Review of the Exploitation of the Mussel, Mytilus Edulis, in Scotland

Review of the Exploitation of the Mussel, Myti/us edulis, in Scotland

David W McKay and Sarah L Fowler No68

Review of the Exploitation of the Mussel, Mytilus edulis, in Scotland

David W McKay and Sarah L Fowler

1997

The Nature Conservation Bureau Ltd 36 Kingfisher Court, Hambridge Road, Newbury, Berkshire RG14 5SJ

Nominated Officer: K Duncan, Aquatic Environment Branch Report date: 1996 Report to: Scottish Natural Heritage Contract No: RASD/026/195 AEB

This report should be cited as follows:

McKay, D.W. and Fowler, S.L. 1997. Review of the Exploitation of the Mussel, Myti/us edulis, in Scotland. Scottish Natural Heritage Revjew. No 68

Scottish Natural Heritage Scottish Natural Heritage Publications Section Research and Advisory Services Directorate Battleby, Redgorton, Perth PH1 3EW 2 Anderson Place, Edinburgh EH6 5NP UNITED KINGDOM UNITED KINGDOM

ISSN 1350-3111

Review ofthe Exploitation ofthe Mussel, Mvtilus edulis in Scotland

Contents 1. Summary ...... 1 2. Introduction ...... 2 3. Methods ...... 3 3 .1. Questionnaire survey ...... 3 3.2. Literature review ...... 3 3.3. Collation and analysis of fisheries landing data ...... 4 4. Biology ...... 5 4.1. Taxonomy ...... 5 4.2. Habitat and geographic range ...... 5 4.3. Ecology and life-cycle ...... 7 4.4. Feeding ...... 9 4.5. Pollution and mussels ...... 2 5. The fishery ...... 12 5 .1. Market requirements ...... 12 5.2. Catch statistics ...... 12 5.3. The Domoch Firth fishery ...... 14 5.4. The Montrose Basin fishery ...... ' ...... :...... 14 5. 5. Other wild Scottish fisheries ...... 15 5.6. Future projections ...... 16 6. Aquaculture ...... 19 7. Environmental considerations ...... 21 7 .1. Environmental role of mussels ...... 21 7.2. Environmental impacts of dredging wild mussel beds and relaying seed ...... 22 7.3. Environmental impacts of suspended mussel culture ...... 25 7.4. Environmental impacts of hand collection ...... 28 8. Comparisons with elsewhere in Europe ...... 29 8.1. England, Wales and Northern Ireland ...... 29 8.2. Spain and Ireland ...... 29 8.3. France ...... 30 8.4. Dutch, German and Danish Wadden Sea ...... 30 9. Legislation ...... 32 9 .1. Ownership of mussel fisheries ...... 32 9.2. Public health ...... 33 10. Recommendations for further research and management ...... 34 10 .1. Research priorities ...... 34 10.2. Management recommendations ...... 35 Acknowledgements ...... 36 References ...... 36 Appendices ...... 41 1. Copies of questionnaires sent to SNH and SFP A offices. 2. SOAEFD records of mussels landed in Scotland, 1975-1994. 3. List of potentially relevant legislation Figures 1. Areas supporting populations of commercial-sized mussels in east Scotland ...... 6 2. Tonnage of mussels harvested by statistical rectangle, 1975-1994 ...... 12 3. Landings from the Montrose Basin and Domoch Firth fisheries, 1975-1994 ...... 13 4. Monthly pattern of landings from the Domoch Firth Fishery, 1993-1994 ...... 14 5. Reported locations of mussel harvesting activity, Scottish Natural Heritage staff...... 17 6. Reported locations of mussel harvesting activity, Scottish Fisheries Protection Agency staff.. 18 Tables 1. Catches of shellfish in Scotland in 1994 ...... 2 2. Mussel harvesting data, 1974-1994, 1895-1900 and 1933-38 ...... 13 3. Farmed mussel production for the table by region 1993-1994 ...... 19 4. Farmed mussel production for all Scotland, 1986-1994 ...... 19 5. Ecological effects of mussel fisheries in the Wadden Sea ...... 25 6. Removal of carbon, nitrogen and phosphorous from coastal ecosystems by mussel farming ... 26 7. Faecal waste production and sedimentation from shellfish farming ...... 27 8. Sediment accumulation below shellfish farms ...... 27

Review of the Exploitation of the Mussel, Mytilus edulis. in Scotland

1. SUMMARY

The common mussel (Mytilus edulis Linnaeus 1758) is widely distributed around Scotland, both on rocky shores and within sediment areas in inlets. Large, commercially exploitable stocks are generally confined to more sheltered areas, particularly where there is some freshwater influence, and make up large beds in the lower littoral and shallow sublittoral zones. These extensive mussel beds comprise an important part of the ecosystem. Long-lived stable mussel beds provide a particularly important benthic habitat which supports a wide range of associated species and may be of high marine nature conservation importance. They also provide an essential food source for invertebrate and vertebrate predators (including internationally-important populations of shorebirds and seaduck). They probably also have significant effects on coastal hydrology and chemistry, in that they can stabilise large sediment areas, are very important consumers of phytoplankton, and may play a key role in the cycle of production and breakdown of organic matter, including the stimulation of denitrification and the possible reduction of eutrophication levels. Many of the areas where mussel beds occur naturally are sites of high nature conservation importance.

Collection of mussels for food and for bait for other fisheries has been undertaken in Scotland since prehistoric times. Catches of mussels have been recorded in Scottish Sea Fisheries Statistical Tables since 1886, indicating a very significant decline in harvesting levels over the past 100 years, primarily as a result of changing fisheries practices. In 1994 mussels were the seventh most important shellfish in terms of weight landed and the twelfth most important in terms of value. There is now an important mussel farming industry on the west coast of Scotland, although less productive than the wild fishery.

This report reviews the current knowledge of the biology of mussels in relation to their fisheries in Scotland, and briefly assesses the environmental impacts of mussel harvesting and aquaculture. Much of the background information used for this assessment is drawn from published research carried out on the very much larger fisheries of the Dutch, German and Danish Wadden Sea. There are also important fisheries in England, Wales, Spain, Ireland and France.

The extent of mussel collection around the Scottish coast was evaluated with the aid of a questionnaire survey which drew on the local knowledge of Scottish. Fisheries Protection Agency and Scottish Natural Heritage staff. Legislative, marketing and other operational constraints on the industry are examined. Probably the most significant constraints on the future expansion of mussel fisheries are the Crown ownership of mussels on most of the Scottish coast (they were removed from the public fishery by Act of Parliament in 1847), marketing problems, and the public health implications of poor water quality in many of the larger estuaries where commercially-viable populations occur. Possibilities for the further expansion of wild mussel fisheries are considered, and the possible impacts these may have on environmentally sensitive areas assessed.

The report also recommends the further research necessary to enable mussel fisheries in Scotland to be managed to protect long term yields and minimise environmental damage. Priority areas for attention are considered to include the following: • Surveys of areas containing mussel beds to identify those stable mussel bed habitats which are of highest marine nature conservation importance and which act as the nucleus for recruitment of commercial stocks. These beds should be excluded from commercial fisheries licenses. • Surveys to quantify the extent of mussel beds in major estuarine complexes which are of importance for diving duck and shorebird populations, assess the food requirements of these bird populations, and hence the carrying capacity of areas for commercial mussel (and cockle) fisheries which may be sustained by the surplus shellfish stocks. • Initiation of a long-t.erm study of mussel spat-fall patterns in relation to environmental conditions. • Research into the role of mussel beds in the primary productivity, chemical, hydrological and sedimentary regime of estuaries and marine inlets, and the effects of mussel harvesting.

Review of the Exploitation of the Mussel, Mytilus edulis. in Scotland

2. INTRODUCTION

The common mussel (Mytilus edulis Linnaeus 1758) is widely distributed around Scotland. Small individuals are frequently found on rocky shores, but large specimens are largely confined to more sheltered areas, particularly where there is some freshwater influence, where they make up large beds in the lower littoral and shallow sublittoral zones. Where they are present in large beds they comprise an important part of the ecosystem, both as consumers of phytoplankton and as prey for invertebrate and vertebrate predators, and provide an additional benthic habitat which supports a wide range of associated species. Seed ( 1996) has recently reviewed the biodiversity of mussel patches on rocky shores.

Mussels have been collected for food and for bait for other fisheries since prehistoric times (for at least 3 - 400,000 years in Europe, Siegfreid 1994). Detailed records of catches of fish and shellfish in Scotland have been published since 1882 and catches of mussels have been recorded separately in Sea Fisheries Statistical Tables since 1883 (some decades after mussels were removed from the public fishery - see section 9). However, the traditional small-scale collection of mussels in Britain has now been replaced by larger-scale commercial harvesting using mechanical techniques, and market demand is increasing. The relative importance of mussels in the Scottish shellfishery can be seen in Table 1. This indicates that in 1994 mussels were the seventh most important in terms of weight landed, although only the twelfth most important in terms of value. As well as being subject to a wild fishery, mussels are farmed - primarily on the west coast of Scotland. In comparison with wild mussel fisheries, farmed production in Scotland is small and, despite a high quality product and strong market de111:and, has not increased in line with the industry forecasts.

Many of the areas where mussel beds occur naturally are sites of considerable nature conservation importance. As a result, the increased interest in extending the commercial harvesting of mussels to new sites on the Scottish east coast in the early 1990s led to concern over the potential impact of this activity on the natural heritage. Scottish Natural Heritage recognised the need to estimate the potential for exploitation of this limited resource, particularly in view of the apparent lack of studies on the ability of mussel banks in estuaries to recover from harvesting and the time-scale required for re establishment and growth to market size of individuals. The impact of suction dredging on the currents, hydrology and potential for erosion of sediment on mussel banks is also poorly understood.

This report was commissioned to review the current knowledge of the biology of mussels in relation to their fishery in Scotland. It assesses the potential for expansion of the industry and the possible impacts this may have on environmentally sensitive areas and was required to make recommendations for the management of mussel populations and fisheries in Scotland, with particular regard to natural heritage interests. It also recommends the further practical research necessary to enable the fishery to be managed to protect long term yields and minimise environmental damage.

Table 1. Catches of Shellfish in Scotland in 1994 (after Scottish Sea Fisheries Tables) Species Catch Value Species Catch Value (tonnes) (£,000) (tonnes) (£,OOO) Nephrops norvegicus 19,853 41,026 Squid 203 340 Scallops 9,020 14,506 Brown shrimp 150 246 Brown crab 6,200 5,484 Crawfish 45 565 Velvet crab 2,732 4,474 Razor Fish 41 59 Queen scallop 2,424 1,465 Pink shrimp 35 43 Winkles 2,053 1,456 Squat Lobster 16 7 Mussels 1,156 198 Octopus 6 2 Whelks 797 207 Oyster 3 5 Lobster 493 4,941 Red crab 1 2 Cockles 452 237

Review ofthe Exploitation ofthe Mussel, Mytilus edulis in Scotland

3. METHODS

This review was carried out at the same time as a similar review for Scottish Natural Heritage (SNH) which examined the extent of winkle harvesting in Scotland (McKay & Fowler, 1996). The mussel review was undertaken in three main parts: a questionnaire survey, a literature review, and collation and analysis of fisheries landings data. These stages were undertaken simultaneously for both reviews.

3.1. Questionnaire survey The questionnaire survey was designed to draw on the local knowledge of Scottish Natural Heritage (SNH) staff and Fishery Officers of the Scottish Fisheries Protection Agency (SFP A) to obtain an assessment of the extent to which this activity was known or thought to take place in their areas, while requiring the minimum effort to complete on their part. Staff of both agencies were sent similar questionnaires for both the mussel and winkle harvesting surveys, outline coastal maps for their relevant section of coast, and covering letters explaining the background to the study. (The letter to SNH staff asked whether they could provide any photocopies of advertisements in the local press from shellfish merchants requesting supplies of locally-collected winkles or mussels, since it would have been difficult for the contractors to obtain this material from outside each region.) Copies of the questionnaires sent to SFP A and SNH offices are given in Appendix 1. Some of the returned questionnaires were followed up by telephone, to obtain more information.

The SNH questionnaire was sent to Regional aquatic advisory officers, Regional casework officers and Area Managers. The latter were sent additional copies for each of their sub-offices. The SNH letters and questionnaires were also accompanied by a memo from the nominated officer for the winkle harvesting review explaining the background to the surveys and requesting co-operation.

A similar questionnaire was drawn up to send to local representatives of Scottish Fishermen's organisations. This was not used since, following initial returns from the first questionnaires, it was not considered likely to provide any additional useful information. The main mussel fisheries in Scotland were already known, and it was apparent that all other commercial mussel collection from the intertidal was, in fact, illegal (see section 9). It was for this reason, and the fact that most casual mussel collection was likely to be carried out as part of the 'black economy' (i.e. providing undeclared income), that the questionnaires stated that all information provided on mussel collectors would be treated as strictly confidential.

The returns from the questionnaire survey for areas outside the two main fisheries were not very informative. These are summarised in the text and in map form in section 5.5. Because of the current sensitivity of the Dornoch Firth fishery in relation to the recent nature conservation designation of the area, the authors were requested by local SNH staff not to contact the Ross and Cromarty District Council directly for additional information.

3.2. Literature review A brief literature review was carried out, using the literature database in the Marine Laboratory, Aberdeen, with kind permission of the Scottish Office Agriculture, Environment and Fisheries Department (SOAEFD). Aquatic Science and Fisheries Abstracts (ASF A) searches were carried using the following keywords for the period 1988 to 1995 and 1978 to 1987: 'mussel' or 'Mytilus' and 'ecology'; 'mussel' or 'Mytilus' and 'fishery' or 'fisheries'; and 'gastropods' and 'fisheries' (this last was only of relevance for the winkle review).

3 Review of the Exploitation of the Mussel, Mytilus edulis. in Scotland

Abstracts were provided for all papers identified by the ASFA searches. These frequently gave sufficient information for copies of the original papers not to be required. Other relevant published sources known to the authors but not identified by the literature search were also considered, as were a number of unpublished reports to the former Nature Conservancy Council. The extensive literature on mussel culture was not considered in detail, since considered largely beyond the scope of this study, although some recent reviews are noted. Copies of important literature concerning the environmental impacts and management of the Wadden Sea mussel fishery were kindly provided by Norbert Dankers and Cor Smit (IBN-DLO Institute for Forestry and Nature Research, Texel, NL).

3.3. Collation and analysis of fisheries landings data Fisheries (landings) data for mussels in Scotland from 1975-94 were kindly provided by the SOAEFD Marine Laboratory in Aberdeen on disc and in map form (see section 5.2 and Appendix 2). This information is Crown Copyright and the data reproduced here may not be used for any other analysis.

The SOAEFD records studied go back to 1886 (in 1887 total recorded landings in Scotland were over 275,000 cwts or 14,000 tonnes, despite the fact that mussels were removed from the public fishery in 1847). Some data from the peak years of the late 19th Century and in the 1930s (when the fishery was already in decline) were extracted for comparative purposes, but fisheries records were only reviewed in detail for the 20 year period from 1975 to 1994. Annual data were provided by ICES statistical rectangle in map and digital form for every year from 1975, and by month for two years 1993 and 1994. The main recorded method of fishing for the eleven years up to 1985 was 'by hand', with landings ranging from about 900 to 50 tonnes per year. 'Mechanical dredging' appears as the main fishing method from 1986 to 1994. Landings over this last period ranged from just under 400 to a peak of over 3,000 tonnes. These data are presented and assessed in section 5.2.

4 Review ofthe Exploitation ofthe Mussel, Mvtilus edulis in Scotland

4. BIOLOGY

4.1. Taxonomy The mussel (Mytilus edulis Linnaeus, 1758) is the second largest of the Family Mytilidae found in Scottish waters. The other members of this family are given below in descending order of size. Modiolus modiolus (Linnaeus, 1758) Musculus niger (Gray, 1824) Modiolarca tumida (Hanley, 1843) Modio/us phaseolinus (Philippi, 1846) Musculus discors (Linnaeus, 1767) Musculus costulatus (Risso, 1826) Crenella decussata (Montagu, 1808)

Of the eight species, only Musculus niger is entirely sub littoral in its distribution. All the remaining species are found in the littoral and sub littoral zones, though the centre of distribution of all seven could be considered to be the sublittoral zone.

4.2. Habitat and geographic range The common mussel is widely distributed around Scotland. Small, stunted animals are frequently found on rocky shores, but large specimens are generally confined to more sheltered areas, often where there is some freshwater influence in sea inlets or across the shore. In these conditions they may make up extensive beds in the lower littoral and shallow sublittoral zones and have an important role in modifying the benthic habitats of such areas ( see Section 7). Howson et al. ( 1994) note that dense Mytilus edulis beds occur in sealochs on eulittoral mixed sediments (Biotope code SL22), often subject to varying salinity and occasionally to strong currents. In the Western Isles, local patches of large mussels often occur where freshwater outfalls cross rocky and mixed sediment shores.

In most areas where mussels occur they have been present for long periods of time (although the beds may break up regularly, mussels quickly recolonise the same areas). However, in areas where the substrate is mobile, there may be occasional settlements of mussels which develop into beds of commercial-sized mussels, then disappear totally when the substrate moves. In Scotland, these transient populations of mussels have been most often reported from the Solway Firth.

On the East coast, McKay and Smith (1979) recorded Mytilus edu/is from all the coastal squares within their study area. In a similar study, Smith, McKay and Nunn (pers. comm.) found the same situation on the West Coast of Scotland. Although mussels can, therefore, be considered as ubiquitous, only in shelter do they grow to a size where they may be marketable.

On the east coast of Scotland marketable sized mussels may be found on the south side of the Firth of Forth (between Musselburgh and Port Seton), in the Eden Estuary, in the Tay Estuary (particularly around Tayport), in the Montrose Basin, in the Dee Estuary, in the Ythan Estuary, on the Culbin Bars, in the Inverness, Cromarty and Dornoch Firths and in Loch Fleet (Figure 1). The available tonnages of mussels present in the Dee Estuary and on the Cul bin Bars are relatively small. Nearly 10,000 tonnes of mussels were taken annually by hand from the east coast during the peak years of the late 19th century, but landings have not reached 3,000 tonnes during the past few decades.

5 Review of the Exploitation of the Mussel, Mytilus edulis, in Scotland

Figure 1. Areas supporting populations of commercial-sized mussels in east Scotland.

7'W s·w 5'W 4'W 3'W 2·w 1'W 61'N

60'N t 0 20 40 60 80 100 E-3 E---3 km

{}

WESTERN ISLES

58'N

\ Culbin Bars

57'N

--Montrose Basin

56'N

55'N

6 Review ofthe Exploitation ofthe Mussel, Afytilus edulis in Scotland

On the west coast of Scotland, the indented coastline provides many more sheltered areas and it is not possible to provide as detailed list of sites as for the east coast. However, mussel beds are reported by Howson et al. (1994) from 12 sealochs (Lochs Long (Clyde), Striven, East Kyle of Bute, Lochs Fyne, Etive, Sunart, Ailort, Duich, Long (Alsh), Bracadale, Broom and Laxford). It is also the senior author's personal experience that commercial sized mussels are present at the head of almost all the sea lochs on the west of Scotland (reflecting their lowered salinity). West coast mussel landings in the late 19th century sometimes approached the same level as those from the east coast, but were generally about half the volume. This is not necessarily an indicator of overall abundance, but probably rather of the local demand for use as bait in line fisheries. Reported levels of mussel landings are now no more than a few tens of tonnes maximum (some of which probably include cultivated mussels, recorded in error).

Less detailed information is available for the Northern Isles. The senior author has personally recorded marketable sized mussels from a number of Shetland Yoes, but the quantities available were generally small. Annual landings from Orkney and Shetland in the late 19th century occasionally approached 400 tonnes.

There are much larger mussel beds in England and Wales, which yielded about 90% of the UK landings in the early 1970s (Dare 1980). These fisheries were reviewed at a joint meeting of the Ministry of Agriculture, Fisheries and Food and Sea Fisheries Committee Mussel Working Group in March 1996, but unfortunately the minutes were not available at the time of writing this report. Dredging of mussels in some of the Northern Ireland sealochs, despite water quality constraints in some areas, is thought to be increasing (M.Service, Department of Agriculture for Northern Ireland, pers. comm.).

4.3. Ecology and life-cycle The biology of mussels of all species world-wide has been comprehensively reviewed by Bayne (1976). More recent important sources are Gosling (1992) and Bayne (1991). This review of mussel ecology and life-cycles therefore briefly concentrates on those aspects of greatest importance to the fishery.

