About Spot a Shark
Overview of Our Project
Spot a Shark is an open community science approach, enabling greater engagement by the diving community in monitoring the populations of grey nurse sharks (Carcharius taurus). The system is also open to begin monitoring the population on the west coast, where little is known about the population.
Our aim is to encourage community-based management of C. taurus by providing an on-line tool for both researchers and divers. We hope dive communities that regularly visit their local aggregation site and value the health of the population will use this tool. We also welcome other researchers from across Australia and around the world to take advantage of the online database named as Sharkbook, created by Wild Me. The data gathered will feed into other global platforms, such as the Census of Marine Life, OBIS, Image Based Ecological Information System (IBEIS) and GBIF, contributing to global big data analytics.
Spot a Shark has been conducting regular surveys of the grey nurse shark population along the east coast of Australia since 2000. We now have a substantial photographic database of well over 5,000 images, largely thanks to the diving community up and down the east coast of Australia. These divers are all driven by a sense of stewardship for this passive shark.
Our research involves non-invasive photo identification of sharks using computerised pigmentation spot matching technology. This is used to determine site fidelity, migration patterns, and whether the population is stable, declining or increasing. Photo Identification can also be utilised to assess this species abundance, population structure, site fidelity and long-term distance movements. For more on our aims to improve policy, see our conservation page.
We have achieved this through only a small amount of seed funding in the early years, but have been self-funded for the vast majority of our work. We conduct surveys on a monthly basis, at a minimum, and have assisted in three successful rescues of injured sharks at Magic Point, Maroubra. This was done in conjunction with Manly Sea Life Sanctuary. We also support our dive centres by presenting at their social evenings and have delivered training courses for the public at Sea Life Sydney Aquarium on spot matching techniques.
To find out more about our team and
project, please enjoy the video.
Thanks to Chris Miller for making it.
Previous scientific research projects
The first phase of the project started in 2006 aiming to improve our understanding of diver impacts of C. taurus through the use of non-invasive techniques. Video was used to monitor populations in the presence of recreational divers at a key aggregation sites, such as Magic Point cave off Sydney and Fish Rock cave off South West Rocks. Metrics such as the number and distance of divers for shark watching activities were analysed against the number and presence of sharks and their physiological and behavioural changes towards groups of divers. This was done under strict experimental conditions. The research found that long term impacts were unlikely to occur if divers adhered to the national code of conduct for diving with C. taurus and followed appropriate dive briefings. Read the research here.
Our studies revealed diving in large groups of 6 or more within close proximity to aggregations ( < 3 m) could adversely affected their physiology, with changes in frequency of their ventilation and swimming rate (Barker et al 2011 a-b). The number of sharks in aggregation also changed, however this was relatively short lived. Two peer reviewed journal papers were subsequently published for which can be used for Government guidelines for sustainably diving with C. taurus at sites with relatively high touristic diving activity.
Diver Impacts
Photo ID
The second phase of our research involved documenting individuals using non-invasive photographic identification (Photo-ID) techniques. C. taurus have unique spots patterns along their flanks which can be used to identify individuals (Barker and Williamson 2010). Images of sharks dating back to 2000 at multiple sites in NSW and QLD were taken by our research group but images were also donated by the public through our website SpotaShark.com.
The number of images increased substantially and we currently have a library of over 5,800 images of C. taurus. A computer algorithm was used to search for images so that individuals can be recorded as new (unsighted before), or existing. This enables the placement of individuals in time and space. Individual sharks, especially juveniles, can occupy sites for extended periods of months and years (Barker and Williamson 2010). Existing sharks can also be re-identified at multiple sites. Read more on this research here.
Illustration of how we can identify the same shark even with years apart
Photo-ID can also be used to document impacts from recreational fishing. Images can sometimes uncover whether sharks acquired hooks at their occupied Critical habitat site. We have also documented images of sharks within days or weeks of having no visible signs of hooks and then subsequently resighted at the same location with a hook (see Conservation page for more). Some individuals have been through this multiple times. Hooks can be ingested by the sharks and can cause pain starvation and a slow agonising death.
