PROJECT TITLE: Auditory abilities of sharks and their relatives
RESEARCHERS: Prof. Shaun Collin, A/Prof. Robert McCauley, A/Prof. Nathan Hart and Lucille Chapuis
LOCATION: University of Western Australia
Sharks are subjected to intense fishing pressures worldwide and their numbers are being decimated, notably due to bycatch and entanglements in beach nets. Finding alternatives to the culling of sharks is crucial for the continued conservation of these iconic megafauna.
Determining hearing thresholds of sharks and their relatives (i.e. frequencies and intensities) is vital in assessing how natural and anthropogenic noise affects natural behaviours. A possible outcome of this behavioural research will include the development of a shark acoustic repellent device at both personal and beach-based levels.
The elasmobranch taxa (sharks, rays and skates) use hearing to process information about approaching predators, the location of food and potential mates, compass bearings for migration and their position in space. These early vertebrates also hold keys to the series of events that have led to the evolution of our own sensory systems.
Although fish audiograms (graphic displays of a hearing test) have been obtained for only 10 of approximately 500 species of the elasmobranch taxa, recent studies in their laboratory have revealed high inter-specific diversity of the inner ear structures from species from different environments 1,2. Exploring those patterns, linking the functional structure to the ecology of sharks and rays, understanding interactions of these species with their habitat, and promoting better conservation management are the fundamental objectives for this study.
Examining all the different components of the auditory apparatus in a variety of species will identify both ecological and phylogenetic influences on the evolution of the inner ear. This same approach will also allow us to determine whether hearing abilities may change over a species’ lifecycle, especially in species like sharks that are known to alter their habitat as they mature.
1. EVANGELISTA, Carla, MILLS, Morena, SIEBECK, Ulrike E. & COLLIN, Shaun P. (2010) A Comparison of the External Morphology of the Membranous Inner Ear in Elasmobranchs, JOURNAL OF MORPHOLOGY 271:483–495
2. MILLS, Morena, RASCH, Ron, SIEBECH, Ulrike E. & COLLIN, Shaun P (2011) Exogenous Material in the Inner Ear of the Adult Port Jackson Shark, Heterodontus portusjacksoni(Elasmbranchii) THE ANATOMICAL RECORD 294:373–37