The amount of fish either produced by aquaculture or caught at sea has increased during the last years. While the capture of fish increased from 78 Mio tonnes (1984) to 94 Mio tonnes (1997), aquaculture production raise from 10 Mio tonnes (1984) to 36 Mio tonnes in 1997. By comparing the trophic levels of caught fish during the last decades a serious development can be seen. Nowadays relatively more fish at lower trophic levels are caught due to an overfishing of high-valued species. Over the last years aquaculture production has increased all over the world. Especially in “low income food deficit countries” (LIFD), such as several Asian countries, the volume has increased by more than 80%. Aquaculture has become a more important factor in the production of fish, especially for human consumption.

In industrialised countries, aquaculture becomes a more and more important factor contributing to local, regional and national economics. Salmon farming in Northern Europe is a good example: In 1994 Norway produced 205 722 metric tonnes with a high growth rate, attaining an output of over 360.000 tonnes in 1999.

The present production strategy must change because of decreasing natural resources available for wild fisheries and because of future limitations of water resources available for aquaculture. Therefore, aquaculture employing especially recycling technology can be a reasonable new and innovative methodology of production for future development. HESY goes this new way of aquaculture production. Innovations like the Blue lable system are a step in the direction of a better future in fish farming.

Aquaculture systems

The roots of Aquaculture can be found in Chinese carp culture in ponds, established more than several thousands years ago. Depending on species, the requirements and availability of resources, various types of aquaculture facilities have been developed subsequently. At present more than 70% of the aquaculture production is farmed in system similar to this traditional type, many of them employing resource recycling in traditional forms (e.g. dike-pond-concept).

Aquaculture in Europe has also a long tradition. Established since the Roman times and developed further during the Bohemian ages, at present it is growing at industrial scale (Figure 2). Present facilities are characterised by higher technical expenditures and energy inputs on the one hand; on the other hand they allow higher densities, increased production level, automation of processes, better control of environmental conditions within, and outside the farm.

This figure includes extensive and intensive systems as well as seaweed, molluscs, and crustacean culture. In industrialised countries there is a tendency to save water, therefore an increasing number of attempts are presently being made to employ recirculation technology. These systems are defined as units including a tank and mechanical and biological water treatments. Early systems date back to the late 1950’s and used the known urban wastewater treatment methodology. The experience gained during the 1980’s and 1990’s helped to intensify the production.

Recycling technology has been established in aquaculture systems all over Europe. Examples of this technology are the culture of eel in Denmark, The Netherlands and Germany, and the culture of marine species in Southern Europe using land-based systems, mainly in hatcheries. HESY has participated in this development and has planned, build, and upgraded several culture systems for different fish species all over the world.

Future development of recirculation systems

Reliable performance of recirculating systems is a prerequisite for fish farming to attract agricultural farmers and other investors. The need for sustainable use of aquatic resources including water will lead to increased supplementation of flow-through facilities by recycling technology. Depending on site-specific conditions, additional advantages of these systems are the decreased use of land area, less labour, the exclusion of external disturbances, such as bird predation, a higher degree of control of the environment, and a production close to the local market. After decades of investigating in the process management itself, present industry and scientists focus on production reliability and on production increase per unit of capital investment. HESY is a central partner in this process and project like the blue lable are recognised all over the world by scientist, farmers, and investors.

HESY's recycling technology allows: a) the introduction of new species into aquaculture. b) becoming largely independent from water sources. These are the two important factors in future aquacultural production.