鄱阳湖刀鲚的渔汛特征及渔获物分析

Changes in the Fishing Season and Daily Catch of Coilia ectenes in Poyang Lake

通过探究鄱阳湖刀鲚(Coilia ectenes)的渔汛特征和渔获物现状,为有效地保护其种群资源提供科学依据。2013-2014年在鄱阳湖设置3个调查点,对刀鲚进行逐月采样调查,共取样986尾、41.54 kg,随机抽样调查不同捕捞网具的整船次鄱阳湖刀鲚渔获物数据,测量体长、体重等生物学参数。采用Pearson相关分析刀鲚单船日渔获重量WB与水文因子关系。结果表明,鄱阳湖刀鲚体长范围为17.9~38.1 cm,其中21.2~23.6 cm是优势体长组,占总个体数的37.02%;体重范围为14.3~198.2 g,其中25~40 g是优势体重组,占总个体数的57.20%。鄱阳湖刀鲚体长L(cm)和体重W(g)幂函数方程为:W=0.0019L3.1378(R2=0.8997;n=986;P<0.01)。湖口水域刀鲚出现时间主要集中在每年的5-6月,高峰期在6月,7月很少见;单船渔获数量NB为(3.2±4.1)尾/d,单船渔获重量WB为(0.12±0.11)kg/d。湖口水域刀鲚单船渔获重量WB与该水域水位、流量均呈显著正相关(P<0.05),WB与水位的相关性更为显著。与历史资料相比,鄱阳湖刀鲚渔获规格以小个体居多;渔汛稍有推迟,持续时间大幅度缩短;种群规模急剧缩小,表明刀鲚资源正在严重衰退。

Coilia ectenes is an anadromous fish with high economic and ecological values in the middle and lower Yangtze River and adjoining waters. Poyang Lake,vital habitat of C. ectenes,is important for spawning and reproduction. The capture size and population characteristics of C. ectenes in the Yangtze River have been reported,but the current resource status of C. ectenes in Poyang Lake during fishing season is not well documented. In this study,the fishery resource status of C. ectenes was investigated monthly in three areas of Poyang Lake（ Poyang Lake estuary,Duchang and Yugan） from December 2013 to November 2014. The relationship between C. ectenes population and hydrological factors was analyzed,aiming to understand the population characteristics of C. ectenes during fishing season and to explore the factors driving population changes in Poyang Lake. The study provides base data for conserving wild C. ectenes populations. The investigation was conducted using fixed nets（ mesh size：1 cm）,gill nets（ mesh size： 1 cm） and trawling（ mesh size： 1. 5 cm）,along with data on the daily catch per fishing vessel. The body length and weight of each specimen were measured. A total of 986 C. ectenes specimens were collected with a total weight of 41. 54 kg. During the investigation,data on water level and runoff at Poyang Lake estuary and Jiujiang section were recorded each day. The relationship between fish catch per boat（ WB） and hydrological factors in Poyang Lake estuary was analyzed by Pearson correlation. The body length range of C. ectenes was17. 9-38. 1 cm and the range 21. 2-23. 6 cm accounted for 37. 02 % of the total. The body weight range was14. 3-198. 2 g and the range 25-40 g accounted for 57. 20% of the total. The relationship between body weight and body length of C. ectenes in Poyang Lake is given by the equation,W = 0. 0019 L^3. 1378（ R^2= 0. 8997,n = 986,P 〈0. 01）. In the Poyang Lake estuary,C. ectenes emerged mainly from May to June,peaking in June and rarely spotted in July. Both the daily catch per boat（ NB）,（ 3. 2 ± 4. 1） ind/d and total weight per boat（ WB）,（ 0. 12 ±0. 11） kg/d were significantly and positively correlated with water level and runoff（ P〈0. 05）. Compared with historical data,C. ectenes in Poyang Lake have become smaller and the fishing season is shorter and occurs later.The C. ectenes resource in Poyang Lake has decreased dramatically.