In the common mussel the sexes are separate and, like most other bivalves, fertilisation takes place following the release of gametes into the water column. The main spawning season is in late spring to early summer. Following a planktonic phase of some four to six weeks, the spat settle on filamentous seaweed and other similar substrata. There are actually three distinct stages of spat development in the early life history of the species. Planktonic spat (less than l .Smm long) can be subdivided into primary and secondary settlement stage plantigrades. Primary spat (0.25-0.4mm) have a brief attachment stage on filamentous materials, mainly in the subtidal. They then develop into secondary spat (0.5-1.Smm), which detach and become planktonic again before resettling in the recruitment stage onto hard or creviced surfaces, into existing mussel beds (where they preferentially settle on old byssus threads) or on new grounds. This stage is collected on ropes for cultivation. Ground spat are secondary spat which have settled (frequently going through a mobile crawling phase at 2-Smm in size) and have reached about 1Smm in length. Reports from mussel farmers indicate that the times of peak spat settlement vary from place to place and year to year. Some places regularly experience several settlements in a year (there may be a good settlement from an autumn spawning) while others may see only one, usually between May and August, following the main spring spawning.

Most growth takes place in summer and early autumn, slowing or stopping in the winter. In suspended cultivation, growth may be very rapid and mussels may reach the marketable size of 55mm in two years. In the wild situation, growth rates are highest at the bottom of the shore and in shallow sublittoral beds in sheltered areas, but even here growth rates are usually lower than in suspended

7 Review ofthe Exploitation ofthe Mussel, Mytilus edulis in Scotland cultivation. Small mussels may be present in large numbers on exposed rocky shores, but few of over 1O- l 5mm will be found, although these animals may be several years old.

Where extensive mussel beds form, for example when large quantities of spat settle on stony scalps in estuaries, they quickly produce large quantities of mussel mud (faeces and pseudofaeces). To avoid smothering, the young mussels need to move upwards and tend to form a carpet ( one mussel deep) overlying a layer of soft mud and accumulated washed sand. A depth of 0.3 to 0. 75 metres of mussel mud can accumulate in four or five months (Dare 1973 & 1976 - in a Morecambe Bay population). The amount of mussel mud produced by seed mussels over a one year period was calculated by Davies et al. (1980) in crab-proof experimental plots where mud depth averaged 0.35-0.4 m; they estimated that the weight of mussel mud was 17-19 times that of the seed mussel production (or a ratio of 9: 1 for dry weight of organic material). In Morecambe Bay, growth pressure ultimately results in the mass of seed breaking loose on the soft mud surface and the whole bed becoming unstable due to wave action and tidal scour. Loosened mussels can be washed into drifts and suffocated, and autumn storms frequently result in the partial or complete destruction of the seed, with the stony scalps cleared for the new season's settlement. In more sheltered conditions, in a fenced plot, a reduction in mud depth from 0.4 to 0.06m took 18 months after the removal of the mussels (Davies et al. 1980). Dredging of seed for relaying and ongrowing in sheltered waters elsewhere generally takes place once a thick layer of mussel mud has accumulated under the carpet of seed mussels. Weight ratios of the yields of marketable mussels to the weight of the seed relayed on mussel plots range from 3: 1 to 1:2 in the Wadden Sea (Dankers 1993). This is generally much higher than the yields on natural beds. Most of the beds exploited in this way for sources of seed probably only have a very short natural lifetime if left unfished (Common Wadden Sea Secretariat 1992).

McGrorty et al. ( 1990) suggest that only those mussel beds that have developed slowly over many years, or even decades, will form stable beds over a layer of pseudofaeces reinforced with empty shells. These beds contain mussels of many different age classes and are presumably maintained as a result of spat being preferentially attracted to settle on the byssus threads of older mussels. They are also associated in the Wadden Sea with tidal pools and complex communities including a rich epibenthic flora and fauna (Common Wadden Sea Secretariat 1992). Stable mussel beds also form at current-swept sites where pseudofaeces are removed - as in the narrows of sealochs.

The common mussel is not the only bed~forming mussel to be found in Scottish waters. The much larger and long-lived horse mussel Modiolus modiolus is found in large sublittoral beds. As yet, this species is not fished commercially, though it is collected and eaten by local people in a few places, especially on the west coast of Scotland. The senior author has observed large catches of Modiolus on vessels dredging for queen scallops in Shetland. Large Modiolus are otherwise only infrequently caught by commercial scallop dredgers in Scottish waters. Studies have been carried out into the ecological impacts of trawling over sublittoral Modiolus beds for queen scallops Aequipecten opercularis in Strangford Lough, Northern Ireland (Brown, 1989). The primary concern in Strangford Lough is that these Modiolus beds, which form very stable communities made up largely by very old individuals and are of high marine nature conservation interest, are being destroyed by these fishing operations and will be extremely slow to regenerate. An additional consideration is that this activity could also detrimentally affect the levels of recruitment of queen scallops to neighbouring are~s of the lough. Research in the area has reported a strong correlation between the occurrence of Modio/us and Aequipecten ( although the latter are also found away from the Modio/us beds). One likely explanation for this is that the hydroids and other emergent epifauna associated with the Modiolus beds provide particularly good settlement sites for scallop spat, and indeed enhance recruitment of the stock in the area as a whole (M.Service, pers. comm.).

8 Review ofthe Exploitation ofthe Mussel, Mytilus edulis in Scotland

4.4. Feeding Mussels are filter feeders which largely eat phytoplankton (zooplankton, if filtered out, are voided as pseudofaeces). Thus, much higher growth rates can be achieved in suspended cultivation (where mussels are able to feed continuously but are isolated from benthic predators) than on the shore. The poor growth performance of mussels in exposed situations, compared with that on sheltered shores, may be explained by the greatly reduced capacity of mussels to filter seawater in heavy surf, and possibly the tendency for larger, fast growing mussels to be detached from the rocks.

4.5. Pollution and mussels As filter feeders, mussels accumulate coleoenteric bacteria and viruses where they are exposed to polluted waters. They also accumulate the naturally-occurring toxins that are present in plankton blooms and, like other bivalve molluscs, heavy metals. As a result, they are widely used as an important indicator of pollution. For example, Davies and Pirie (1980) used mussels as bioaccumulators to compare levels of heavy metals in various estuaries, and MAFF ( 1994) use them for monitoring levels of heavy metals and tributyltin around the UK coast. Widdows et al. (1995) present the effects of contamination by polycyclic aromatic hydrocarbons from vehicle exhausts in urbanised areas on the scope for growth of mussels along the North Sea coast.

Because mussels accumulate pollutants, their harvesting and marketing is covered by public health legislation, including the EC Shellfish Directive (see Section 9 for more information). SOAEFD's classification of Bivalve Mollusc Production Areas is carried out under this Directive. This classification is based on the level of faecal coliform bacteria (primarily derived from sewage outfalls) from the flesh of mollusc samples from each area reported by the Marine Laboratory in Aberdeen on behalf of the Scottish Office. The most recent classification available was circulated in January 1995, and includes 78 areas where mussels are farmed or fished. One site (the Eden Estuary in North East Fife) is classified as unfit for production. Seven, including Port Seton, Granton, Tayport, the Ythan Estuary, part of the Montrose Basin, Kirkwall Bay and Loch Ryan, are Category C (requiring shellfish to be relayed for at least two months, or purified before consumption). Five other east coast sites, including the other section of the Montrose Basin, and three sites in the south-west are category B (requiring heat treatment or depuration to meet category A requirements). The Dornoch Firth and most northern and western areas are category A (for at least part of the year), and shellfish from these areas may go direct for human consumption.

The most recently published Scottish Office survey data from a 1990 survey (SOEnD 1992) classified rivers, standing waters, estuaries and coastal waters in Scotland on the basis of their water quality. The report concluded that 96% of Scottish estuaries are of Class A (good) or Class B (fair) water quality, and over 90% of coastal waters Class A ( excellent) or Class B (good). These classifications are made according to a series of points awarded for biological, aesthetic and chemical parameters in estuaries, with the addition of use-related descriptions and bacteriological conditions on the open coast. However, untreated or unsatisfactorily treated sewage outfalls and trade effluents were found to affect local water quality in these areas. Around Tain, mussel samples did not comply with the bacterial standards of the EC Quality of Shellfish Waters Directive, although the main mussel scalps in the Dornoch Firth are classified as a Category A Bivalve Mollusc Production Area (see above). On the open coast, areas of 'severely polluted' waters were found off Lossiemouth, Buckie and Banff, and attributed to sewage discharges. The results of the 1995 water quality monitoring should be available later in 1996 (Scottish Office AEFD in prep.). Coastal water quality data are also available in the annual reports of the seven River Purification Authorities, but were not consulted for this study.

Several questionnaire returns mentioned water quality issues. These were not only related to bacteriological water quality classifications, but also to the occurrence of events of Paralytic Shellfish Poisoning (PSP). The latter can pose a serious danger to human health (for example, one response

9 Review of the Exploitation of the Mussel, Mytilus edulis. in Scotland

noted that the periodic incidence of PSP along the Northeast Fife coast has resulted in warnings against the consumption of cockles and mussels in the area). PSP and Diarrhetic Shellfish Poisoning (DSP) events are caused by natural toxic plankton blooms, primarily associated with fronts between oceanic and inshore waters. Suggestions that eutrophication as a result of man's activities could theoretically increase their frequency and severity are apparently not supported by any published data.

In 1991/92 SOAEFD undertook a programme to assess the levels of nutrients entering the sea from several east coast estuaries between the Tweed and the Domoch Firths. The survey in the Dornoch, Cromarty and Inverness Firths showed that the nutrient levels were very low and that the Firths were unusual in the low nitrogen content of their freshwater inflow. Blooms are not a problem in most Scottish estuaries, even where nutrient levels· are high, because the water is too turbid for phytoplankton to grow well. However, Harding-Hill (1993) notes that considerable areas of poor and moderately polluted waters exist and occasional algal blooms (not necessarily of toxic dinoflagellates) occur within the inner Firths in the Moray area. The eutrophication of the Ythan Estuary has been well documented by Raffaelli et al. (1989, 1991).

The EC Shellfish Directive also lays down standards in relation to PSP and OSP, which can occur naturally on any part of the Scottish coast. When levels of PSP or DSP above the limits contained in the EC Shellfish Directive are identified by the Marine Laboratory, Aberdeen, the Scottish Office closes the Shellfish Fisheries in the affected areas using the provisions of the Food and Environmental Protection Act ( 1985). Monitoring of PSP was begun on the north east coast of England and south east Scotland in 1969, following a serious poisoning incident in 1968. This monitoring programme indicated that PSP toxins were detected in the area in most years between 1968 and 1987 (Ayres and Callum 1978, with addendum giving data to 1987). Following the development of the shellfish farming industry on the west coast of Scotland, the monitoring programme was extended to include three sites on the west coast of Scotland in 1987. Following the detection of very high levels of PSP toxins on the north east England coast in May 1990 and the closure of shellfisheries in the area, routine PSP monitoring was extended to the entire Scottish coast to reassure consumers of the safety of Scottish shellfish. As with many other such exercises, this programme has detected PSP toxins in a number of areas where no monitoring had previously taken place (D.McKay pers. comm.). However, the time series of data are not yet adequate to identify any pattern in the incidence and severity of blooms.

Frequent (presumed natural) occurrences of DSP cause serious problems for the extensive areas of roped mussel culture in Bantry Bay, Ireland (Eric Edwards, pers. comm.).

10 Review of the Exploitation of the Mussel, Mytilus edulis. in Scotland

5. THE FISHERY

5.1. Market requirements The shellfish market prides itself in offering a high quality product, with the highest value being obtained for product which may be sold 'in shell'. There are outlets for pickled ex-shell mussels, but the first sale value of mussels for this processing outlet is low. Currently there is no processing outlet for such mussels within Scotland. The authors have therefore concentrated on the market requirements for 'in shell' mussels.

The 'in shell' market requires mussels that are black or dark brown in colour with thin shells and as high a meat yield as possible. The mussels must also be free of grit, mud and pearls. The UK market generally requires mussels that are at least 55mm long, but the French market will accept mussels of only 45mm (from their bouchot cultivation system). There is no minimum landing size imposed by SOAEFD - the market provides the only control.

All the information available to the authors indicates that the majority of the natural mussel beds in Scotland consist of large thick-shelled blue mussels which would only be suitable for the processing market. Many contain large quantities of pearls, which exclude them even from this market.

5.2. Catch Statistics The annual production figures for mussels in Scotland since 197 5 were provided on a statistical rectangle basis by the Marine Laboratory, Aberdeen, from the Scottish Office data base. The Scottish Office collects landings data for all wild marine fish and shellfish species via the Fishery Offices of the Scottish Fisheries Protection Agency. The landings are collated into a data base by month and statistical rectangle. A statistical rectangle is an area of sea 0.5 of a degree of latitude by 1 degree of longitude. At 60 degrees north this represents a square with sides of 30 nautical miles. The north south dimension of the rectangle remains 30 nautical miles throughout the Scottish Sea Fisheries Area, but, (because of the curvature of the earth) the east-west dimension increases as one travels in a southerly direction. No data are recorded within official records on an area smaller than a statistical rectangle. Some older figures for mussel landings were also extracted from SOAEFD paper records for comparison. The recent detailed data are given in Appendix 2, and summarised information is presented in Table 2a. Figure 2 presents the total reported landings of mussels in each statistical rectangle for the 20 year period 1975 to 1994.

These data indicate that the majority of landings in Scotland between 1975 and 1993 came from grounds on the East coast of Scotland. ·The landings data also indicate small sporadic landings from the West coast of Scotland; it is the senior author's opinion that most of these are farmed mussels that have been reported to the Fishery Office in error (farmed shellfish production figures are collated from questionnaires and published separately by the SOAEFD Marine Laboratory - see Section 6). However, some may represent opportunistic collection of naturally settled marketable mussels from buoys and other artificial structures, and those in the Solway Firth area in October 1994 probably refer to the opportunistic landings by brown shrimp dredgers of mussels from subtidal beds ( which were also reported in a SFPA questionnaire return). Most of the landings reported from the east coast were made from the Domoch Firth (which is now the largest single mussel producer in the UK, generating profits of £270,000 in 1992) and the Montrose Basin. The annual landings from these grounds are given in Table 2a and shown graphically in Figure 3. From these it can be seen that, after a small rise in the early 1970's, the landings declined rapidly to a mere 23 tonnes in 1984, before rapidly rising to a maximum production of 2,968 tonnes in 1993. Table 2b has been extracted from older SOAEFD records and added for comparison with the present-day situation. It presents some much earlier information on mussel landings in the late 18th century when the fishery was probably at its peak, and in the 1930s, when it was already in decline.

11 Review of the Exploitation of the Mussel, Mytilus edulis. in Scotland

Figure 2. Tonnage of mussels harvested by statistical rectangle, 1975-1994 (from SOAEFD data)

51 E2 E3 E4 ES EG E7 ES E9

s1·N

50 N

0 20 40 60 80 100 49 km 0 t so·N

48 0

45 (5.6}

58"N

4 57'N II

42 1.4

ss·N

55"N

38 0.2 rw s·w 5·w 3"W 2·w 1·w I

12 Review of the Exploitation of the Mussel, Mytilus edulis. in Scotland

Figure 3. Landings (tonnes) from the Montrose Basin and Domoch }1rth fisheries, 1975-1994.

500 Montrose Basin

400

300

200

100

2500 Dornoch Firth

2000

1500

1000

500

Table 2a. Mussel harvesting data (in tonnes, excluding cultivated mussels), 1975-1994. Dornoch Montrose Other east North coast West coast Total Firth Basin coast sites & Islands & Islands 1975 462.8 238.3 4.0 705.1 1976 575.6 172.2 1.9 749.7 1977 475.1 135.7 1.7 612.5 1978 804.7 94.4 22.9 922.0 1979 725.4 88.4 4.4 0.6 818.8 1980 398.4 87.2 0.2 40.5 526.3 1981 55.9 54.4 0.3 34.9 145.5 1982 26.1 23.9 50.0 1983 0.1 30.3 2.4 32.8 1984 23.1 23.1 1985 284.5 27.5 312.0 1986 1,320.8 11.3 0.3 0.5 1,332.9 1987 354.5 27.0 2.3 383.8 1988 1,196.9 23.8 0.9 1.6 1,223.2 1989 1,021.7 41.4 0.1 0.1 1,063.3 1990 1,453.6 14.7 0.1 1,468.4 1991 2,785.4 8.5 0.4 2,794.3 1992 2,386.4 581.8 96.9 3,065.l 1993 1,733.8 1,733.8 1994 1,153.5 2.0 1,155.5

Table 2b. Mussel harvesting records (tonnes), 1895-1900 and 1933-38. East Northern West Total East Northern West Total coast Isles coast coast Isles coast 1895 6,373.8 360.7 3,116.0 9,850.5 1933 3,661.0 49.4 639.9 4,350.3 1896 7,552.2 388.6 4,429.1 12,370.0 1934 3,146.4 52.1 686.8 3,885.3 1897 8,902.5 309.9 5,061.9 14,274.3 1935 2,833.8 . 199.1 334.4 3,367.3 1898 6,504.0 130.0 3,107.8 9,741.8 1936 1,752.1 96.5 215.5 2,064.1 1899 4,594.8 180.4 3,844.4 8,619.7 1937 1,829.3 93.8 293.2 2,216.4 1900 4,035.0 279.9 2,971.3 7,286.2 1938 1,783.8 48.3 241.0 2,073.0

13 Review of the Exploitation of the Mussel, Mytilus edulis, in Scotland

To understand the changing patterns of mussel landings illustrated in the above tables, it is necessary to look at the history of mussel fisheries in Scotland. Almost all the traditional mussel fisheries in Scotland were developed to produce bait for the small line fisheries for haddock. These small line fisheries declined following the development of the seine net fishery, and by the early 1980's the only commercial line fishery for haddock and cod in Scotland was based in Gourdon, Angus. With the decline in demand for bait, the mussel fisheries also declined.

5.3. The Dornoch Firth fishery The Domoch Firth mussel fishery was given by Robert the Bruce to the people of Tain (the Tain 'Common Good' Fund) in 1312. Following local Government reorganisation in the late 1970's, this historic right passed to the Ross and Cromarty District Council which now manages the fishery.

The Ross and Cromarty District Council sought to develop the mussel fisheries in the Domoch Firth as part of their Industrial Development initiative. A Fisheries Development Officer was appointed, one of whose tasks was to develop a sustainable fishery for mussels that were acceptable to the 'in shell' market. This has been implemented by having regular surveys of the Firth carried out to estimate the quantity and quality of the mussel stock available on each of the scalps (stony mussel beds). The results are used to determine future production levels and reseeding strategies. Currently the fishery is prosecuted by two small fishing vessels owned by the District Council, which work year round in the Firth, with most collection taking place in autumn and winter and grading taking place on board (see Figure 3 for monthly yields). Where necessary, mussel scalps are dredged to thin out mussels and to provide seed mussels (seed are usually less than 2 years old and 10-20 mm in shell length) for reseeding other areas of the Firth. Mussels have also been moved about within the Firth to enhance growth rates and meat yields. These practices are very similar to those that were used in the Dutch mussel fisheries (Korringa, 1976).

Figure 4. Monthly pattern of landings (in tonnes) from the Dornoch Firth Fishery, 1993-1994.

5.4. The Montrose Basin fishery The Montrose Basin Fishery is owned and operated by J & J Johnstone, Montrose. This fishery was largely prosecuted to provide bait for the Gourdon Line fishery for haddock and cod (activity is now very greatly reduced as a result of declining fish stocks). Some experimental work has also been carried out in Northwest Scotland on fattening mussels from the Montrose Basin. In 1992 a dredge fishery developed to provide mussels for a processing plant on the Wash, in England, but soon after it began it was realised that the Montrose Basin had been inadvertently included in an area where mobile gears had been banned by the provisions of the Inshore Fisheries (Scotland) Act (1984). It is possible that the rescheduling of this static gear reserve could be considered when the Act is next under review.

14 Review of the Exploitation of the Mussel, Mytilus edulis. in Scotland

Although there have not been any reported landings on record here since the dredge fishery ceased in 1992 (see Figure 3), local SNH and SFPA staff report that some local fishermen are still employed by J & J Johnstone to hand-gather a few bags a week at various times of the year. Since water quality here is poor, these mussels must be purified before they can be sold for the table (they may, however, be harvested for bait).

5.5. Other wild Scottish fisheries In addition to the two main mussel harvesting operations described above, it was considered possible that some mussel collection from the shore might also be carried out by individuals on a small scale elsewhere along the coast. The questionnaires circulated to SNH and SFPA area offices (see Appendix 1) were intended to draw on these officers' local knowledge and obtain their assessment of the extent to which this activity was known or thought to take place in their areas. The results demonstrated that mussel collecting activity outside the two main commercial fisheries described above was probably very infrequent, with most questionnaire responses indicating no local knowledge of commercial mussel collection, or at most a small amount of collection for personal consumption or fishing bait. All locations for mussel collection reported in the questionnaire returns are illustrated in Figures 5 and 6.

