Are sharks present in greater numbers in Australian waters? And are shark interactions increasing with humans? Some Australian politicians claim that this is the case. Let’s take a look at the research. The Australian Shark Attack File is the most reliable source of shark incident data in Australia. It is maintain at Sydney’s Taronga Zoo.
The Conversation created the map below using data from Australia’s Shark Attack File. It shows shark attacks and human incidents in Australia between 1997-2017. The map has filter buttons that allow you to search the data by year, season or type of injury. To reset the search, press the show all button.
Although the number of shark-human encounters in Australia has increased slightly between 1997 and 2017, it is not clear why. The Australian population has increased by 33% over the past two decades. However, this alone does not explain the rise in shark encounters.
- The data shows that the population grew by 7% between 1997 and 2017.
- Injuries resulting from incidents increased by 1.59%
- Incidents without injury rose by 0.36%
- Fatalities rose by 0.07%
Human-shark encounters can be unpredictable and hard to predict. The increase in shark encounters between 1997 and 2017 is relatively small and could be explain by factors other than shark populations, such as increased reporting or beach use. Is there more sharks around the Australian coast than we think?
White Sharks (formerly Great White Sharks), are responsible for 28 of 36 shark attacks that occurred in Australian waters between 2017 and 2017. They are also the primary target of shark mitigation strategies by the Western Australian, New South Wales, and Queensland governments.
White Sharks In Australian Waters Then?
It is hard to estimate the population of marine species, particularly long-lived migratory species such as White Sharks. There is no evidence to suggest that White Sharks are increasing in numbers, either in Western Australia, or along the Eastern coast. These numbers are stable, or slightly declining, despite targeted conservation efforts.
Two distinct White Shark populations are found off the Australian coasts: one is to the west and the other is to the east. This Strait separates Tasmania from mainland Australia. New Zealand White Sharks are part of the eastern population.
The most recent work done by the CSIRO’s Marine Biodiversity hub under the National Environmental Science Program has resulted in the most accurate and reliable estimate of the species’ population size. According to the CSIRO study, there has been a slight decrease in adult White Shark numbers since 2000.
The current adult population of eastern Australasia is approximately 750. There is uncertainty range from 470 to 1,030. The adult population in the southern-western region is approximately twice as large, at 1,460. There are uncertainties ranging from 760 to 2,250 https://qqonline.bet/.
With the information available about juvenile White Sharks, the total size of the eastern population was 5,460 in 2017, with uncertainty ranging from 2,909 up to 12,802. Because of the time it takes for juveniles to mature, White Sharks are difficult to track population trends. This is around 15 years. Since White Sharks were protect in the late 1990s and are now in their current population, any fluctuations in abundance will only be beginning to show up.
Measure White Shark Populations?
Traditional methods for measuring fish and shark populations are to examine long-term catches from commercial fisheries. Scientists can determine if changes in catchability of sharks are related to their abundance by correcting for fishing effort. This is done by looking at the number of hooks, nets, and tows used by fishermen.
However, due to the rarity of White Sharks being caught by fishing vessels this method is not as reliable as the more recent genetic studies by the CSIRO.
Western Australia has a comprehensive measure of White Shark numbers, based on catch data. The Western Australian Department of Fisheries published a report in 2016 that attempted to analyze changes in the population of white sharks in southern-western Australia since the 1930s. Four scenarios were presented by the authors, none of them suggesting a steady increase in White Shark numbers.
There has been an increase in shark bites in New South Wales over the past few years. The NSW Department of Primary Industries data from the NSW Shark Meshing Program (Bather Protect) Program that shows a recent rise in White Sharks being caught in nets near ocean beaches.
When it comes to shark populations, however, we shouldn’t assume they are connect. Remember that even though two things might be relate, that doesn’t necessarily mean they are connect.
These patterns could indicate that animals are moving closer to shore rather than an increase or decrease in population.