1. Spawning substrate quality is a major factor influencing the early ontogeny of European nase (Chondrostoma nasus), a target species of conservation.
2. Analogous to findings from salmonids, restoration of spawning grounds was hypothesized to enhance spawning, development and thus recruitment success of nase, by improving the substrate quality, and subsequently spawning site use, egg infiltration and protection of larvae in the interstitial zones before emergence. These assumptions were tested using a comparative approach by cleaning 50% of the area of each spawning ground in two Bavarian rivers.
3. Substrate cleaning resulted in an immediate reduction of ~70% fine sediment content with improvements still detectable 2 months later. Spawning nase used the restored areas of spawning grounds preferentially, which was evident in the number of spawning fish and the significantly higher number of eggs laid.
4. Infiltration of eggs into the interstitial zone was distinctly more successful in the opened interstices of the cleaned spawning substrate, where they were found down to a depth of 20 cm. The same was true for larvae, which could be found down to 30 cm and up to 13 days after hatching. Moreover, higher peaks in the drift density of emerging larvae from the restored spawning substrate were detected (2.5 compared with 1.7 larvae m⁻³ discharge for the River Mangfall and 0.3 compared with 0.03 larvae m⁻³ for the River Sims).
5. These results clearly indicate that gravel cleaning is a successful short‐term restoration tool for nase spawning grounds. It is a quick, cheap and effective method for the conservation management of nase, which may also be applicable to other riverine species with a similiar ecology and incubation time, such as Barbus barbus, Squalius cephalus, Leuciscus leuciscus and Phoxinus phoxinus. This especially holds true if streams lack internal dynamics and suffer from high loads of fine sediment and colmation.

中文翻译：

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整理床铺：砾石清洁有助于养护纳瑟（Chondrostoma nasus L.）产卵和募集成功

1. 产卵底物质量是影响作为保护目标物种的欧洲nase（Condrostoma nasus）早期个体发育的主要因素。
2. 类似于鲑鱼的发现，有人认为恢复产卵场可通过改善底物质量，并随后在产卵前利用卵产区，卵浸润和保护幼虫来增强底物质量，从而增强nase的产卵，发育。通过比较方法，通过清洗两条巴伐利亚河中每个产卵场面积的50％，对这些假设进行了检验。
3. 清洁基材可立即减少约70％的细沉积物，但2个月后仍可观察到改善。产卵nase优先使用产卵场的恢复区域，这在产卵鱼的数量和产卵的数量明显更高的情况下很明显。
4. 在清洁后的产卵基质的开口空隙中，发现卵进入间隙区域明显更成功，在那里发现卵到20厘米的深度。幼虫也是如此，可在孵化后30厘米至13天内发现。此外，检测到在从恢复的产卵基板新兴幼虫的漂移密度更高的峰（2.5与1.7幼虫米相比^-3放电为川Mangfall和0.3 0.03幼虫米相比^-3为川SIMS）。
5. 这些结果清楚地表明，砾石清理是成功的短期修复工具，可用于养护产卵场。这是一种快速，廉价，有效的方法，用于nase的保护管理，也可用于其他具有相似生态学和潜伏期的河岸物种，例如Barbus barbus，Squalius cephalus，Leuciscus leuciscus和Phoxinus phoxinus。如果溪流缺乏内部动力，并承受大量细颗粒沉积物和准直作用，则尤其如此。