Historically, the River Tyne was very polluted, but recently there have been great improvements in water quality. Consequently, important species of fish have returned after an absence of many years.
Of particular significance is the recovery of both the Atlantic salmon and the sea trout.
As a result, the River Tyne is presently regarded as one of the most important game fisheries in England and Wales. In contrast to many other rivers in Britain and continental Europe, the numbers of salmon and sea trout migrating upriver to spawn continue to rise annually. Additionally, there are locally important commercial fisheries in the Tyne estuary, and a diversity of coarse fish species along the tidal sections. Despite the recent improvements in water quality, however, low oxygen levels in the lower reaches of the river can adversely affect fish populations during the summer. Fish mortalities can occur at such times.

The potential impacts of the construction project on the river's ecology relate primarily to the disturbance of sediments during the construction phase. Suspended sediments could affect the physical and chemical quality of the Tyne, at least in the short term.
The Environment Agency and various national and local fisheries organisations are concerned that the works in the river could adversely affect salmon and sea trout migration. Restrictions on the timing of the main dredging works to the period from November to March, thereby avoiding the main salmon and sea trout migrations, should minimise any adverse effects. However, the behaviour of migrating fish is not fully understood, and it is acknowledged that even with mitigation measures, there could remain a residual risk. Therefore, negotiations are in progress with both the Environment Agency and the Tyne Riparian Owners and Occupiers Association (TROOA) to agree a package of measures to improve the quality and 'robustness' of the fishery elsewhere on the Tyne. This would be undertaken in conjunction with a comprehensive fish monitoring programme expected to run from 2002 to 2009.

Additionally, the scheme may affect the marine ecology of the River Tyne through alteration of the riverbed habitat where the tunnel is constructed, loss of bottom-dwelling plants and animals within the dredging zone and loss of inter-tidal habitat. The conclusion drawn from the marine ecological assessment is that construction activities would have either negligible or minor adverse effects on the marine ecology of the river.

Source :Evironment Agency - Riding Mill Fish Counter

Source :Evironment Agency - License Returns

Fish monitoring