Freshwater Fisheries Research Center, Chinese Academy of Fishery Science, Wuxi, Jiangsu, ChinaSummaryChinese sturgeon (Acipenser sinensis Gray), a species withimportant scientific and economic values, has been listed as aFirst Class Protected Animal by the China Government in1989. Due to the effects of human activities, the wildpopulation of A. sinensis has declined drastically in the past30 years. Though a series of policies and protective measureshave been implemented, the number of A. sinensis continues todrop. Considering the declining trend of A. sinensis populationresource, some new conservation strategies are presented. Onthe one hand, some measures should be taken on themanagement side: (i) fishing should be prohibited in theYangtze River, (ii) a solid plan on A. sinensis resourcesconservation should be identified based on scientific criteriafor which research should be completed, and (iii) managementof the water environment in the Yangtze River system shouldbe enhanced. On the other hand, a lot of emphasis should beplaced on studies of the natural population, including theexisting and remaining core natural spawning grounds andhabitats of A. sinensis. Additionlly, cryopreservation ofgametes for gene banking and constructing aritificial spawninggrounds for broodstock management are highly necessary,while also the establishment of closed-cycle systems formaintaining captive broodstock is needed in order to providethe quality control needed for the foundation of sustainablefarming while at the same time serving as a tool for thepreservation of the gene pool of A. sinensis species.IntroductionChinese sturgeon (Acipenser sinensis Gray) is a large andtypically anadromous species, which is mainly distributed inthe Yangtze River system and along the continental shelf areasof the East China Sea and Yellow Sea (YARSG, 1988). It wasalso listed as a Critical Endangered species in the IUCN RedList (IUCN, 2010). In the late 20th century, due to increasedhuman activities, such as hydroelectric projects, overfishing,water pollution, heavy shipping, dredging of navigationchannels and quarrying have altered the river system, blockedthe migration route, changed the spwaning grounds, alteredthe river bed morphology and substrate types of the habitatsfor A. sinensis. Meanwhile, the`se human activities have alsochanged the hydrogeology, and the water quality as well asspatial distribution of natural runoff of the Yangtze River (Huet al., 1985). All of these changes have failed to satisfy theconditions (habitats and hydrologic and water quality) neededfor natural reproduction of A. sinensis (Hu et al., 1992; Yanget al., 2006; Zhang et al., 2007). It was reported that thespawning grounds have been limited to <5 km of the riverreaches below the Gezhouba Dam, which is <1% of thelength of the original 600 km upstream spawning reaches thisspecies historically used in the Yangtze River. Particularly, thelength of its core spawning area is now being restricted to onlyabout 3 km (Kynard et al.,1995; Wei et al., 1998; Yang et al.,2007; Tao et al., 2009), and as a consequence, the wildpopulation of the A. sinensis has continuously become smaller.In order to protect the population resources, the governmenthas worked out a series of policies to strengthen legislation andpublicized these accordingly. Further, the government has alsoestablished a natural reserve and rescue stations for A. sinensis,where controlled propagation is performed and releasingprogrammes are implemented, while prohibiting commercialfishing, implementing a fishing permit system, and limitingfishing for scientific research as well as establishing closedfishing areas and seasons.However, the number of A. sinensis specimens in thepopulation as well as the quantity of eggs and the spawningfrequency have significantly declined since (Xiao et al., 2006;Hu et al., 2009). The numbers involved in the broodstockpopulation of A. sinensis (from downstream of the GezhoubaDam to Gulaobei; 30 km) has been located in the naturalreserve established for A. sinensis and were determined byBisonics DT-X Echosounder (200 kHz) between 2004 and2005 with the following results: 1, 453 and 789 individuals in2004 and 2005, respectively (Zhang et al., 2007). It wasdeduced that if all factors are maintained at the same level inthe next 20 years, the natural broodstock population ofA. sinensis may reach a minimum by 2019, with about 402individuals being left (Chang, 1999).Therefore, it is necessary and urgent to analysis the reasonswhy the number of A. sinensis population has become alarm-ingly smaller and smaller, while also research must focuson determining effective ways to protect and restore theA. sinensis resources.Reasons for continuous decline of the A. sinensis populationThough the government has taken a series of protectivemeasures, which has certainly slowed down the process ofdecline of the A. sinensis population in some ways, thepopulation is still continuing to decline, and the reasons areas follows.
Read full abstract