Freshwater aquaculture

Unit 1 - Aquaculture

1.2. Origin of aquacutre and agricutlure

• Agriculture first developed 10000 years ago in the middle east when human population changed from hunting-gathering to cultivating wheat and barley.Subsequently there were independednt origins of farming cereal crops on other major land masses
• Middle east wheat and barely
• Rice cultivation began in Asia 7000 years ago
• Sorghum and millet developed in Africa
• And maize in America
• Compared to agriculture the origins of Aquaculture much later
• Common carp culture developed some hundreds of years BC in China
• The first aquaculture text book was written some 500 BC by Fan Lei a Chinese politician
• Africa, America, Australia introduced aquaculture in recent centuries.

The late origin of aquaculture is because humans who are terrestrial cannot readily appreciate parameter of aquatic environment.
Several aquatic parameters affect aquatic organism

• Very low solubility of O2
• High solubility of CO2
• (pH) Hydrogen ion concentration
• Salinity
• Buffering capacity
• Dissolved nutrients
• Toxic nitrogenous wastes
• Turbidity
• Heavy metals and other toxic substances
• Photo and zooplankton concentration
• Current velocity

It is difficult for terrestrial human being to appreciate influence of these environmental factors Causing longer period for aquaculture development than other forms of food production
Construction of physical facilities building up productivity of the system and attainment of skills take considerable period of time, therefore, aquaculture started much later than agriculture.

Further, the major consequence of late origin of aquaculture is that, relatively little genetic selection has taken place in fish being farmed compared to plants and animals used in agriculture and animal husbandry.
Modern agriculture based on organisms vastly different from wild ancestors in heavy cases wild ancestors don’t exist because, selection and domestication took place over thousands of yrs.
In contrast majority of aquaculture is based on wild plants and animals.

Only a few species have been domesticated. Following are the example of fish species that have been domesticated.

• Common carp
• Atlantic salmon
• Rainbows trout
• Tilapia species
• Channel catfish

Many other aquaculture species are based on wild brood stock or larvae collected from the wild.
In some cases production cycle has not be closed i.e., the species have not been matured under captivity and spawned under captive conditions. Therefore there is minimal potential for selective breeding because unless the production cycles are closed selective breeding cannot take place.