The "tax men", the "men in grey suits". The nicknames anglers give to sharks suggest that they share an uneasy relationship.
While many global shark stocks are in decline, plenty of Australian anglers are reporting more and more run-ins with sharks eating hooked fish.
So what's going on?
Mat Hubbard runs Prestige Fishing — supplying restaurants in south-east Queensland with high-end fish species like coral trout and red emperor. Before that, he ran a fishing charter out of Brisbane.
All his fishing is done by line, and he says losing hooked fish to sharks is now the biggest threat to his business.
"Literally in one afternoon on my last trip, I lost 125 fish to sharks.
"As soon as I lose a fish to a shark I'll move, but ... they're on every single reef and it's got really bad."
The technical term is depredation — where sharks attack hooked fish before they can be boated.
For commercial fishers it's bad for business and for recreational anglers it's a pain.
And it's also a spanner in the works for fish-stock management — anglers have quotas for the number of fish they can take according to species. But fish taken by sharks often can't be identified and don't count toward bag limits.
And Mr Hubbard isn't the only one who thinks the situation is getting worse.
Social media pages dedicated to fishing are rife with anecdotal accounts of increasing losses, as well as passionate debate about the causes and potential solutions.
Numbers of some sharks have increased
Colin Simpfendorfer is a marine biologist from James Cook University who's been researching sharks for the past 30 years.
He says that about half the species that occur in shallow waters over continental shelves around the world are "threatened with extinction".
"[But in] Australia the story is quite different," he says.
"We have relatively small fisheries and they're very well regulated. Most of our species are doing well."
But that hasn't always been the case — and that legacy is affecting numbers for some species today.
The east coast population of grey nurse, for example, is critically endangered, having historically been the target of anglers and the victim of bad press — falsely implicated in attacking people.
Great whites are vulnerable due to historical fishing pressure and are still caught in shark nets and drum lines.
Commercial fishing pressure also caused the decline of some of the smaller species, according to Professor Simpfendorfer, but some of those have bounced back.
"Up until about 1986, there was a fairly big foreign fishing fleet that was working in northern Australian waters, at the time legally.
"Some species like black-tip sharks, which certainly are associated with depredation ... those species declined quite dramatically [from overfishing].
"Since then there's been relatively small domestic catch, which has been well managed and we've seen those populations recover."
'Sharks just taking everything'
Mr Hubbard says he supports the conservation of threatened sharks like the great white, but it's some of the smaller and mid-sized species that he most commonly encounters when trying to haul in fish; species such as the whalers, bull sharks and black-tip sharks.
He's noticed a big increase in those sharks in south-east Queensland over the last decade, which he puts down to changed regulations which came into effect in 2009.
That was when a maximum size limit of 1.5 metres and one shark per person, for all non-protected species, was introduced for recreational anglers.
Quotas were also cut for commercial fishers.
"Some of the most significant changes relate to shark, which are slow growing and highly susceptible to overfishing," a statement from Primary Industries and Fisheries minister Tim Mulherin said at the time.
"In response to an independent expert review of the fishery commissioned by the Commonwealth Minister for Environment, Heritage and the Arts, the Honourable Peter Garrett MP, a 600 tonne commercial total allowable catch of shark is proposed. This is a 350 tonne reduction from the current catch."
Similar limits for some species were introduced in WA at the same time, and commercial catch quotas were also cut.
"Two to three years after when fisheries brought that ruling in... [I was running] fishing charters and you've got 10 people on board and you're getting one out of 10 fish [past the sharks], you know, it's such a waste," Mr Hubbard says.
Nigel Webster is a presenter and producer of The Fishing Show on 7Mate.
Like Mr Hubbard, he says he's seen a boom in some shark numbers over the past decade.
"We filmed at Swains reef [GBR] on a mother ship about four weeks ago. There were days where you got no fish back. At one point we went through 75 hooks in three days — sharks just taking everything."
But he says he's also noticed a change in shark behaviour.
"It's getting more and more common now to wind up half sharks — small sharks that are getting eaten by bigger sharks — I never saw that 10 years ago."
Mr Webster, who has a background in resource and environmental management, says he has "no doubt" that some species have increased.
But he thinks that because people are influencing marine food-webs, systems are out of balance.
"As a scientist I tend to look at the whole food chain and go, well ... we take a lot of bait out of the water now in terms of netting.
"I think the fact that we we've kind of belted the lower end of the food chain and sort of let the sharks really run amok in terms of not putting pressure on them anymore, you've got a double effect in my opinion."
"They've also learnt that where boats are, there's an easy feed for them."
All that jazz
The idea that sharks have learnt to target boats for food is more than anecdotal.
Culum Brown is a fish behaviour researcher from Macquarie University.
As a research project, he played jazz music to juvenile Port Jackson sharks.
"The fundamental idea [was to] figure out how quickly sharks could learn to associate any artificial noise with a food reward," Dr Brown says.
"We could have chosen any noise — it could have been the sound of an anchor or an engine starting up or whatever."
Five of the eight Port Jackson sharks learnt to move to the corner of the tank where the food was delivered when the music was played.
It's also been observed in the wild, Dr Brown says.
"There's been some work done where they tagged sharks in an area and when the fishermen were either starting their engines or dropping their anchor chains, the sharks that were tagged actually approached the boat.
