In Italian freshwaters the introgressive hybridization with the alien Atlantic trout represents the principal threat to the native endangered Mediterranean trout. The aim of the research was to test the effectiveness of alien trout removal activities carried out by electrofishing in four streams in Central Italy. The four sites were chosen on the basis of the severe genetic introgression level of the trout populations. The removal activities were carried out from December 2014 to July 2017, for a total of 10 eradication campaigns in each site. During each field activity, five environmental parameters (flow rate, conductivity, average depth, average width, accessibility) were collected, since they could influence both the effectiveness of the electrofishing and the biological characteristics of the fish populations. A total of over 22,000 alien trout accounting for a biomass of over 700 kg were removed from the removal sites. For each site, a progressive drastic decrease over time in density and standing crop values was observed. Removal rates ranged from 94.22% to 100.00% for density, and from 96.57% to 100.00% for standing crop. The correlation analysis showed an inverse significant relationship between catchability and populations abundance, confirming that low density populations are more suitable to removal efforts. The progressive removal of specimens improved the catchability over time, indicating that even the largest populations could be eradicated, providing the necessary number of steps in a fishing season. The improved body condition and the greater growth rates observed during the eradication period, in low abundance conditions, seemed to confirm the key role that intraspecific competition and density‐dependent phenomena play in the Apennine trout population dynamics. The results obtained in the present research provided evidence that electrofishing removal could be an effective management tool for the Mediterranean trout conservation, especially in watercourses of modest dimensions in terms of flow rates, width and depth.

中文翻译：

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外来褐鳟鳟鱼去除活动对地中海溪流本地鳟鱼保护的有效性

在意大利的淡水中，与外来大西洋鳟鱼的渐进杂交是对濒临灭绝的地中海鳟鱼的主要威胁。该研究的目的是测试在意大利中部的四个溪流中通过电钓进行的外星鳟鱼去除活动的有效性。根据鳟鱼种群的严重基因渗入水平选择了四个位点。从2014年12月至2017年7月进行了清除活动，每个站点总共进行了10次清除活动。在每次野外活动期间，收集了五个环境参数（流速，电导率，平均深度，平均宽度，可及性），因为它们可能影响电钓鱼的效率和鱼类种群的生物学特性。总共超过22 从清除地点清除了000只外来鳟鱼，占生物量700公斤以上。对于每个站点，观察到密度和站立作物值随时间逐渐急剧下降。密度的去除率在94.22％至100.00％之间，直立作物的去除率在96.57％至100.00％之间。相关分析显示，可捕获性与种群数量之间呈负相关的负相关关系，这表明低密度种群更适合于清除工作。随着时间的推移，标本的逐渐移出提高了可捕性，表明即使在最大数量的种群也可以被消灭，从而在捕捞季节提供了必要的步数。在低丰度条件下，根除期间观察到的身体状况有所改善，增长率更高，似乎证实了种内竞争和密度依赖性现象在亚平宁鳟鱼种群动态中的关键作用。在本研究中获得的结果提供了证据，证明电钓鱼去除可能是地中海鳟鱼养护的有效管理工具，特别是在流量，宽度和深度方面规模较小的水道中。