WWW.WAS.ORG • WORLD AQUACULTURE • MARCH 2018 49 Although seahorse farming has made great strides in recent years, it is still generally unable to meet the demands of the TCM industry (Koldewey and MartinSmith 2010) and the effects on wild populations is generally unknown. Many technological and economic hurdles must be overcome before seahorse farming can significantly address the overexploitation problem. Sea cucumbers Sea cucumbers (Echinodermata, Holothuroidea) have been traded for centuries, primarily as dried seafood in a form called bêche-de-mer or trepang (Purcell et al. 2012) but also as TCM (Domínguez-Godino et al. 2015). The exploitation of this animal has a long history in China, dating to the Ming Dynasty (1368-1644 BC) (Chen 2003). Their high protein and low fat content make them highly prized as food and tonics. About 20 of China’s 134 species of sea cucumber have commercial value as food, but Apostichopus japonicas is the only species that is cultured in the country. This species is among the most prized and has fetched as much as US$ 2,950/kg dry weight (Purcell et al. 2012). More than 50 tropical species are actively traded. As the total global catch of sea cucumbers is about 100,000 t annually, there has been overexploitation of certain wild populations (Domínguez-Godino et al. 2015). In its early stages in the 1980s, the primary bottleneck in the development of sea cucumber farming was the shortage of seed (Chen 2003). This problem has been mostly solved but poor survival of planktonic larvae to the benthic juvenile stage remains a hurdle (Purcell et al. 2012). Unfortunately, despite the rather long history of sea cucumber aquaculture, much remains unstudied about the biological and ecological requirements of sea cucumbers, particularly tropical species, in captivity. There is a paucity of data regarding feeding, stocking density and culture systems. Nonetheless, current production methods of coculture in earthen ponds have resulted in greater survival rates than in the sea. The conservation impacts of sea cucumber farms have not been adequately reported but Purcell et al. (2012) recommend that resource managers close fishing of wild stocks to prevent local extinction of wild populations. It is doubtful that farmed sea cucumber products can flood the market and lower prices but that they may fill the supply gap of depleted fisheries (Eriksson et al. 2012). Sturgeons In terms of sheer market value, sturgeons (Actinopterygii, Acipenseridae) is one of the most important. It has been extensively traded for its meat and especially its unfertilized eggs (caviar). Top-grade caviar from the beluga sturgeon Huso huso can fetch as much as US$ 10,000/kg (UNODC 2016). It is likely that this trade began as early as the 10th century in the Ponto-Caspian region (Bronzi et al. 2011). Not surprisingly, several species of this fish are heavily harvested from the wild and have become threatened with extinction. The International Union for Conservation of Nature has declared sturgeons as the most critically endangered of all groups of animals, with 85 percent of sturgeons in danger of extinction (IUCN 2010). With no recent international population surveys, (CONTINUED ON PAGE 50) Lateral view of a shovelnose sturgeon Scaphirhynchus platorynchus. Photo: Brian C. Small. An adult white sturgeon Acipenser transmontanus cultured in ponds of the Hagerman Fish Culture Experiment Station of the University of Idaho, Hagerman, Idaho, USA. Photo: Vikas Kumar. “Black gold” or caviar is one of the most premium delicacies in the world. Photo: Charles Weibel.
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