§ 53. Mr. Kilroy-Silkasked the Secretary of State for the Environment what study he has made of the effect on swans of the use of lead shot by anglers.
§ Mr. WaldegraveThere has been a number of scientific studies by the Nature Counservancy Concil and other organisations. Recent evidence shows that there has been a small increase in the overall swan population over the past five years, but it appears that in excess of 3,000 swans continue to die each year from lead poisoning caused by ingesting anglers' weights.
§ Mr. Masonasked the Secretary of State for the Environment (1) if he can indicate from his Department's recent surveys what effect on the swan population has been registered by industrial pollution, diesel fumes and pollution of waters by increased river usage of diesel-driven vessels, dredging and the reduction of riverside vegetation as a result of pollution and dredging; and if he will make a statement;
(2) what effects the increased use of herbicides and insecticides has had on the swan population;
(3) to what extent, in determining lead poisoning in swans, a separate analysis was made of the effects of lead shot from gun sports; and if he will make a statement.
§ Mr. WaldegraveThe 1981 report by the Nature Conservancy Council, "Lead Poisoning in Swans", examined all causes of swandeaths. Post mortem examinations in 1980–81 showed:
Cause Percentage of deaths Lead poisoning 39.2 Collisions with overhead wires and by other structures 27.4 Disease and infection 10.4 Internal injuries 10.0 Shot or deliberately killed 5.5 In the period October 1981 to January 1985, 55 per cent. of post-mortem examinations indicated lead poisoning as the cause of death. Evidence from all postmortems in the period 1973 to 1981 showed that pellets of split-lead shot used in angling were present in 58 per cent. of swans examined, whereas gunshot was found in less than two per cent. of cases.
656WThere is no evidence that industrial pollution, herbicides or insecticides have been a primary cause of death in swans.
In dealing with the suggestion that fumes emitted from petrol-engined boats may cause lead poisoning of swans the 1981 report states:
Evidence from blood lead levels in swans shows that individual birds feeding on the same stretch of river may have very different blood lead levels. The considerable variation between individual birds can only be accounted for by differences in the amount of particulate lead ingested by each individual bird. Such variation is not consistent with the uptake of dissolved lead direct from water, and this must be discounted.The 1981 report does, however, acknowledge that the problem of lead poisoning by anglers' weights seems to be particularly acute in waterways which do not have an abundance of aquatic vegetation, often as a consequence of an increase in river traffic. The report suggests that this may occur because discarded or spilt shot may remain more easily accessible to swans where vegetation is sparse.
§ Mr. Masonasked the Secretary of State for the Environment if he will list the areas within the southern and eastern counties of England and the parts of northern England and Scotland where the swan population has increased over the last 10 years giving numbers and percentage figures where available; and if he will make a statement.
§ Mr. WaldegraveInformation on increases in the swan population over the last 10 years is not available. However, the Wildfowl Trust conducted a national census in 1978 and again in 1983. In this five-year period the overall population increased by 7 per cent. The following counties in England and Scotland showed increases of over 10 per cent. in the period:
County (old boundaries) Number of Swans Percentage Increase 1978 1983 England Northumberland 221 300 36 Westmorland 54 93 72 Yorkshire, West Riding 191 227 19 Lancashire 195 331 70 Lincolnshire 511 714 40 Leicester and Rutland 144 268 86 Northampton 186 338 82 Cambridge 322 422 31 Norfolk 999 1,299 30 Suffolk 375 535 43 Buckingham 208 255 22 Hertford 262 294 12 Sussex 615 795 29 Hampshire 801 1,029 28 Wiltshire 622 699 12 Devon 320 570 78 Scotland Orkney 274 323 18 Aberdeen 208 324 56 Clackmannan 4 8 100 Ayr 69 82 19 West Lothian 8 9 12 East Lothian 83 107 29 Berwick 44 49 11 Kirkcudbright 129 197 53 In addition, the following counties showed increases over 10 per cent., but in these cases either the census coverage was poor or the figures are regarded as suspect from other knowledge, and the figures must be treated with caution: Durham (51 per cent.), Yorkshire, North Riding 657W (230 per cent.), Shropshire (41 per cent.), Stafford (55 per cent.), Essex (53 per cent.), Somerset (27 per cent.), Cornwall (136 per cent.), Inverness (59 per cent.), Kincardine (200 per cent.), Stirling (183 per cent.), Kinross (100 per cent.), Lanark (209 per cent.), Dumfries (160 per cent.).