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Volume 174: debated on Tuesday 12 June 1990

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To ask the Secretary of State for Scotland what conclusions he has drawn from his study of the deep oceanic intake of waters into Loch Coruisk in the Isle of Skye and the surrounding area in relation to sea trout numbers in north-west Scotland.

[holding answer 11 June 1990]: Loch Coruisk is a freshwater loch. Sea water cannot enter the loch, but its outflow is directly into the sea. The long-term sea trout catch records for the lochs on the Strathaird estate, including Coruisk, show a sustained decline. Fishing effort over the same period has remained stable and there has been no change in land use in the catchment area. It could be inferred that the cause of the decline lies in the sea, but there is no evidence to confirm this.

To ask the Secretary of State for Scotland what study he has made of the impact on fishing in Scottish rivers of summer tourists; and if he will make a statement.

[holding answer 11 June 1990]: No special studies have been made on the effect of summer tourists, as opposed to fishermen generally, on fishing in Scottish rivers. It has been alleged that angling for immature sea trout by summer tourists may have contributed to the recent sharp decline in sea trout catches. But it is not possible to say how much, if any, of this increased mortality results from the activities of tourist anglers.

To ask the Secretary of State for Scotland what financial provision he makes for the extra cost of working at night to carry out fishery research.

[holding answer 11 June 1990]: This information is not available in the form requested. Total expenditure on overtime and allowances at the Department of Agriculture and Fisheries for Scotland marine and freshwater fisheries laboratories in 1989–90 was around £375,000.

To ask the Secretary of State for Scotland if he will make a statement on his co-operation in fisheries research with experts in the west of the Republic of Ireland.

[holding answer 11 June 1990]: Scientists of the Department of Agriculture and Fisheries for Scotland keep in close touch with scientists and fishery managers from the Salmon Research Trust of Ireland at Burrishoole and the Department of Marine in Dublin about their respective research programmes. There is also frequent contact with counterparts from the Republic of Ireland in various working groups of the International Council for Exploration of the Sea or meetings of other international organisations.

To ask the Secretary of State for Scotland what study he is making of habitat erosion and fish spawning.

[holding answer 11 June 1990]: Some of the effects of habitat erosion on fish spawning are well understood. For example, bankside erosion is known to cause loss of cover for parr and adults, loss of terrestial food organisms from bankside vegetation and silting up of spawning gravel downstream.These effects may result from over-graving, intensive bankside activity by anglers and changes in flow regime. The latter can have several causes including land use changes or exceptional rainfall in catchments or changes in drainage, planting or clear-felling in forestry. Research has shown that such changes can be minimised by adopting good management practices.A study of the effects on salmonid fishes of changes in drainage patterns following afforestation is currently being undertaken by scientists from the freshwater fisheries laboratory at Pitlochry in co-operation with the Forestry Commission, the Institute of Freshwater Ecology and the Atlantic Salmon Trust. A study of the effects of clear-felling on salmonid fishes is also in progress with Forestry Commission help.Extensive surveys of the distribution of juvenile salmonid fishes have recently been undertaken by freshwater fisheries laboratory staff. These surveys give an important indication of the success of salmon spawning in different areas of Scotland.

To ask the Secretary of State for Scotland what steps are taken to ensure adequate enforcement of legislation providing that if a trawler catches more than 10 per cent. of its catch in the form of protected species, the skipper loses his licence.

[holding answer 11 June 1990]: The by-catch restrictions vary according to the target species and are all vigorously enforced by the fisheries department. The penalty provided for by legislation for exceeding by-catch limits is a fine not exceeding £5,000 plus a fine not exceeding the value of the fish in respect of which the offence was committed or actual forfeiture of the fish. In addition, any person guilty of such an offence is liable to forfeiture of the net or other fishing gear used in committing the offence. This penalty applies rather than licence revocation.

To ask the Secretary of State for Scotland what study he is making of the impact of seals round the mouths of fishing rivers in dry summers on sea trout entering the rivers to spawn.

[holding answer 11 June 1990]: There has been no specific study of the impact of seals at the mouths of fishing rivers although some work has been done on the diet of seals in the Moray Firth. A series of papers has been produced as a result of this and other research on seals commissioned by DAFS and the results will be published over the course of the next 18 months.

To ask the Secretary of State for Scotland what study he is making on Loch Eriboll of the inter-breeding between wild and farmed salmon; and if he will make a statement on the results.

