# Temporal development of the ratio of the number of warm-favouring (Lusitanian) fish species to the number of cool-favouring (Boreal) fish species (1967-2023), December 2024

This metadata describes the ICES data on the temporal development of the Lusitanian (L) /Boreal (B) species ratio in the period from 1967 to 2023. 

Key message: The ratio between the number of Lusitanian (warm-favouring) and Boreal (cool-favouring) fish species are significantly increasing in the Greater North and Celtics Seas. Changes in ratios are most apparent in the North Sea, Irish Sea and West of Scotland whereas there is no significant changes in the more southern Bay of Biscay and Iberian Coast.

Blue dots indicates L/B ratios below 1 (dominance of Boreal species) 
Yellow dots indicates L/B ratios >=1 and <2 (dominance of Lusitanian species) 
Red dots indicates L/B ratios >=2 (high dominance of Lusitanian species) 

The dataset is derived from the ICES data portal 'DATRAS' (the Database of Trawl Surveys). DATRAS is an online database of trawl surveys with access to standard data products. DATRAS stores data collected primarily from bottom trawl fish surveys coordinated by ICES expert groups. The survey data are covering the Baltic Sea, Skagerrak, Kattegat, North Sea, English Channel, Celtic Sea, Irish Sea, Bay of Biscay and the eastern Atlantic from the Shetlands to Gibraltar. At present, there are more than 56 years of continuous time series data in DATRAS, and survey data are continuously updated by national institutions.

The dataset has been used in the EEA Indicator "Changes in fish distribution in European seas" https://www.eea.europa.eu/data-and-maps/indicators/fish-distribution-shifts/assessment-1. 
The dataset has been used for this static map: https://www.eea.europa.eu/en/analysis/indicators/changes-in-fish-distribution-in/temporal-development-of-the-ratio.https://sdi.eea.europa.eu/geonetwork/srv/api/records/d2a7c2fd-816b-4c00-a20e-afb616a9eafc


[More information](https://sdi.eea.europa.eu/catalogue/srv/api/records/d2a7c2fd-816b-4c00-a20e-afb616a9eafc)
    