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i really enjoy
this is course very usefull. thanks all of alizon Support staff.
hay diferentes tipos de pesca, aveces afectan a diferentes especies debido a que cuando se pesca en las redes quedan atrapados peces que no servirán para la producción, por eso se implementa la ganadería de peces. cultivan los animales con fines económicos y para satisfacer la demanda de comida.
What is aquaculture?
Big Quick plan of Malaysia what does it mean?
Is marine live important?
Fisheries are part of United Nations Convention on Climate Change. Fish farming is the answer to restore the stock in oceans. Tilapia is one of the fish breed that can be used in warm waters of Africa.
The ocean provides the biggest location of fisheries. Commercial methods used to harvest these fisheries depend upon the types of fish (e.g. surface dwelling, bottom dwelling) being produced and their tendency to form schools.
Trawlers drag nets along the ocean bottom to catch bottom dwelling (demersal) fish such as cod and shellfish such as shrimp.
Large schools of surface dwelling (pelagic) fish, such as tuna, are caught by purse-seine fishing in which a net surrounds them and then closes like a drawstring purse.
Drift nets up to tens of kilometers long hang like curtains below the surface and entangle almost anything that comes in contact with it.
The major problem with all of these fishing methods is that they tend to kill large numbers of unwanted fish and marine mammals that are inadvertently caught.
An alternative to ocean fishing is aquaculture, a method in which fish and shellfish are deliberately raised for food. There are two types of aquaculture: fish farming and fish ranching.
With fish farming, the fish or shellfish (e.g. carp, cat fish, oysters) are raised in closed ponds or tanks with a controlled environment. When they reach maturity they are harvested.
Fish ranching is used with species such as salmon that live one part of their lives in freshwater and the other part in salt water (anadromous species).
Salmon are raised in captivity for a few years and then released. They are harvested when they return to spawn.
Some of the disadvantages of aquaculture include the need for supplying large amounts of food and water, and disposal of the large amounts of waste that are produced.