Fishery owners are warning that the growing otter population on the river Hull could threaten their livelihoods.

As reported in the Mail the elusive animals were recently spotted in Hull for the first time for more than 30 years.

The first otter was seen on the River Hull in Kingswood and a second on Holderness Drain between Longhill and Bransholme.

Otters came close to extinction in Britain in the second half of the 20th century due pesticides used in farming and loss of habitat as many wetlands were drained for farming.

Over the past ten years, officers at the Yorkshire Wildlife Trust (YWT) have worked with landowners along the River Hull from Driffield to Hull to encourage otter re-colonisation.

But fishery owners say the otters destroy their valuable fish stocks costing them thousands of pounds.

Nigel and Fiona Williamson who own Barmston Farm Holiday Park and Fishing Lake at Woodmansey have spent about £70,000 over the last nine years re-stocking ponds which have been depleted by otters.

They put £7000-worth of fish in last year and have just taken delivery of another £5000 restock.

Footprints show the otters coming across the field from Barmston Drain to fish in the lake.

Mr Williamson said: "Otters eat a huge amount of fish and are very, very elusive.

"We find their footprints and some of the fish killed and discarded.

"For every positive, there's a negative, there's two sides to every story and the fact that someone has seen an otter in Kingswood has probably cost me £35,000."

The couple have been forced to spend another £15,000 erecting a six-foot fence designed to lean at 45 degrees to keep otters away from the fishing ponds.

Mr Williamson said: "We had two options, either give up and stop putting fish in the ponds and leave it with only a small number of fish in it or grab the bull by the horns and protect the pond as best we could and re-stock."

The Williamsons also have an ornamental pond on the site which contained £2,500-worth of coy carp.

Every single fish was killed within three months.

But to fence this pond would ruin its 'ornamental' look.

Mr Williamson believes the otter population needs controlling.

He said: "They need to be kept in designated nature reserves really.

"To let them spread willy nilly all the way up the River Hull or anywhere else means anyone with a fishing lake will need to fence it properly or go out of business."

Fishing enthusiasts say otters often hunt and kill fish for fun then leave the ruined carcasses uneaten.

Gary Leek a keen fisherman from Cottingham, said: "The YWT would say that the furry fun loving creature is just taking advantage of some of the overpopulated commercial fisheries.

"I would not disagree if Mr Otter only took what it could eat.

"But when you observe specimen sized fish pulled up onto the bank with its face and fins chewed off and just a couple of strips of flesh eaten off them.

"Then observe the next day an other freshly killed fish with the same done to them.

"Mr Otter is just like a fox in a chicken run really.

Yorkshire Wildlife Trust say it works hard to engage with local fishing community and get their input into all wildlife projects.

Jon Traill, conservation project manager at YWT who runs the River Hull Project, said: "I have worked with many river keepers and angling groups to manage and improve aquatic habitats for the benefit of a wide range of species, including targeted work for fish.

"It is true that otter numbers have recovered over the last 20 years, but it is also important to remember that the River Hull is a relatively small river catchment and will never become 'overrun' with otters."

He added that YWT has never sought to "re-introduce" otters to the area but only to improve river habitats to allow all wildlife populations to flourish.