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Thesis Advisor曹文宣
Degree Grantor中国科学院水生生物研究所
Place of Conferral中国科学院水生生物研究所
Degree Discipline水生生物学
Other AbstractSpecimens of goldfish (Carassius auratus auratus) were taken at frequent intervals from April, 1988 to March, 1989. The total mortality was 0.60, with the natural mortality of 0.33 and the catching mortality of 0.27. Analyses of monthly mortalities of each age suggested that the closed season had conduced to protecting of fisheries resources. The formula of the fish length corresponding to the scale radius was selected as follows: L = 9.7266 + 23.9808·R Where L = length of fish R = scale radius Selective fishing mortality may be the cause of Rosa Lee's phenomenon. The Von Bertalanffy expression for goldfish was written as: L_t = 159.38 {1-exp[-0.2289 (t + 0.2021)]} Where Lt in mm. Females grew significantly faster than males after one year of age. Majority of goldfish reach maturity at 2-age. The range of sizes at first spawning was 39-60mm. Goldfish had a prostrasted Spawning period from March to July, and an analysis of size frequency distribution of eggs showed that goldfish sheded eggs in batches. The sex ratio of females to males was 2.5:1 in younger age groups with a more dominance of females in older age groups. Relationship between fecundity and length was presented by: F = 10~(-4) * 4.6001 * L~(3.5420) "Diminution phenomenon" refers to a few species of short-life span, slow-growing small fish dominate the fish yield, some of long-life span, fast-growing large fish disappear and abundance of other species decrease drastically. Fish stocks in a "diminution phenomenon" lake become younger and have smaller lengths at each age. Causes leading to the "diminution phenomenon" may be: (1) environmental alterations (obstruction of passages between Honghu Lake and rivers, overblooming of submerged plants, changes of water depth, etc.); (2) overfishing; (3) compensatory mechanisms.
Document Type学位论文
Recommended Citation
GB/T 7714
张国华. 洪湖鲫鱼种群的研究及洪湖鱼类资源小型化现象的初步探讨[D]. 中国科学院水生生物研究所. 中国科学院水生生物研究所,1989.
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洪湖鲫鱼种群的研究及洪湖鱼类资源小型化现(1528KB) 限制开放--Application Full Text
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