Liver buoyancy

DAGE is widely distributed in various fish (Mori et al., 1972). Some fish, however, possess extraordinary high levels of DAGE in their muscles (Table 1.7) (Endo et al, 2001 Iida, 1971 Mori et al., 1972 Nichols et al., 2001 Sato et al., 2002). DAGE is likely used in deep-sea fish to achieve buoyancy (Endo et al., 2001). Little is reported on the toxicity of DAGE. Capsules of DAGE derived from the livers of deep sea dogfish, however, are widely marketed as neutraceuticals for human consumption (Nichols et al, 2001). 

Sharks and related cartilaginous fishes lack swim bladders and may adjust their buoyancy with large and fatty livers (>25% of body mass). The hydrocarbon squalene (C30H50) has a density of 0.866 at 5 C and is often... 

The species richest in squalene, C. uyato, is a small shark (up to 1 m long) that lives mostly at depths of between 500 and 1000 m in most seas of the world. The role attributed to the enormous amount of squalene, whose density is around 0.86, is to ensure buoyancy dose to zero at the usual depths where this shark lives. When the concentration of squalene is low, the liver oil is rich in diacylglyceryl ethers whose quantity can be modulated by the shark to regulate its buoyancy (Morris and Culkin, 1989), and triacylglycerols are also present. For detailed studies of the hydrocarbon composition of shark liver oils, see Nevenzel (1989) and Deprez, Volkman, and Davenport (1990). Squalene is used in the cosmetics industry and its hydrogenated derivative, squalane, is also used in cosmetics and serves as a stationary phase in gas chromatography. 

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