Trophic interactions between introduced lake trout ( Salvelinus namaycush) and native Arctic charr ( S. alpinus) in a large Fennoscandian subarctic lake

• Published in: Ecology of Freshwater Fish
• Main Authors: Eloranta, Antti P., Nieminen, Petri, Kahilainen, Kimmo K.
• Other Authors: The Ella and Georg Ehrnrooth Foundation, The Ellen and Artturi Nyyss�nen Founadtion, the Jenny and Antti Wihuri Foundation
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2014
• Subjects: Arctic charr; Fennoscandian; Inarijärvi; Northern Finland; Subarctic
• Online Access: http://dx.doi.org/10.1111/eff.12132; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Feff.12132; https://onlinelibrary.wiley.com/doi/pdf/10.1111/eff.12132

Abstract Introduced fishes may have major impacts on community structure and ecosystem function due to competitive and predatory interactions with native species. For example, introduced lake trout ( Salvelinus namaycush ) has been shown to replace native salmonids and induce major trophic cascades in some North American lakes, but few studies have investigated trophic interactions between lake trout and closely related native Arctic charr ( S. alpinus ) outside the natural distribution of the former species. We used stomach content and stable isotope analyses to investigate trophic interactions between introduced lake trout and native Arctic charr in large subarctic Lake Inarijärvi in northern Finland. Both salmonids had predominantly piscivorous diets at >280 mm total length and were mainly caught from the deep profundal zone. However, lake trout had a more generalist diet and showed higher reliance on littoral prey fish than Arctic charr, whose diet consisted mainly of pelagic planktivorous coregonids. According to length at age and condition data, lake trout showed slightly faster growth but lower condition than Arctic charr. The results indicate that introduced lake trout may to some extent compete with and prey upon native Arctic charr, but currently have only a minor if any impact on native fishes and food web structure in Inarijärvi. Future monitoring is essential to observe potential changes in trophic interactions between lake trout and Arctic charr in Inarijärvi, as well as in other European lakes where the two salmonids currently coexist.