Some questionnaires reported a small amount of collection of mussels for personal use, either for the table or as fishing bait (primarily sea angling, and presumably for recreational rather than commercial line fisheries). This is probably a much more wide-spread, but a largely ignored or overlooked activity around the Scottish coast, although poor water quality should prevent collection for consumption in some of the more industrialised coastal sectors. Most SNH staff did not consider this activity was a problem locally, but some expressed concern about possible damage to natural heritage sites if large scale commercial collection was to take place.

SNH staff report the following sites being exploited in this way: • Green Scalp, Tayport Bay, NE Fife District: possible collection for sea angling bait. • Culbin shore SSSI, (Moray and Nairn District): on mussel scalps, about five local fishermen mainly active in summer - this was not considered to pose a threat to the nature conservation interest of the site. The tradition of local collection by Nairn locals seems virtually to have ceased, and the RSPB reportedly hold the commercial mussel fishing rights from Nairn to Burghead. • Several sites in the northern part of Wester Ross, including near Ullapool, Ardmair, Altandhu and (possibly) Enard Bay: reports of casual collection being carried out by 'travellers' for resale to local hotels throughout the year. • North Lochaber, Skye and Lochalsh: occasional and infrequent gathering of mussels 'for the pot'. • Western Isles: occasional and infrequent gathering of mussels 'for the pot'. No known activity was reported in questionnaires returned from other areas. No response was received from some SNH Area Offices (Argyll & Bute and Dumfries & Galloway), nor from any of the local sub-offices in Southwest Region, nor from the Orkney sub-office. It is assumed that the staff here also had no knowledge of activity in these areas.

SFPA staff responses were similarly sparse: • Bay of Nigg, near Aberdeen: mussels taken by casual visitors for sea angling bait. [Senior author's note: these records probably relate to the Dee estuary, since there are not thought to be mussels in the Bay itself.] • Loch Inchard and Laxford Bay, Sutherland: two full time commercial mussel collectors are thought to be active in the area, and about four people work each site. • Kyles of Bute, upper Loch Fyne (Otter Spit), Davaar Island and Loch Riddon: an estimated twelve collectors (reportedly social security claimants) take mussels commercially (and illegally), mainly between September and January each year. [Senior author's note: large quantities of seed

15 Review ofthe Exploitation ofthe Mussel, Afytilus edulis in Scotland

mainly between September and January each year. [Senior author's note: large quantities ofseed mussels were taken from Otter Spit in the late 1980s, from a site which was claimed to be part of the Crown Estate.] • Solway Firth (English side of Silloth): an attempt at dredging for sublittoral mussels had been undertaken by vessels based at Annan (normally engaged in the brown shrimp fishery). [Senior author's note: a cockle dredger based at Kirkcudbright was also involved.] This was considered to be a 'one off and targeted at a large bed of mussels which had resulted from a recent settlement. The fishery was stopped by the Cumbrian Sea Fisheries Committee as the mussels were below the minimum landing size imposed by local bye-law. Recent information was that the size of the bed was reducing as a result of starfish predation and erosion. No response was obtained from SFPA offices in the Western Isles or Scrabster. It is assumed that the latter office was covered by the response from Wick, and that there was no information on wild mussel collection from the former area.

5.6. Future projections There is a thriving national and European market for mussels, both good quality wild stock (preferably thin shelled and certainly without a high pearl content) and cultured shellfish. Processed cultured mussels are even being imported to the UK from outside Europe to meet the demand for a high quality product. In addition, the availability of European stocks of mussels has suffered from the virtual collapse of the Wadden Sea fishery and the subsequent introduction of more stringent management in bordering countries. This situation would appear to have considerably increased the scope for expansion of the industry in Scotland, both of adult mussels for the market and seed mussels for relaying elsewhere (particularly in England and Wales), and may have led to the reported interest in expanding the Scottish wild harvest in the early 1990s.

However, the scope for expansion of the Scottish fishery appears to be very severely limited by the Crown ownership of wild mussel stocks, the need for production and marketing of bivalve molluscs to meet the requirements of the EC Shellfish Hygiene Directive (see section 9), and the apparent inability of the aquaculture industry to meet its forecasts of increased production levels. Certainly, the first two of these factors means that there is presently very little scope for uncontrolled development of wild mussel fisheries.

Virtually all expansion of the fishery to new sites will be signalled well in advance by applications for Crown Estate Commission (CEC) licenses to dredge mussels. SNH and SOAEFD should certainly be consulted over any such applications, although the final decision on whether to grant the license will rest with the CEC. For example, experimental dredging in the Cromarty Firth was carried out under license from the CEC (and the mussels taken at the time appeared to be suitable for the market). Other mussel dredging operations known by the senior author to have been carried out in the past in Loch Etive and Loch Fyne did not have CEC permission and were therefore illegal and quickly discontinued. Exceptions may occur where other landowners or communities demonstrate conclusive proof that the ownership of mussel beds has been transferred to them, but there is apparently no existing register or record of such transfers (other than for the Domoch Firth Fishery).

The other means of monitoring any possible expansion of mussel fisheries will be through an examination of the present classification of bivalve mollusc production areas (see Appendix 3), with particular regard to those areas which are identified as having been classified for mussel production (bearing in mind that most, but not all, of the west coast and island sites will have been classified for aquaculture rather than wild mussel dredging). As is the case for CEC licenses, SNH should presumably be consulted on any proposals to classify new bivalve mollusc production areas for mussel harvesting, and will therefore be forewarned of any proposed introduction of wild mussel exploitation to new sites.

16 Review of the Exploitation of the Mussel, Mytilus edulis in Scotland

Figure 5. Reported mussel harvesting activity (arrowed), Scottish Natural Heritage staff.

61"N 7*W s·w s·w 4·w 3"W

SO*N t 0 20 40 60 80 100

km {}

NORTHERN ISLES ~ p- (Orkney) ~

59"N NORTHWEST REGION ifl,f K:rkwall Occasional collection for the pot

WESTERN~ ISLES NORTH EAST 58"N REGION

~STN

SOUTH EAST ! REGION i I i I f-ss·N I I I

SOUTHWEST REGION 55*N

17 Review of the Exploitation of the Mussel, Mytilus edulis. in Scotland

Figure 6. Reported mussel harvesting activity, Scottish Fisheries Protection Agency staff.

rw s·w s·w 4"W 3"W 2·w 1·w 61"N

N t 60"N 0 20 40 60 80 100 E--3 E---3 km

59"N

no collection

58"N no collection

no mussels

57"N

56"N

12 collectors in district 55"N

18 Review ofthe Exploitation ofthe Mussel, Mvtilus edulis in Scotland

6. AQUACULTURE

Following the expansion of other shellfish fisheries in Scotland during the 1960's, the SOAEFD Marine Laboratory, Aberdeen reviewed the possibilities for widespread mussel fisheries. Mason (1973) concluded that most of the wild mussels in Scotland were unsuitable for the higher-priced 'in shell' market. The Laboratory did, however, see a future for the production of fanned mussels in Scotland and carried out much of the pioneering work into mussel fanning (Mason 1972, Mason and Drinkwater 1981, Drinkwater 1987). The industry has developed slowly since then, not because of an inability to produce high quality fanned mussels, but due to the general structure of the mussel fanning industry in Scotland. The yield from the dredge caught east coast wild mussel fishery still greatly exceeds that from the aquaculture industry.

The Fish and Shellfish Fann Registration Scheme (SOAEFD 1995) provides the framework for an annual survey of production. This is based on an annual survey questionnaire of all registered Scottish shellfish fanning companies and provides the most comprehensive analysis of the production of fanned shellfish in Scotland. A total of 196 companies operating 324 active sites (197 of which produced shellfish) returned questionnaires for the year 1994. Of these, some 36 companies produced 716 tonnes of mussels, with an average value of £7 50 per tonne ( see Table 3 ). This is a 1% increase on the 1993 figure, despite significant losses due to eider duck predation for a few companies, but well below the peak production of 1,024 tonnes in 1991. Of the 36 companies which made production returns, 16 were in Highland Region and ten in Strathclyde, with smaller numbers in the Western Isles, Shetland and Orkney. These companies are mainly very small, with a production of less than 10 tonnes a year. Three companies produced 34% of the total yield.

Table 3. Farmed mussel production for the table by region 1993-1994 (from SOAEFD 1995) 1993 1994 Highland 261 199 Orkney 50 27 Shetland 2 19 Strathclyde 338 411 Western Isles 58 60 Total, all Scotland 2702 716 (figures are rounded to the nearest tonne)

Table 4. Farmed mussel production for all Scotland, 1986-1994 (from SOAEFD 1995) 1986 1987 1988 1989 1990 1991 1992 1993 1994 For the table 262 271 384 346 462 1,024 923 708 716 For ongrowing 0 1 3 3 30 73 131 12 (figures are given to the nearest tonne)

It is not possible to identify the precise locations of the farm sites from the data presented in the Annual Production Survey. The data held by Scottish Office are confidential and under the terms of the Registration Scheme may only be used for disease control. Most (but not all) shellfish farms operate on sites leased by the Crown Estates, so it is theoretically possible to determine precise site locations from the lease information held by the Crown Estates Commissioners. SNH are routinely consulted on the issuing of shellfish fanning leases by the Crown Estate. Using the data held by SNH it would be possible to visit shellfish farm sites and attempt to assess their activity. This would, however, be a very time-consuming procedure and was outside the scope of this study.

Much public funds (particularly through the Highlands and Islands Development Board and the Sea Fisheries Industry Authority) have been invested in researching the market for Scottish fanned

19 Review ofthe Exploitation ofthe Mussel, Mytilus edulis in Scotland mussels. The results have indicated that the quality of Scottish farmed mussels is generally considered to be superb, and that barriers to the expansion of the industry are more related to its fragmented nature than to the quality of its product. However, the forecasts of farmed production made by these organisations have been very over-optimistic.

Eric Edwards and some west coast mussel farmers (pers. comm.) consider that predation by eider ducks is one of the single greatest impediments to increased yields of farmed (raft and line) mussels in Scotland. Despite extensive studies on the subject, many farmers have been unable to resolve this problem. As a result, the Scottish industry cannot compete with the much lower cost bottom-farmed industry in England.

In relation to the above points (although irrelevant to this study), it would be interesting to determine whether long lines, which cannot be protected effectively from eider predation, are still being used in preference to mussel rafts with vertical underwater nets and appropriate scaring techniques, as recommended by Institute of Aquaculture (1989) and Milne and Galbraith (1986). It is also important to determine whether these techniques for protecting rafts are actually as effective as implied by these references (comments from mussel farmers to the senior author suggest not, and that a move from long lines to rafts will not solve the eider predation problem). Other recommendations in loA (op. cit.) for additional study in this area included further research into the relationship between eider ducks and shellfish farms, including the relationship between eiders and wild mussel populations; investigating whether annual fluctuations in the severity of eider problems at farms are related to changes in the availability of natural food; and studies into how individual birds utilise farms.

20 Review ofthe Exploitation ofthe Mussel, Mvtilus edulis in Scotland

7. ENVIRONMENTAL CONSIDERATIONS

7 .1. Environmental role of mussels Mussels, especially where they occur in large beds, are keystone consumers and bioturbators, form an important part of the food chain, and provide a specialised habitat for a diverse community of organisms (Dankers and Zuidema 1995, Dankers 1993, Seed 1996, Suchanek, 1985). They are primary herbivores living directly off phytoplankton filtered from the water column (and therefore compete with other suspension feeders). They are also important prey species for a number of invertebrate and vertebrate predators. Their high levels of production have been compared to that of tropical rainforests and kelp beds (Leigh et al. 1987, cited in Seed op. cit.).

The main natural invertebrate predators of mussels are the shore crab Carcinus maenas, the dog whelk Nucella lapillus ( especially where mussels occur on rocky shores), and starfish (particularly Asterias rubens) which attack sublittoral mussel beds and suspended mussel cultures which touch the seabed and, during neap tides, lower littoral populations (particularly seed mussels). Among vertebrates, the main predators in Scottish waters are eider ducks Somateria mollissima and oystercatchers Haematopus ostralegus. Oystercatcher predation is restricted to mussels that are exposed at low water, and can take up to 30-40% of large mussels on a bed each year (Dankers and Zuidema 1995, Zwarts 1991). Eiders feed by diving and can exploit sublittoral mussel beds as well as intertidal beds during high tide. Mollusca form more than 80% of all food items for this species in the Baltic and North Sea (Kallenborn et al 1994 ). Extensive work has been carried out on the biology of eider ducks by the University of Aberdeen's Zoology Department. Newly settled mussel beds also attract large numbers of feeding fish, such as plaice Pleuronectes platessa and flounder P .jlesus, when covered by the tide (S.Fowler and D.McKay, pers. obs. and Dare 1976).

As well as being predators, eiders have another, indirect, impact on mussel quality, and hence potential mussel fisheries. Many wild mussels in Scotland have high numbers of pearls making them unsuitable for the market. This high pearl loading is almost certainly related to the old age of many of these mussels, since Fernandes & Seed (1983) found that the incidence of pearls in mussels in North Wales increased with age. Many agents have been found to promote pearl formation in mussels. Stunkard & Uzmann (1958) found that digenean parasites of the eider duck and black scoter, using the mussel as an intermediate host, stimulated the host mussels to produce pearls. Similarly, Lauckner (1986) linked the very high incidence of cysts of the parasitic trematode Hismasthla elongata in mussel muscle tissue in the Wadden Sea to the greatly increased populations of aquatic birds in the area following the foundation of the National park Wattenmeer.

As well as providing a food source, mussel beds also provide a habitat for other invertebrates. Their species richness and diversity is correlated to the age, structural complexity, tidal level and size of the mussel bed (Seed 1996). Up to 56 species have been recorded in a M edulis bed in North Wales (Lintas and Seed 1994), 96 species in a M edulis bed in the Wadden Sea (Dittmann 1990), 99 species in a southern France bed of the very similar M galloprovincialis (Tsuchiya and Bellan-Santini 1989), and about 270 species in a North American M ca/ifornianus bed (Suchanek 1979). In large inlets dominated by mobile substrates, mussel beds are often the major hard substrate habitat in the area, and the live mussels and the dead shells trapped in the byssal web provide habitat for a wide range of gastropod molluscs such as Lepidochitona cinereus, Acmaea (Colisella or Tectura) tessulata and Littorina spp., which live by grazing on hard substrates. The mussel shells also provide a settlement site for barnacles. The byssal net provides crevice habitat for extensive populations of annelid worms such as Nereis. Cultivated mussel ropes also provide substrata for some of these communities and additional subtidal species, such as tube worms and sea squirts (Drinkwater 1987), particularly on sections where mussels have not settled successfully. Overall, mature intertidal Mytilus edulis beds,

21 Review of the Exploitation of the Mussel, Mytilus edulis, in Scotland with their wide range of associated species and habitat diversity (including tide pools), are potentially of high marine nature conservation interest and importance for feeding birds.

Smaal (1991) describes the impacts of natural mussel beds on the coastal ecosystem, with regard to their uptake of particulate material and release of inorganic nutrients, and hence effects on the production and turnover of the phytoplankton. The stabilising influence of these benthic suspension feeders on the energy flow of the first and second trophic levels is noted, and the possible differences between the ecological effects of natural mussel populations and those in suspended culture (see following sections). Dankers and Zuidema (1995) list a number of papers concerning the role and function of the Wadden Sea mussel beds in breaking down organic matter and in the cycle of production and breakdown of organic matter, including the stimulation of denitrification and the possible reduction of eutrophication levels. However, more research is needed to solve these questions (Asmus and Asmus 1991).

The role of newly settled spat in forming seed mussel beds and accumulating and releasing mussel mud and other sediments has already been noted (Section 4.3). It seems very likely that the presence of large mussel beds, particularly where these are permanent, will have a significant influence on local hydrology in estuaries. However, no literature dealing with this subject could be identified.

The environmental impacts of benthic mussel fisheries and farming (suspended culture) differ, and are considered separately below.

7 .2. Environmental impacts of dredging wild mussel beds and relaying seed Dredging mussel beds, either for collection of seed for relaying or during final harvesting, disturbs the microhabitat by breaking up the beds and removing the mussels. Without the live mussels to produce a byssal web, the dead shells and other material trapped in it get washed away or buried in the sand and mud. The deep muddy sediments formed from pseudofaceces which usually accumulate beneath the mussel bed are also released by dredging, suspended in the water column and redeposited elsewhere. This may cause clogging and smothering of other benthic species and adjacent areas of mussel beds. Jim Munford (pers. comm.) reported the die-off of a mussel bed at La Spezia, Italy, due to the redeposition of mussel muds released during channel dredging operations and smothering of the remainder of the bed. Korringa (1976) records the use of chain harrows to clear mud from open lays in Holland, prior to restocking with seed. However, it should be noted that, in many areas, autumn storms have the same effect, by dislodging carpets of seed mussels which have become established during the spring and summer and releasing large quantities of sediments (Dare 1973). Literature (e.g. Dankers 1993) on the Wadden Sea fisheries notes that the environmental impact of dredging seed or larger mussels from unstable intertidal or sublittoral beds is not serious. However, the destruction of stable, mature intertidal beds, which are long-lasting and contain a wide range of mussel age classes, has severe ecological effects.

At present, wild mussel fisheries are restricted to two sites on the east coast of Scotland, in the Domoch Firth and Montrose Basin (see Section 5). Both sites are listed in the Nature Conservation Review (Ratcliffe 1977) and are of international importance for nature conservation (Prater 1981). Most of their intertidal area is designated as Sites of Special Scientific Interest and proposed as Special Protection Areas (under the EC Birds Directive), Wetlands of International Importance (Ramsar Convention) and Special Areas of Conservation (under the EC Habitats Directive). The Domoch Firth is a part of the Moray Basin, Firths and Bays Important Bird Area (IBA, Pritchard et al. 1992), a complex of adjacent firths, bays and inshore waters which forms an integral unit for internationally important populations of wintering and passage waterfowl. The Montrose Basin is an Important Bird Area with some internationally and nationally important wintering bird species. These

22 Review of the Exploitation of the Mussel, Mytilus edulis. in Scotland designations require environmental quality to be retained, however this should not preclude the maintenance of sustainable yields of bivalve resources in well managed fisheries (e.g. Dankers, 1993).

Mussel populations in these two Important Bird Areas are of particular significance to those species of birds which are most heavily dependent on mussel beds for food; primarily the diving ducks - eiders, common and velvet scoters (Melanitta nigra and M.fasca), and oystercatchers. The Moray Basin IBA is of international importance for wintering populations of all of these species ( 1,450, or 4% of British population of common scoter; 850 or 28% of velvet scoter; 2,240 or 5% of the British population of eider; and 11,500 or 4% of British and 1% of East Atlantic Flyway populations of oystercatchers) and for several other wintering seaduck (e.g. over 8,200 long-tailed duck, or 41 % of the British population). The outer Dornoch Firth and Loch Fleet area is also important for large flocks of moulting eider (up to 2,000) in late summer/autumn. The Montrose Basin is of national importance for its wintering populations of eider (2,360 or 5% of the British population) and oystercatcher (3,550 or 1% of British population) and for a large breeding colony of eider (400 pairs and increasing, or 2% of the British population). (All the above figures are five year averages from 1985/86 to 1989/90.)

Current mussel extraction rates, particularly from the Domoch Firth, are higher than those of the 1970's and 1980's but lower than those seen earlier in the century when haddock lining was widespread. The extant mussel fishery in the Domoch Firth does not simply exploit the wild beds, but seeks to enhance them by reseeding programmes, so that the removal of some mussel bed habitat is replaced by creating new beds. Most of the invertebrate species which coexist with the mussels in this habitat are short-lived. The harvesting programme is unlikely, therefore, to pose a threat to the long term survival of species in that area, although the dredging operation will undoubted destroy the individual populations in the mussel bed that is being dredged.

Considering the impacts on vertebrate predators, the dredging operations take place at high water, so will have little direct effect on oystercatchers which feed at low water. Indeed, it may be argued that the dredging operation may, in the short term, increase food availability to the birds by breaking up the byssal web and detaching mussels, although specialist mussel feeders probably need little artificial assistance of this kind. Eider and other diving ducks which feed at high water may experience some disturbance from dredging vessels, but birds rapidly exploit the increased food supply provided by fishing operations. The authors have no direct observations of eiders following mussel dredgers, but have observed eiders following a suction dredger that was fishing for razor shells Ensis ( of course this dredging will have exposed bivalves which were previously buried in the sediment and presumably mainly unavailable to diving ducks).

However, Meikle and Spencer (1992) report that proposals for bottom mussel cultivation on the Culbin Sands, Morayshire, (an RSPB reserve and a Site of Special Scientific Interest) raised concern over the potential disturbance to waterfowl and conflict with feeding wader populations, such as oystercatchers, and the proposal was withdrawn. These authors and Pritchard et al. (1992) highlight the importance of east coast sites, particularly the Moray Firth, for their internationally-important seaduck populations. They note the potential for conflict between intensification of shellfish harvesting or cultivation and wader and seaduck populations.

