鲮(Cirrhinus molitorell)入侵长江水系的可能性探讨

DISCUSSION ON THE POSSIBILITY OF MUD CARP(CIRRHINUS MOLITORELLA)INVASION TO THE YANGTZE RIVER

鲮(Cirrhinus molitorella)是分布于我国华南地区的一种热带、亚热带鱼类,历史上未曾分布于长江水系。鲮食性广、性成熟时间短,繁殖量大,但不耐低温。2010年10月,对长江宜昌江段鱼类资源调查中发现了一种非长江水系土著种的野鲮亚科鱼类。基于鳞片、鳍条、口器、腮耙等特征鉴定为鲮(C.molitorella)。进一步结合鲮的生物学特征和长江水温及水生态环境状况对鲮的进入途径和成为入侵鱼类的可能性进行了初步的探讨,并对其成为入侵鱼类的危害和防治进行了初步讨论。

Mud carp(Cirrhinus molitorella),a cyprinid endemic in South China,is one of the most important commercial fish in this area.Lower water temperature is the limiting factor to prevent it from spreading to higher latitude waters.There was no historical record of mud carp distribution in the Yangtze River.A Labeoninae fish,which is a non-indigenous fish to the Yangtze River,was found in the Yichang reach of the Yangtze River during an investigation in 2010.Judged by the complicated mouth structure,such as the separated upper lip from the maxillary,well developed snout skin,and the separated lower lip from the mandible,and without hard spine in the dorsal fin,the fish was first identified as one species of Labeoninae.The edge of upper lip dose not split into leaflet or flaw,which is one important character of Cirrhinus genus.Especially there is a diamond dark patch composed of 8~12 scales marked with turquoise blue crescent spots above the pectoral fin on both sides of the body,which is one key diagnosis character of mud carp(C.molitorella).Additionally,in combination with the characters of fin rays,gill rakers and mouth etc.,it was unambiguously identified to be mud carp(C.molitorella).Furthermore,based on the biological characters of mud carp,moderate body size,and a naturally omnivorous fish,tolerance to lower dissolved oxygen,strong resistance to disease,and relatively shorter span to mature and strong productivity,and in recent years the lowest water temperature in Yichang Reach of the Yangtze River in winter is over 10.7 ℃,which is much higher than the mud carp lethal temperature(7 ℃),and in addition to the environment disturbance of the Yangtze River from human activity,the possibility of mud carp invasion to the Yangtze River,as well as the possible damages and preventing strategies to the mud carp invasion,were discussed in this paper.