"Certainly if you read some [scientific] papers, it's pretty apparent that the sharks have figured out where these recreational fishing hotspots are, and that if they hang out there, they're going to get a free feed."
Which is what fisheries biologist Jon Mitchell from the Department of Agriculture and Fisheries looked into for his PhD.
He used what are called BRUVs or baited remote underwater video systems off the Ningaloo coast in Western Australia over six days.
On each day he recorded how long it took the sharks to come to the bait, and how long until they started feeding.
Lemon sharks, spot-tailed sharks, grey reef-sharks and black-tips were the main species attracted to the bait off Ningaloo.
"What we found is that the sharks arrived quicker and quicker each day to the point where on the sixth day, they arrived within literally a few minutes — very quickly," Dr Mitchell says.
"So that really was quite a surprising result and really showed that sharks were able to learn pretty quickly that there's a predictable source of food in the same spot."
Fisheries working on more data
Professor Simpfendorfer says he thinks shark behaviour is definitely one factor in the increase in depredation. But that there are other factors that we don't fully understand yet.
One of those could be the amplifying effect of social media.
"You used to tell a couple of friends down the pub after you've been fishing that you had a couple of fish taken by sharks. Now you tell thousands [via social media] — we've seen the power that can have in changing people's perceptions of what's happening."
But what does the research say on shark numbers?
For some species, like grey nurse and white sharks, there's quite good data.
But for others, it's not as strong.
Fisheries work with commercial fishers to get a lot of their shark data. But often sharks aren't identified to species level when they're caught.
There are also knowledge gaps about the biology of some species — how fast they reproduce for instance.
Dr Mitchell says researchers are putting in a lot of work right now to better understand depredation.
"Some of the work we did over the past few years identifies that it can be up to around 12 different shark species causing this depredation.
"Basically in terms of population assessments for those species, it's pretty lacking for almost all of them."
A spokesperson for Fisheries Queensland told the ABC that they're working to understand how much shark depredation impacts fish stocks, and what is happening with shark numbers.
"Through our shark monitoring program and other information collected on sharks, we can start to quantify the rate of fish lost to depredation and, we can include that information in stock assessments to understand its impact on the overall abundance," the spokesperson said.
'Pretty scary' for commercial fishers
Leo Guida from the Australian Marine Conservation Society says he's experienced first hand losing fish to sharks in Hervey Bay, and understands the frustrations anglers feel.
But he questions the idea that sharks are "out of control".
He also thinks that sharks have learnt to associate boats with an easy feed, but that overall they're an important part of a healthy system.
"If we're to have amazing fishing into the future, a healthy ocean needs healthy numbers of sharks," Dr Guida says.
Mr Hubbard thinks that shark behaviour is probably part of the picture, but it doesn't tell the whole story.
"People say sharks have got smarter and they follow boats. That might be the case, but it makes very little difference because there are so many more sharks now."
He thinks lifting restrictions on recreational fishers for some species could help with depredation.
"I think they really need to get rid of the 1.5m rule.
"Bull sharks, whalers are prolific. Let people target them [from] the beach. Let the recreational fishers enjoy that fishery."
"If something's not done, the fishery is going to totally roll over and you're going to have a lot of businesses that aren't able to catch fish ... it's pretty scary now for a commercial [fisher] like me."
Mr Webster agrees, and says that while he's not a fan of culling, it could be time to think about it for some species.
But Dr Guida is concerned that changing the 1.5m rule could put some species at risk.
"We risk negatively impacting sensitive shark populations, particularly for species like dusky whalers that take anywhere upwards of 18 years to mature, and only pup every two to three years, he says.
He's also critical of commercial gill netting, which can kill a number of threatened species like turtles and dugongs.
The Fisheries Queensland spokesperson said that size and bag limits were subject to ongoing monitoring and review.
"Size and bag limits exist to manage the sustainable harvest of sharks and rays in Queensland in line with our harvest strategies.
"Limits may be reviewed in consultation with stakeholders if information becomes available through our monitoring programs that indicates a change in management arrangements is appropriate."
Professor Simpfendorfer has run workshops around Australia bringing together stakeholders to help work out the best shark management strategies.
He agrees that shark depredation can be a big problem for recreational and commercial fishers.
He says there needs to be more research to help improve management decisions.
"Some of the solutions talked about by fishers are things like culling sharks or increasing shark fishing so that populations are reduced."
But, he says, while that may work in some contexts there are some downsides.
"We know sharks are vulnerable to overfishing and so on."
Given the interests and values of the different stakeholders, Professor Simpfendorfer says the subject causes a lot of conflict.
"There's a lot of emotion involved in this topic."
"We've had a number of workshops in Australia over the last year or so with a whole range of stakeholders in the room, talking about how do we deal with this, what are the facts, what do we know, etc.
"And I think we're still a long way from having a good answer."
'Tips from the experts'
RecFish West is WA's peak body representing recreational fishers.
These are their "tips from the experts" to avoid depredation:
- Keep moving fishing spots
- Avoid known shark 'hotspots'
- Consider using shark-deterrent devices
- Turn off motor and sounder before fishing
- Free-spool fishing reel if being chased by a shark
- Avoid berley and replace flesh baits with lures
- Reduce line length when trolling
- Drift rather than anchor
- Fish as shallow as possible
- Clean fish on land
