拉萨市拉鲁湿地鱼类现状与保护

Fish Assemblage at the Lhalu Wetland:Does the Native Fish Still Exist

拉鲁湿地是西藏拉萨河流域重要的湿地之一。近年来,由于人类活动的影响,拉鲁湿地生态系统发生了较大的变化。本文于2010年4月、6月及2011年4月,通过刺网和地笼对拉鲁湿地的鱼类现状进行了调查。结果表明,拉鲁湿地现有7种外来鱼类:鲫Carassius auratus(Linnaeus)、鲤Cyprinus caupio Linnaeus、草鱼Ctenopharyngodon idellus(Cuvier et Valenciennes)、麦穗鱼Pseudorasbora parva(Temminck et Schlegel)、泥鳅Misgurnusanguillicaudatus(Cantor)、鲇Silurus asotus Linnaeus、黄黝鱼Hypseleotris swinhonis(Gunther)和5种土著鱼类:尖裸鲤Oxygymnocypris stewartii(Lloyd)、拉萨裸裂尻鱼Schizopygopsis younghusbandi younghusbandi Regan、异尾高原鳅Triplophysa stewartii(Hora)、细尾高原鳅T.stenura(Herzenstein)、西藏高原鳅T.tibetana(Regan)。外来的麦穗鱼和鲫为绝对优势种,而5种土著鱼类的数量极少、几近灭绝。不均衡的群落结构导致拉鲁湿地的鱼类多样性极低。在分布上,麦穗鱼和鲫几乎遍布整个湿地,而土著鱼类仅分布于小部分水域中。当前,拉鲁湿地的鱼类群落已散失其独特性,而转变为以外来鱼类为主体、部分土著鱼类残存的格局。今后,改善拉鲁湿地的水质、加强群众对外来鱼类识别的能力和危害的认识、清除外来鱼类等措施对于保护拉鲁湿地的鱼类及其生态系统将有重要的意义。

Non-native invasive fishes have been shown to be highly dangerous to aquatic ecosystems,and have caused huge ecological and economic costs.The Lhalu wetland,one of the most important wetlands in the Lhasa River basin,Tibet,China,represents the highest and largest urban wetland in the world.The ecosystem of the wetland was intensively disturbed by human activities before it was listed as a national reserve in 2005.Although 2 exotic fishes（Carassius auratus（Linnaeus） and Monopterus albus（Zuiew）） were found in the wetland in a survey which was carried out from 2001 to 2003,unfortunately they did not receive enough attention they deserve.In order to examine whether the native fish still exists,the fishes were studied by gillnets and setting nets in April and June in 2010 and April in 2011.Of the 12 species collected,C.auratus（Linnaeus）,Cyprinus caupio Linnaeus,Ctenopharyngodon idellus（Cuvier et Valenciennes）,Pseudorasbora parva（Temminck et Schlegel）,Misgurnus anguillicaudatus（Cantor）,Silurus asotus Linnaeus,and Hypseleotris swinhonis（Gunther） were alien species,and Oxygymnocypris stewartii（Lloyd）,Schizopygopsis younghusbandi younghusbandi Regan,Triplophysa stewartii（Hora）,T.stenura（Herzenstein） and T.tibetana（Regan） were native species.The non-native fish P.parva and C.auratus were the dominant species,as the former took up 83.9 % of the total fish abundance performed by setting nets and the latter accounted for 93.0 % of that performed by gillnets.Both of them had a wide distribution,almost spreading all over the wetland.By contrast,all the 5 native species were rare,with poor abundance（〈 2% by number） and low occurrence.Non-native C.carpio,C.idellus,M.anguillicaudatus,S.asotus and H.swinhonis were found at low density and low occurrence.For the unevenness of abundance among species,the fish assemblage had little diversity,as the value of the Shannon-Weiner index,Simpson index and Pielou’s evenness index of fish assemblage sampled by gillnets were 0.343,0.866,and 0.213,respectively.Those indexes of fish assemblage sampled by setting nets were 0.638,0.855,and 0.290 respectively.This study demonstrates that although 5 native fishes still exist,the Lhalu wetland has been thoroughly invaded by non-native fishes,and no longer supported a distinct fish assemblage.It is suggested that restoring the water quality of the wetland,enhancing training and education for local people on the dangerousness of non-native fishes and eradication of non-native fishes are important to the conservation of fish fauna and ecosystems of the Lhalu wetland.