Mystery surrounds the disappearance of critically endangered grey nurse sharks from an ocean stronghold on the NSW Mid North Coast.
Ecologist Dr Keith Bishop detailed his concerns to Yahoo News Australia as he continues to investigate the situation around Statis Island, off Seal Rocks.
While it’s normally people afraid of sharks, Dr Bishop is concerned in this case it the opposite is true.
He suspects "Instagram culture" is compelling divers to venture too close as they try to get the perfect selfie up close with a shark.
Affectionately describing grey nurse sharks as “labradors of the sea”, he said they are easily spooked.
That’s despite there being severe penalties for “unethical diver behaviour” and “petting” endangered species.
"They're trying to touch them, get their image in association with a shark and a photo or something like that," Dr Bishop said.
Dive operator suspects visiting divers to blame for shark loss
It's not unusual for individual sharks to move between aggregation sites for short periods, but the length of time they've disappeared from Statis Island is unprecedented.
Dive Foster tour operator Ron Hunter said Statis Island was previously a "reliable" place to always see grey nurse sharks.
He would regularly see between 10 and 20 during trips. That was until large numbers of "out of town" diving groups started visiting the area amid the Covid-19 travel restrictions.
While Mr Hunter is not accusing them of intentionally chasing the sharks away, he fears their conduct could be to blame.
"People perhaps didn't know what they were doing," Mr Hunter said.
"If people go into the gutters and chase after them and try to get a photo instead of waiting for them to swing by, you'll spook them and they'll move."
Mr Hunter hopes the divers visiting the area in future will adhere to the code of conduct and in time the sharks will return.
NSW Department of Primary Industries (DPI) told Yahoo News Australia they had been unaware of poor behaviour in the area.
"Grey nurse shark advisory signs are located at key sites in NSW, and DPI will consider installing additional signage in areas where there has been ongoing reports of unethical diver behaviour," a spokesperson said.
"Any incidences of interfering (this includes petting) should be reported immediately to the Fisher’s Watch Hotline 1800 043 536 for investigation by Fisheries Compliance, along with any evidence (video, boat names, vehicle registrations etc.)"
Top four theories for shark disappearance revealed
Dr Bishop has four key theories as to why the grey nurse sharks have vanished from Statis Island.
Instagrammers getting too close and frightening sharks
Extra wave energy from La Nina drawing sharks into deeper waters
Larger predacious sharks scaring them into more protected areas
Flooding disrupting near-coast movement of sea mullet, a primary food source
Sudden drop in grey nurse shark numbers
Around 42 sharks were known to be living off Seal Rocks, a significant number given the state was recently found to have a breeding population as low as 400 across eastern Australia. That's out of a total regional estimate of 2000 individuals.
The disappearance has been been sudden, with the average density between 2015 and 2020 at 8.75 sharks per kilometre, compared to 2021 and 2022 when it dipped to 1.25.
Dr Bishop calculated the change by regularly completing a standardised transect of 1.3 km along the same route, an average of two to three times a month, and a total of 209 samples.
NSW Authorities respond to shark decline reports
Despite these mounting concerns about grey nurse sharks around Statis Island, anecdotal evidence suggests disappearances have not been experienced in other nearby areas like Foster.
The DPI maintains there is no evidence of declining populations when looking across the entire Mid North Coast.
It was unable to clarify if this was because they had evidence to the contrary, or had simply not collected the evidence.
DPI confirmed Covid-19 “did affect some aspects of (its) work”, but monitoring of grey nurse sharks was undertaken at Seal Rocks in June 2021.
It declined to reveal the outcome of this fieldwork ahead of publication which is expected to be released this year.
Call for authorities to better monitor grey nurse sharks
Research by Associate Professor Adam Stow from Macquarie University's School of Natural Sciences found eastern Australia's grey nurses are isolated from other populations.
He believes the low number of breeding adults in this group suggests they "are not as resilient as they might be" to environmental changes.
According to his analysis, any one of the changes suggested by Dr Bishop could have driven the shark disappearance at Statis Island.
Animal welfare campaigners from Humane Society International are concerned the situation for grey nurse sharks could be "critical".
The charity's marine biologist Lawrence Chlebeck said he would like to see increased monitoring of the sharks, and he worries about the impact of one population stressor in particular.
"Recreational fishing is the greatest threat to the survival of the species," he said.
"It is essential that regulations to prevent berleying and live bait near their habitats are properly enforced to prevent the critically endangered animals getting caught and/or ingesting hooks."
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