长江安庆段刀鲚的线虫感染现状及时间特征

Nematode infection status and temporal characteristic of estuarine tapertail anchovy Coilia nasus in Anqing section of the Yangtze River

为掌握长江刀鲚Coilia nasus感染线虫的现状,于2018年4—7月在长江安庆段进行72 d的调查,共采集1658尾样本。结果表明:刀鲚的线虫感染率为96.32%,平均感染强度为(10.69±9.67)条/尾,平均感染丰度为(10.16±9.67)条/尾;感染的刀鲚中,52.53%的个体感染线虫数量为1~9条,感染数量大于30条的个体较少,仅占3.93%;线虫寄生于刀鲚腹腔内壁及各脏器,胃、幽门盲囊和肠道内及表面均有寄生,性腺和肝脏表面有附着或嵌入组织内,各部位线虫寄生数量以肠道和幽门盲囊最多,占比分别为41.26%和31.15%;线虫抽样鉴定结果显示,刀鲚共感染线虫2属6种,其中异尖属线虫2种,宫脂属4种,优势种为派氏异尖线虫Anisakis simples;不同规格刀鲚的感染强度有所差异,感染强度随刀鲚体长增加呈先升高后降低的趋势,其中,280~300 mm体长组感染率最高,260~279 mm体长组平均感染强度和感染丰度最高;调查期间,随着时间的推移,刀鲚的线虫感染指标呈先升高后降低趋势,其中6月上半月感染情况最严重。研究表明,刀鲚感染的线虫均为海水性寄生虫,感染情况较为严重,线虫的寄生对刀鲚肝脏等寄生部位产生了机械损伤,刀鲚感染线虫的情况与其规格和洄游时间有一定的相关性。

In order to grasp nematode infection status of estuarine tapertail anchovy Coilia nasus in the Yangtze River,the nematode infection was surveyed in 1658 samples of C.nasus collected at the Anqing section of the Yangtze River from April to July 2018 for 72 d.The results showed that the infection rate of the whole samples was 96.32%,the average infection intensity was(10.69±9.67)individuals per fish,the average infection abundance was(10.16±9.67)individuals per fish.In the infected C.nasus,52.53%of individuals were infected with 1-9 nematodes,and a few fish infected with nematodes more than 30,accounting for only 3.93%.Nematodes are parasitic on the body cavity and organs of C.nasus,including the stomach,pyloric caecum,and intestinal tract.The gonads and liver are attached to the surface or embedded in the tissue.There was the maximal nematodes in intestine and pyloric caecum,and the proportions nematodes were 41.26%,and 31.15%respectively.The results of nematode sampling and identification showed that C.nasus was infected with 6 species of 2 genera,including 2 species of Anisakis and 4 species of Hysterothylacium,the dominant species is Anisakis pegreffii.The infection intensity of C.nasus in different sizes was different.With increase in body length,the infection intensity of C.nasus showed a trend of increasing first and then decreasing.The infection rate was the highest in the body length group of 280-300 mm,and the average intensity and abundance were the highest in the 260-279 mm body length group.In addition,during the investigation period,as time passed,the infection index of C.nasus was first increased and then decreased,and the infection was the most serious in the first half of June.In summary,this study has basically grasped nematode infection status of C.nasus in the Yangtze River,and may have a positive impact on the follow-up study which focused on the impact of nematode parasitism,and the C.nasus population dynamics after infected with nematode.