Issues
Fancy having a go at managing your own virtual river catchment? Play the Catchment Detox game!
CASE STUDIES
Salmon Decline in the River Catchment
In 1867 15,000 salmon were caught by the Ribble netsmen. In 1868 the catch had dropped to 12,900 salmon but by 1900 only 34 salmon were taken. In recent years there has been some recovery with the netsmen averaging 170 fish p.a. The rod catch averages 800 p.a., of which over 60% are safely returned to continue their journey to the spawning grounds. A comparison of the 1992 and 1998 surveys of juvenile salmon stocks in the Hodder and its tributaries demonstrates the deterioration in the recruitment of salmon:
- In 1992 salmon fry (newly hatched salmon) were absent from 46% of sites surveyed.
- In 1998 salmon fry were absent from 82% of sites surveyed.
- In 1992 salmon parr (developing young salmon 2-3” long) were absent from 46% of sites surveyed.
- In 1998 salmon parr were absent from 64% of sites surveyed.
This clearly demonstrates one of the problems facing the salmon. The streams, which the eminent naturalist Hugh Falkus described as the river’s “smolt factories” are not producing sufficient fish to ensure the survival of the species – the salmon being Europe’s 10th most endangered species. Salmon and other salmonid species are an excellent indicator of water quality and the health of our rivers in general. If their populations are in “good status”, then it is possible to assume that that the river is in good health.
Eel Population Crashes by 99%
The salmon are not the only species under threat. Eels and dace have also suffered a dramatic decline. Recently, there has been a massive decline in the number of eels returning to our rivers. The eel, like the salmon, lives alternately in freshwater and seawater. Unlike the salmon however, the eel spends its adult life in freshwater then swims down the river and is thought to migrate out to The Sargasso Sea to spawn. This mass spawning produces vast numbers of larvae which drift/swim with the ocean currents across the Atlantic. These larvae then reach our rivers during the spring. This huge decline has been linked to factors in the freshwater environment including land use and increased numbers of impassable barriers.
CAUSES
There are many threats to the health of our rivers and streams and a lot of these don’t relate to the water itself or to problems within the river. The common misconception is that the river’s problems are within the river and work carried out to the river itself will solve everything. However the problems start well away from the river banks, for example how we use water, land and air in general. It is for this reason that rivers give a really good indication as to how healthy the entire catchment area is. To protect and improve the water environments we must identify the problems that affect the Ribble catchment.
The Environment Agency who are charged with protecting our environment (under the Water Framework Directive or WFD – for more information visit www.environment-agency.gov.uk ) are working with its partners to identify the “Significant Water Management Issues” (SWMI) and other problems. These are the main threats to our rivers and work is being carried out through the River Basin Plan.
The SWMIs for the Northwest are:
- Point pollution from rural areas
- Diffuse pollution from roads and urban areas
- Diffuse pollution from rural areas
- Point source pollution caused by discharges from the industry
- Point source pollution from discharges from sewerage systems
- Physical modifications of rivers and the coastline
- Abstraction and other artificial flow pressures
The Other Problems include: