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- 1. Conservation and rehabilitation efforts for lake sturgeon Acipenser fulvescens throughout the Great Lakes include the re‐establishment of self‐sustaining stocks in systems where they have been extirpated.
- 2. Information on the suitability of potential lake sturgeon habitat in tributaries is important for determining their capacity to support lake sturgeon stocking and to develop system‐specific rehabilitation strategies.
- 3. Geo‐referenced habitat information characterizing substrate composition, water depth, and stream gradient were applied to a life‐stage specific lake sturgeon habitat suitability index in a geographic information system to produce spatially explicit models of life‐stage specific habitat characteristics in five northern Lake Michigan tributaries from which lake sturgeon have been extirpated.
- 4. Habitat models indicated that high quality lake sturgeon spawning and staging habitat comprised 0 to 23% and 0 to 9% of the available habitat, respectively, whereas high quality juvenile lake sturgeon habitat was relatively ubiquitous throughout each river and comprised 39 to 99%.
- 5. Comparison of these data to lake sturgeon habitat availability in Lake Michigan tributaries currently supporting populations indicated that spawning and staging habitats may limit the ability of these systems to support spawning. Efforts to re‐establish lake sturgeon populations in these systems should consider the creation of spawning and staging habitat to increase reproductive and recruitment potential prior to the initiation of stocking efforts.
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ABSTRACT: The changes in physical habitats and responses of fish, e.g. the Kirikuchi charr Salvelinus leucomaenis japonicus , were examined by placing instream structures in a stream on the upper drainage of the Totsu River system of the Kii Peninsula, Japan, over a two-year period. Instream structures created pools below the structures, and these pools have maintained their functions as fish habitats over two years. In two treatment sections, sections A and B (some red-spotted masu salmon were removed in advance in section B), mean water depth increased soon after placing the structures, but decreased over two years. Mean water velocity slowed after placing the structures in both sections. Total fish abundance has been relatively high at the two treatment sections compared with a control section after placing the structures. Age 1 Kirikuchi charr, however, increased only in section B. These results indicate that instream structures can serve as habitat enhancement for fish, including Kirikuchi charr, in the study area if other appropriate habitat factors for respective species are taken into consideration. 相似文献
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Abstract Scales from hatchery-reared, stocked and wild mulloway Argyrosomus japonicus (Temminck and Schlegel) captured in the Georges River, and a library of mulloway scales from coastal New South Wales, were examined for the presence of scale checks. Checks specific for hatchery-reared fish were present in 100% of recaptured hatchery-reared mulloway; the origin of which was confirmed by the presence of a chemical mark in the otolith or fin spine. Up to 7% of wild mulloway were incorrectly classified as hatchery-reared on the basis of these checks. An abrupt reduction in salinity from 35 to 5 and 6 days starvation successfully induced checks in the scales of hatchery-reared mulloway. The marking efficiency for stocking checks was comparable to that obtained using oxytetracycline hydrochloride, and supports the short-term use of scale stocking checks to evaluate mulloway stock enhancement programmes in Australia. 相似文献
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为了使FY-2C/D 卫星资料反演云系微物理特征参数更好地应用于人工影响天气作业中,利用2010 年8 月17—19 日山西夏季积层混合云降水过程的雷达、卫星、机载云物理探测平台的综合探测资料,对云系演变特征、人工增雨的可播性以及催化效果进行分析。结果表明:云系维持时间达35 h,17日白天到夜间云层不断增厚,云粒子有效半径(Re)稳定变化较小,降水少,云系的自然降水过程较弱,具有较好的增雨作业潜力。8 月17 日白天云顶温度-10℃,云滴有效半径小于12 μm,云系密实,云中过冷水含量丰沛,大粒子与冰晶含量较少;夜晚在高云的播种效应之下,产生较大降水;持续稳定的中低层状云系存在较好的增雨作业机会。综合分析可知,适宜于这次夏季积层混合云降水人工催化条件的卫星判据为:云系厚度大于2 km,云顶温度-10~-20℃,云顶云粒子有效半径小于15 μm。 相似文献
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相依自然降水序列干湿游程特征量的模拟分析 总被引:2,自引:0,他引:2
以游程理论中SenZ.的方法为基础,研究了相依自然降水序列的主要干湿游程特征量──有限样本长度,给定截取水平的交互点数,干湿游程长的期望值,正、负游程和的期望值等的理论模拟模式。并以郑州10年逐旬降水序列对模拟结果进行了验证,理论与实际结果具有较好的一致性。 相似文献
38.
利用ECMWF再分析数据验证PRECIS对中国区域气候的模拟能力 总被引:52,自引:8,他引:52
本文利用1979~1983年的ECMWF再分析数据作为准观测侧边界条件驱动Hadley气候预测和研究中心的区域气候模式系统PRECIS,验证PRECIS对中国区域的气候模拟能力。选择典型的观测站点北京模拟的日最高,最低气温、太阳短波总辐射和月均降水量与观测结果进行直接比较,显示:PRECIS具有很强的模拟地面气候季节变化的能力。全国740个台站的观测与模拟值的统计分析表明:尽管模拟的最高,最低气温在0℃附近有一‘锯齿’状的偏差,PRECIS能够很好地模拟全国范围最高,最低气温的型态分布特征;从全国范围看,模拟的降水值偏高,但显示出很强的模拟极端降水事件的能力;模拟的地面太阳短波总辐射与全国122个台站的观测结果的比较显示:PRECIS模拟的辐射值偏高,全国范围内约高22%。因此,当应用PRECIS输出结果进行气候变化的影响评价时,需要对模式的输出结果进行订正。 相似文献
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