On distributional responses of North Atlantic fish to climate change

Abstract Changes in fish distribution and climate in the North Atlantic have been observed for millennia by seafaring peoples, chronicled in many historical anecdotes, and recently studied systematically. For temperate to Arctic North Atlantic fish, a literature compendium of limits of temperature, salinity, and depth during feeding and spawning was used to investigate factors that influence distribution. Latitude and depth were negatively correlated with species number and density. Peak numbers of species feed at 0–4°C, but spawn at 2–7°C and salinities of 32.5–33.5. Principal components of feeding depths and temperatures suggested four groups of species: (i) small pelagics characterized by shallow habitat and cooler temperatures; (ii) most groundfish in deeper and warmer waters; (iii) warm-water large pelagics; and (iv) deepwater species. Spawning temperatures, salinities, depths, and timing produced groupings consistent with feeding components for pelagics, but differing for distant migrants such as tunas. Principal components (PCA) of spawning characteristics explained 56% of the variance in species resilience (doubling time), while PCA of feeding characteristics explained only 23%. We infer that the small pelagics capelin (Mallotus villosus) and herring (Clupea harengus) react strongly and quickly to climate change because of their physiological limits and potential for fast population growth. Verification comes from Icelandic and Greenland waters, which warmed considerably during 1920–1940, and where capelin, herring, cod (Gadus morhua), and other species shifted north very quickly.