Environmental Drivers of the Summer Distribution of Lumpfish (Cyclopterus lumpus) in the Eastern Atlantic Ocean

Lumpfish (Cyclopterus lumpus) spawn in coastal waters in the North Atlantic Ocean, yet little is known about the distribution outside of the spawning season. Using data from an extensive pelagic trawl survey that takes place annually in the Nordic Seas, we examine the distribution and abundance of different life stages of lumpfish during summer. Utilising generalised additive models, random forest and support vector machine, we investigate environmental variables that potentially could influence their distribution. Our results reveal that lumpfish have an extensive distribution covering the Irminger Sea, Denmark Strait and Norwegian Sea. However, their frequency of capture is lower south of Iceland and in the North Sea in comparison with other coastal and oceanic areas. Temperature emerged as a primary constraint on the distribution. Lumpfish were caught at over 90% of the stations when temperature at 20-m depth ranged between 4°C and 9°C but less frequently when temperature was outside of this range. Other environmental variables, such as salinity, mixed layer depth and measures of primary and secondary production, had low influence on the distribution of lumpfish.