SPECIES

Fisheries

From the headwaters of the Calder and the Aire, through Castleford, and down to the river to the sea the rivers support thriving fish populations.

The headwaters support a wild brown trout fishery with increasing numbers of grayling. Below Skipton the fishery continues to be predominantly a trout fishery with increasing numbers of chub,dace, pike and roach.

The distribution of trout and grayling extends further downstream into the sections around Leeds and Bradford, a positive indication of much cleaner water. The river also supports increasing populations of mixed coarse fish. Major improvements to the quality of effluent, or waste, released from Marley, Esholt and Knostrop sewage treatment works and major re-stocking of the river by the Environment Agency has led to coarse fish populations being re-established in areas that were once unable to support them.
The lower River Aire is now a thriving coarse fishery very popular for angling for species such as roach, bream, perch, chub, dace and gudgeon.

Historically the Aire was a salmon river with catches recorded into the early part of the nineteenth century until the effects of pollution brought a halt to their presence. In recent years salmon have returned to the lower reaches of the river and the first recorded rod caught salmon was at Eggborough in 2001.

Significant water quality improvements have been made to the river but more improvement is required before it can support a sustainable salmon fishery.
Salmon are migratory and the main obstacle to their re-colonisation is the large number of weirs. Fish passes need to be installed on them to help salmon in their journey upstream to spawning grounds. The Environment Agency, British Waterways and Castleford local community, together in a partnership, raised funds to install a fish pass on Castleford Weir as part of the Castleford Natural Heritage Project in 2006/07.

Several weirs have already been surveyed with a view to installing fish passes as funding becomes available.

Details on fish species can be found at
http://www.environment-agency.gov.uk/subjects/fish

Anglers (aged 12 years or over) fishing for salmon, trout, freshwater fish or eels in England (except the River Tweed), Wales or the Border Esk and its tributaries in Scotland, must have an Environment Agency rod licence.


Otter

Otters are members of the Mustelid family which includes badgers, polecats, martens, weasels, stoats and mink. Otters can swim at speeds of 12km/hr underwater and can travel for up to 400m before surfacing for air. When it dives, an otter closes its nostrils and ears. Otters are the only truly semi-aquatic members of the Mustelid family.

There are 13 known species of otter in the world but the only one found in the UK is the European (or Eurasian) otter (Lutra lutra). The European otter has an acute sense of sight, smell and hearing. The eyes are placed high on the head so that it can see when the rest of the body is below water.

Otters are medium to dark brown above and lighter underneath. They eat mainly fish, but also birds, small mammals, amphibians, crustaceans and molluscs.

Otters live mainly in rivers, but also canals, marshes, small streams, ditches, ponds and lakes. They also inhabit estuaries and coastal areas. Their range depends on food supply but can be from 1 km along a rich coast to 40km along some rivers. Resting sites are called holts and can often be tree roots drains, caves and holes in rockfalls. They will also rest above ground in vegetation, sometimes called couches.

As otters are very territorial they tend to live alone, except during mating (only once every 2 years) and for a period after the cubs are born, as they remain dependent on their mother. Otters can live on average 4 years, this is low due to so many threats, although they can live 8-12 years.
(© Environment Agency)

Further information on otters can be found at
http://www.environment-agency.gov.uk/subjects/conservation


Water Vole
Arvicola terrestris

Water voles are the largest British vole and are often mistaken for a rat.
They are dark in colour, have a round body and a chubby face. They live close to water in ditches, dykes, slow moving streams/rivers and grassland.
They eat grasses and vegetation. They are excellent swimmers and are active day and night.

They have a short lifespan of only two years but produce up to 5 litters during the spring and summer, each litter averages 6 young.

Water voles are threatened by:
* Predation by mink
* Habitat loss
* Disturbance
* Pollution of watercourses and poisoning by rodenticides
The population has declined by 90% since 1990. However signs of local recovery are now evident in some areas due to concerted habitat improvement and conservation efforts.

Further information on otters can be found at
www.environment-agency.gov.uk/subjects/conservation


White-clawed crayfish
Austropotamobius pallipes

Crayfish are the largest, most mobile freshwater invertebrates, and are considered keystone species. It can easily be distinguished from introduced species, such as the North American signal crayfish, by its pinkish-white underside, as well as other key characteristics. Adults may reach over 12 cm from the tip of the snout to the tail plate and undisturbed can live for about 10 years. Their breeding season is autumn/early winter and the young are very prone to predation.

White-clawed crayfish are threatened by:
* Crayfish plague caused by the fungus Aphanomyces astaci.
* Competition for food and habitat from non-native crayfish.
* Habitat loss.
* Pollution, particularly pesticides and sewage.
They have suffered a dramatic and continuing decline in numbers, as American signal crayfish have spread throughout southern and central England.