Mariculture

Mariculture, ie the controlled or useful and planned accordingly consummated rearing of aquatic organisms in the sea, is also known as mariculture. It is mostly based on net cages in the sea, where, for example, salmon are reared. The enclosure can also be omitted. In its place, then pass protection or propagation basis bidding structures that do not facilitate the capture but even more difficult to selectively, especially since there is a clear relationship between fertilization rate, fishing efficiency and cost pressure, which the fishermen must submit. The lower the rate of fertilization occurring fish, the closer is woven the web of interference points and more frequent fishermen must obtain their nets again. The close-meshed these " disturbing" points is chosen so that the networks just from point A to point B can be kept in tow, so you will not lose in this catch and net. The combination of wind, tide and current power plants with anchored on the seabed protection devices is a useful addition. For example, fish are very well conditioned to sound. In the open sea, only those "points" of fish are driven, the protection or offer some type propagation basis.

Economically significant is the rearing of different shells such as oysters and mussels as well as the court holding and locking function on corresponding migration routes to the respective spawning grounds.

Further areas of mariculture are the micro -and macro- algae production to feed a seedling breeding or for the purpose of, for example, agar - agar.

Ecological problems

By mariculture allochthonous species, ie the ownership of living beings outside of their natural range such as the Pacific clams Tapes philippinarum ( Japanese carpet shell ) or Crassostrea gigas ( Pacific oyster ) in Europe, native species are displaced, it changes the species composition. Ultimately, what matters most to a decline in biodiversity, and ultimately to a decline in the production of biomass.

The construction of new facilities and the use of heavy machinery for sowing and harvesting of mussels also have significant environmental impacts. The type of fishing - for example Grundtrawlfischerei, vacuums - leads to a general disturbance of the balance and a change in the seabed with potential negative consequences for the important as a food fish and waterfowl fauna of the benthos. Other effects are a general equilibrium change in the Sedimentationsrhythmus and the chemical composition of the sediments. It often occurs by feeding to pollution and eutrophication of water bodies.

The establishment of non-native species, the risk of spreading parasites increases. The intensive management - for example, are from the Japanese clam Tapes often 2000 copies per square meter of seabed located - it may come to the explosive proliferation of the parasite. The complex life cycles of most parasites also affect the food chain and the entire ecosystem.

As in many areas, mariculture is not operated long, there are few or no studies on the long-term effects on the ecology and economy of the fisheries.