Cyprinidae, A. d'Orbigny, 1844

Cyprinidae View in CoL , Leuciscidae , Gobionidae and Tincidae

These four families were earlier considered to belong to one single family – Cyprinidae . I therefore, for simplicity, treat them together here. A total of 16 species belong to these families, whereof five species are introduced and non-native ( Table 1 View Table 1 ). On average only three papers were published for each of the non-native species, compared with on average 11 articles for the native species. However, the number of articles published for the native species was very biased, with most articles being published for only four species (roach Rutilus rutilus (Linnaeus, 1758) , Eurasian minnow Phoxinus phoxinus (Linnaeus, 1758) , bream Abramis brama (Linnaeus, 1758) , crucian carp Carassius Carassius (Linnaeus, 1758)) .

Both the roach and the minnow are classified as regionally non-native species and suggested to have a high to very high ecological risk to the local ecosystem. However, few of the articles on the roach were relevant in order to evaluate the effect of translocations, but were rather classical ecological studies (L’Abée-Lund and Vøllestad 1985, Vøllestad and L’Abée-Lund 1987, L’Abee-Lund and Vøllestad 1989). Further, most of these studies was published during the period 1980- 1995. This was a time when biomanipulation of freshwater ecosystems in order to increase water quality was popular ( Carpenter and Kitchell 1992, DeMelo et al. 1992); this was evidently the focus for some of the studies ( Brabrand et al. 1990, Faafeng et al. 1990, Brabrand and Faafeng 1993). During recent years, most of the retrieved studies actually did not focus on the roach, but information on the roach was rather a by-product of the main topic of the study. The listing of roach as a species with potentially high ecological impact when translocated to new locations has seemingly not led to more studies. However, in 2021 a new study trying to forecast the distribution of roach was published (Perrin et al. 2021). This study also discussed several other species that are considered as regionally invasive.

The Eurasian minnow has been studied in different contexts. Most studies are set in an ecosystem context, with focus on predator-prey relationships ( Borgstrøm et al. 1985, L’Abée-Lund et al. 1996) and parasite-host dynamic (Museth 2001, Pettersen et al. 2016, Borgstrøm et al. 2017). It has been a clear focus on the interaction between the minnow and the native fish fauna, in particular interactions with the brown trout (Lien 1981, Museth et al. 2007). During recent years there has been an intensive action by various management authorities to reduce the spread of the minnow to new locations (Museth et al. 2007), but it has only to limited degree led to increased and relevant research activity on the species.

The crucian carp is also classified as regionally non-native, but it is assumed to have only low ecological effects in the new environment. Most of the reported studies are focused on the particular physiology of the crucian carp (Sollid et al. 2005), in particular its ability to survive long periods without oxygen (Poléo 1993). This ability also makes the species very tolerant to high concentrations of labile aluminium at low pH (Poléo et al. 2017). Also, the fact that the crucian carp develop different body shapes in the presence or absence of gape-limited predators has attracted some attention (Poléo et al. 1995). However, no studies up to 2020 focused on the crucian carp as a regionally invasive species with potential negative effects. Such studies seem to appear more recently ( de Meo et al. 2022).

A total of 11 articles were found to report data on the bream – indicating at least some interest in this species. Almost 50% of these articles are from the National History Museum at the University of Oslo, and focus on distribution, feeding and parasites ( Brabrand 1984, Brabrand et al. 1994, Sterud and Appleby 1996). The bream is an important component of many large lakes in the south-east part of Norway. It is therefore strange that so little attention has been diverted to learn more about its ecology, and potential interactions with other species.

The rudd Scardinius erythrophthalmus (Linnaeus, 1758) is classified as a regionally non-native species with a potential for very high ecological effects. However, in total only four articles have been published on this species. None of these studies focused on ecosystem effects or on potential interactions with native species. However, the potential future establishment of this species was evaluated in a 2021 study (Perrin et al. 2021).

The five non-native species in these families are classified as having variable ecological risks ( Table 1 View Table 1 ). Three species were classified as having high ecological risk following translocation, and the other two were assumed to have limited ecological risk. However, only a very limited number of papers (varying from 2-7) was published for each of the species. For the carp Cyprinus carpio Linnaeus, 1758 a total of seven papers were registered. Most of these papers were notes of the present and historical distribution of carp (Kålås and Johansen 1995, Kleiven 2013), but there was no paper on its ecology and interaction with other species. For the tench Tinca tinca (Linnaeus, 1758) , one paper on age and growth was found (L’Abée-Lund 1985). For the three other species (sunbleak Leucaspius delineates (Heckel, 1843) , gudgeon Gobio gobio (Linnaeus, 1758) , goldfish Carassius auratus (Linnaeus, 1758)) , no study on ecology was found. In total, for most of the species that was classified as either non-native and invasive at the national scale or at the regional scale very limited ecological information has been gathered during the period 1980-2020.

Two species were classified on the Norwegian Red List during 2006 ( Table 1 View Table 1 ), but not on the later iterations of the list. Thus, I would assume that some ecological information had been gathered to facilitate this new evaluation. The silver bream Blicca bjoerkna (Linnaeus, 1758) was classified as NT in 2006. However, only four papers focusing on this species were found – the newest from 1996. This paper was on parasites ( Appleby and Sterud 1996). The asp Aspius aspius (Linnaeus, 1758) was classified as VU in 2006. Only two papers were found for this species, one on a potential observation in a new location (Spikkeland and Basnes 2009), and one on parasites ( Sterud and Appleby 1996). Thus, basically no relevant information has been published formally either before or after the Red list listing.

For the remaining species in these four families very little published information could be found. In total, the information available is very biased towards a few species. Even the non-native species with suggested high ecological risks (impacts) have not been studied to any extent. This is, of course, unfortunate.