中国近海主要鱼类种群变动与生活史型的演变

POPULATION DYNAMICS AND LIFE HISTORY PATTERNS FOR MAIN MARINE FISHES IN THE COASTAL WATERS OF CHINA

物种为了种族的延续和繁衍,在历史的长河中,通过自然选择形成了适应其生存的一系列生态学特征,即生活史的选择型。具有不同生活史型鱼种的数量变动形式也不同,换言之,种群数量的变动方式是各个种生活史的反映,种群动态与其生活史选择型有着密切关系。 随着海洋渔业的发展,以及人类对海洋渔业资源开发与利用的增强,一些传统经济种类的资源受到严重威胁。有的资源潜力削弱,甚至有的生物种群的再生机制受到破坏,使其资源面临着枯竭的危险。在强大的捕捞压力下,海洋渔业资源的结构发生了很大变化。生命周期长的种类被生命周期短的种类所代替;

This paper describes the evolution of the life history patterns for main marine fishes such as hairtail Trichiurus haumela (Forskal), small yellow croaker Pseudosciaena polycactis B!ee-ker, large yellow croaker P. crocea (Richardson), filefish Navodon septentrionalis Gunther, herring Clufea harengus Pallasi, Spanish mackerel Scomberomorus niphonius (Cuvier et Valenciennes), mackerel Pneumatophorus japonicus Houttuyn, harvestfish Pampus argenieus (Euph-rasen) and Chinese herring llisha elongata (Bennett). The relationships between life history patterns and populations dynamics are compared and summerized as follows.The population structure has become simpler. Formerly the remainder dominated spawning stock but recently recruitment of stock exceeds the remainder. For large yellow croaker the remainder of the stock exceeds the recruitment. Maturation is usually spread over several years and the composition was of complicated structure in the 1950s. The life spans of the large and small yellow croakers which could reach to twenty nine and twenty three years in the 1950s, decreased to seven and two years respectively. With the change of the stock structure the life history patterns of population change from stable k-selection to unstable r-selection.The average life spans and lengths of species for the most part have declined. Their growth goes on at an accelerated pace, and sexual maturity comes earlier, and their biological indices undergo a series of changes, after the stock decrease, the results show life history patterns in marine fishes of the China Sea are mostly that of r-selection, but that more and more are tending to be of the r-selection ipattern with the change of the population structure.The population structure of a species or of groups within a species has a certain stability. In addition, a species exists under continuously changing conditions, so the structure resembles other features of the species in changing continually within certain limits, which represent adaptation to the changing conditions of life. It has been demonstrated that fishing has marked and various effects on populations, depending on their population dynamics. Overfishing of some species has reduced their numbers and led to a progressive fall in catches, especially for bottom fishes