巢湖刀鲚食物组成及渔获量变化的初步分析

Preliminary Analysis on Diet Composition of Coilia ectenes and Changes of Its Catches in Lake Chaohu

对2007年8～9月采集的164尾巢湖刀鲚（Coilia ectenes）的食物组成进行了初步分析,并结合历年巢湖鱼类渔获量统计情况,对其渔获量的变化规律进行了探讨。结果显示：巢湖刀鲚8月份主要摄食枝角类,个数组成比例为（73.28±10.00）%,其次是桡足类占（10.05±6.32）%;9月份刀鲚也以摄食枝角类为主,组成比例（46.18±13.58）%,其次为桡足类占（34.70±11.21）%。同时刀鲚食物中还发现少量微囊藻。刀鲚渔获量由1990年的3728 t上升至2007年的9540 t,平均占总渔获量的比例为（58.05±4.22）%;刀鲚绝大部分个体在80 mm以下,体重在2 g以下,生长年龄为0＋和1＋,代表巢湖刀鲚的主要群体。结果表明：刀鲚是巢湖鱼类的绝对优势种,但存在低龄化现象。

Diet compositions of 164 Coilia ectenes collected from August to September in 2007 were analyzed. The results indicated that C. ectenes in Lake Chaohu mainly fed on Cladocera which accounted for（73.28 ±10. 00）% in indiviual composition of the fish diet in August and（46. 18 ± 13.58）% in September. Copepoda accounted for（ 10. 05±6. 32）% in August and（34. 70 ±11.21 ）% in September. There were also some Microcystis in the fish diet in August and September. The record showed that the fish catches increased from 3728 t in 1990 to 9540 t in 2007, and the proportion of the fish catches was（58.05 ±4. 22）% of total fish catches on average during the period from 1990 to 2007. Most of C. ectenes was less than 80 mm and weighed less than 2 g, the age was 0 ^＋ or 1^＋. The conclusion showed that ： C. ectenes was the absolute dominant fish species, and it had young tendency.