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A fish's hypoxia tolerance can be represented in different ways. A commonly used representation is the critical O 2 tension (P crit), which is the lowest water O 2 tension (P O 2) at which a fish can maintain a stable O 2 consumption rate (M O 2). [2] A fish with a lower P crit is therefore thought to be more hypoxia-tolerant than a fish with a ...
Fish farming or pisciculture involves commercial breeding of fish, most often for food, in fish tanks or artificial enclosures such as fish ponds. It is a particular type of aquaculture , which is the controlled cultivation and harvesting of aquatic animals such as fish, crustaceans , molluscs and so on, in natural or pseudo-natural environments.
It covers 11.4 million square kilometres (4.38 million sq mi), which is the second largest zone in the world, exceeding the land area of the United States. [5] According to the FAO, in 2005, the United States harvested 4,888,621 tonnes of fish from wild fisheries, and another 471,958 tonnes from aquaculture. This made the United States the ...
Fish farming and shellfish production usually spew far less greenhouse gas emissions than production of beef and other animal protein, but aquaculture can still cause serious environmental problems.
According to a 2019 FAO report, global production of fish, crustaceans, molluscs and other aquatic animals has continued to grow and reached 172.6 million tonnes in 2017, with an increase of 4.1 percent compared with 2016. [23] There is a growing gap between the supply of fish and demand, due in part to world population growth. [24]
Conversely, one of the most unsustainable practices within the fish farming industry occurs is when farmers feed the fish pellets of animal waste. The quality of ocean water in and around fish farms is up to the farmers to maintain, and due to the fact that the mesh cages take up only a certain amount of space in the ocean, fish farmers can ...
One of the factors that controls primary production is the amount of energy that enters the producer(s), which can be measured using productivity. [12] [13] [1] Only one percent of solar energy enters the producer, the rest bounces off or moves through. [13] Gross primary productivity is the amount of energy the producer actually gets.
To produce one kilograms of farmed salmon, products from several kilograms of wild fish are fed to them – this can be described as the "fish-in-fish-out" (FIFO) ratio. In 1995, salmon had a FIFO ratio of 7.5 (meaning 7.5 kilograms of wild fish feed were required to produce one kilogram of salmon); by 2006 the ratio had fallen to 4.9. [ 103 ]