|
|
|
|
6. The marine fish farming industry has two main components :
In addition, freshwater salmon farms produce smolts for on-growing in seawater but are outwith the scope of this paper.
7. There are around 330 marine salmon farms and 360 shellfish farms in addition to which there are a small number of sites where other marine species such as halibut, sea trout, cod and turbot are farmed. The requirements of each sector of the industry in terms of water and land area, buildings, equipment and technology may vary considerably, but there are many elements in common.
8. Currently, virtually all marine finfish production takes place in the inshore waters of the west coast and islands, where the most favourable operational conditions for marine aquaculture are to be found. Shellfish farming shows a similar distribution, though there are relatively few shellfish farms in Shetland and Orkney, where lower water temperatures result in slower rates of growth, although having said that, there has been a significant growth in the number of applications for mussel farming sites within Shetland.
Salmon
9. The Atlantic salmon (Salmo salar) is the main finfish species farmed in Scottish waters. Nearly all UK salmon production is located in Scotland and salmon production is the most economically important sector of the marine fish farming industry. Salmon farming expanded rapidly during the last 10 years with production rising from some 32,000 tonnes in 1990 to 110,000 tonnes in 1998. Expansion has been achieved both through the development of new sites and increased productivity.
10. Almost all Scottish farmed salmon are grown in seawater cages. A variety of sea cage systems are currently in use in Scottish coastal waters. In most designs fish are contained in net bags suspended from floating collars. Most installations consist of rafts of cages, often arranged round a framework of walkways to facilitate servicing. Larger and more robust semi-submersible cage systems have been developed for use in open sea conditions. A finfish farm site may contain several installations, each maintained in position by its own mooring system.
11. The industry makes an important contribution to Scotland’s rural economy. The value of salmon output in 1998 was around £260 million, greater than that of the Highland beef and lamb industries put together. It is estimated that salmon farming and its ancillary industries currently provide around 6,500 jobs in Scotland, many of them in remote locations where alternative employment opportunities are scarce.
Rainbow Trout
12. The other main finfish species farmed commercially in Scottish waters is the rainbow trout ( Oncorhynchus mykiss). Most Scottish trout production takes place in freshwater. However 6 marine sites, which enable the trout to grow larger, are engaged in production. In 1998 these contributed 502 tonnes or 10% to total rainbow trout production in Scotland.
Shellfish
13. Shellfish farming in Scottish coastal waters is almost exclusively concerned with mollusc production. The main species are mussels (Mytilus edulis), native oysters (Ostrea edulis), Pacific oysters (Crassostrea gigas), and king and queen scallops (Pecten maximus and Aequipecten opercularis).
14. Mussels are grown on weighted ropes suspended either from buoyed lines (the long line system) or wooden rafts. Oysters are grown either in trestles placed in the intertidal zone, in stacks of trays located just below the low water mark, or in net bags suspended from rafts. Scallops may be grown in nets hung from buoyed lines or rafts, or suspended on ropes by threading a tag through a hole drilled in one of the lobes of the shell ("ear-hanging"). They can also be grown on the sea bed.
15. Although there are similar numbers of finfish and shellfish leases, the scale of shellfish cultivation is still relatively small, with a value in 1998 of only about £2 million. While a few relatively large farms account for the bulk of Scottish production, most Scottish shellfish farms are small enterprises producing less than 10 tonnes per year. Shellfish farming employs about 350 people in rural areas and provides a valuable source of income in many crofting communities, much of the employment being part-time.
Other Species (in development)
Halibut
16. Six companies, operating from 7 sites, are currently involved in the development of halibut farming. 1997 saw the first commercial harvest of the species, amounting to about 0.5 tonnes. Estimates suggest that this could rise to about 80 tonnes by 2000.
Sea trout
17. 1 company operating from 2 sites in Shetland is currently producing sea trout. Estimates suggest a harvest of some 70 tonnes in 1999.
Turbot
18. Three companies, operating from three sites, are currently involved in the development of turbot in Scotland. The first commercial harvest from these operations is expected to reach 100 tonnes in 1999.
Cod
19. The development of cod farming is still in its infancy but research being conducted by the Sea Fish Industry Authority (SFIA) in collaboration with a number of fish farms and retailers is producing very encouraging results. The first commercial harvest is expected in 1999.
Future Prospects
20. Despite major growth by the salmon farming industry in Scotland over the past 10 years, the industry in Europe as a whole continues to be dominated by the Norwegians whose production is about three times that of ours. Recent times have seen acute downward pressure on market prices, giving rise to amalgamations of companies and fears of possible closures. Matters have been further exacerbated by the outbreak of Infectious Salmon Anaemia (ISA), which resulted in culling of affected stocks and movement restrictions being placed on a significant part of the industry in order to contain the outbreak.
21. Prospects for continued growth in the market for salmon remain good and there is potential for further expansion of the industry in the medium to long term, provided that present difficulties can be overcome. With most suitable inshore sites already having been taken up, the scope for further development close inshore is limited. While advances in marine fish farming technology now make it possible to operate in more exposed locations, the equipment and servicing costs are considerably higher. Economic returns from salmon farming will therefore have to improve markedly before there is a major move into exposed off-shore locations.
22. Production of rainbow trout in sea water in Scotland is currently limited. The technology used is the same as for salmon and most companies owning sea sites find the margins with trout to be a disadvantage for this species to be widely farmed. However there are some indications of an increased interest in the growing of steelhead trout (a naturally sea migrating strain of rainbow trout) particularly in association with the put-and-take industry requirement for the proportion of large fish in their ponds to attract anglers.
23. The technology used for sea trout used is similar to salmon, but as a species Salmo trutta is difficult to rear. At present, the widespread production of sea trout is not anticipated.
24. Halibut culture is believed to be economically viable and is a way for the British aquaculture industry to diversify. The fish are easy to grow (once at the juvenile stage) are resistant to most salmonid diseases and demand a high market price. However, one difficulty is the high larvae mortality and hence the high price of juveniles for on growing. For the industry to flourish larval survival must be improved and hence on-grower production.
25. The technology for turbot culture is longer established than that for halibut and cod, with much initial research being conducted by White Fish Authority/Sea Fish Industry Authority (WFA/SFIA) in Scotland particularly in the 1970’s and 1980’s. The appearance of the List II disease, VHS, led to the closure of a land-based Scottish farm in 1994, although it is possible that it may re-open in the future. There are currently small industries in France and Spain, one farm on the Isle of Man and currently three farms in Scotland, one of which is expected to produce a small tonnage in 1999.
26. Cod are much easier to produce than halibut, having a much shorter larval stage, but are much more aggressive. Siblings frequently cannibalise each other if inadequately fed. The single experimental hatchery believes it has developed a robust method for producing cod and hopes the fish will adapt to intensive production more easily than halibut. Prices for good quality fresh cod have risen even with current stock levels and quotas. Preliminary economic analysis indicates that commercial cod farming may be close to viability under existing conditions without a further collapse of stocks or introduction of severe quotas.
27. Mussel, oyster and scallop cultivation in Scotland operates on a relatively small scale but advances are being made in husbandry, mechanisation and marketing. The healthy demand and buoyant market for all cultured species which occurred in 1996/97 continued into 1998 and it is predicted that output will increase steadily over the next few years as improved efficiency leading to lower production costs allows greater access to markets.
|
|
|