Detectives searching for Nicola Bulley are looking at who had permits to fish the river around the time she vanished near its banks.
Mum of two, Nicola, 45, disappeared without a trace during a dog walk along the River Wyre in the village of St Michael's, Lancs, on January 27.
Police have said their working theory is that Nicola, a mortgage advisor, fell into the river.
But today it emerged that local fishing clubs have been approached by officers wanting information about who was ticketed to be on the river around the time of her disappearance.
It comes just days after a report from a potential witness who claims to have seen two men acting suspiciously on the river the day before and the morning Nicola vanished.
The men were described as attempting to hide their faces with "dark clothing" and "hoods or hats" while also carrying fishing rods.
The anonymous witness added that these men were acting "very strange" and the sighting made him feel "uneasy".
He recalled that the men didn’t seem to have a tackle or bait box, which he found bizarre.
However, it was only following the news of Nicola's disappearance that he decided to report what he had seen to police on January 29.
Nine days later police contacted the witness to take his full account.
But fishermen in the area have rejected claims that these suspicious characters were anglers.
One local angler said: "It sounds like they are trying to work out if anyone was fishing on the river that day and saw something, but nobody was."
He revealed police had first called fishermen the day after Nikki’s disappearance, but only to ask about the nature of the water where she went missing.
The angler continued: "The only people that were on the river that day were dog walkers. I can guarantee you that. The dog walkers were there."
The man, who asked not to be named, has been fishing the river for decades.
He said if Nicola did fall into the water, anyone walking along the bank wouldn’t have seen her as the currents would have dragged her under.
Fishing permits have been temporarily suspended by the local angling society since Nicola's disappearance out of respect.
But Nicola's partner, Paul Ansell, 44, has called for police to stop focusing on the river and instead widen their land search.
Paul, an engineer, has also reached out to Mercedes to see if the company can track Nicola's car keys, which vanished along with her.
The "devoted mum" was last seen at around 9.10am after dropping her daughters at school and leaving her car parked there.
Just over 20 minutes later, her dog Willow was found by the river banks, and her phone on a nearby bench.
Speaking to Channel 5's Dan Walker, Paul said he wants "every house, every garage, and every outbuilding scrutinised" in a new land search.
"I want it all searched. I want it all scrutinised, every piece of it. And you're not gonna appease me with anything else," he said.
Mr Ansell also told the programme that he believes someone in the local area knows something, as he revealed he is '100 percent convinced' that Nicola is not in the river.
Speaking about the area he said: "You see the same faces every single day, and on the very odd occasion when you see somebody that you don't know, they stand out like a sore thumb."
"Everyone's the same. So whatever has happened, in my eyes has to be somebody who knows the local area, who knows that.
"And the fact that nothing's been seen or heard, I just truly believe that it's something in the village."
