Otters have been present in the British Isles since the Ice age, an oversized weasel with a paddle for a tail and a talent for sub-surface swimming, their numbers took a rapid decline from the 1950s to the 1970s with populations restricted to parts of Scotland, Wales and south West England. The decline was closely linked to insecticides such as dieldrin used on seed dressings. When first used these chemicals proved to be persistent organic pollutants and caused large scale mortalities in several species, the impact the greatest among top predators because of the of the build up of the chemicals in the food chain and numbers of birds of prey and mammals such as the otter experienced a rapid decline. Once dieldren and related chemicals were withdrawn from use, isolated populations of otters that had survived in areas with low intensity agriculture responded and along with a series of introductions of captive bred otters during the 1980s and 1990s spread to every county in England and Wales.
Adaptable and opportunistic they will inhabit any body of water that is unpolluted and contains a population of fish. With a lifespan of up to five years, an adult otter can weigh between fifteen and twenty five pound and requires around 3lb of fish a day to keep it in trim. Fish make up 95% of its diet and they do not just eat eels as has been suggested in some quarters. All fish are targets and this has raised problems for inland fisheries across the UK as otters are protected under the Wildlife and Countryside act and EC Habitats directive. It is an offence to kill an Otter or to disturb its habitat.
A resident otter will have a clearly defined territory that may extend to twenty miles depending on the amount of food available. On the southern chalkstream where I work, the territories are considerably smaller due to the high density of food available. Within this territory the otter will have several above ground resting sites, these are generally in undisturbed areas such as dense scrub or reedbeds, the territory will also included a number of underground holts that can be any hole in the bank that is of sufficient size, one of which will be used by the female to raise her offspring which can occur at any time of the year. On this river the largest litter that I have seen is two but there are reports of Otters raising four young.
The most obvious sign that an otter is in town is half eaten fish on the bank, be it the back end of an eel, half a roach or a double figure carp with a chunk out of his shoulder. Adult otter footprints are relatively easy to identify and are around five centimetres across with five digits, larger than a mink with a greater area of webbing. Otter apologists will often cite mink as the reason for dead fish on the bank, but as well as the difference in footprints the otter spraint is easily distinguished from a mink scat. The spraint is more cylindrical in shape, black through to green with a slightly sweet scent; the mink scat is squiggly and does not smell at all pleasant. Ten years ago if evidence suggested that an otter was about it was rare to actually see the animal, the slightest hint of human activity sent them scuttling off to a quieter part of their territory. Today, as numbers have increased, it is not that uncommon to see them in daylight. The otters on this river have become more accustomed to human activity, I have stood on the riverbank with my two dogs and had a female otter and her two full grown pups stop and stare at me for over a minute. An angler trotting for grayling one winter afternoon on the beats above had a single otter bumble along the bank towards him making its way to some fish rearing ponds a little further upriver, it turned back at the sight of the angler but made three attempts in the following hour to get past.
To commercial fisheries, fishing clubs and fish farms the impact of otter predation is significant. A fishery in the south of England recently lost a carp of over forty pounds to an otter, one fish that would cost in excess of £5000 to replace. In 2008 the British record barbel was found dead on the bank of the Ouse with a bite out of its underbelly. These big fish deaths are particularly galling amongst anglers as little of a fish that has reached such a great age and size is actually eaten. Large carp in lakes are particularly susceptible during the winter months when they are sedentary creatures and easy targets. Big barbel in rivers can take on a similar torpor in low water temperatures and are also easy pickings for a hungry otter. When otters returned to this stretch of river a decade ago we lost two hundred one and a half pound brown trout from our fish rearing ponds in the space of one winter month. All of our ponds are now protected by fencing which is the only effective means of keeping the otter out. In the neighbouring river the fish must take their chance as it is impossible to exclude otters and all species, trout, grayling, roach, chub, perch and pike must take their chance.
Fencing ponds and lakes is an expensive business; an effective fence of metal mesh with several strands of electric can cost around £5 a metre to install. The cost of protecting stock from predators has been part of the fish farmer’s budget for years, but the cost of protecting a lake of a few acres or more can prove prohibitive to fishing clubs and syndicates and stock is subsequently lost. Money has been made available through the environment agency to those in need of help, but the national annual budget of £100,000 to help fisheries protect their stock against otters is a token gesture at best to the angling world whose contribution to the UK economy estimates put at between four and six billion pounds a year.
Most keepers on the chalkstreams with fish rearing ponds have fenced their stock ponds, metal mesh up to five feet high with a few strands of electric are the minimum requirement. Otters are persistent creatures and will repeatedly test a pond’s defences, a keeper on the middle Test was asked to produce twenty four hours of video footage of the “mother of all” electric fences protecting a pond, the night time footage revealed regular sparks of light as electricity arced towards the wet nose of Tarka who despite the shocks, kept coming back for more. A heavy fall of snow reduced the efficiency of the electric defences surrounding one of our own ponds; several trails that resembled a small canoe being dragged through the snow betrayed three otters who swiftly took full advantage of an easy evening meal.
The revival of the otter is one of the biggest conservation success stories in recent times and whether we like it or not, the otter is here to stay. A lake that I used to fish with my son not far from my home contained a balanced population of coarse fish with most species present in various sizes in clear water to a depth of eight feet, it was a perfect place to teach youngsters to fish and provided an introduction to angling for many in the surrounding area. Two winters of twenty cormorants paying it a visit did for all the fish up to two pound in weight and last year a family of otters dined for several months on the remainder of the fish that were predominantly carp aged thirty years or more up to a weight of twenty pounds. The pond is now unfished, dead water that is financially not worth restocking. The impact of cormorants is slowly being addressed across the UK, but the otter’s impact on inland fisheries in the coming years must be closely monitored. There are extremes of view on either side of the otter debate but a middle way must be found that meets the needs of a balanced population of otters and the angling world in the UK.
Chris de Cani is a middle aged riverkeeper in Hampshire a role he has carried out for 26 years. Knees click and ache when he runs but can still manage stairs. Hair grows where it shouldn’t and is missing where it should. Struggles with teenagers but dog still finds him reasonable company. Still believes that he is good enough to play football for Liverpool, cricket for Hampshire and would have been great at the javelin if Fatima Whitbread hadn’t kept jumping the queue
He writes regularly online at www.testvalleyriverkeeper.blogspot.com and is open to invitations to fish anywhere for anythimg.
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