Divers have revealed footage of a rescue operation to save a tiger shark that was stabbed and left to die off a jetty south of Perth.
Vivien Matson-Larkin and her friend Darcie Young found a two-metre tiger shark, unbalanced and taking sand into its gills while diving at Ammunition Jetty at Woodman Point on February 9.
Ms Matson-Larkin said she and fellow divers saw animals "hacked" up and thrown into the water on a regular basis - she said it had become a particular problem near ammunition jetty at Woodman Point.
She said she was not confident that fisheries officers were policing the matter.
"They should police it better," she said.
Ms Matson-Larkin said on the night they rescued the shark at Ammunition Jetty, fishermen had warned the pair as they arrived that a tiger shark had been dumped off the end of the jetty after being stabbed.
"I thought it must've been dead," she said.
It was not until about two hours into a three hour dive that the pair came across the shark which she said had some blood on it and realised it was still breathing.
Ms Matson-Larkin said she was not scared of the shark at all.
"I've dived with sharks before... and you could tell by looking at this one that it was very weak," she said.
When her fellow diver turned the shark over, a plume of silt came out of its gills.
She said she held onto the shark's tail for a while to let it rebalance and massaged it to help it regain its strength.
"It'd been out of the water for too long and its oxygen had been depleted," Ms Matson-Larkin said.
Her fellow diver Ms Young coaxed the shark to help it swim further out into the water. She then followed it for five minutes to make sure it was able to swim away safely.
Ms Matson-Larkin said she was confident the shark would have a good chance at survival after being rescued.
She said she had been diving along the WA coast since 1987 but had noticed more and more animals being unnecessarily harmed by humans near the Woodman Point area in the past three years.
Ms Matson-Larkin said this included chopping the tails off blowfish, and cutting the tails off rays or stabbing them.
"I don't know if it's a young group of fisherman who are sick in the head," she said.
"It's probably a rogue group."
Ms Matson-Larkin said the majority of fishermen were responsible and only caught what they could eat or caught and released animals without stressing them.
"The majority of fishermen are fine; they are interested and ask what you can see down there."
A Department of Fisheries spokesman said patrols of the Woodman Point area had been increased since they were told about the injured shark on Thursday.
"The department does not condone the torture or inhumane treatment of fish and we ask anyone who witnesses such behaviour or any illegal fishing activities to report the matter," he said.
"There is a national code of practice for recreational and sport fishing, which promotes responsible fishing; including looking after our fisheries, protecting the environment, treating fish humanely and respecting the rights of others.
"Education is considered to be the most effective tool in limiting unnecessary suffering and we encourage all fishers to adhere to that code."
By reporting through FishWatch, incidents can be recorded and a picture can be built of the regularity of inhumane treatment, the circumstances and locations.