§ Mr. Alton
asked the Secretary of State for the Environment (1) whether unusual numbers of birds have died on the Mersey estuary this autumn; and, if so, whether they have died in circumstances similar to those reported in the autumn of 1979;
(2) what pollutant is considered responsible for the deaths of wild birds reported in autumn 1979 and subsequently in the Mersey estuary;
(3) what is the source of the pollutant responsible for the bird mortality on the Mersey estuary; and what steps are being taken to prevent future releases to the estuary.
§ Mr. Fox
Between 8 August and 6 November this year about 850 bird deaths in the Mersey estuary were recorded. Most were gulls, but there were also about 150 duck and other wildfowl. I understand that the body tissues of all birds showed higher than usual levels of lead, but that only in the cases of the duck and other wildfowl was this sufficient to cause death. The gulls may have died of other diseases having been physically weakened by the presence of lead. There is no clear evidence that the circumstances of this incident are similar to that of last autumn when about 2,500 birds died.
The pollutant identified as responsible for the 1979 incident was an unusually large discharge of tetra-ethyl lead, but its source has not been identified. Although discharges of lead compounds are strictly controlled, in an industrial area like that adjoining the Mersey estuary accidental discharges occasionally occur. The water authority is working closely with the industrialists to find ways of minimising the risk of pollution incidents of this kind.