Cottidae, Bonaparte, 1831

Cottidae View in CoL

In total three species of sculpins are found in Norwegian freshwaters ( Table 1 View Table 1 ). Only the alpine bullhead Cottus poecilopus Haeckel, 1835 is distributed over a larger geographic area. The other species, bullhead C. gobio Linnaeus, 1758 and fourhorn sculpin have very limited natural distribution.

I found no publication on the fourhorn sculpin during the time period investigated. This species is only observed in two large lakes, Mjøsa and Store Le, but there is almost no information about population size or biology. The species has also been listed on the Norwegian Red List both in 2010 (VU) and 2015 (DD). However, it was removed from the list in 2021 ( Hesthagen et al. 2021b). Even if no articles were recovered by the formal search, there are a few Norwegian reports available.

The bullhead is also a species with very limited distribution in Norway. However, it has relatively recently been found in new locations and may be spreading ( Frilund et al. 2009). The limited natural distribution led to a listing as Near Threatened on the 2006 Red List; it was subsequently removed from the list. There is, however, almost no knowledge about this species in Norway.

The biology of the alpine bullhead, on the other hand, has been studied to some degree. In particular it has been studied how it might interact with sympatric species such as trout (Holmen et al. 2003, Hesthagen et al. 2004, Hesthagen et al. 2011a) and Atlantic salmon ( Gabler and Amundsen 1999, Gabler and Amundsen 2010, Sanchez-Hernandez et al. 2016). The studies of the interaction with Atlantic salmon were initiated because the alpine bullhead had invaded a salmon river (River Tana/Teno with tributaries), producing a need to know more about how bullhead and other species may engage in competitive interactions. Following this, there has also been some studies on how the alpine bullhead may be a vector for important parasites such as Gyrodactylus salaris (Winger et al. 2008a, Bakke et al. 2019).

In general, there is very little knowledge about population biology (dynamics, structure) and ecology of the three sculpin species under Norwegian conditions. This lack of knowledge is shared with a number of other small-sized species with little economic interest.