The ISECI (or F index) has been the first fish index to be recommended by the Italian Ministry of the Environment to assess the rivers ecological status with regard to fish communities, in accordance with the Water Framework Directive 2000/60 EC. In addition to ISECI, other fish indices have been developed such as the Forneris Ichthyic Index (I.I.) and a revised version of ISECI, the so-called NISECI. The latter is nowadays the reference Italian index in the framework of the Water Framework Directive. In this work, we analyzed 30 sampling sites along 18 watercourses in Northern Italy and computed the results of fish monitoring to evaluate the strength of ISECI and NISECI, as well as to assess weak points limiting their application. We detected several issues that undermine the ISECI effectiveness. The weakest point regarded the mismatch between the expected reference fish community and the sampled ones, which decreased the overall algorithm efficiency in the evaluation process. On the other hand, the results confirm the improvements introduced by NISECI. Although with some advancement, all three proposed indices revealed their weaknesses in the overall assessment of the ecological status of the water course, as also highlighted by a pioneering comparison with three expert-based blind judgements.

中文翻译：

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《水框架指令》规定的不同意大利鱼类指标的优缺点

ISECI（或F指数）是意大利环境部根据《水框架指令2000/60 EC》推荐的第一个评估河流与鱼类群落生态状况的鱼类指数。除了ISECI，还开发了其他鱼类指数，例如Forneris鱼鳞指数（II）和ISECI的修订版本，即所谓的NISECI。如今，后者已成为《水框架指令》框架内的意大利参考索引。在这项工作中，我们分析了意大利北部18条水道上的30个采样点，并计算了鱼类监测的结果，以评估ISECI和NISECI的强度，并评估限制其应用的薄弱环节。我们发现了几个影响ISECI有效性的问题。最薄弱的一点是预期的参考鱼类群落与采样的鱼类群落之间的不匹配，这降低了评估过程中的总体算法效率。另一方面，结果证实了NISECI引入的改进。尽管取得了一些进步，但所有三个拟议的指标都揭示了它们在水道生态状况总体评估中的弱点，与三个基于专家的盲目判断的开创性比较也突显了这一点。