To ask the Secretary of State for Scotland if he will publish a table in the Official Report to show the species of seals and the number of each species found and/or resident in Scottish coastal waters, and indicate how many (a) juveniles, (b) adult males and (c) adult females there are of each species; what the numbers were five, 10 and 20 years ago; and if he will indicate his estimate of the amount of fish consumed by each seal species every year and the breakdown of fish species consumed by weight and/or number or as much of such information as is available to him.
[holding answer 10 July 1990]: There are no complete counts of either grey or common seals in Scottish waters, and no separate figures for the numbers of juveniles, adult males, or adult females of either species.
Estimates of total population of seals, resident in Scottish waters, made by the sea mammal research unit (SMRU) of the Natural Environment Research Council are as follows:
- GREY SEALS
- 1989—between 76,500 and 97,500
- 1984—between 58,500 and 74,500
- 1979—between 41,000 and 53,500
- 1969—between 27,000 and 34,000
- COMMON SEALS
- 1989—19,900
The figures for grey seals are based on counts of pups, and the ranges given reflect the confidence limits of indirect calculation in this way. The estimate for common seals in 1989 is the only such estimate available at present.
The diet of seals varies with locality and season and it is difficult to analyse or estimate accurately prey taken by seals at sea.
Estimates of total diet of grey seals in the North sea in 1985 have been made by SMRU for a report, "Impact of Grey and Common Seals on North Sea Resources", under a research contract for the Commission of the European Communities (Contract Number ENV 665 UK(H)). The estimates, based on faecal analysis, were as follows:
Estimated consumption by grey seals in 1985
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Tonnes
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Northern North sea ICES division IVa
| Central and Southern North sea ICES division IVb and IVc
| |
| Cod | 1,250 | 9,575 |
| Whiting | 146 | 1,245 |
| Haddock | 690 | 788 |
| Saithe | 2,278 | 933 |
| Norway Pout | — | 31 |
| Ling | — | 374 |
| Plaice | — | 127 |
| Lemon Sole | — | 407 |
| Mackerel | — | 21 |
| Sandeels | 29,803 | 5,180 |
| Dover Sole | — | 304 |
| Flounder | 535 | 481 |
| Dab | 196 | 95 |
There are no reliable estimates of consumption by either species of seal in waters to the west of Scotland (ICES division VIa).
Methods of estimation of consumption by seals are known to have limitations. Further research is being undertaken to improve identification of the species and estimation of the quantities of fish in seal diets. The findings of these studies will be published in due course.