At the moment, though, Jason "One For" Nunn from Fisherman's Warehouse says it's prudent to wait on test results from the EPA.

"It's obviously something you never want to see and to be honest, who knows what's responsible," Jason said.

"There are a few theories being thrown up but we'll have to wait for the toxicology reports.

"We've seen similar incidents up the river where fish have been rolled.

"Last year there was an incident off Raymond Terrace where a lot of black water from a dam got washed into the river and a lot fish died.

"Maybe that's what's happened here in the lake. There's suggestions of gas leaks from the lake floor, and question marks about mining, and outfalls.

"They're all worth investigating in terms of getting to the bottom of it.

"Some explanations offered up by some authorities so far seem a little hard to comprehend.

"You'd like to think if someone knows they're responsible they'll put their hand up, but time will tell.

"Moving forward, prevention will be better than cure."

It's not looking too bad for a fish this weekend.

There's a few showers forecast for both Saturday and Sunday, but winds (NW-WNW up to 20mph) and swell will be comparatively negligible.

"Saturday looks like the pick for a fish outside," Jason said.

"In the deeper water, there's plenty of kingfish on The Farm and Texas reefs, up and over the metre mark.

"Word is they are thick and in even better news, the pesky barracouta are thin.

"Jigs have been working well. Also snapper and long-fin perch about.

"The NW wind will be a good one to travel down with, and if it rains, you should be able to shelter adequately enough under the canopy until it blows over."

Inshore, there's still a few tailor on the reefs around that 30m mark and some really nice reds ranging from 2kg to 4kg.

"It's the second year in a row we've seen good in close," Jason said.

"It's really improved over the last few seasons and good to see these quality fish showing up all the way from Caves up to Dudley, Merewether and Newcastle.

"With the full moon tonight and a big 2.09m tide I reckon there will be plenty about."

Beach and rock fishing will also be ideal as the swell drops back, providing a great chance to target luderick and drummer on the rocks and bream and whiting on the beaches.

Swansea channel is still fishing well for salmon, with heaps in Salts Bay on the run-out tide this week.

"It looks like you don't have to concentrate so much on the run-in tide as we thought," Jason said.

"This weekend ahead you can fish for them all day and mixed in with them you'll find trevally and bream."

There's also a lot of luderick in the channel along the breakwalls but green weed is hard to get.

"With flatter conditions this weekend you might be able to duck down to the ocean platforms," Jason suggested.

"The luderick will remain strong until late September when they spawn.

"It will be the same in Newcastle Harbour and up at Port Stephens.

"The luderick will be around in numbers and are a great little fighting fish."

Tailor are spread out across the lake with some nice fish coming out of the middle in particular.

"There is already a sense that spring is not far away too," Jason noted.

"Interestingly, people are now starting to buy tube worms to target bream and whiting.

"It won't be too long before we see species transition with the season."

One negative that's come to light this week with the salmon in Salts Bay is a grey nurse shark washed up on the beach with a hook and trace deeply embedded.

"We know they come into the channel when the salmon are in Salts Bay," Jason said. "It might be worth considering that if you are fishing round the entrance to the channel, to not target the sharks there.

"Incidents like this are not a good look and may generate backlash that might add to restrictions on where you fish in future.

"A good starting point might be to consider the use of circle hooks that give a better chance to survive."

A reminder to all recreational fishers that the new recreational fishing rules for Dusky Flathead and Lobster in NSW are now in effect.

The new rules are you can take three lobster per person, per day; and you are allowed five dusky flathead between 36cm and 70cm per person per day.

Anything over 70cm must be released.