Most work on the environmental and nature conservation impacts of mussel fisheries and bottom culture has been carried out in the Wadden Sea, which supports a very extensive mussel fishery in the Netherlands, Germany and Denmark (see section 8). The literatµre on the subject, much of which was kindly identified for the authors by N. Dankers and C. Smit, is very interesting and potentially relevant to the harvesting and relaying for harvest of wild mussels in Scotland. However, it must be stressed that the Wadden Sea is a very much larger-scale fishery, operating over a much wider area which supports many more seabirds, than is the case for the Scottish mussel fishery sites.

23 Review of the Exploitation of the Mussel, Mytilus edulis, in Scotland

Additionally, while mussel beds are quite widespread through the Moray Firth complex, the commercial fishery is restricted to the Dornoch Firth, representing only a small part of the habitat.

Laursen and Frikke (1987), in their preliminary study of eider populations in relation to the Danish Wadden Sea mussel fishery, noted that the increase in mussel harvest from 1983 to 1986 coincided with a decrease in the proportion of eider using the inner Wadden Sea from 75% to 57% of the area population. The decline was most pronounced in winter when food demand is at its height. Total numbers of eider had also fallen, with their almost complete disappearance from the most intensively fished areas. A later paper by Laursen et al. ( 1990) confirmed these observations, adding that a decrease in numbers also occurred during the summer moult, and also noted a change in diet composition and prey size as mussel stocks were depleted. Body weight also decreased significantly. They concluded that it is highly probable that the mussel fishery had caused the observed changes in the condition and status of eiders, since alternative explanations (severe winters, hunting activity and population changes outside the Wadden Sea) could not account for the observed changes. This was only one of several species dependent on mussels which had been affected.

Hulscher et al. (1993) report that excessive commercial fishing effort combined with poor spatfall reduced the abundance of cockles and mussels in the Wadden Sea in winter during the early 1990s (see Smit 1994 for details of bivalve stocks and bird counts). They consider this to have resulted in a decrease in the winter population of oystercatchers in the area, with the birds having switched to alternative prey items of smaller size which are found at lower densities. This means that the birds need to spend more time feeding to collect the amount of food they require, and have to move to alternative areas inland when weather conditions reduce the feeding time available during low tide. Smit ( 1995) attributes a decline in Dutch Wadden Sea eider numbers to 40,000 birds, or one third of the 'normal' figure, during the 1992/93 winter to the shortage of mussels and cockles caused by poor spatfalls and intensive fishing.

Dankers and Zuidema (1995) describe the impacts of mussel cultivation on bird populations (mortality and decreased breeding success) which have resulted from bad spatfalls and over exploitation of bivalves in the Dutch Wadden Sea. They consider that the relaying and bottom culture of mussels in the area since 1949 has generally increased the mussel biomass and hence the consumption of phytoplankton in the area, resulting in a food shortage for several animal groups. (In a year with average population size, mussels can filter the equivalent of the western Wadden Sea within one week, removing almost all suspended organic and inorganic matter.) However, the potential primary production induced by nutrient release from a mussel bed exceeds its uptake of phytoplankton (Asmus and Asmus 1991). Additionally, a wide range of organisms can take advantage of the increased quantities of mussels, including eider ducks and oystercatchers. The impact of dredging of seed mussels is considerable, but not of great concern to nature conservation interests unless it results in the destruction of intertidal beds. These intertidal areas are of particular importance for feeding waders, with different species taking different sizes of mussels and other associated invertebrates. Mussel beds may contain more than 200 birds per hectare, and beds occupying 3-4% of the intertidal contain about 25% of all waders at low tide (Zwarts 1991). Some intertidal beds (probably only a very few) also have the potential to develop over a period of several years into mature mussel beds with a complex structure and marine nature conservation interest where they provide the only hard substrata on sediment shores. Overall, the positive and negative impacts of mussel culture and harvesting are dependent both on natural and human influences, and it is possible to take measures which will partly overcome the detrimental effects of this activity. Dankers and Zuidema' s ( 1995) recommendations include the improvement of seed fishing practices with the banning of removal of intertidal seed, and the establishment of culture lots in sheltered areas to reduce the need for seed to provide the required fishery yield.

24 Review of the Exploitation of the Mussel, Mytilus edulis. in Scotland

Table 5. Ecological effects of mussel fisheries in the Wadden Sea (from Dahl et al. 1994)

Intensive fishery for mature mussels and seed mussels results in: • loss of old mature mussel beds with associated bottom fauna • food shortage for birds in years with low mussel stocks Establishment of culture lots: • eliminates natural benthic communities • has qualitative and quantitative effects on plankton and sediment ecology of their surroundings. Fishing gear damages the bottom fauna and seagrass vegetation.

As a result of the decreasing fishery yields and the increased awareness of the environmental effects of the fishery in an area of international nature conservation importance, the authorities decided that new regulations were necessary for the Wadden Sea (Dahl et al. 1994). Large intertidal and subtidal areas were closed to all kinds of mussel fishery and culture lots in 1993. The areas closed permanently included 26% of the area inside the islands of the Netherlands, with a possible extension up to 40% after evaluation in 1997, and additional closures to ensure that 60% of the mussel and cockle stock normally used for bird consumption is left for the birds (it is assumed that the additional 40% necessary will be provided by switching to alternate prey species). The food requirements of bird populations are based on inventories carried out in May (Smit 1995). Some of the licensed culture banks in Schleswig-Holstein are located within the most strictly protected areas (zone 1) of the Wadden Sea National Park and have ceased to operate. These may be replaced with an equivalent area elsewhere, but the total designated culture lot area may not be increased above the 1991 level. Subtidal seed collection rights inside the Park were retained by mussel growers, although more strictly controlled (Borchardt, 1995), and other fisheries continued. Forty-one per cent of the Niedersachsen culture lots is in similarly protected zones, but only 25% of the total Wadden Sea area of this region has been closed since establishment of the National Park in 1986 (this was of minor importance for mussel fisheries due to poor water quality). Management of the mussel fishery here is still under discussion, but may soon also be more tightly controlled. The closed area in Denmark makes up 46% of the area inside the islands and 23% of the total nature reserve. The closures of the above areas and the decline in shellfish stocks which led to these management decisions may well have an impact on the European market for dredged mussels (and cockles), and hence demand for new sources of seed and marketable shellfish from Scotland.

7.3. Environmental impacts of suspended mussel culture Mussel farming in Scotland is all carried out in suspended cultivation either on rafts or longlines. The mussels are generally collected in situ by settlement from the plankton and grown on the collecting ropes until at least some of them have reached market size. The ropes are then stripped and the undersized component tubed and resuspended in the water column. Drinkwater (1987) gives a useful overview of shellfish cultivation methodology.

The Institute of Aquaculture ( 1989) presents a detailed review of the impacts of fishfarming in Scotland, including the effects of shellfish mariculture on birds, the water column, sediment and benthos, and should be consulted for more information. This source was also used by Meikle and Spencer (1992). An earlier and less detailed assessment by Blake (1983) for the Nature Conservancy Council is unpublished. Most of the information presented below is summarised from the Institute of Aquaculture report, together with some additional notes based on the authors' personal knowledge.

Because cultivated mussels are effectively grown in a three dimensional array, it is possible that mussel farming could provide serious competition for other wild filter feeding animals in the area around the farm. Although Jones (1981) found no significant change in the phytoplankton population of water passing through mussel rafts in Caol Scotnish, Loch Sween, later anecdotal reports from this very enclosed location were that a large increase in the stocking rate of mussels resulted in greatly

25 Review ofthe Exploitation ofthe Mussel, Mvtilus edulis in Scotland very enclosed location were that a large increase in the stocking rate of mussels resulted in greatly depressed growth rates due to lack of phytoplankton, with mussel farming eventually being discontinued here and moved to a location with better water exchange (S. Fowler pers. comm.). This was attributed to the very high filtration rate of the mussels in a relatively small inlet. Tenore et al (1985) estimate that over 80% of the water volume of the Ria de Arosa is filtered daily by mussel farms, but this is an extreme example where shellfish rafts cover more than 10% of the water surface area (the level of cultivation in Caol Scotnish was probably quite similar, since a large proportion of this shallow but steep-sided inlet was occupied by buoyed mussel lines stretching from shore to shore, S. Fowler, pers. ohs.). Dankers (1993) also notes that phytoplankton availability in an estuary can determine mussel yield and quality, and that the carrying capacity of the Eastern Scheidt for mussel culture had been reached.

However, most Scottish farms are small and therefore unlikely to produce serious competitive pressure on wild filter feeders, unless in similar locations to that in Caol Scotnish where the production of the farm itself in an area of poor water exchange was affected to such an extent that production was discontinued. Table 6 (from Institute of Aquaculture 1989) gives details of the quantities of nutrients removed from coastal ecosystems by mussel farming.

Table 6. Removal of carbon, nitrogen and phosphorous from coastal ecosystems by mussel farming (from Institute of Aquaculture 1989) Species and system Nutrients removed {kg/tonne production) Reference Mytilus edulis (rafts) 32.5 kg Carbon 6.6 kg Nitrogen Rodhouse et al (1985) [ 17.4 kg Carbon 3.5 kg Nitrogen]* Mytilus edulis (long-lines) 0.5 kg Phosphorus Larsson (1985) * These bracketed figures take into account the input of nutrients to the local environment as seed mussels. If seed mussels are collected locally, the former estimates of nutrient removal are correct.

Mussels in suspended cultivation can, as with wild mussels, produce large (if not 'tremendous' - Tenore and Gonzalez (1975) cited in Blake 1983) quantities of faeces and psuedofaeces - far more than other molluscs. In wild populations this is manifested by the presence of 'mussel mud' beneath the mussel bed, and similar deposits of soft mud are found beneath mussel ropes and cages where tidal streams do not carry these away (S Fowler pers. obs. and confidential internal Nature Conservancy Council reports on fish farm surveys carried out in the Western Isles in 1983).

The Institute of Aquaculture ( 1989) notes that it is difficult to interpret the widely varying estimates of faecal and pseudofaecal solid waste production from mussel farms. Tables 7 and 8 (from IoE 1989) give some examples. Eric Edwards (pers. comm.) considers that no more recent studies have been published. The picture is complicated by the fact that a significant proportion of the solid waste is ingested by other epifauna living on the mussel ropes (Tenore et al 1985 suggest that, although up to 35 g carbon/m2/24hrs is produced by mussel rafts in Spain, only 0.5~2.5 g carbon/m2/24hrs actually reaches the sediment). However, studies at a sheltered site in Sweden demonstrated that the benthic communities beneath a newly established mussel farm changed to those characteristic of organic enrichment within 6-15 months, with the zone of effect extending 20m from the farm. There was only minor recovery 12 months after cessation offarm operations (Mattsson and Linden 1983). Similar effects have been recorded in the Ria Arosa and under mussel longlines in New Zealand (Tenore et al 1985, Kaspar et al 1985). Mussel mud is enriched with carbon and nitrogen (in comparison with natural fine sediments, Kautsky and Evans, 1987) but, unless extremely intensive shellfish farming takes place, the benthic enrichment effects of mussel lines and rafts in Scotland are likely to be very localised.

Other materials deposited on the seabed beneath mussel lines include large quantities of dead and detached shell (which are usually quickly buried in the mussel mud), and the remains (dead and

26 Review of the Exploitation of the Mussel, Mytilus edulis. in Scotland living) of other epibiota which are associated with the mussel ropes. Thus, many of the mussel pseudofaeces ingested by other biota will eventually contribute indirectly to the accumulation of organic material on the seabed beneath the farm.

Table 7. Faecal waste production and sedimentation from shellfish farming (from Institute of Aouaculture 1989) Species and system faecal production Reference Mytilus galloprovincialis 14.3-149 .3 mgDW/individual/24h Arakawa et al ( 1971) Mytilus edulis (natural shore 1.76 gDW/gDW mussel/yr Kautsky and Evans (1987) population) 0.13 gC/gDW mussel/yr 0.0017 gN/gDW mussel/yr 0.00026 gP/gDW mussel/yr M. edulis (rafts) 9.5 kg carbon/m2/yr Rodhouse et al ( 1985) 1.1 kg nitrogen/m2/yr M. edulis (long-lines) 0.88 kg carbon/m2/yr Rosenberg and Loo ( 1983) M. edulis (rafts) 27 g carbon/m2/24hr Cabanas et al (1979) M. edulis (long-lines) 2.4-3.3 g carbon/m2/24hr Dahlback and Gunnarsson (1981) 1.7 (reference station) M. edulis (rafts) 0.5-2.5 g carbon/m2/24hr Tenore et al (1985)

Table 8. Sediment accumulation-below shellfish farms (from Institute of Aquaculture 1989) Species and system water depth current velocity sediment accumulation Reference Mytilus edulis 11-13 m 'very weak' 7-30cm Weston (1986) M. edulis (long lines) 8-13 m - 3 cm/s 10-15 cm Dahlback and Gurtnarsson (1981) M. edulis no data > 1 cm/yr Misdorp et al ( 1984) M. edulis (rafts) >15m up to 200 cm/s no sig. biodeposits, Rodhouse et al mussel shells present (1985) M. edulis 'strong currents' no. sig. biodeposits, Earll et al ( 1984) (2 long lines, 3 raft sites) mussel shells present

Large quantities of mussels in cultivation, particularly in areas where they greatly increase the total biomass of this species in enclosed bodies of water, may have a significant effect on the composition of zooplankton by competing for phytoplankton, removing zooplankton in pseudofaeces, and contributing very large quantities of planktonic larvae during spawning. Where the production of mussels is not particularly high, as on the west coast of Scotland or in Killary Harbour, Ireland (Ryan et al 1986), although Mytilus edulis larvae may numerically dominate the zooplankton during spawning, they do not contribute a large amount to the total zooplankton biomass or significantly change its overall composition. However, in the Ria Arosa in Northwest Spain, rather than the usual dominance by copepods, the zooplankton is dominated by the larvae of the small crab Pisidia longicomis, dominant as adults in the mussel epifauna (Alvarez-Ossorio 1977, Corral and Alvarez Ossorio 1978).

Mussels in suspended cultivation are widely predated by eider ducks. The eiders remove and eat mussels, causing severe losses to the farmer. The losses are exacerbated by loss of uneaten mussels which fall from the ropes when the byssal attachment of the mussel clumps is disturbed by the removal of some of the clump by the eiders. Up to 2.7 kg of mussels per day per bird can be lost from mussel lines. Detailed studies on the interaction of eiders and mussel farms have been carried out by Milne and Galbraith ( 1986) and Galbraith ( 1987). Shooting was the most common method of killing eiders reported by the Institute of Aquaculture (1989), which noted that mussel long-lines are almost impossible to protect, but rafts can be protected from eider predation by underwater nets and scaring

27 Review of the Exploitation of the Mussel, Mytilus edulis. in Scotland

techniques. However, as already noted, many mussel farmers say that these techniques do not work as well as implied and consider that rafts do not offer significant advantages over long-lines with regard to control of eider predation.

Mussels may also have a detrimental effect on other fish fanning developments. Bruno (1989) reports an unusual occurrence of autumn settlement of post-veliger mussel larvae directly onto the gill filaments of farmed Atlantic salmon smolts recently transferred to net cages. This resulted in high mortality rates and very poor growth for the surviving fish stock, which was heavily infested. He also notes that significant fouling of cage nets by Mytilus edulis causes problems for farmed fish through reduction of water exchange through the nets. Regular changing of nets is required, particularly through the summer months, to avoid this problem (Bruno 1987).

7 .4. Environmental effects of hand collection Historicaliy, huge quantities of mussels were collected by hand (including raking from sub littoral beds) from all around the Scottish coast in order to provide bait for line fisheries and food (see Table 2b). The environmental effects of removing such large quantities of mussel by hand, including disturbance to shore birds and littoral habitats, must have been significant in at least some areas, but are unrecorded. Today, there is very little collection underway except in a few locations for sports angling bait, for personal consumption, occasional illegal collection (see section 5.5) and collection in the Montrose Basin fishery. The likely environmental impacts of this very limited activity are presumably proportionately small, although not studied or recorded for the UK.

Relevant studies carried out elsewhere are described in Siegfreid (1994). For example, there is a major intertidal 'fishery' by hand collection for mussels in South Africa, centred on the brown mussel Perna pema (which takes two to three years to reach a collectable size). Up to 12 tonnes of mussels are collected by subsistence gatherers per kilometre of coast in south-east South Africa, and more than 5,500kg/km of shellfish are estimated to be removed over a 1OOkm length of rocky coast in Transkei. It is noted that people are much more efficient harvesters than are the natural shore predators (there is no refuge in large size), and more destructive than short term events of bad weather and rough seas. Hence, large-scale modification of natural communities may be caused by collecting activities. Not only are beds or clumps of mussels and other filter feeders (including oysters and tunicates)

considered to be important as refuges and nurseries for other invertebrates in these areas 1 but their removal can have significant impacts on community structure. There is also evidence that the impact of mussel collection has resulted in a decrease in abundance and maximum size of P. pema. In some locations the species may only persist in the intertidal because of the presence of large unexploited subtidal populations down to a depth of 16m which act as a source of recruitment. This publication also reviews the historical evidence for decreased size structure and abundance of several exploited species of intertidal molluscs having taken place thousands of years ago; this despite the seasonality of collection.

Hockey (1987), cited in Siegfreid (op. cit.) considered that one of the factors which could have contributed to the extinction of the Canarian black oystercatcher Haematopus meadewaldoi may have been intensive exploitation of intertidal organisms. The limpet Patella canedei is still locally extinct as a result of this activity. Siegfreid notes that there is no evidence for subsistence collection having resulted in the global extinction of any alga or invertebrate. Collectors prey-switch long before this

might occur1 and these species are generally widely dispersed with refuge populations for recolonisation. However, it is considered that there is a need for information on minimum viable populations sizes for prey species, and better information on scale of collection. Lack of historical records1 commercial confidentiality and the illegal nature of much collection makes such data very difficult to obtain. The publication concludes with a wide-ranging assessment of management options for such fisheries.

28 Review of the Exploitation of the Mussel, Mytilus edulis. in Scotland

8. COMPARISONS WITH ELSEWHERE IN EUROPE

The senior author considers the UK fisheries to be the only commercial truly wild European mussel fisheries still in existence. In addition to those described for Scotland, there are important (and much larger) historic fisheries at various locations around the English and Welsh coast (e.g. Dare 1980). In addition a large mussel fishery has developed in Lyme Bay in recent years. Elsewhere in Europe, major mussel fisheries occur in Spain, in the Dutch and German Wadden Sea, and in Ireland. These are also much larger than the Dornoch Firth or Montrose Basin fisheries. However this large scale mussel production (even in areas of traditional natural beds) is now considered so reliant on relaying seed that it can be considered virtually as farming (Dankers 1993 suggests that only 5% of marketable mussels are now fished from natural beds in the whole of the Wadden Sea). The Danish fishery (now largely closed due to failure of spatfall and over-exploitation) was not so heavily reliant on relaying of seed onto culture areas as those in the Netherlands and Germany, but little information on the methodology which was used here could be identified.

A full review of the various methods used to farm mussels in Europe (excluding Ireland) is given in Korringa (1976). Although produced some time ago, the basic principles of the farming methods in the various countries is still valid, though in many countries the production process is much more mechanised. There therefore seems little point in producing a full review of the farming methods used in the various countries; this review will simply highlight the similarities and differences in the various methods and their relevance to the Scottish situation.

8.1. England, Wales and Northern Ireland Extensive mussel beds in England and Wales yielded about 90% of the UK landings in the early 1970s (Dare 1980). Some seed has, in the past, been taken from Scotland to relay on commercial beds in England and Wales. Up to date information on these mussel stocks should shortly be available in the minutes of a joint meeting of the Ministry of Agriculture, Fisheries and Food and Sea Fisheries Committee Mussel Working Group, March 1996. Dredging of mussels in some of the Northern Ireland sealochs is thought to be increasing, despite legal constraints on harvesting in some areas due to poor water quality (M.Service, Department of Agriculture for Northern Ireland, pers. comm.).

8.2. Spain and Ireland In Spain (one of the two largest European producers of mussels) and Ireland, mussel production is almost entirely from suspended cultivation, using rafts in Spain and longlines in Ireland. Both raft and long line culture is used in Scotland but the information available suggests that the production levels from a given area of water are much lower in Scotland. In Ireland and Spain, as in Scotland, spat mussels are collected on the ongrowing ropes. In Spain, however, spat are collected from the shore when natural settlement on the ropes is poor and bound onto the growing ropes using cotton mesh, which rots away once the spat have byssally attached to the ropes. In both countries mussels that are too small to meet market requirements at harvest are also used for ongrowing after reattachment to the growing ropes.

