Trends during development of Scottish salmon farming: An example of sustainable intensification?
Commercial farming of Atlantic salmon in Scotland started in 1969 and has since expanded to produce N 179,000 t year −1 . A government department has published annual statistics and information on the seawater and freshwater sub-sectors of the Scottish salmon farming industry since 1979, and this review collates and dis cusses metrics covering aspects of production, farm sites and systems, fish performance, socio-economics and en vironmental pressures. Trends illustrated in this case study of
... uaculture development include: initial increases in numbers of farms and companies, followed by decreases due to industry consolidation; increases in average farm size, and productivity of systems and employees; increases in survival, size at age and productivity of fish (yield per smolt, ova per broodstock); reduced dependence on wild stocks for ova. This case study also illustrates the importance of disease management, control of biological processes to overcome natural seasonality (i.e. pro duction of out-of-season smolt), and the international nature of aquaculture. Improvements in fish survival, growth and productivity are attributed to progress in vaccination and health management (including fallowing), husbandry, system design, feed formulation and provision, and introduction of technology and mechanisation. Salmon farming is discussed in relation to the challenging strategy of "sustainable intensification". Improved growth and survival over a period of increasing rearing unit size, farm size and output and decreasing relative staff input counters the common assumption that intensification compromises animal welfare. The value of cap turing time series data on industry wide metrics is illustrated as it enables identification of trends, underperformance and bench-marking, as well as assessment of resource use efficiency, environmental pres sures, and ultimately sustainability. Statement of relevance: This review is an original collation of a comprehensive set of time series of official statistics on an entire, discrete and regionally important sector of commercial aquaculture. Crown