It's been an ‘unusual’ year for great whites, DPI says
THERE are a lot of questions about the presence and behaviour of great white sharks on the North Coast at the moment. We put a few of them to DPI shark expert Dr Vic Peddemors.
Do you have an estimate of the shark size yet?
The NSW DPI shark biologist is currently reviewing evidence related to this case to determine the size of the white shark involved in this incident.
What process do you follow to identify a shark and its size?
The NSW DPI shark biologist analyses images of the wounds and surfboard, for patterns of sharkbite damage, such as interdental distances and bite circumference. Once the species has been determined, estimates of total length can be made if the photos include a scale bar that can be used as a reference for comparison to the DPI data base.
To maximise the accuracy of predictions of shark species and size involved, additional information needs to be taken into consideration, such as the distribution of the potential species within the geographic area and water depth and temperature.
There has been dredging in the Evans River. Could that be a contributing factor to the shark being in the area?
Aerial surveys have detected a number of white sharks in the region at the moment. Although this appears to be unusual, potential causes are unknown. However, it is unlikely that dredging in the Evans River would affect white shark movements as they are not normally considered an estuarine related species.
Are great whites likely to stay in one area for long or would it be long gone? What is their typical behaviour?
Normally, white sharks do not spend extended periods in any one area. Even research into their movements around more productive feeding sites, like seal colonies, shows that they do not spend extensive periods off these colonies.
Locals can't remember many shark incidents at Evans. Is it unusual for this area?
Although the first records of shark interactions with humans in the region of Iluka/Evans Head go back to 1879, shark bites in the region are infrequent.
Are great whites more curious or more likely to bite someone in the water than other sharks?
Generally, there are three shark species that occur in nearshore waters that could pose a potential risk to humans. Those are the bull, tiger and white shark. Whites are considered to be curious and will approach objects in the water, but whether they are more curious than the other species is not known. All three species will potentially bite an object they encounter.
Is this the time of year they are more likely to be around our area? Is there a safer time of year when sharks aren't so likely to be about?
The occurrence and abundance of white sharks in northern NSW is not well known, but certainly this year appears to represent an unusual year in that there are more sightings, reports and interactions with humans.
There are potentially dangerous sharks in coastal NSW waters throughout the year.
Visit http://www.dpi.nsw.gov.au/fisheries/info/sharksmart for more information.