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本文着重阐述渔业资源数学模型的意义、类型与建立数学模型的原则,并具体建立了浮游生物、单种群渔业资源及捕食者与被食者种群生态平衡的数学模型。  相似文献
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Rheophilic cyprinids have been detrimentally affected by impoundments, which alter flow regimes, the physical environment and block migration routes. Initial evidence for a southern African cyprinid, smallmouth yellowfish Labeobarbus aeneus, suggested that dependence on riverine spawning areas limits their success within the turbid impoundments of the Orange River system. However, well‐established impoundment populations have since been documented. A comprehensive assessment of L. aeneus biology and population dynamics was undertaken to understand the drivers of successful colonisation in Lake Gariep, South Africa's largest impoundment. Labeobarbus aeneus exhibited slow growth, delayed maturity and longevity, most likely resulting in slow population growth rates. Highest adult and juvenile abundances were observed >100 km from the inflowing Orange River during the peak and post‐spawning seasons, respectively, suggesting that the species displays high ecological plasticity and may not be dependent on inflowing rivers for spawning. Meta‐analyses of life history parameters indicated consistency among riverine and lacustrine populations. Although experiencing an initial lag phase, L. aeneus has successfully adapted to the lacustrine environment.  相似文献
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Plasticity in life‐history traits provides advantages for introduced fish in overcoming demographic bottlenecks that would otherwise inhibit establishment. Here, the influence of population density, temperature and latitude was tested on the growth increments and growth rates of invasive populations of topmouth gudgeon Pseudorasbora parva, a small Asian cyprinid fish that is invasive across Europe. Aquaria experiments tested the roles of fish number and temperature on growth increments under a fixed food supply, pond experiments tested the role of density on growth increments, and a field study completed in England and Wales tested the influence of density and latitude on growth rates. In aquaria experiments, whilst growth increments were higher at 21 and 23 °C than at 19 and 25 °C, fish number had a greater influence on growth than temperature. Higher growth increments were produced at lower densities. In experimental ponds, growth increments were significantly higher in ponds with low densities of P. parva compared with those at elevated densities. In the field study comprising 10 wild populations across a latitudinal gradient of 4.0°N, a difference in mean air temperatures of approximately 3 °C, and estimated densities between 0.5 and 65.0 m−2, population density was the only significant predictor of growth rates. Whilst populations at very low densities comprised of significantly faster growing individuals, there were no significant differences when densities were between 15 and 65 m−2. Thus, invasive P. parva populations have considerable growth plasticity, especially at low densities, with this likely to be important in their ability to colonise new environments.  相似文献
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