DOI: 10.5061/dryad.zs7h44jhf
title: Data from: Rapid climate change increases diversity and homogenizes composition of coastal fish at high latitudes

description: 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.
description: Refer to the associated paper for a description of methods.
description: # Rapid climate change increases diversity and homogenizes composition of
 coastal fish at high latitudes
 [https://doi.org/10.5061/dryad.zs7h44jhf](https://doi.org/10.5061/dryad.zs7h44jhf) The dataset contains summary statistics of fish diversity and composition from demersal trawls along the Norwegian coast. Raw data comes from an annual scientific survey and was collected by the Norwegian Institute of Marine Research (IMR). The results are based on a selection of 59 fish taxa, and presented per year (1995-2019) and sub-section along the coast. The coast was divided into 10 equally long intervals of c. 167 km each. Please read the paper or contact the author for more details. ## Description of the data and file structure | **Column** | **Explanation** | | :----------- | :-------------------------------------------------------------------------------------------- | | year | Year of sampling | | coastint | Coastal interval, 167 km long segments along the coast, numbered from 1 (south) to 10 (north) | | S | Mean species richness, number of species per trawl haul | | J | Mean Pielou\`s eveness index per trawl haul | | H | Mean Shannon\`s diversity index per trawl haul | | totcount\_nm | Mean fish abundance per trawl haul, standardised to counts per nautical mile trawled | | ntrawls | Number of trawl hauls per year and coastal interval | | north\_perc | Percent of trawls assigned to the northern fish assemblage type |