Gurriaren (1978), in a study of the feeding of the velvet crab Macropipus puber in the Ria Arosa, Spain, found that mussels made up.a significant proportion of the diet of the crab in the areas around mussel rafts. He suggested that mussel farming has enhanced the velvet crab population by providing additional food, both mussels and the pea crab Pisidia longicomis (which has become abundant on mussel rafts), and by altering the bottom substrate through the drop-off of mussels from ropes and discarding of material during harvesting operations.

29 Review of the Exploitation of the Mussel, Mytilus edulis. in Scotland

8.3. France In France almost all of the production of mussels is from bouchots - poles set into the foreshore between MTL and L WS. Spat mussels are collected on special collector bouchots, thinned out and attached to the bouchots in the growing on areas. The methodology is labour-intensive and produces relatively low yields of small mussels, but is economically viable in France because of the high prices which these mussels bring and the absence of competition from other cultivation systems (Dare 1980). There is no comparable system of growing currently operating in Scotland, although the introduction of this technique has occasionally been proposed in licence applications. It seems unlikely that this type of cultivation will be economically viable in Scotland, or indeed likely to receive permission because of its visual and navigational impact on intertidal flats.

8.4. Dutch, German and Danish Wadden Sea The nearest comparison to the practices currently operating in the Dornoch Firth is the Wadden Sea mussel fishery (which, with Spain, is one of the largest European producers of mussels). This is primarily a dredge fishery that depends on seeding areas of the bottom with seed mussels gathered from specialised nursery grounds. Mussels are dredged and moved several times before final harvest. Korringa (1976) gives full details of how this f'1!flllng/fishery operation works, and several of the references noted in section 7.2 include more recent information on methodology. Dahl et al. (1994) illustrate the total landings of mussels in all regions of the Wadden Sea from 1965 to 1992. Their graphs indicate that average landings were over 100,000 tons wet weight per annum in the early 1980s, but declined after this. (This is compared with a maximum annual Scottish harvest of about 3,000 tonnes over the same period.)

As described in section 7 .2, the Wadden Sea industry is currently suffering from a prolonged period of poor settlement of mussels (and cockles). Following pressure from the Dutch, ICES set up a working group to study settlement in bivalve molluscs. The report of this working group to the 1994 ICES meeting indicates that there was a reasonable spat settlement in 1993 but that it was largely destroyed by gales. There is little analysis of the reasons behind the poor settlement, but it suggests that it could be due to the succession of mild winters. No firm data is presented to relate settlement to winter temperature, but the long-held belief that cold winters promote good spat settlement is repeated in the report (Dijkema 1994). Dare (in Dijkema 1992) reports that analysis of spat settlement of mussels and cockles in the Wash indicated heavy settlements of spat from low spawning stock levels after very cold winters.

Dahl et al. (1994) describe trends in the Wadden Sea fishery as follows. The Dutch fishery in the west is dominant, although catches fell in the early 1980s. The fishery in Germany and Denmark then intensified in compensation, particularly in the Danish area from 1984-87 (where 37,000 tonnes were taken in 1986, according to Laursen and Frikke, 1987, falling to 1,200 t in 1988, despite a quota of 4,500 t having been allocated). A severe winter in 1986/87 combined ~ith over-exploitation resulted in a serious collapse in Danish mussel stocks in 1988 and the virtual closure of this fishery, with the exception of a controlled scientific and intensively monitored fishery in the east. This 1994 paper reports that no successful recruitment of mussels had taken place in the Danish area since 1987 (which was also the last date of a good spatfall in the Dutch culture fishery). The German mussel fisheries subsequently increased their yields, but low spatfalls in 1992 and 1993 were expected to cause a decrease in following years. Smit (1995) suggests that lack of mussel seed and the resulting over-exploitation of mature mussel beds in the Dutch Wadden Sea are possibly the main causes of a total disappearance of its intertidal mussel beds in 1992.

Dankers and Zuidema ( 1995) describe and quantify the mussel populations and methods and scale of 2 cultivation in the Dutch Wadden Sea, where about 5% of the area (70 km ) is comprised of subtidal or lower intertidal culture lots, although only half of these are in use.

30 Review of the Exploitation of the Mussel, Mytilus edulis. in Scotland

Borchardt ( 1995) records that four mussel fishery companies with nine vessels (eight of which are fully licensed) are operating in the Schleswig-Holstein region of the German Wadden Sea, over about 50 culture lots (areas where seed mussels are laid artificially) with a total area of about 3,000 ha (an increase from 1,000 ha in 1980, 1,300 in 1985, and 2,850 in 1991). Only about 1-10% of mussel landings originate from natural beds, which are unstable and cover a sublittoral area of only a few hundred hectares. Mussel fisheries in this area have been continually intensified over the past few decades as the result of the above rise in the area of culture plots; 7 ,OOO tonnes were harvested in the 1970s, 17,000 tin the 1980s and 23,000 t from 1990-1994 (with a peak of 42,500 tin 1992). Reduction in minimum landing sizes and lowered prices resulted in a harvest of only 4,600 t in 1994. The area of all tidal mussel beds in the Niedersachsen area of Germany showed a decrease of 50% in 1990-91 from that in 1993 (Michaelis 1993). High catches in the 1980s were followed by very variable yields; good in 1990 and 1992, low in 1991 and 1993. Low spatfall in recent years suggests future yields will be poor.

There is considerable debate on the impacts of the Dutch, Danish and German Wadden Sea mussel fisheries on nature conservation interests (and vice versa), particularly where fishing takes place in areas designated as national park (Ruth 1991; Munch-Petersen and Kristensen 1987; Berkel and Revier 1991). Not only is there direct competition between fisheries and bird populations for food (see Section 7 .2), but increased levels of trematode parasites in mussels are attributed to larger aquatic bird populations (see Section 7.3). Changes in the mussel population since 1976 at a permanent monitoring site in an inlet of the Waddensea are described by Michaelis (1991). The very erratic nature of spat settlement was considered to be a major factor affecting fluctuations. Major declines in stock in the 1980s were attributed by this author to increasing eider duck populations, intensification in the fishery, and a series of three severe winters (with associated ice drift). As can be seen, there has been considerable debate between the fishing industry and environmental interests on the apportionment of blame for this decline.

However, to conclude this section, it must be stressed that the scale of the mussel fishery, the area of mussel beds and the wintering bird populations supported (for example the 40,000 wintering eider in 1992/93 were only a third of the 'normal' figure - Smit 1995) in the Wadden Sea are at least an order of magnitude larger than the present Scottish fishery. Direct comparisons are, therefor~, probably inappropriate.

Review of the Exploitation of the Mussel, Mytilus edulis. in Scotland

9. LEGISLATION

Summaries of relevant, or potentially relevant legislation are presented in Appendix 4. This information is mainly taken from Burbridge and Burbridge (1994) who reviewed the major issues relevant to the sustainable development of coastal areas and_ resources in Scotland. Their report includes an inventory of relevant legislation (based on an old listing produced by the former Nature Conservancy Council in 1989) and an outline of the main agencies involved-in coastal management, with their divisions of responsibility. Some additional information was obtained from Cleator and Irvine (1994). The following considers some of the more important issues relating to mussel fisheries.

9.1. Ownership of mussel fisheries The public right of fishery gives the public an inalienable right to collect shellfish other than oysters and mussels from any shores in Scotland, provided that they have a right of access to the foreshore (and there is a general public right of access in Scotland). Mussels and oysters were removed from the public fishery by The Mussel Fisheries (Scotland) Act 1847 and The Oyster Fisheries (Scotland) Act 1840. Therefore, for most of Scotland, mussels belong the Crown and mussel fisheries may only be prosecuted by leasing the fishery from the Crown Estate Commissioners, which manages the rights to these fisheries. (Although about half of the foreshore of Scotland is non-Crown, this does not mean that the rights to collect these shellfish have been similarly transferred.)

However, the collection rights for these shellfish are alienable and heritable. There are many areas where the Crown has ceded title to mussel and oyster fisheries to local landowners or communities, either by express grant or following prescriptive possession. Examples are the granting of the Domoch mussel scalps to the people of Tain, and the rights for mussel collection from Nairn to Burghead, also on the east coast, now said to be leased by the Royal Society for the Protection of Birds (David Law pers. comm.). No public record of these titles is readily available (indeed, even the Crown Estate does not have a clear record of areas where Crown ownership of oysters and mussels has passed to third parties - Ian Pritchard pers. comm.). Local control generally only becomes apparent where it is claimed.

The Acts which removed mussels and oysters from the public fishery pre-date the judgement of Hall v Whillis (see Fowler 1992) which supports the concept of a public right to collect naturally occurring shellfish or other bait species (including mussels) by hand, provided that they have legal access to the foreshore (and there is a general public right of access in Scotland) and the end use is non commercial. As a result, the legal situation re. collecting mussels for bait is rather confused, but collection for personal use is probably a tolerance of the Crown. (Judging from the high levels of landings recorded at the end of the 19th century (see Table 2b ), these rights were exercised widely around the Scottish coast at this time.) Nevertheless, this judgement should not affect the rights to commercial fisheries.

The Crown Estate has granted very few licences for shellfish collection in recent years, and these have tended to be on an experimental basis (SNH have been consulted on all applications). For reasons of confidentiality, lists of tenants' nam~s and addresses are not available (Ian Pritchard, Crown Estate Fish Farming Estate Manager, pers. comm.).

Mussel fisheries are also subject to the Sea Fisheries Act (1964), extended to Scotland by the Several and Regulated Fisheries (Form of Application) Regulations 1986, which allows the setting up of Several and Regulated Fisheries. This was used for the first time in 1990, and was introduced · primarily to overcome the problems of ongrowing scallops to a marketable size on the seabed. However, as there is no right of Public Fishery for mussels, it could be questioned as to whether this Act has in fact any relevance to mussel fisheries in Scotland, and it has never been applied for this

32 Review of the Exploitation of the Mussel, Mytilus edulis. in Scotland

purpose. The simplest method of control of mussel fisheries is through the provisions of the lease granted by the Crown Estates (outlined above).

9.2. Public health Mussels, like all other bivalve molluscs, are subject to the provisions of the EC Shellfish Directive 91/492/EEC, which lays down the health conditions for the production and marketing of live bivalve shellfish. This directive categorises production areas on the basis of the bacterial loading of the shellfish found there. There are three categories, of which only one, category A, allows shellfish to go direct for human consumption. The other two, categories B and C, allow shellfish to be sold after appropriate purification. Areas where the shellfish have bacterial loadings higher than the upper limit of category C are considered unsuitable for production. The Directive is implemented through national legislation, including The Control of Pollution Act (1974), Environmental Protection Act (1990), and Food and Environment Protection Act (1985).

The Marine Laboratory, Aberdeen, has carried out testing of Scottish bivalve mollusc production areas. The most recent report on the results is given in Appendix 3. From this it can be seen that on the East Coast of Scotland only the Domoch Firth has been classified as category A for mussels. Most other areas are category B or C although one, the Eden Estuary, is considered unsuitable for production. Some areas on the East Coast where mussels are known to occur have not as yet been classified for mussels, and no production may take place from these areas until this has been done. As classification requires testing over a period of time, it might be advantageous to SNH to develop a mechanism where they will be forewarned of areas where classification has been requested. Such forewarning will allow SNH to make representations to the owners of the mussel rights, if it is perceived that the exploitation of mussels in these areas has significant nature conservation implications.

As well as laying down standards for bacterial contamination, the EC Shellfish Directive also lays down standards in relation to Paralytic Shellfish Poisoning (PSP) and Diarrhetic Shellfish Poisoning (DSP). Testing for these naturally occurring toxins is also carried out by the Marine Laboratory, Aberdeen, on behalf of the Scottish Office. When levels of PSP or DSP are encountered which are above the limits contained in the EC Shellfish Directive, the Scottish Office closes the Shellfish Fisheries in the affected areas using the provisions of the Food and Environmental Protection Act (1985).

33 Review of the Exploitation of the Mussel, Mytilus edulis. in Scotland

10. RECOMMENDATIONS FOR FURTHER RESEARCH AND MANAGEMENT

Two of the aims of this study were: • to develop recommendations for the management of mussel populations in Scotland (based on reviews of knowledge on the mussel fishery, its potential for expansion and the impacts of harvesting) and • to make recommendations for practical research projects to further inform this management.

The review of the mussel fishery and its impacts has demonstrated two main points. Firstly, the scope for uncontrolled expansion of the fishery in Scotland is extremely limited due to the ownership of most mussel beds by the Crown and the strict EC controls on the production and marketing of bivalve shellfish (see previous section). Secondly, despite a considerable amount of work on the impacts of mussel harvesting having taken place in the Wadden Sea (where the fishery is on a huge scale in comparison with that in Scotland) there is little existing research which can be directly applied to the Scottish fishery. The following sections have, therefore, been developed in this context. For example, some of the management recommendations are derived from those recommended for the Wadden Sea and could prove not to be fully applicable to the Scottish situation once additional research and survey has been completed.

It is suggested that a useful starting point would be for SNH staff to undertake a fact-finding trip to some of the Wadden Sea countries to investigate in more detail the similarities and differences between the situation here and in Scotland, and determine the most important lessons to apply to the management of a future potential expansion of wild mussel fisheries in Scotland.

10.1. Research priorities The following areas of research and survey should provide the basis for enabling mussel fisheries in Scotland to be managed to protect long term yields and minimise environmental damage.

1. Surveys of areas containing mussel beds to identify those mature, stable and long-lasting mussel bed habitats which are of highest marine nature conservation importance and which act as the nucleus for recruitment of commercial stocks. Locations requiring such surveys as a priority are the commercial fisheries and adjacent unfished areas in the Domoch Firth and Montrose Basin, but mussel habitats in west coast sea lochs should also be targeted. This work should be carried out in collaboration with SOAEFD, which has already been carrying out video surveys of the Domoch Firth mussel beds.

2. Surveys to quantify the extent of mussel beds (including both existing and potential mussel fishery sites) in major estuarine complexes which are of importance for diving duck and shorebird populations (in collaboration with SOAEFD, see above). Research to assess the food requirements of these bird populations, particularly in winter and other times of the year when food supplies may be limited. Compare these results with the peak periods of demand in existing and potential fisheries and hence determine the carrying capacity of areas for commercial mussel fisheries ( and cockle fisheries, if relevant) which may be sustained by the surplus shellfish stocks. It is important to consider the major estuarine complexes as a unit (e.g. the Moray Firth complex from Loch Fleet to Findhom), particularly bearing in mind that only small areas are presently subject to fisheries.

3. Research to investigate the role of mussel banks and impacts of harvesting on the primary productivity, chemical, hydrological and sedimentary regime in estuaries and other marine inlets, including competitive pressure on other wild filter feeders from mussel culture in Scottish lochs.

34 Review of the Exploitation of the Mussel, Mytilus edulis. in Scotland

4. As recommended by Dankers ( 1993), use the results of the above to develop a mathematical model to study the carrying capacity of one of the major estuarine systems (Dornoch Firth, and ultimately the Moray Firth complex). This model must consider not only the target fishery species, but also the effects of competition for food or space on other species, which will be particularly important in years when mussel stocks are low. It must differentiate between fisheries on short-lived littoral and sublittoral beds and mature, long-lived beds (if present).

5. Study, with the co-operation of the Ross and Cromarty District Council and SOAEFD, the dredging and reseeding operations in the Domoch Firth and how these affect the total mussel population structure in the area. Use unfished stocks in the Cromarty and Inverness Firths as control populations for comparison.

6. Develop, with the participation of SOAEFD and Scottish Fisheries Officers and similar organisations in other countries (possibly through the ICES Spatfall Working Group), a long term research project on monitoring patterns of mussel spat fall. This would not require a high level of input or funding, but should run for at least ten years to provide useful results. The project should develop a standard index of spat abundance and examine the effects of weather conditions, spawning stocks and other environmental variables on spatfall.

Some of the above research could be carried out as part of a PhD studentship, based at a Scottish University (possibly Aberdeen) and in collaboration with SNH and SOAEFD. However, much of the research is multi-disciplinary in nature (e.g. recommendation 10.1.3) and would best be carried out by a group of researchers, including hydrographers, planktologists, shellfish biologists, marine ecologists and ornithologists, rather than by a single individual. Indeed, since the subject of mussel fishery management is of considerable interest to fisheries and natural heritage managers in several European countries ( certainly throughout the UK and in the Wadden Sea area, but probably also in Eire and the Iberian Peninsula), a collaborative submission to the EC for funding, perhaps under the LIFE Programme, could be worth pursuing. Contacts are being made with potential collaborators in several countries to determine whether they are interested in such an approach and to investigate their personal recommendations for research priorities.

10.2. Management recommendations The whole subject of managing mussel fisheries in areas of high nature conservation importance in Scotland requires careful study. While similar work is underway in the Wadden Sea, the results of these studies are probably not directly applicable to the Scottish context. As noted above, a fact~ finding visit by SNH staff would help to clarify some of these points.

1. Areas of mature, stable and long lasting mussel beds, identified during surveys recommended in 10.1.1, should be excluded from commercial fisheries licenses and protected through management plans or zoning agreements.

2. Once the carrying capacity of shellfish beds for bird populations and fisheries has been assessed, consider how zoning might operate to allocate areas for fisheries or wildlife refuge use on the basis of their bivalve mollusc production area classifications and other criteria

35 Review ofthe Exploitation ofthe Mussel, Afytilus edulis in Scotland

ACKNOWLEDGEMENTS The authors are grateful for the input of Sue Scott to this study and for her comments on the drafts of the report. The Fisheries Officers of the Scottish Sea Fisheries Protection Agency, staff of Scottish Natural Heritage, Colin Chapman, Trevor Howell, Aileen Shanks and other staff of the SOAEFD Marine Laboratory in Aberdeen also made particularly valuable contributions, as did Norbert Dankers and Cor Smit (IBN-DLO Institute for Forestry and Nature Research, Texel, NL), Peter Walker (MAFF) and Peter Dare, Shelagh Smith, Jim Munford, Nick Davidson, Eric Edwards (Shellfish Association), Ian Pritchard (Crown Estate Commissioners) and Matt Service (Department of Agriculture for Northern Ireland).

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Scottish Office Agriculture and Fisheries Department. 1995. Scottish Shellfish Farms Annual Production Survey. Report ofthe Scottish Office Agriculture and Fisheries Annual Survey ofShellfish farms for 1994. SOAEFD Marine Laboratory. Aberdeen.

Scottish Office Agriculture, Environment and Fisheries Department. In preparation. Water quality survey of Scotland 1995. The Scottish Office. [title provisional.]

Scottish Office Environment Department. 1992. Water Quality Survey ofScotland 1990. Civil Engineering and Water Services. The Scottish Office.

Seed, R. 1996. Patterns of biodiversity in the macro-invertebrate fauna associated with mussel patches on rocky shores. Journal of the Marine Biological Association ofthe United Kingdom, 76, 203-210.

Siegfreid, W.R. (ed.) 1994. Rocky shores - Exploitation in Chile and South Africa. Ecological Studies Vol. 103. 177 pp. Springer-Verlag.

Smaal, A.C. 1991. The ecology and cultivation of mussels: new advances. Jn: The Biology and Cultivation of Mussels. Special Issue Aquaculture vol. 94, no. 2-3, pp. 245-261.

Smit, C.J. 1994. Alternatieve voedselbronnen voor schelpdier-etende vogels in Nederlandse getijdewateren. IBN rapport 077. Instituut voor Bos- en Natuuronderzoek (DLO-IBN), Wageningen, Netherlands.

Smit, C.J. 1995. Food for shellfish eating birds: can prey species other than cockle and mussel provide sufficient alternative food for birds in meagre years? Wadden Sea Newsletter, 1995 No. 2: 5-8.

Stunkard, H.W. & Uzmann, J.R. 1958. Studies on digenic trematodes of the genus Gymnophallus and Parvatrema. Biological Bulletin 115: 276-302.

Suchanek, T.H. 1979. The Mytilus californianus community: studies on the composition, structure, organization and dynamics of a mussel bed. PhD thesis, University of Washington, Seattle.

Suchanek, T.H. 1985. Mussels and their role in structuring rocky shore communities. Jn: P.G. Moore and R. Seed (eds), The ecology ofrocky coasts. Pp. 70-96. Hodder and Stoughton, London.

Tenore, K.R., Corral, J. and Gonzalez, N. 1985. Effects of intense mussel culture on food chain patterns and production in coastal Galicia, N.W. Spain. ICES, C.M 1985/F:62.

Tenore, K.R. and Gonzalez, N. 1976. Food chain patterns in the Ria de Arosa, Spain: an area of intense mussel aquaculture. Jn: Persoone, G. and Jaspers, E. JOth Europ. Symp. on Mar. Biol. 2, pp. 601-619. Western Belgium, Universa Press.

