Introduced salmonids have invaded almost all Patagonian freshwater environments, and yet the effect they have had on native fish populations is difficult to evaluate due to a lack of data prior to their introduction. In this study we focused on evaluating trophic interactions during the juvenile period of Oncorhynchus mykiss, and the ecologically similar native Percichthys trucha. For this purpose, we evaluated the diet and size range of juveniles of both species in the Caleufu River over one yearly cycle. The functional response (FR: the relationship between prey density and consumption rate) and functional response ratio (FRR = attack rate/handling time) were estimated for each species, in mono-specific and multi-specific trials. Comparison of the diet of these species by season showed high similarity for spring and summer. It was also found that juvenile sizes of these species overlap during early ontogeny. Additionally, both species presented a type II FR in mono-specific trials, with similar functional curves. In multi-specific experiments O. mykiss juveniles were dominant, leading to a reduction in P. trucha food intake. FRR was higher for O. mykiss than for P. trucha in mono-specific experiments, a difference which increased in multi-specific experiments, indicating the high potential ecological impact of O. mykiss. Our results show it is very likely that O. mykiss and native P. trucha compete in lotic environments, O. mykiss being competitively superior, highlighting the potential detrimental effect they may have during the juvenile period, especially in habitats and seasons where food resources are scarce.

引进的鲑鱼几乎侵入了巴塔哥尼亚的所有淡水环境，但是由于它们在引入前缺乏数据，因此很难评估它们对本地鱼类种群的影响。在这项研究中，我们重点评估了Oncorhynchus mykiss和生态相似的本地Percichthys trucha幼年时期的营养相互作用。为此，我们在一年的周期内评估了Caleufu河中这两种物种的幼鱼的饮食和大小范围。在单特异性和多特异性试验中，估计了每种物种的功能反应（FR：猎物密度与消耗率之间的关系）和功能反应比（FRR =攻击率/处理时间）。按季节对这些物种的饮食进行比较显示，春季和夏季具有高度相似性。还发现这些个体的幼体大小在个体发育早期重叠。此外，两个物种在单特异性试验中均表现出II型FR，具有相似的功能曲线。在多特异性实验中，my.kiss幼鱼占主导地位，导致tru。trucha食物的摄入减少。FRR较高O.虹鳟比P. trucha在单特异性实验，这在多特异性实验增加，表明的高电位生态影响的差值O.虹鳟。我们的研究结果表明它很可能是O.虹鳟和本地P. trucha在激流环境下竞争，O.虹鳟是优越的竞争力，突出的潜在不利影响在少年时期，他们可能有，尤其是在栖息地和食物地方资源的季节稀缺。