[holding answer 11 June 1990]: In February 1989, a large number of growing salmon escaped from fish farm sea cages into Loch Eriboll in northern Scotland as the result of a single accident. By August it had become clear that escaped farmed fish were entering the nearby River Polla with the native run of wild fish. Scientists from the Department of Agriculture and Fisheries for Scotland supported by the Atlantic Salmon Trust, the university of Stirling and the Scottish Salmon Growers Association, studied the spawning of wild and farmed fish in the river.The movements of radiotagged fish were monitored and it was established that wild fish and farmed escapees could be distinguished by appearance and by pigment analysis of samples of muscle taken from fish of both types. All the fish entering the river were sexually mature and farmed fish of both sexes were observed to spawn. All the females captured towards the end of the year had become spent. Farmed and wild fish were observed to cross. Wild fish were distributed throughout the river's length at spawning but the distribution of farmed fish was more restricted. Farmed fish of both sexes tended to spawn especially in the lower reaches of the river. This tendency was particularly marked in the case of females. The difference in the distributions of farmed and wild fish at spawning was confirmed, in the case of females, by pigment analysis of eggs sampled from redds located throughout the river's length. Farmed females tended to spawn later than wild ones. Farmed females cut redds on areas of spawning gravel on which redds had previously been constructed by wild fish.The results of the study were presented at an international symposium in Norway in April 1990 to consider "Interactions between Cultured and Wild Atlantic Salmon". Full details of the study have been submitted for publication in the scientific literature.Study of the River Polla will be continued this year to determine whether farmed salmon enter the River Polla again and, if they do so, whether last year's findings may be generalised between years at the same site. Further studies are being performed to establish whether escaped farmed females spawned in the Rivers Hope—Strathmore —and Dionard which flank the River Polla to the east and west, respectively. Pigment analyses will be performed on eggs and alevins sampled recently from both rivers. In addition, with the Queen's university of Belfast, it is intended to test whether observations of the crossing of farmed and wild fish can be confirmed using genetic "fingerprinting" techniques to establish the parentage of juveniles.

To ask the Secretary of State for Scotland if he will give his salmon advisory committee a remit to concern itself with sea trout.

[holding answer 11 June 1990]: We have no plans to do so. The salmon advisory committee already has a very substantial programme of work to complete on Atlantic salmon.

To ask the Secretary of State for Scotland what study he is making of fish-bearing pathogens.

[holding answer 11 June 1990]: Scientists at the Department of Agriculture and Fisheries for Scotland's marine laboratory investigate the causes of pathological conditions in wild and farmed fish in Scotland and carry out research on the detection of pathogens and the diagnosis and prevention of infectious diseases in fish.This research provides the basis for advice to my right hon. and learned Friend on the use of his powers under the diseases of fish legislation and to district salmon fishery boards, fish farmers and fishermen to help them prevent or minimise the effects of diseases in farmed fish.

To ask the Secretary of State for Scotland what research is being undertaken on the marine phase of sea trout life cycles.

[holding answer 11 June 1990]: Research has been undertaken by the Scottish Marine Biological Association on the movements and feeding behaviour of sea trout in sea lochs in Argyll. This will be followed up by a coastal sampling programme in north-west Scotland to obtain additional information on seasonal diets, insights into the distribution of the sea trout and material for parasitological and microbiological examination.The work will be undertaken by scientists from the Department of Agriculture and Fisheries for Scotland's marine and freshwater fisheries laboratories, in cooperation with local fishermen.

To ask the Secretary of State for Scotland what research is being undertaken on the relationship between marine temperatures and the growth of sea lice on fish.

[holding answer 11 June 1990]: The Fisheries Departments have commissioned a study on the biology of sea lice at the Institute of Aquaculture, university of Stirling. This study, which is still in progress, has shown that the life cycle of the louse—lepeophtheirus salmonis —is temperature dependent. The following information has been gained from the project so far.

Sea temperatureTime to complete cycle (weeks)
6–9°C (Scottish west coast winter temperature)8–9
13·5–14°C (Scottish west coast summer temperature)7

To ask the Secretary of State for Scotland what conveniently available figures he has for the costs of ship time in all weathers for the study of rare migratory fish, such as sea trout.

[holding answer 11 June 1990]: The daily cost of operating inshore launches to conduct research is between £200–£250. In the open sea the daily cost of the departmental research vessels is £2,450 for the smaller Clupea and £8,150 for the Scotia. These figures do not include the salaries and related costs of scientists on board ship.