Tsuchiya, M. and Bellan-Santini, D. 1989. Vertical distribution of shallow rocky shore organisms and community structure of mussel beds (Mytilus galloprovincialis) along the coast of Marseille, France. Mesogee, 49,91-110.

Weston, D.P. 1986. The environmental effects of floating mariculture in Puget Sound. College of Ocean and Fishery Science, University of Washington, Seattle, Washington.

Widdows, J., Donkin, P., Brinsley, M.D., Evans, S.V., Falkeld, T.N., Franklin, A., Law, R.J., and Waldock, M.J. 1995. Scope for growth and contamination levels in North Sea mussels Mytilus edulis. Mar. Ecol. Prog. Ser. 127,131-148.

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Review ofthe Exploitation ofthe Mussel, Mvtilus edulis in Scotland

Appendices

Appendix 1. Copies of questionnaires sent to SNH and SFP A offices. Appendix 2. SOAEFD records of mussels landed in Scotland, 1975-1994. Appendix 3. List of potentially relevant legislation

Review ofthe Exploitation ofthe Mussel, Mytilus edulis in Scotland

Appendix 1. Copies of questionnaires sent to SNH and SFP A offices. Mussel harvesting questionnaire survey

The common mussel Mytilus edulis has in the past been and pressure for expansion in the context of available widely collected by hand from some Scottish shores and markets and stocks (both wild and aquaculture). This estuaries. The small scale of these operations has made work is being carried out in liaison with SOAFD. them generally sustainable and their impact on the There is no intention to impose new controls on wild environment has been minimal. mussel harvesting. SNH merely aims to promote the However, more recent larger-scale commercial sustainable use of natural resources and hopes to harvesting using mechanical techniques could identify options for improving yields. potentially take much larger quantities. There is interest This questionnaire is being circulated to a number of in introducing commercial harvesting at some new relevant agencies and organisations in order to obtain sites, and concern about the impacts of this activity on some information of these and other aspects of this the natural heritage. Aquaculture of mussels is also activity. We would be most grateful if you could please increasing the potential Scottish yield of this shellfish. spare a few minutes to fill in the following questions. Scottish Natural Heritage has commissioned a review of Your more detailed comments on this review would also mussel harvesting in Scotland which aims to draw be most gratefully received; please attach them. together the information known about the impacts of different methods of collection harvesting, the potential Thank you very much for your help.

1. Your name . Position in. orgarrisation ...... Address

Telephone no. I fax no.

2. Geographical area of your orgarrisation' s coverage (please show on attached map):

3. Number of mussel collectors thought to be active in area: (how accurate is this estimate?)

4. . Their.main.?ccupations. (p!ease tick) ...... crofters i fishermen i casual l commercial l other (please state) ~ ~ visitors l collectors 1

5 · . I·~: o~!@(please tir~;~ona1··········--·-···············--····~·· further. away···········-··-·······-···-··········-····· r·un1mown ·-··--··-···-···-·--·l

6. . Estimated.proportion .of time. spent haryestin~ musselsjplease. tick): ...... ,...... full time l half time j regular 1 occasional 1 infrequent I unknown ~ l (activity most l (a few times a 1 (perhaps once or ! 1 i months'\ 1 vear). l twice a Y.ear). l ••••••••••••••••••••••••.••••••••••••••••••••••••••••••••••••••••••J!••••••••••••••••••••••,r{.••••••••••••••••••••••••••••.••••••••••••••••••••••••••••••••••••••••••a••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••• Comments:

7. Time(s) of year when (most) collection takes lace in our area:

8. Estimated interval between harvesting activities at any one location: (i.e. time taken for supplies to recover) Scottish Natural Heritage mussel harvesting questionnaire, page 1 9. Geographical areas and/or shore habitats most widel used for harvestin :

I O. Name(s) of site(s) or description( s) of location(s) where harvesting is lmown to take place regularly:

(please provide grid references if possible and indicate roud} position on map)

11. ITotal number of people working each . shore?

12. I WJiere and how does mussel grading take . place?

13. Estimated distances mussels are transported by harvesters to shellfish buyer:

14. Names or locations of local/regional mussel buyers: (please give names & addresses ifposSI"ble):

15. Do you lmow of any collectors who could be prepared to provide more information on their methods and supplies (in strict confidence, anonymity guaranteed). How may they be contacted?

16. Has this activity caused any problems with designated sites or any other natural heritage interests? Please attach details of sites, action taken, permits issued. Is more information available for reference?

17. Have water quality issues caused any problems locally which affected this activity? Please attach details of sites, action taken. Is more information available for reference?

18. Other comments:

Thank you very much for your help with this questionnaire. Please return it to: Sarah Fowler, The Nature Conservation Bureau Ltd., 36 Kingfisher Court, Ham.bridge Road, Newbury, Berkshire RG14 5SJ

Scottish Natural Heritage mussel harvesting questionnaire, page 2 Mussel harvesting questionnaire survey

The common mussel Mytilus edulis has in the past been and pressure for expansion in the context of available widely collected by hand from some Scottish shores and markets and stocks (both wild and aquaculture). This estuaries. The small scale of these operations has made work is being carried out in liaison with SOAFD. them generally sustainable and their impact on the environment has been minimal.· There is no intention to impose new controls on wild mussel harvesting. SNH merely aims to promote the However, more recent larger-scale commercial sustainable use of natural resources and hopes to harvesting using mechanical techniques could identify options for improving yields. potentially take much larger quantities. There is interest in introducing commercial harvesting at some new This questionnaire is being circulated to a number of relevant agencies and organisations in order to obtain sites, and concern about the impacts of this activity on some information of these and other aspects of this the natural heritage. Aquaculture of mussels is also activity. We would be most grateful ifyou could please increasing the potential Scottish yield of this shellfish. spare a few minutes to fill in the following questions. Scottish Natural Heritage_ has commissioned a review of Your more detailed comments on this review would also mussel harvesting in Scotland which aims to draw be most gratefully received; please attach them. together the information known about the impacts of different methods of collection harvesting, the potential Thank you very much for your help,

1. ·····-·····-················································--············-····-··--··-·--·······-········--··-·-·-··--·---···········-·-··-·----·-·-·········-···----····--·-····---·······--·-···Yourname .. Position in. organisation ...... - ...... ,--...... - ...... - ...... ,... _.. __ ,___ ...... ·. Address

Telephone no. I fa-x no.

2. Geographical area of your organisation's coverage (please show on attached map):

3. Number of mussel collectors thought to be active in area: (how accurate is this estimate?)

4. . Their. main .?ccupations (piease tick) --·-. ----·-·--·"""""'' . ·-·------·---.. ---·--·--...... _ ...... _ ...... crofters i fishermen i casual i commercial i other (please state) l ~ visitors ~ collectors ~

5. . Their oriw,n_(please ti~k): ------·-·····------·•-----o•--o-••--••--••-•••••• Local ~ re ·onal ~ further awa ~ unkno~vn

6. _g~~!ed,.EE~P.~~

1. Time(s) of year \vhen (mo_st) collection takes lace in vour area:

8. Estimated interval between harvesting activities at any one location: (i.e. time taken for suoolies to recover)

Fishery Officer mussel harvesting questionnaire, page 1 9. Geographical areas and/or shore habitats most widel used for harvestin :

10. Naine( s) of site( s) or description( s) of location( s) where harvesting is knovvn. to take place regularly:

{please provide grid references if possi'ble and indicate rou.e:h position on map) ll. ITotal number of people working each shore?

12. IWhere and how does mussel grading take place?

13. Estimated distances mussels are transported by harvesters to shellfish buyer:

14. Names or locations of local/regional mussel buyers: (please _give names & addresses ifpossi'ble):

15. Do you !mow of any collectors who could be prepared to provide more information on their methods and supplies (in strict confidence, anonymity guaranteed). How may they be contacted?

16. Are there any Several Orders locally ·which regulate or restrict shellfish gathering? Please attach details. Is more information available for reference?

17. Have water quality issues caused any problems locally which affected this activity? Please attach details of sites, action taken. Is more infonnation available for reference?

18. Other comments:

Thank you very much for your help '1tith this questionnaire. Please return it tp: Sarah Fowler, The Nature Conservation Bureau Ltd., 36 Kingfisher Co~ Hambridge Road, Newbuzy, Berkshire RG14 SSJ Fishery Officer mussel harvesting questionnaire, page 2

Review of the Exploitation of the Mussel, Mytilus edulis. in Scotland

Appendix 2. SOAEFD records of mussels landed in Scotland, 1975-1994. SOAFD mussel harvesting data by ICES statistical rectangle, 1975-1994. (Landings in tonnes, UK vessels only. Spurious records from offshore areas excluded)

1975 1976 1977 1978 1979 1980 1981 1982 1963 1984 1985 1966 1987 1988 1989 1990 1991 1992 1993 1994 T ota I/ ICES SQUa re ICES rectangle 49E8 (Shetland) 4.4 0.1 4.5 46E6 (Orkney/North) 0.9 0.9 45E2 (Hebrides) 5.6 5.6 45E3 (Hebrides) 1.3 22.9 0.6 40.5 20.4 20.8 2.3 108.8 44E2 (Hebrides) 0.3 0.3 44E3 (Hebrides) 0.3 0.2 0.5 44E5 (Dornoch Firth) 341.4 341.4 44E6 (Dornoch Firth) 462.8 575.6 475.1 804.7 384.0 398.4 55.9 0.1 284.5 1,320.8 354.5 1, 196.9 1,021.7 1,453.6 2,785.4 2,386.4 1,733.8 1, 153.5 16 847.7 43E2 (Hebrides) 0.5 0.2 0.7 43E3 (Skye) 0.2 0.2 43E4 (Skye/west) 0.2 0.2 42E2 (Hebrides) 0.8 0.2 0.3 0.1 1.4 42E3 (Hebrides/west) 0.9 0.9 42E7 (Montrose Basin) 238.3 172.2 135.7 94.4 68.4 87.2 54.4 26.1 30.3 23.1 27.5 11.3 27.0 23.8 41.4 14.7 8.5 581.8 1 686.1 41 E3 (West coast) 0.6 0.6 41 E4 (West coast) 2.0 2.0 41 E7 (East coast) 0.2 0.3 0.5 40E4 (West coast) 0.1 8.9 2.0 0.3 0.1 82.0 93.4 40E5 (West coast) 0.1 0.2 0.2 0.1 0.1 0.1 0.8 40E7 (East coast) 0.3 0.3 39E4 (West coast) 0.4 0.3 0.2 14.7 15.6 38E4 (West coast) 0.2 0.2 38E5 (West coast) 2.5 1.0 3.5 38E6 (Solwav Firth) 2.0 2.0 ITotals I 705.1 I 749.7 I 612.5 I 922.0 I 818.8 I 526.3 I 145.5 I 50.0 D32.8 I 23.1 I 312.0 I 1,332.9 I 383.8 I 1 223.2 I 1,063.3 I 1 468.4 I 2 794.3 I 3.065.1 I 1,733.8 I 1,155.5 19,118.1 U.K. Vessels Landing in Scotland January 1975 to December 1975 Species: Mussels Units: 100 kg Gear: All gears CROWN COPYRIGHT MARINE LABORATORY ABERDEEN D9 EO E1 . E2 E3 E4 E5 E6 E7 ES E9 FO F1 F2 F3 F4 FS F6 F7 i ,_4 I 0 !

i I !

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w 2" E Source: Scientific Database Run date: 14-Aug-95 U.K. Vessels Landing in Scotland January 1978 to December 1978 Species: Mussels Units: 100 kg Gear: All gears CROWN COPYRIGHT MARINE LABORATORY ABERDEEN 09 EO E 1 E2 E3 E4 E5 E6 E7 E8 E9 FO F1 F2 F3 F4 F5 F6 F7 j l I : t i ! J 63° I ! I i ' 54 l I l I ! I I i I l I ! l ! I I i I ! ; l i ! i ! I - ! ! I ! I i ! L ~ 53 i i l i I .. ' ; ; I ! i I l i l I -· l i I ; --· - 62° l I \ i ' i I l i l I t '; ! i ! I ' Ii ' -·· 52 ! !I I .. ! I l : ! i ; J l i ' l l 1 ~. _J l -~-. 51 1 i i .i· so I .....--·1 ----+-:....--...;.---.....--.;-----+--'· .. l 49 ! i---'----"----'--~..;.__.~~------'--~~ l .. c· 48 I !

I l -!- ! 45 1 .2291

; . l t· I i ; ' .) 1 l i ' ; I l ! ' ! I ; I i 43 i I ! l i ! ; ! I l I ! i l ' I I l l' l 42 l 944 J Il i· ! L I ! l i 41 I . ;.....!_--4- ______,_ ____ - ...:...J_

401: t l. . l ! ~I~_;_~------.----;----r I

39 1 1 55" 38 \ __,;,,,,.--+---+-1-_.._1------+------.>----+-~:· -----"---

37. ! I 540 36 i ·· 1._____._i-+--1 -+-----:------+----r-1-! .... 1 ,_·- 1 35 i ! 1 l I I 153°1 34 I l 1 ~ --+ -, I ! 3'"' I l " I' -is20 I r- i . 32 1 l' -:--· T -· 31 !,_._;______....______~~ I ROCKALL. 30 i

I 29 l '----~.;.._------'r---r--~----~-----;---+---.-- 28 •

I . w 10° 40 oo Source: Scientific Database Run date: 14-Aug-95 U.K. Vessels Landing in Scotland January 1977 to December 1977 Species: Mussels Units: 100 kg Gear: All gears(+ is< :50 kg)

CROWN COPYRIGHT MARINE LABORATORY ABERDEEN 09 EO Ei E2 E3 E4 ES E6 E7 E8 E9 FO F1 F2 F3 F4 FS F6 F? I I I . l , ,~· · 63" I /~ ...... ~, ..,..,. ~ 54 I i I ,..3 I ..I .. ,. I ,_.; ::::, I .,,,-·., !-----.!.--+--+-----+--~--+---+------+----!--~--+-~---:---r---;1-··i· I ., .. J62° 52 J

51 ! --+--...;.._-+---+-----':...... ---+--+--+--t---+---+---+--+--t-1 ;·· 50 ,__l-...... [,>'.< I .. ~:~ +1° i,...._---'----+----4----'-----+---;---+---r-----:---h.. :·,.,..;.:,i-----+----r--__,__-+----+--· 49 i <:_~;> ';/. · ·. i 1 -·····6QO 48!;..... --+---+---+---:-I ---+---+--+--+---t---,:.'--.1---+-~---+----r--+---+----,,X/ . I j I I j· 47 l I ·._·'.! l~~-.--..;..._-~_;____;_--;._-+_ --+--!----+----,..--+----+---+--+-- ! I ~1.~ 46 ! i !...... ----+---.-----+!-. ..~ ,. /·v-;::-··,'.:,,,<>,~.. :.·:'"::", ...... ! -~--+---+---;----t---!-----:-----ir----~·· 451 13! ' ; . ,;;;,:;> i 530 :1 :~{~1~,-,-,-1-1--,-1:~-~-~-+--~-~-~~-~-~--~

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391 .. I ~r .. .;,} ,r .. ' '_,,__-+l--+--.;---+---;--~--r---r---.--i' 550 38: 1/::~ ..· · -~··· ·. ·• '\I , 37 ; • L-' .. 1,; I , ';:' . \}> I 54'

36 '-1- · 1, l ["· :''.\·<·, ,,.<~\: '1 2764 ·:,,[~

-,- . 1 I _.3-J·-.,-:<\., ·· ,k-,,;~-;-,-:-:~}--.. ,-,,/--"".:"l.~--.__ > 35 /,,-,,-,'----;---....---+--(...... --- -~~";_'=,....______,___ 1./I . , l ·,:. . .'•,,; 34 l 33 52° 32 ,- 1 ~ ::~/'--,---+-11 ---+J-.·.. . 6~: ·- ·-· ··-· -... 31 i I ( I 51° l ROG.KALL 30. I 05 ;4006 13"07 12"08 I 45 I 29 1 .1 r--- I I ! ...---+~-+---+-~-;---,------+---t---r--~r-----1----,--, I 5V 50° 44 28 J I ,..... I I !;..---l..-11 ------~--i---+---+------'1----+----r-!· -_J-.. -... ----,-!._,,.> 43 27 I . I l 57" I l I I ! w 10° 40 20 20 40 E Source: Scientific Database Run date: 14-Aug-95 U.K. Vessels Landing in Scotland January 1978 to December 1978 Species: Mussels Units: 100 kg Gear: All gears CROWN COPYRIGHT MARINE LABORATORY ABERDEEN 09 EO E1 E2 E3 E4 ES E6 E7 E8 E9 FO F1 F2 F3 F4 F5 F6 F7

54 _!63'

53 I1 -! 62' 52 l -:; 51 l ~61' 50 -il 49 I -;60 48 l 47 159 46 _,l

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29 I I I I I i I ! I I 28 I i I I I 27 I I i I I I I I w 10° 30 50 40 20 oo 20 40 50 E Source: Scientific Database Run date: 14~Aug-95 U.K. Vessels Landing in Scqi1and January 1979 to December 1979 Species : Mussels Units :<· · lOO kg Gear: All gears · CROWN COPYRIGHT MARINE LABORATORY ABERDEEN

09 EO E 1 E2 E3 E4 ES E6 E7 ES E9 FO F1 F2 F3 F4 FS F6 F7 630 54 i--__:__ _;__--:.-_...:,___J....-___.._ _..;.... _ _,_._-1--_.;..---1,,_~--+----'---+----..----+-___;,~ J,:=J

53 1---1....:,_____..:.--+-----,!.;...,·,;___i___!..--i.....-~~-l---~-+---+-1 .· , \2° 521 ' 1 ..: 1 51 I I ----::-f i,·. i :.·: i --,-1610 so l ) '.'.. ·,--. . ·... ··. I I~~-'--~+------4--4--~~__.__-~-,___,..--:·~\~i--,------.---+--+---+- H '1,i .'., • 49 -~, .. 160 48 j I )2 · ·_:._.·. >1 ,:,

,-r-~-...... _--;._-J.... _ _:___.!.,_____J._ _.....,_-+--..:-----:.--+-~--+------.--+1-- ·"s.;.,, 47 ! 11·1, .:_:,::.; ,,- ' <·'a-~T .-~1 t I l ,:~c·,-----1----_.:,__..;..______,:._--+--..;..-----.....,1-·:,1,'.~,f , /,,_:,.,· 590 46 I ;.i •. , ... , ., ··. :.:;<,~· ·; ; ;:: :·'.·. ·~· . .,, ~ l ..:....--.L.-----+.--+---l---+---+-----+---+---+:-'"•,·:,·. " I ···.:....;...:':::(\-· , (;J{~\\.: 45 I I '"f(:~:1t&s !I l I l 1580 44 I l i l

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I ./, :o_.::.·· I I ;,"' i : ~ ._ . ! v 34 \' __..,. . >~/,··' ... j l I ! ! :..:..-----:.--.l..-- 331_, ... · ; j "' ·· 1 I / ·,._~, - ~j I i l '"l I ·. 52° 'l --+--J_:}::~~- 32 i j ;:.,_,~ .. /_~-,--I I : I ; I" -·· H -.. --4,---+------..--l·.~- 31 , i I 't t/- ·.>;-___ .. ,.. ""' -... ,...... ____ _ / l I I -~' 51° / .. ,, ROCKALL r- .. -- ,. - •, ... 05 wD6 3"'07 z,D8 I I I 1 1 i !'. 45 I I I l ,/ I I.. , ~so' 2s I -<-' 44 j I i ,L-. i.,.,:.::. 431 ls,0 ; l I ! I i 20 oo 20 40 60 E Source: Scientific Database Run date: 14-Aug-95 U.K. Vessels Landing in Scotland January 1980 to December 1980 Species: Mussels Units: 100 kg Gear: All gears CROWN COPYRIGHT MARINE LABORATORY ABERDEEN 09 EO E1 E2 E3 E4 E5 E6 E7 ES E9 FO F1 F2 F3 F4 FS F6 F7 . ! 53c _! 1 53 L- I I 52 162° I ......

