Data from: Rapid climate change increases diversity and homogenizes composition of coastal fish at high latitudes

Rapid warming at high latitudes triggers poleward shifts of species’
distributions that impact marine biodiversity. In the open sea, the
documented redistributions of fish lead to a borealization of Arctic
fauna. A climate driven borealization and increased species diversity at
high latitudes is also expected in coastal fish communities, but it has
not been previously documented on a large, biogeographic scale. Here, we
investigate the impact of temperature change over the last 25 years on
fish communities along the coast of Norway. The study area, spanning
different ecoclimatic zones between 62° and 71° N, harbors over 200
species of boreal and Arctic fish. Several of these fish species are
harvested by coastal and indigenous communities, influencing settlements
geography and livelihood. The long-term data on coastal water temperatures
and fish species were obtained from monitoring stations and scientific
surveys. Water temperature measured at three fixed sampling stations
distributed along the coast show increased temperatures during the study
period. The fish species distribution and abundance data were obtained
from the annually standardized scientific bottom trawl survey program.
Fish species richness, which was highest in the south, increased with
warming first in the south and then, gradually, further north, eventually
affecting biodiversity in the whole study area. Fish community composition
showed a distinct latitudinal pattern early in the study, with Arctic fish
species confined north and boreal species dominating south. The poleward
shifts eventually eroded this zoogeographic pattern, resulting in more
boreal fish species in the north and an increased homogenization of
species composition along the Norwegian coast. The climate-driven
reorganization of fish communities affects coastal ecosystems that are
exposed to fisheries, aquaculture and other rapidly expanding human
activities, stressing the urgent need for a climate adaptation of
integrated coastal management.