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利用长江口水域20世纪90年代的拖网生产资料以及生物学测定数据,分析该水域拖网生产的渔获种类及优势种的资源变化状况。结果表明:20世纪90年代各时期长江口水域拖网生产的渔获物中,鱼类占92%以上,头足类和甲壳类所占的百分比较小,分别在8%和1%以下。每个时期的拖网生产的种类数基本相当,都为40种左右;同一时期的不同季节和各季节的不同时期间的种类数均有明显的变化。随着时间的推移,长江口水域拖网渔获物优势种类的组成发生了一定的变化。从90年代初期到末期,大部分传统优势种的渔获比例相对稳定,某些优势种的渔获比例有较大的波动或急剧减少,小型低质鱼种的渔获比例和种数增加。对带鱼、小黄鱼的体长组成结构分析表明它们的群体从20世纪80年代开始趋于明显的小型化,当前的小型化程度已经相当严重;而在此期间黄鲫的体长组成结构变化不大。该水域的优势种类组成和主要优势种类体长组成结构的变化是和逐渐增加的捕捞力量以及水域环境变化相关联的。
Using the trawl production data and biological measurement data of the 1990s in the Yangtze River Estuary, the types of catch and the resource changes of the dominant species in the trawling area were analyzed. The results showed that in the catch of the Yangtze River Estuary in the 1990s, fish accounted for more than 92%, while the percentage of cephalopods and crustaceans was less than 8% and 1% respectively. The number of trawl production in each period was basically the same, about 40 species. In the same period, the number of species in different seasons and seasons varied markedly. With the passage of time, the composition of dominant species of trawl catch in the Yangtze Estuary waters changed. From the early 1990s to the end of the decade, the catch rate of most traditional dominant species was relatively stable, the catch percentage of some dominant species fluctuated or decreased sharply, and the proportion and number of catches of small low-quality fish species increased. The structure analysis of the body length of octopus and small yellow croaker showed that their population tended to be obviously miniaturized since the 1980s, and the current miniaturization degree has been quite serious. In the meantime, the body composition of yellow crucian carp did not change much . The dominant species composition and main dominant species in this water area are related to the gradual increase of fishing forces and changes of water environment.