Rainbow Trout in Europe: Introduction, Naturalization, and Impacts

Abstract

The rainbow trout (Oncorhynchus mykiss) is probably the most widely introduced fish species in the world. Since the first translocation outside of the range of its natural distribution, the species has been introduced into at least 99 countries and has established reproducing populations in many different parts of the world. The present review aims to synthesize the existing information on these translocations, with special emphasis on self-sustaining populations in Europe, where continuous introductions have in general not led to naturalization. Our survey produced a list of more than 130 confirmed or potential self-sustaining populations across 16 European countries. The highest abundance of such populations was observed in the Alpine foothills of central Europe where naturalization is not limited to modified waters less suitable for native salmonids but also occurs commonly in pristine and near-natural waters. There is no consensus on the reasons for the absence of self-sustaining populations of rainbow trout across much of Europe, partly because knowledge of the mechanisms involved is limited, while the data collected here shed new light on the invasion biology of the species.

Catch‐related and genetic outcome of adult northern pike Esox lucius stocking in a large river system

“…Despite the lack of data about fishing pressure, the 9.6% catch rate of stocked fish was unexpectedly low. Consequently, in such recreational fisheries, it could be questionable to stock large E. lucius intended to be harvested as commonly applied for rainbow trout Oncorhynchus mykiss (Walbaum 1792) (Stanković et al ., ). At best, E. lucius may also be stocked after the spawning period to increase their probability of being caught before the spawning season.…”

A regional fish inventory of inland waters in Northern Italy reveals the presence of fully exotic fish communities

“…These sites did not show significant habitat degradation or hydrologic alteration; however, the community was not composed by native trout and gobies or cottids, but rather solely composed by rainbow trout (Oncorhynchus mykiss). This species was previously reported to establish in different areas of Italy (Stanković et al 2015), even if many more populations are known but not yet reported (Milardi, unpublished data), but its interactions with native fish and invertebrates are still largely unexplored. Candiotto et al (2011) hypothesized that rainbow trout could colonize mainly river stretches where no other fish were present.…”

Dietary niche expansion and niche shift in native marble trout (Salmo marmoratus) living in sympatry with introduced rainbow trout (Oncorhynchus mykiss)

“…Many studies have shown large negative effects (i.e. Rainbow trout have been introduced in Slovenia in the early 20th century for recreational purposes and have established numerous self-sustaining populations in Slovenian Adriatic basin (Stanković et al, 2015), threatening the viability of the endangered native salmonid species marble trout Salmo marmoratus Cuvier, 1829. Rainbow trout have been introduced in Slovenia in the early 20th century for recreational purposes and have established numerous self-sustaining populations in Slovenian Adriatic basin (Stanković et al, 2015), threatening the viability of the endangered native salmonid species marble trout Salmo marmoratus Cuvier, 1829.…”

“…Marble trout in lower Idrijca coexist with non-native rainbow trout, which were introduced only once in the 1960s and have been established since then, but they are absent in upper Idrijca (Stanković et al, 2015). Marble trout in lower Idrijca coexist with non-native rainbow trout, which were introduced only once in the 1960s and have been established since then, but they are absent in upper Idrijca (Stanković et al, 2015).…”