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I 2 I -:- -+-~-~----;....--+---+----+--...:.---+----+---!1560 1 40 j . ! l i j ;...____ ,___,______~~-- 39 !I

37 ! ) l '--+---+----+----+------;------, 54c-

36 I,__,- 1 -~~--!--~-~~------;------l r- l 35] --l53o 34: j 33: ! -ioi,..20 l 32 i 1 1__ • l ; ? -i ...... ' l vt I =.j 51 ° ROCKALl l 30 · 05 wDS ~vD7 1z,D8

I ~ 0; ; 2 ..., ) 45 l I ss· _j50° l 44 l 28: l !l 27 IL___L, _...l___ _L __ _;__~ _ _.:._ __;____ L.__~. ------,-~------,.-4-3-===~. ==::::::::::==:::::;::i===-J~~7~"__J! w 10° s~· 6° 4c 2° 0° 2° 4° 6° E Source: Scientific Database Run date : 14-Aug-95 U.K. Vessels Landing in Scotland January 1981 to December 1981 Species: Mussels Units: 100 kg Gear: All gears

CROWN COPYRIGHT MARINE LABORATORY ABERDEEN 09 EO E 1 E2 E3 E4 ES E6 E7 E8 E9 FO F1 F2 F3 F4 FS F6 F7

I 53 I ~i-...l--~~__:,~-l-'~----~-.:-----:.~-4---l.-_...:..- _____;---+---+---.--:.,. ! ' 52 I 51 1·__.__i ___..l.._....:..___...;_~--+--~-+----1---+--+---+--+---+-~1·/,.

61°

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39 _I------;'·~··:~°'\i.'.'.-. _..__+----.;--+--.;....--+--+--+-----+---i 550 j 38 ! !

52°

28 I . I I 30 6'' 40 2c E Source: Scientific Database Run date: 14-Aug-95 U.K. Vessels Landing in Scotland January 1982 to December 1982 Species: Mussels Units: 100 kg Gear: All gears CROWN COPYRIGHT MARINE LABORATORY ABERDEEN D9 EO E 1 E2 E3 E4 ES E6 E7 ES E9 FO Fi F2 F3 F4 FS F6 F7 ! ,63° l ! I ! 53 I I I l I.

46 I -+-.·· 45 i .208 j l l ! ) ... J . 44 r·!! _ __,;... ______"ii-....li /

43 ! 5, i I I l I 42 I ! 3!_ 1 41 ! I 1 1l .. . I ( ! l - -+- ' 40 ! l I 20 j i I I ' l I l I ! j ~l-~---:.---1!---;..--;- ! ; T ~al .. i I . l I 1 ._i_ I I ! .:}v! r I I I l 38 l~------37. 1...-._....____ .,___~------..---ij 54c 36: ·,. l

·~-,---+------l---+----i ~ l 35: l · J ;____ ~53c l 34 i , _j l ! 33rr- --i52° 32 l I _] r-- T 31 I ROCKALL -.s1° 30: 05 ,.DS ·,07 ~ ,08 14 13 2 ' l l l 29; 45 ! ! ! I ; ss 1so~ 28; 44 _I L. !

i ! ; t w 10° 40 20 oo 20 40 E Source: Scientific Database Run date: 14-Aug-95 ,· •••• < ,'' U.K. Vessels Landing in Scot·lari·g· January 1983 to December 1983 Species: Mussels Units :_100 kg Gear: All gears{+ is< so k~.) .. CROWN COPYRIGHT MARINE LABORATORY ABERDEEN 09 EO E1 E2 E4 ES E6 E7 E8 E9 FO F1 F2 F3 F4 F5 F6 F?

45 I 44 l

43 ; ' 42 ! j

i 41 ! 40 l l 39 Il 381 ! I 371 L· 361- i· ' I 35 I 53°

52°

E Source: Scientific Database Run date: 14-Aug-95 U.K. Vessels Landing in Scotland January 1984 to December 1984 Species: Mussels Units: 100 kg Gear: All gears CROWN COPYRIGHT MARINE LABORATORY ABERDEEN D9 EO E1 E2 E3 E4 E6 E7 E8 E9 FO F1 F2 F3 F4 F5 F6 F7 163'~ j { 54 i -l !- 1 ;..--...---'---'---..__~+ -----~~~--'--_.;..--1---...;..---;---..--,----+---+- 52 I t.___..;___-+-_ _.:..__ ;..._. __ -l-~-+-----4--+---+---+---,---~..;---+---+--i---+j~ I. s1 I I!~ ~-i...~_;_~_..;..~--"'-~~~___;'"--~;.._~-i--~4-~...;._~....._~_:,-~-:-~-;-~_;...~-+- 50 ! l l j 49 ,______:_ ____...__ ___ Ll ______._.....__-+------.....---,--...... --- i l 481 ~; _ _..;,.. __,.....__...i..---!-~_...,~~+----+---+---;--+-~-i-~------:--+------+- '

471;..... _..._.._ __,1.--_....._ _ _,______.. 1 ___.;..__..,..__-,..... ______.___-+--~---+-·J~. l ··-i"

46 l l i -!--.. 45 ! [ -·.. -;-.-., rrl 44 I ! 1.- i 43 I ' -;-______..._ _ _;,...._-'---l----+------+----ll57o' l 42 i . 231 ! ! 41

j 40 l;...--~----~---~--'--~ 39 !,______' -.;.-~,.._-~------~------iisso 38 l i------+--- I i' 37 -----4--~~__.;...~-+-----..--~--i!54~ I !· ! --+--~~..,---+---1---~-~ ~;j 35: i

33 !

,-·-

31 ! ROCKALL 30 05 ~4 .-06 , 3 .. 07 :z· D8

29 45 l __...__ _ _...______, 5e· __J 50° I 28 '. 44 ! _J ( 27 i 43 LI~_;,_ __ ;__~..;._-_;______.i.._~_;_-_L~~~~~~-----~~------===:::::::===::::======~'25:~'___: 6;:; 40 20 E Source: Scientific Database Run date: 14-Aug-95 U.K. Vessels Landing in Scotland· January 1985 to December 1985 Species : Mussels Unit.s : 10.0· kg Gear: All gears C:ROWN COPYRIGHT MARiNE LABORATORY ABERDEEN 09 EO E1 E2 E3 E4 ES E6 E7 E8 E9 FO F1 F2 F3 F4 F5 F6 F7

i i i \ i ! j i i i / -· 530 54 ' I I l I I I t._:~:; -, i l .__---4~-..!.~~~-l-~__;..~-,-~-+-'~-+-~_._Ii l I I l i ~-1~· ~--+-~~1~--,-1~--+:~-+~-+1~-+-i~. l j I i i l ,' ··. ~ i 53 ! ' I I l i •·· i i I : I I i I I I : ' J i i 620 l ! j<· I ! 52 ! i t I .! ; ! I ! i I l I i I I I 1 ! i I i 51 I I I i l I j I 1 I i >er ~e,c !----!...---l---l---4------1.--..l.....--:.,-~i----.;1i ' _ __.,;_!---'i_-+i--;1_-+j-...... !.--~i ' 50 ! J~ ! .~~-4-~_,__~..--~--~-----'-~----~-'---

49 1 I 60c i 48 1 l

j ' ! i i i ! ! ! l i l I ! i I ! l l i i j l I i I I 1 l I ' i I ' i l I ! i

I w 10° E Source: Scientific Database Run date: 14-Aug-95 U.K. Vessels Landing in Scotland January 1986 to December 1986 Species: Mussels Units: 100 kg Gear: All gears CROWN COPYRIGHT MARINE LABORATORY ABERDEEN

t::;::: 09 EO Ei E2 E3 E4 ;.....;/ E6 E7 E8 E9 FO F1 F2 .F"' ,.) F4 F5 F6 F7 I ' 1630 54 j

! , 53 \ i i l!62° 52 t l ! ' _! ! j I I 51 Il .' •-' '.'' I ~61c i 50 ! I 49 I i 1·/ r;, ~soc 48 l ~ I - I 47 / i \ I ) -- --l 59° I I 46 .. ,.. J, i _l__ I " .-,1 ! . ! 45 ! 1 "' -··, ! I t 158° +- i I ! 113208\ .. ,.. , .... '~-~-! l 44 ! i I -;,

; 43 "1 I l i 1 57':, ! 42 ! 1131 ; ! 41 l ,, !, l -·- l i5sc ! 40 31 2 3 l I ' t . ( I 39 ! !ss 0 38

37 ' :54° 1 36 I } I . ·; i t l 35 r t· : j -- -i53° 34 I -' ~\ J i 33 I ,__i- -!o{... 20 32

! 31 ROCKALL -:s1° 30 l i 05 ~4 06 ~ D7 1z,Q8 t 3 -i 29 45 ! I 58 ~soe ! 44 28 ;

I 27 43: ! 57' l ; w 10<) go 6" 4·; 20 0" 20 40 6~ E Source: scientific Database Run date: 14-Aug-95 U.K. Vessels Landing in Scotland. January 1987 to December 1987 Species: Mussels Units: 100-kg Gear: All gears(+ is< 50 kg) CROWN COPYRIGHT MARlNE LABORATORY ABERDEEN

09 EO E 1 E2 E3 E4 E5 E6 E.7 E8 E9 FO F1 F2 F3 F4 F5 F6 F7

i i j ; I ; t l i ! l l •.' 63° I /-- ,." i I __ l 54 'i I ! I ! i f i i I i I ! i i I l I I l I i I ,I:. l I i i i ~ i i i ( ! I ! 53 I i I I L/ l i ! } ! J I I ! I I I ! .., I i 62° I I I l I •. i i l ·1 I i I • I I l I i ! W" I ! ! I ! ! ! 1 I I i I I -...... ~ ,

42 I '.,. ---.J ------+--- .. L 41 ! i I l i560 i 40 I l l } l

! ,,.,.: ... , 39 ! I I I i-----+--+-- 38 I k~·.:·i.:, · -,--).-_ --- 37 ! 361-·· >· 351 i , 34 i l ,' l--J .. i i I / 33 1 ,.--·- l I . .. '! i I \--•' ,.1,. l ----i 52° I ! I ·... · :1 I l I ,., ! ! I j "' ·r·--·. I I ';,' I _l, - . ~ ~~-· ::H I I 51° ROCKALL . 1 ···-- I .. 30 •" I I I I l I I DS wD6 13"07 1~08 I J I 29 I I 451 I r 1 l I I sz, i 50° i I, I 28 I I 44 I I i l I l l i i I I -~. I i ···- .. /~ 27 i -...._,,.,.. 43 l L---1---L--~-_!_~J___,..L_---!~-1.~-t-~------~~__;..;....;,.;_~~===:::;:,======;:::==::::....:;5i~'__JI I I I i l i w 10° 30 6v 40 20 oo 20 40 60 E Source: Scientific Database Run date: 14-Aug-95 U.K. Vessels Landing in Scotland January 1988 to December 1988 Species: Mussels Units: 100 kg Gear: All gears CROWN COPYRIGHT MARINE LABORATORY ABERDEEN 09 EO E1 E2 E3 E4 ES E6 E7 E8 E9 FO F1 F2 F3 F4 F5 F6 F7 j l. 163° l 54 l l ! _! ! 53 I ! ~62'' I 52 I _J 51 I l I - l 161~ 50 I! j ! { 49 i ! !ooc ! 48 1 i i l -j ·· 1 ... 47 li------~-_..______.,__ -- __..,..__-4-- _ _.;..._--;-_--,--+--...;.--··!~ l I i' -1s9° 46 I J/ ,} .-,. -c:9 l .. ! ' 45 I _.,...._{_):i...;__i _.;.__----i-----+--+----+-----f--...... ___-t-j -·'-.+--· ·--1 ssc I 44 l 1 l ) .

i 43 l ·l11

i 42 i 1 _23_s-,.-_____....;__-+------~~~-+--__._~--i----i~-I 41 'l ------+----.--~---+--,------~---~-__,:55c! I ! 40 I

I ) i ' 39 : 3i ! I -----....------+------~--~-----';55° ! 10i 38 I ' 37 i i___....._~---~~-+---...--.;..--~--1540 I l 36 I l i ;-- ---~~------+------~---..- --; j 35 ! l _J530 I 34: . ; ,------+ 33; -· -is2° J '"'2 l ! ; .::) l ' -i l 310 l-.. o I -':--- ROCKA:.. _L I O : 30: D5 ~4_.06 ,3. D7 :2<'D8 ~ 29 45 1 . , ______...__-+-_: se·· ~ ,...o:i l ! !o 28\ 44 ~

271L ~~~l__~L______:_~~-'--~__;_~_L..._-....l-~~----~~~~4-3...:::::::::::;==:=::::===::::===='25~~----2! 1 W 10~ 20 o~ E Source: Scientific Database Run date: 14-Aug-95 U.K. Vessels Landing in Scotland January 1989 to December 1989 Species : Mussels Units ·_.: 10 o kg Gear: All gears . CROWN COPYRIGHT MARJNE LABORATORY ABERDEEN 09 EO E1 E2 E3 E4 E5 .E6 E7 ES E9 FO F1 F2 F3 F4 FS F6 F7 54; l ;'~J_ ~': > l630

53 l----+-----'"----'---+--_:._~--+----+--___._-+----l---+--+---~-i---:ll--,..r---+-J-,,,... / j---'____· ·_ 620

s2 l I;;:- !

41 l ,_____.,.~__..~-+~---'--- 40 l

391. I ! ! ...... ~--i-~--+------+-~_.....~---~----,-~~,55° t 381 I I:~:>.> .i __ /_L,:· - 37 -:-. _ 5 L 1 I :: Lr ,i ------I I /~ ~u "---+-,._r/ ;,.-.. 53° 341 l_ .-" L-_J .. I ---t. I : I 33 j ., ! ______..._ ·- ,.L .,,/ I ;-.- ( 321 ;· L--..... i I -<...,! ,··;, __// ...... i-/ ----..! _ __;_ __ J:;' ./ ! I I I l:- 31 j i r / ; ~ ! I -;- I. ---- ) -~~~~~~ --- -- 51° 30 I ··1 :r · 1 j D5,~D6,~07 ,~08

29 i I i------....__--J-_.,;___.:,__-4---___,...'1_--~-~---"----il:,..___1..--I I l 45 1,...---4--____,l:,..__ __1 ~ - ""00 ' I l / l I I O I 44 2s I I.t, ! i I i !1---....;.------l ___ +----il I i i i I i .. ; ~--- ""·· '""- 43 l 271 I I IsT· I f 1 I I I w 100 30 40 20 oo 20 40 E Source: Scientific Database Run date: 14-Aug-95 U.K. Vessels Landing in Scotland January 1990 to December 1990 Species: Mussels Units: 100 kg Gear: All gears(+ is< 50 kg) CROWN COPYRiGHT MARINE LABORATORY ABERDEEN D9 EO E1 E2 E3 E4 E5 E6 E7 ES E9 FO F1 F2 F3 F4 FS F6 F7 - I 63° 041~-~-~-__;.--'---...;.--_;______~-+------+---l---+---+-----f--~+-~-+-- 53 ! ! 52 ! ! 51 l i ··-... ! l, -·-;--·-· I J. 50 {

49 .____...;,__...... _._ __..__ ,;__ ___ ...... ;..._---1 __ ,..__ _ __:.__ -..----+------+--..----+----+------'r;·· l 48 l l 47 i <: J.. ~I---'---"------i,,~~..,._------~-l------l----'"--i---....,...... --'----+~ i I 46 l ,,,,,j -l-- i 45 ! !~ : _...._ ;______1 '. l 44; 14536t" ---.------;,...--...----;.,_____.__.;..__,r80 43 i

42 . r .. ~1-47---+---....----1,--~.;._--i----i-~-...~~--+--~1570 41 ·1. ______,. __...------+---....;----;.,....-_..;.. ___ ---._-:j _6c '::>

40 lI

154' ~-+---,------_...;

... l __ ~53° J 33 -:,0'r-20 32 -i 31 l ROCKALL -i51,;; 30 [ ~-~-_;_-_....;.----~ DS 1~-D6 ~3 07 11,08 j 29 l 451 1 i l i------58·' ~: soc 28 44 ! ) -i 27 43: :...__ _:___ _:...._ __;,_~.:__-...!,__ _.;,._ __J____ ~-~~-~---~---.:====:====::::::::==:::;.:,===::'....~57~'___J W i0° 6':,' 0° 2" 4c 6° E

Source: Scientific Database Run date: 14-Aug 0 95 U.K. Vessels Landing in ~cdtlancl January 1991 to December 1991 Species : Mussels Units :: 10·0 kg Gear: All gears (+ is < 50. kg ) CROWN COPYRIGHT MARINE LABORATORY ABERDEEN

D9 EO E1 E2 E3 E4 E5 E6 E7 ES E9 FO F1 F2 F3 F4 F5 F6 F7 I i l I i I I 63° 54 j ' l I ,~·J .. __ ~~·; i l l l l I I I ! l I : I I I i I I l I l ·~,· "· I I ·., ! ! : ,, ' I ' I ,• / ., i ! ! I ! I 53 I! t I l ! . ~~-- : I I I l ! I I l l I i '" I I '. I i. ·~ ! l 62° i ! I l I I ! 1 I 52 I ; I 'i j ! f I i I ! ! I I i I l I ,· i I 1 ! i 1 I 'i 1 j 51 i i ' I l r l .: ~· ~::.::::' i 1 I i I I l l l l ! I t t I ] ! '! ! ' ' ' ' ' l. ! so I ,,.,,,,.·· l

. I

I ! i : I SS·' I I 1 i I/· l ' J I ! l 28 I I I I I 44 I I i I i i I 1 i i I: . I I ! I I I ; l I l - ! I, ,j~,/'. ! ! ,,, . ' I 27 i I I • ~. r 43 l l l I i ! i i I I I . .. .. Is,., I I ! I \ ! I I I w 10° E Source: Scientific Database Run date: 14-Aug-95 U.K. Vessels Landing in Scotland January 1992 to December 1992 Species: Mussels Units: 100 kg Gear: All gears CROWN COPYRIGHT MARINE LABORATORY ABERDEEN 09 EO E1 E2 E3 E4 E5 E6 E7 E8 E9 FO Fi F2 F3 F4 FS F6 F7 I ! .!. J63o 54 j l l , I -l

53 l! .1 J ! -1.·s2° s2 l~--1--_,.....____,___~ _ __.____:.___;._---,---..,------+---~I: ··~ 51 I I:"' ... r I '6F ,,,.o i I ! ::) :~~..:._ _ _,;..l ______....;._ _ _,.;..._~------~------c--- l ] 49 ! I l I 1 L_____ .__,;.. __ .;.,._ __;___~ __ ,,__ __._ ___ -...-1 ---+------'-----+------/ · ~ 60:, l 1 ! ! , 1•··· l 48 l I , ! l H--L._ _;...._...i...,___ --'-_-l..-_.. _ __..__ _.___l_--'-_-+---i----+---+-- r !

47 I, I __ _._ _ ___.:. __+----+--+---:-----+----i-- l,, -.· ...... l .. l -90 ! ! ! · 1b 46 ! - 1 ',··--~--! 1 l ',. ~ ! I 45 I i. ·~-'-~~l~---..---16~!----+----+------.~--'~~I~·--~~-lsac l ! 44 l . 238641 J I I < t .. i i i I 43 ; i l i. ~-l~~....----'------l--+------i---+------;---~57c 42 5818! j

4i I I j ~ 1 ___.....;,__4- ______---;,_--4,,_--;.... ___ -}j 56° ! 820: l 40 I l j ; J 39 ! 147' 38 ! 1

1 I 37 I

1-·

{ 36 j L_.

35 !

