In fact, eels with esophageal fistulae die of cellular and extracellular dehydration within 5 days after SW transfer if ingested water is not reintroduced into the stomach ( Takei et al., 1998b). However, drinking is as important in SW fishes as in terrestrial animals because it is the major route for obtaining water that has been passively lost to the environment.
Importantly, the dipsogenic potency of Ang II in teleosts is 1/100th that of mammals but anti-dipsogenic potency of ANP is 1000-fold more potent in teleosts than in mammals ( Takei, 2002). Reflecting the dominance of inhibitory mechanisms in fish, most hormones that regulate drinking are anti-dipsogenic hormones ( Ando et al., 2003 Kozaka et al., 2003), except for Ang II, AM2, and IT, as mentioned above. McCormick, in Fish Physiology, 2012 4.1 Brain Control of Drinkingĭrinking is usually suppressed in FW fishes because water enters the body by osmosis and fish are exposed to a constant threat of overhydration ( Takei, 2002 Takei and Balment, 2009). Because of the high value of bluefin in the sashimi market, ranching is a growing enterprise in many countries, including Australia, Croatia, Japan, Mexico and Spain. This involves catching adult bluefin tuna and transporting them to pens in inshore areas, where they are held and fed until reaching a marketable size and condition. In the meantime, attempts at what is known as bluefin ranching are being increasingly successful. It is anticipated that this research will eventually make it possible to complete the life cycle of yellowfin tuna in captivity, an essential precondition to rearing tuna commercially. At the Inter-American Tropical Tuna Commission's Achotines Laboratory in Panama, scientists have been able to spawn yellowfin tuna held in captivity in onshore tanks on a regular basis, and have also successfully reared the hatched eggs to the juvenile stage. In Japan there has been limited success in spawning bluefin tuna in captivity, hatching the eggs, and rearing the young. The pelagic habitat, migratory nature, and large size of pelagic species make rearing them in captivity difficult, and only recently have scientists been able to spawn and rear tunas artificially. Over the last few years mariculture has contributed about 10% to the total annual landings of all marine fishes. Propagation of freshwater fish has been practiced for centuries, but it is only in recent times that the culture of marine fish (mariculture) has become important on a commercial scale. Joseph, in Encyclopedia of Ocean Sciences (Second Edition), 2001 Mariculture The successes of these programmes have been due to the development of best practices for broodfish management, artificial breeding, larval rearing, fingerling production and management of infectious diseases, and guidelines which minimise the effects of domestication, maintain genetic identity of stocked populations, and maximise genetic variation providing a basis for fitness and evolutionary potential of each species. This chapter reviews these declines and the use of captive breeding and stocking programmes since the late 1970s to aid the recovery of threatened species, establish and maintain large recreational fisheries, and restore lost biodiversity.
Throughout the 1900s, the distribution and abundance of native freshwater fishes in inland and coastal drainages in southeastern Australia were significantly reduced, and there were extirpations of some populations. Rowland, in Advances in Aquaculture Hatchery Technology, 2013 Abstract:įreshwater fishes are one of the great natural resources of the world, but anthropogenic activities have adversely affected aquatic ecosystems and many species are threatened with extinction.
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