predators. While this ability has been documented in various elasmobranchs such as rays, cryptic behaviour has been scarcely documented in catsharks (family Scyliorhinidae), a common sight through the waters of Gansbaai. Freezing behaviour by leopard catsharks Poroderma pantherinum and shysharks Haploblepharus spp. in response to sightings of a smoothhound shark Mustelus mustelus and Cape fur seals Arctocephalus pusillus pusillus was recorded during four separate baited remote underwater video (BRUV) deployments near Gansbaai, South Africa. Catsharks were seen actively swimming (foraging) most of the time (97.72%), and occasionally resting on the bottom, showing active buccal pumping, a breathing method utilised to allow rest. In the presence of a potential predator, they rapidly ceased all movement, including decreased gill movement, and immediately sank to the bottom. This response was initiated only when the predator swam into visual range of the catshark, and thus the freezing behaviour seems to be induced by visual cues only. The freezing behaviour is suggested to complement the colour pattern of the species in camouflage. This finding of predator avoidance behaviour in catsharks may inspire future research on predator recognition and avoidance to gain further insight into sharks’ predator–prey behaviour.
The paper can be accessed via the link, for the full in depth analysis: https://doi.org/10.2989/1814232X.2024.2419457