Salmonidae A total of 11 species belonging to the Salmonidae family are registered in Norway. Of these, five species are non-native. As shown in Figure 3 this family in strongly over-represented when it comes to research effort as determined by number of publications. For most of the native species, I found a relatively high number of publications with Atlantic salmon on top, followed by the brown trout and the Arctic char (Figure 5). The non-native species are on average little studied, listing between one and 15 publications per species during the whole period (Figure 5) The chum salmon is probably not established with reproducing populations in Norway, whereas the pink salmon Oncorhynchus gorbuscha (Walbaum, 1792) has appeared in large numbers during even years lately (Mo et al. 2018, Sandlund et al. 2019). Management authorities has initiated large efforts to keep the pink salmon invasion at bay, and this might lead to more publications on this species in the years to come. For example, interesting questions arise on how energy in transferred from the marine environment to the freshwater and terrestrial environments as large numbers of carcasses of pink salmon decomposes (pink salmon are semelparous) (Dunlop et al. 2021a, Dunlop et al. 2021b). Studies in order to understand the population dynamics of this species is underway (Paulsen et al. 2022). It is more worrying that there is so little information on species such as the rainbow trout O. mykiss (Walbaum, 1792), lake trout Salvelinus namaycush (Walbaum, 1792) and brook char S. fontinalis (Mitchell, 1815) (but see Hesthagen et al. 2018). These species have been present in Norwegian freshwaters for decades, but still very little is published on their biology and potential interaction with other species. The rainbow trout is classified as having a high ecological risk, whereas both the lake trout and the brook char has low risk. In total, it is worrying that the ecology of these three species basically in unknown in Norwegian freshwater systems. Six salmonid species are categorized as native to Norway. The two species belonging to the Salmo genus, Atlantic salmon and brown trout, are extensively studied both in Norway and globally (Table 1). For both species I retrieved more the 500 publications for the 1980-2020 time period. Further, the Arctic char was treated in 320 publications, whitefish Coregonus lavaretus (Linnaeus, 1758) in 98 publications and the vendace C. albula (Linnaeus, 1758) in 50 publications. The grayling Thymallus thymallus (Linnaeus, 1758) is the least studied of these species, with only 37 publications listed. These six species, however, deserve separate chapters.

Published as part of Vøllestad, Leif Asbjørn, 2023, A paradoxical bias in knowledge about Norwegian freshwater fishes: research efforts during 1980 - 2020, pp. 6-30 in Fauna norvegica 42 on pages 12-13, DOI: 10.5324/fn.v42i0.4965, http://zenodo.org/record/16906986