The earliest form of aquaculture practiced consisted of trapping wild aquatic animals in lagoons, ponds or small shallow lakes, so that they would be available at all times. This method dates back to the Neolithic age, when man started to act on natural resources, namely around 4000 B.C. in Europe. This minimalist practice no longer exists in Europe because all aquaculture involves at least one technical interaction with the environment or the animal.
In the second stage in its evolution aquaculture no longer relied solely on nature: aquatic environments favourable to the development of fish, molluscs and/or crustaceans were developed. Carp rearing in China is the most sophisticated form of this type of aquaculture, evidence of which dates back to the fifth century B.C. in the famous Treatise written by Fan-Li. In South America, the Aztec cultivated agricultural islands known as chinampas in a system where plants were raised on stationary (and sometime movable) islands in lake shallows and waste materials dredged from the chinampa canals and surrounding cities were used to manually irrigate the plants. This system is believed to be the earliest ancestor of modern aquaponics.
And in Europe? The Romans kept oysters and fattened fish in specially designed tanks. However, it was not until the Middle Ages that pond farming techniques began to develop, particularly in monasteries which needed a non-meat source of food for the many days of fasting imposed by the Christian faith. In southern Europe, fish farming in brackish water also dates back to this time, when lagoons and coastal ponds were first fitted out to retain fish swept in by the tide, including seabass, seabreams and mullets. This practice often alternated on a seasonal basis with salt production.
The intertidal pole culture for mussels and oysters, called "bouchots" in French dates back to as early as the 13th century. This technique spread widely along the French Atlantic coastline over the 19th century, while Northern European countries developed bottom culture plots.
In time, traditional combined forms of fish farming in ponds and lagoons increasingly evolved into more managed production modes described as semi-extensive aquaculture. Producers were no longer satisfied with enhancing the natural development of the pond or lagoon. They began to assist nature by introducing fry from hatcheries into the sites and providing supplemental feed. The best example is the rearing of carp in ponds, which is very widespread in the central European countries. Aquaculture in brackish water in southern Europe also turned more to hatcheries and commercial feed to compensate for the decline in natural recruitment.
As for seaweed, the first written record of human consumption appeared in Japan more than 1500 years ago. However the intervention of men on seaweed production seems to have started in 1670 AD. At this time, Japanese fishermen were ordered fresh fish every day for the Shogun and realised that the bamboo fences used to farm fish were covered by seaweed. They then realize that they could make the seaweed grow quicker by moving the bamboo fence in the estuary where it would receive some nutrient input from the land.
In Europe seaweed was traditionally gathered by coastal populations on foot and without mechanization or any equipment to be used as fertiliser for land crops. Changes in this activity are very recent and mechanical seaweed harvesting started only at the beginning of the 20th century with the discovery of methods to extract salt and iodine, then later on colloids and alginates (gels and gum production)
Starting in the 17th century, freshwater fish stocks began to decline in certain places, probably due to increases in the human population. The authorities started to explore the idea of restocking rivers with fry hatched in captivity. In nature, fish release a huge number of eggs and only a few individuals reach adulthood after surviving predators, disease, the lack of food, pollution, thermal shock and other dangers. Hatcheries not only provide fertilised eggs, they also to control all parameters so that a maximum number of individuals can reach the juvenile stage, when they can be released into the natural environment with a good chance of survival.
In 1741, Stephan Ludwig Jacobi, a German multidisciplinary scientist, built the first trout hatchery in Westphalia. It took another century for his discovery to be implemented on a large scale to restock bodies of water depleted by the first effects of the Industrial Revolution in Europe, the United States and Japan. Scientific research then went on to include charrs, whitefishes, Atlantic Salmon and also the rainbow trout in the United States, which was introduced into Europe in 1874 thanks to its excellent performances.
From the end of the 19th century, rainbow trout led the progress in European fish farming. This American species proved to be better adapted to aquaculture than its European cousin, the brown trout: it is hardier, grows faster and can put up with higher rearing densities. Until the mid-20th century, however, aquaculture performances were limited because of unsuitable feed and excessive vulnerability to the epizootic diseases that plagued fish reared in high densities in sites open to attacks from external sources. It was only with the discovery of the specific health and dietary needs of fish at the different stages of its development that change was made possible.
In the 1960s this progress led to the commercial development of intensive rainbow trout farming, first in Denmark and then throughout Europe. Today, European fish farming has diversified considerably, in terms of both product quality and species. Alongside rainbow trout, which still dominates, other freshwater fish are reared intensively: river trout, brook trout, Arctic charr, whitefish, tilapia, zander, Siberian sturgeon, etc. At the same time, a major innovation in fish farming was developed in Japan: the floating cage. Fish are held captive in a large pocket-shaped net anchored to the bottom and maintained on the surface by a rectangular or circular floating framework, originally made of bamboo but soon replaced by plastic. The Japanese used the device to fatten amberjacks and seabream. The idea was exported to Europe, where floating cages were originally used to farm rainbow trout in the sheltered waters of the Norwegian fjords.
In the late 1960s, the cages made the farming of Atlantic salmon possible in Europe. The hatchery stage had been perfected years earlier and was producing ample smolts, young fish that have acquired the ability to live in the marine environment. The next step was then taken of fattening the young fish at sea in floating cages until they reach adulthood. European salmon farming subsequently became a success story of the 1970s and 1980s. Salmon, due to its scarcity in the wild, had become a luxury product. Its new availability at a reasonable price proved to be an unprecedented commercial success that turned sea farming into an up-and-coming sector in Europe. Farms cropped up in fjords and bays in the North Sea and west of the British Iles, especially in Norway and Scotland.
This Nordic success gained followers. The Mediterranean countries studied and developed the rearing of. seabass and gilthead seabream. During the 1990s, farming of these species spread throughout the Mediterranean and the Canary Islands. Salmon, seabass and seabream remain the flagship products of European marine fish farming.
Regarding shellfish farming, traditional culture of mussels and oysters was improved during the 1970s by the use of suspended culture with ropes and longlines. It was also in the 1970s that the Pacific cupped oyster was introduced from Japan into European waters after the depletion of the Portuguese oyster (Crassostrea angulata), decimated by several successive diseases. With its fast growth and adaptability to different settings, the Pacific cupped oyster is now the most widely reared oyster worldwide, including in Europe.
The farming of carpetshells (grooved carpetshells or short-necked clams) began in the 1980s, when taking fish by hand or by dredging was discouraged in order to protect resources.
The 1990s and 2000s saw the development of another form of intensive farming, this time of flatfishes. Floating cages are not suited to these fish, which need to rest on a sandy bottom. Tanks on land supplied with sea water were therefore introduced. Progress in recirculation technology now offers new prospects for land-based farming of marine species. What is more, the possibility of controlling the water parameters, particularly its temperature, frees the activity from climate constraints. The farming of turbot, seabass and seabream is thus expanding to the north of Europe.
Another field of research and development in European aquaculture is the move towards offshore mariculture. The technological challenges are tremendous, though. The Mediterranean is one of the world’s deepest seas and the Northeast Atlantic is one of the planet’s windiest and stormiest zones. New systems, such as submersible cages, have to be developed to keep fish enclosed but solutions are also needed for their feeding and remote monitoring. The co-location with existing platforms, such as e.g. wind farms, represents a promising option.
At the global level, aquaculture provides approximately half of the seafood we consume each year, and its contribution is growing steadily.