Published: Invasive Rainbow Trout (Oncorhynchus mykiss) Are Not Affected by Different Land Uses in a Multi-Use, Mediterranean Climate Landscape

Figure 1 - FishSitesThe concept of altered landscapes providing ecological benefits for native species may seem controversial. However, reality is often more complex than initial assessments indicate. In Central Chile, pine plantations and trout are often found at the same elevations. Both pine trees and trout are not native to Chile, but there is ample evidence from around the Northern Hemisphere (where trout are native) that plantation forestry can have seriously deleterious effects on resident trout populations, due to increased sediment transport and decreased stream shading, both of which reduce the amount of available habitat for trout (among other things). Furthermore, examining the native species of Central Chile, we see that the much of the community is comprised of generalist species that can occupy a wide range of river settings, including those that are far warmer with more sediment than trout prefer. Finally, we know that the movement range of trout in Central Chilean rivers are highly delimited by thermal boundaries (meaning that they are only really found in the foothills and mountain streams during much of the year, but can descend into the valleys during the winter).

When considered together, we are presented with an interesting question: can pine plantations create negative pressures on trout that are far greater than any potential negative pressure on native species? In this study, I examined rainbow trout caught in 10 headwater basins (5 from pine-plantation-dominated basins, 5 from native-forest-dominated basins; see above) to see if there was any effect on populations’ physical condition (basically the ratio of a fish’s length to its weight).

The manuscript detailing findings from this study are have been published by Fishes.

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