1.. 34 [ . __ --: 33 '-- -.s2~ 32

31 ROCKALL l 30 D5:~D6,~07 ~~08 , 29 451 1 ~-;------$3· -'. 50° 28 44 '.

l w 100 40 E Source: Scientific Database Run date 14-Aug-95 U.K. Vessels Landing in Scotland· January 1993 to December 1993 Species: Mussels Units: 100 kg Gear: All gears CROWN COPYRIGHT MARINE LABORATORY ABERDEEN D9 EO E1 E2 E3 E4 E5 E6 E7 E8 E9 FO F1 F2 F3 F4 FS F6 F7 541 I I ._ I : j630 531~ ...;..______.;----.!..---!..--~--1.-~---+---l----,----+---+--+----+--l ---1----'-_l · :; .····· 1

-2 I i' i • ]···. s20 o , , I ~:·

51 ~--_.___.....__...... ;___....__..l..,__ _;_--t--l______..;...,.. ______...... ---+---+----..;.--....----'-1 ':::c".' J, 61° 50 ! : .. :·· . i ·-----4,: .. ,, ., ; ~-ii ... --1 49 i ' ----..-----,--- '_;l:.____..;_--i_ __..,_---;.,_-+--+---'\::<. ; __J 600 481 .· 1 1 471 ; ·. i 1 1 ~~~-+--+----4-~---+---+-~-"----+-~ ~59° 1 ' I :-::-1· .... l 46 I .J ,,J . 0 ~ C'-i : . J l...,..____. _ _...., ·------:- \~~~· .1~ ! ! . ! <> l .::>,t-- _ _.___...... __...... _!- i ! ! - ..·-·~ ~~ ~

44 1,.. • , · . i ·. · ·, 2bma,~~- ,~_ ·,·.·- -L .. • " I,,... ! .·-:. I.~~ '------'------·---+ ... '>J, '< ., 43 l r '----'----'--...... ~-....-...... _ 42 I i ',. '! 41 I I ,...-...--'---"---'-~--- i i 40 i : 39 i I • -'-:· .. , 381 l I 1

.,.,,..... !_.,.~,. ... - 371 . J. i 36L. "'! i f' 3,. I I ::, l \ / 34 !. i,., I L r-' i I 33 L !.. ! ·i 32 i .. l--t 31 I I

30 I I ··. t 29 l l I 1 I 28 I l i I

27 I ! l l W 10° 40 6<> E Source: Scientific Database U.K. Vessels Landing in Scotland January 1994 to December 1994 Species Mussels Units 100 kg Gear: All gears(+ is< 50 kg) CROWN COPYRIGHT MARiNE LABORATORY ABERDEEN 09 EO E1 E2 E3 E4 ES E6 E7 E8 E9 FO F1 F2 F3 F4 FS F6 F7 ! 1630 54

53 --1 _ .. 1620 l' f 52 i. t _1 '. I 51 ! ' I I ~ . ~6i 0 i l . l 50 i 1 !' i' i

49 I ;

~60°I 48 ! 47 ______...,.... __ .,...______',! 1 ''"'Ov i .-iov ! 46 l r- 45 1 ~----'--~----"--~...... ~-.--~...... ~------~~~---~·-··._,·!sa 0 ! 44 )1535'- I 1 43 ~"""----..______.______...___,I s-r 42 -~--~-----~~...... --~~------,,.-~t I ! 41 i ------.----,------,...------~---,----1,56° 40 + ! l

38 20

37 ~- 36 ; 35 -

34 ; --: 33 \....__ --j52° 32 i _i t--- l \ \ 31 l-~~ --, Ol ~ ROCKALL l 30 D5,Q06 :~D7,r~8 I

1 29 I 45: 1 i 1 r--+:-----+---.i ss, ~ 500 i 44 \ i 28 I ~ ~ 43 ! 27 '57' I w 10'' so 20 40 E Source: Scient;fic Database Run date 14°Au9-95 Review ofthe Exploitation ofthe Mussel, Myti/us edulis in Scotland

Appendix 3. List of potentially relevant legislation Appendix 3. List of potentially relevant legislation and government agencies

Burbridge and Burbridge (1994) have reviewed the major issues relevant to the sustainable development of coastal areas and resources in Scotland. Their report includes an inventory of relevant legislation (based on an old listing produced by the former Nature Conservancy Council in 1989) and an outline of the main agencies involved in coastal management, with their divisions of responsibility. The following appendix is mainly summarised from this report, and from Cleator and Irvine (1994).

Acts, EC Directives and Conventions

Natural heritage Countryside (Scotland) Acts 1967 and 1981 Covers agreements on land management and compensations between SNH and landowners/occupiers for the purposes of conservation. Includes some provisions in Section 56(1) which allow local authorities to make bye-laws to control some aspects of vehicles on land and water. Amended by the Natural Heritage (Scotland) Act 1991.

National Parks and Access to the Countryside Act 1973 Concerned with establishing nature reserves down to Mean Low Water of Spring Tides and enables bye-laws to protect them. Reserves are established by SNH (for National Nature Reserves) and Local Authorities (Local Nature Reserves). Some Scottish reserve bye-laws control collection of shellfish and bait digging.

Natural Heritage (Scotland) Act 1991 Enables designation and protection ofNatural Heritage Areas of high landscape and nature conservation value. Legal effects of designation are minimal. No new National Scenic Areas can be created. Amended the Countryside (Scotland) Act, changed powers of the River Purification Authorities and transferred the responsibilities of the Nature Conservancy Council for Scotland and the Countryside Commission for Scotland to Scottish Natural Heritage.

Sea Fisheries (Wildlife Conservation) Act 1992 Places a duty on the Secretary of State for Scotland to acknowledge the conservation of marine fauna and flora with regard to his functions in relation to fisheries.

Wildlife and Countryside Act 1981 (amended 1985) Allows for designation by SNH of SS Sis to protect important wildlife, geological or physiographic sites. Designation is only possible for areas above the Mean Low Water of Spring Tides. Restrictions are placed on owners and occupiers, and certain 'potentially damaging operations' are prohibited unless authorised by SNH. Nature Conservation Orders made by the Secretary of State strengthen existing protection granted by SSSI designation, by extending controls to any person, not just owners and occupiers, and increasing penalties for infringement. Marine Nature Reserves may be designated by the Act (although there are none in Scotland) and can include subtidal areas. The Wildlife and Countryside Act (Bye~laws of Marine Nature Reserves) Regulations 1986 governs the application of local authority bye-laws to rvINR.s.

Fisheries Fisheries Act 1981 Fishery Limits Act 1976 Fish (Conservation) Acts 1967 Sea Fisheries Act 1968, Sea Fisheries Consezyation Act 1992 These Acts regulate most fishing operations in Scotland, including licensing of all fishing for commercial gain from fishing boats. They do not affect the inalienable public right to collect shellfish (other than oysters and mussels) from any shore in Scotland where there is a public right of access. Indeed, no fisheries legislation currently exists that will allow Scottish Office to modify this right. Additionally, apart from recent legislation introduced to control tractor dredging for cockles, no fisheries Acts exist that can be used to control fishing activities that are not vessel-based. It may even be the case that the primary legislation that allows the imposition of minimum landing sizes in Scotland may be inadequate if it is decided to impose a minimum size for any species collected on the shore. Completely new primary legislation would probably therefore be required to regulate the collection of shellfish from the shore.

Mussel Fisheries (Scotland) Act 1847 Oyster Fisheries (Scotland) Act 1840 These Acts removed mussels and oysters from the public fishery. These shellfish now belong to the Crown in Scotland and fisheries may only be prosecuted by lease from the Crown Estate Commissioners. However, the collection rights for these shellfish are alienable and heritable, so some have been transferred out of Crown ownership.

Sea Fisheries (Shellfish) Act 1967 Provides powers to make Several and Regulating Orders concerning shellfisheries. Several Orders encourage the establishment, improvement or maintenance of a shellfishery, granting exclusive rights to a person or company to take named species from within a defined area. Regulatory Orders enable Local Authorities to regulate fisheries via regulations and restrictions and to levy tolls or royalties. Prohibits the deposit of shellfish to prevent the spread of shellfish disease. Amended by Sea Fisheries Act 1968.

Inshore Fishing (Scotland) Act 1984 Enables the Secretary of State to regulate fishing in specified inshore waters. The Minister can make orders controlling fishing from vessels by area and gear type and imposing temporal restrictions on fishing effort. Under the order concerned with the Prohibition of Fishing and Fishing Methods in Scottish Inshore Waters (1985), static gear reserves are identified where there are restrictions on the use of mobile gear such as dredges. The Montrose Basin is a static gear area, which has prevented the use of mussel dredges in this fishery.

Planning and management Civic Government (Scotland) Act 1982 Deals with District and Island Councils' powers with respect to the seashore and adjacent waters (lOOOm from MLWS). Gives bye-law making powers for purposes such as preserving or improving amenity of the seashore and conserving its natural beauty by regulating trade, business, sporting or recreational activities. Enables them to improve or restore the amenity of the seashore. Although the Act does not specify the conservation of flora and fauna, it was proposed as a possible mechanism for regulating the control of cockling in the Solway Firth.

Town and Country Planning Act (Scotland) 1972 The major piece of planning legislation. Jurisdiction usually stops at MLWS. Numerous other planning acts regulate the powers of local planning authorities. With the completion of the local government in Scotland and the likely introduction of many more single tier councils, much of this legislation will be reviewed or amended.

Crown Estates Act 1961 Provides powers exercisable by the Crown Estates Commissioners for the management of the Crown Estate, including foreshore and seabed. Pollution control Control of Po11ution Act 1974 (COPA) Concerned with freshwater, estuaries and coastal waters. Defines 'controlled waters' including territorial sea up to three nautical miles from the baselines and other areas beyond this limit, if so designated by the Secretary of State. Enables Water Quality Objectives to be set, and discharges of effluents to be regulated by River Purification Authorities.

Environmental Protection Act 1990 (EPA) Re-enacts and amends part of COPA 1974 and Food and Environment Protection Act 1985. Allows the formation of the Scottish Environmental Protection Agency (SEPA)

Food and Environment Protection Act 1985 (FEPA) Concerned with dumping at sea and issue of licenses for such activities.

Sewage (Scotland) Act 1968 Administered by the Regional and Islands Councils. Concerned with sewage and waste water treatment discharges.

European Directives Directive 92/43/EEC on the Conservation of Natural Habitats and of Wild Fauna and Flora (The Habitats and Species Directive) Aims to promote the maintenance of biodiversity, taking into account economic, social, cultural and regional requirements. Special Areas of Conservation (SACs) and Special Protection Areas (SPAs, see Birds Directive below) must be designated to establish a European network called Natura 2000. Coastal SACs containing marine habitats listed on the Directive which have been provisionally identified in Scotland include some estuaries and large shallow inlets. Article 6 of the Directive imposes strong protection measures for designated sites, including management plans, special measures to avoid significant deterioration of the conservation interest of the site, environmental assessments and a ban on any project which will adversely affect the integrity of the site (unless necessary for imperative reasons of overriding public interest). Monitoring and scientific research will be encouraged at these sites. Implementation of the Directive (with respect to SA Cs) will be undertaken through the designation of SS Sis above the Mean Low Water of Spring Tides, and through other existing legislation and bye~law making powers below the MLWST.

Directive 79/409/EEC on the Conservation of Wild Birds (The Birds Directive) Provides habitat protection by the establishment of a network of protected areas for birds (including some birds which may feed on intertidal shellfish or shellfish beds). Special measures are needed to protect these habitats from pollution or deterioration, and to avoid the disturbance of birds. These measures include the designation of Special Protection Areas (SPAs) for 175 rare, vulnerable or regularly occurring migratory species listed in Annex 1. The Directive is implemented by the designation of Sites of Special Scientific Interest (SSSis) under the Wildlife and Countryside Act (1981). SSSis may only cover land and intertidal down to Mean Low Water of Spring Tides, not offshore areas. Very few intertidal SPAs have been designated. These sites will also form part of the network Natura 2000 (see above).

Directive 79/923/EEC on the quality required for shellfish water (Shellfish Growing Water Directive). This is aimed at ensuring a suitable environment for shellfish growth. It lays down the health conditions for the production and placing on the market of live bivalve molluscs. Under the Directive, the competent authority (SOAEFD in Scotland) must establish the location and fix the boundaries of coastal bivalve mollusc production areas requiring protection or improvement, list them, and classify them according to the degree of contamination by faecal indicator bacteria present in samples of mollusc flesh. Pollution reduction programmes for these designated areas are required so that they conform, within six years of designation, to the physical, chemical and bacteriological standards set out in the Directive. Implementation in the UK is through the Control of Pollution Act (1974).

The first list of sites designated were those which already met the required EC standards, or should do so under existing improvement plans, by November 1987. Designated sites include: Dornoch Firth, Arbroath coast, St Andrews-Fife Ness coast, North Berwick-Dunbar coast, Loch Ryan, Ayrshire coast, Loch Long/Loch Goil, Kyles of Bute, and the Loch Fyne coastal strip. Not all of these areas are presently used for shellfish farming, and there have therefore been some queries as to why they are designated. However, these are presumably known to be used for the collection of wild shellfish.

The most recent list of Bivalve Production Areas presently available, presented in Appendix 3 to this report, dates from the end of December 1994. The December 1995 update should be available very shortly. In due course, maps may be provided to accompany these site lists.

Directive 91/492/EEC on Shellfish Hygiene Defines end product standards for shellfish. Requires shellfish buyers to register with their local environmental health department to get appropriate testing carried out before issue of export licences.

Directive 91 /271 /EEC Concerning Urban Waste Water Treatment. This Directive aims to protect the environment from detrimental effects caused by the discharge of urban waste waters ( domestic and industrial waste water and urban runoff). It deals with the collection, treatment and discharge of such wastes (not including all industrial sectors) into freshwater, estuaries and coastal waters, recognising that some areas and water bodies are more sensitive than others and therefore require different levels of treatment. Member States are required to identify sensitive and less sensitive areas according to criteria laid down in the Directive, and monitor receiving waters and treatment plants.

Directive 91/676/EEC Concerning the protection of waters against pollution caused by nitrates from agricultural sources. This Directive aims to protect the aquatic environment from eutrophication caused by nitrates from agricultural sources. Nitrate Sensitive Zones must be identified and measures taken to reduce the influx of nitrates into these waters.

Council Regulation (EEC) 1973/92 establishing a financial instrument for the environment (LIFE) The LIFE financial instrument for the environment may finance demonstration projects in a number of areas, some of which may be potentially relevant to work on the sustainable exploitation of fisheries within areas of high nature conservation importance. For example, areas to be financed include: the implementation and development of models designed to incorporate environmental concerns into landuse planning and the management of the rural environment; conservation measures concerning nature sites; programmes for the recovery of priority species; inventories by major eco systems; emergency actions for priority habitats or species.

International Conventions Ramsar Convention on Wetlands of International Importance Especially as Waterfowl Habitat (1971). Amended 1982. Aims to prevent the increasing loss of wetland habitats, particularly those of importance for bird conservation. The co-ordination and identification ofRamsar sites in Scotland is the responsibility of the Joint Nature Conservation Committee, advised by Scottish Natural Heritage. Conditions of designation in Scotland apply only to Sites of Special Scientific Interest and may extend to the mean low water mark of Spring tides. Berne Convention on the Conservation of European Wildlife and Natural Habitats (1979) Aims to ensure the conservation of wild flora and fauna and natural habitats by promoting cooperation between European States. Implemented in Scotland by the Wildlife and Countryside Act 1981. The EU Birds Directive covers the provisions of the Convention for wild birds and the EU Habitats Directive for other species.

Bonn Convention on the Conservation of Migratory Species of Wild Animals (1979) Aims to conserve threatened migratory species of wild animals (invertebrates, fish, reptiles, mammals and birds). Implemented in Scotland by the Wildlife and Countryside Act 1981. See also the provisions of the Bern Convention and EU Birds Directive.

Agencies and responsibilities

Crown Estate Commissioners The Crown Estate Commissioners (CEC) are responsible for the management of the foreshore (representing area of the Scottish coast which lies between the high and low water marks of spring tides). Naturally occurring stocks of oysters and mussels in Scotland belong to the Crown and the rights are administered by the Crown Estates. About half of the Scottish foreshore is not owned by the Crown; even so, rights to collect oysters and shellfish may still have been retained by the Crown. Since these rights are alienable and heritable, they may also have passed to third parties. There is no clear single record of such ownership. This situation may not affect a probable public right to collect mussels and other shellfish by hand for non-commercial use.

Virtually all the seabed which lies below the low water mark and as far as the 12 nautical mile limit of territorial waters is Crown Estate property (Crown Estate Act 1961). Additionally, the natural resources of the seabed ( other than coal, oil and gas) beyond the 12 mile limit are also vested in the Crown Estate (Continental Shelf Act 1964). However, Crown ownership is subject to the public rights of fishing and navigation.

Scottish Office Agriculture. Environment and Fisheries Department SOAEFD was formed in spring 1996 from the merger of the Scottish Office Agriculture and Fisheries Department and the Scottish Office Environment Department. There have been some changes in the Divisions and Branches of these two former Departments, but full details were not available at the time of writing.

Scottish Office Agriculture and Fisheries Department Now combined with the Environment Department (see above). SOAFD was divided into a number of Divisions and Branches, dealing with different aspects of the Department's responsibilities. Division E dealt mainly with matters concerning European co-ordination, support and policy. Division J had four branches concerned with: 1 fish stock conservation, 2 Licensing and effort control, 3 Marketing and trade, and 4 Statistics on landings and vessels. Division K dealt with: Branch 2 salmon and freshwater fisheries, and Branch 3 marine pollution, marine conservation and wildlife policy, the oil and gas industry, FEPA and coast protection. The Fisheries Research Service, including the Marine Laboratory at Aberdeen, carries out research to support the Department's fisheries management and stock monitoring responsibilities, and research related to the Department's responsibilities under FEPA, COPA and North Sea oil. The Scottish Fisheries Protection Agency enforces fisheries legislation and helps in fish stock conservation. Scottish Office Environment Department Now combined with the Agriculture and Fisheries Department (see above). The Rural Affairs and Natural Heritage Division, Branch 1, sponsored Scottish Natural Heritage and was concerned with all aspects of wildlife or nature conservation, including national and international legislation, directives and conventions. Branch 2 dealt with national and international countryside and landscape issues, such as access policy, EC Directives, environmental education and environmental tourism. Branch 3 was concerned with rural and coastal policy coordination. Planning Services' Rural Group provided advice and information on national and rural land use issues, including nature conservation, fish farming, rural development plans and environmental assessment. Various aspects of planning issues were dealt with by the Policy Planning Division and the Planning Services. Water pollution control matters, including the EC Shellfish Directive, were dealt with by the Engineering and Waste Water Directorate.

River Purification Authorities The RP As are entrusted with the task of protecting and improving the quality of the water environment up to the low water line or closing line of estuaries within their catchment areas, and tidal areas specified in Section 31 of the Rivers (Prevention of Pollution) (Scotland) Act 1965. They include seven mainland boards and the three Islands Councils, and their jurisdiction extends out to three miles from the mean low water mark of Spring tides.

Scottish Natural Heritage SNH aims to secure the conservation and enhancement of the natural heritage of Scotland and to foster its understanding and facilitate its enjoyment. Its responsibilities include the encouragement of environmental sustainability in all forms of economic development, including issues relating to natural resource management.

Local Government The Regiona~ Councils and Island Councils represent most of the local government authorities in Scotland, and provide the major local and regional services. They are either already unitary authorities, or soon likely to become reorganised as such when their duties will be merged with those of the District Councils (but with the Water Services Departments split oft). Some new unitary authorities may cover smaller areas than the original Regional Councils. Where they still exist, District Councils form the second level of local government authority. Their responsibilities include local planning, environmental services, tourism, amenity services, nature conservation, leisure and recreation. Their responsibilities include the establishment and management of nature reserves, under the National Park and Access to the Countryside Act 1949. Bye-laws may be enacted to protect intertidal areas of nature reserves from some types of wildlife collection (e.g. bait digging).

Ministry of Defence Has responsibilities under the Military Lands Act (1900), Land Powers (Defence) Act (1958), Protection of Military Remains Act (1986). PL (Lands) 3 is responsible for nature conservation and subject to the Wildlife and Countryside Act ( 1981 ), although military aspects take precedence. PO (Lands) (Safeguarding and Bye-Laws) Division has responsibility for bye-laws covering MoD practice ranges, within which public access to the shore may be restricted.

Designations

Inshore Static Gear Areas Designated under the 1984 Inshore Fishing (Scotland) Act. This Act removed the previous three mile exclusion zone for mobile gear and enabled new exclusive areas to be designated that are restricted to static gear only for all or part of the year, thus reducing conflicts between fishermen using static gear and those operating mobile gear. The 1989 'Order for the Prohibition of Fishing and Fishing Methods in Scottish Inshore Waters SI 962' identified 22 'static gear reserves', ten closed all year around and 12 closed seasonally. The Montrose Basin is a static gear reserve, preventing mussel dredging there.

Several and Regulating Orders These Orders are administered by SOAEFD, under the Sea Fisheries (Shellfish) Act 1967. They apply to areas of intertidal and subtidal land and regulate shellfish fisheries within these areas. Thus, individuals or groups are given exclusive rights to the fishery for specified shellfish, and may use these rights to establish or improve, maintain and regulate shellfisheries. The holder of a Regulating Order may impose tolls or royalties on those who wish to take the specified shellfish, and regulates fishing by third parties through issuing licences. A Several Order gives the holder exclusive rights over the named species, and regulates the type of fishing which a third party can carry out in the Several Order area.

Marine Nature Reserves and National Nature Reserves There are no Marine Nature Reserves (MNR) in Scottish waters. Should MNRs be established, bye laws may be used to restrict certain activities. Under the current form of the legislation, any bye-laws concerned with fisheries would have to be enacted by SOAEFD, not SNH. Where National Nature Reserves include areas of intertidal, bye-laws to protect the nature conservation interest of the reserve may be enacted by SNH (e.g. at Caerlaverock).

Local Nature Reserves These are established by local authorities under the National Parks and Access to the Countryside Act 1949. These local authorities have bye-law making powers, which extend to the low water mark. For example, bait digging is prohibited under bye-law in the Aberlady LNR.

References

Burbridge, P.R. and Burbridge, V. 1994. Review ofScottish coastal issues. A consultants' report to the Scottish Office. Scottish Office, Edinburgh.

Cleator, B. and Irvine, M. 1994. A review oflegislation relating to the coastal and marine environment in Scotland. Report to Scottish Natural Heritage.from C/eator Associates.