Scientists believe that there are almost 300 known species of fish in Norwegian waters, comprising of 257 saltwater varieties and 42 freshwater fish. Of the saltwater species, we are only aware of 177 that reproduce in Norwegian waters. When a commercial fisherman or angler catches an unknown or rare species, The Institute of Marine Research is a natural place to turn. Often our biologists can determine the species of a fish based on a photo and a description, although in some cases they need to examine the fish more closely in order to be sure.
How do they get here?
Some of the foreign species of fish that are observed reach us by pure chance: accidentally carried north by the currents or brought in the ballast water of foreign ships. A number of fish from a single cohort may also arrive here due to the presence of favourable currents. However, in other cases, a large number of observations may be a sign of more fundamental changes. Particularly within the context of climate change, frequent observations of foreign species – and an equivalent decline in sightings of local species – may suggest permanent changes due to higher sea
A shift in the fish fauna
When the water gets warmer, it makes it easier for species from further south to establish populations in Norwegian waters. Over time, these species can cause a shift in the fish fauna. If they are big predators, for instance, local fish populations may end up being eaten by the newcomers or face greater competition for their food. In extreme situations, the arrival of new species can lead to permanent changes to the ecosystem. A reliable system for reporting fish observations, as we are now putting in place in collaboration with The Norwegian Biodiversity Information Centre and The Norwegian Zoological Society, will give scientists more information about coastal populations in general. It will also give them access to more data when assessing whether increased sightings of foreign species are down to chance visits, short-term phenomena or longer term changes.