Spatially resolved past and projected changes of the suitable thermal habitat of North Sea cod (Gadus morhua) under climate change

Ismael Núñez-Riboni,Moritz Mathis,Miriam Püts,Marc H Taylor,Alexander Kempf,Henn Ojaveer

doi:10.1093/icesjms/fsz132

Ismael Núñez-Riboni, Moritz Mathis + Show 4 more

Open Access

https://doi.org/10.1093/icesjms/fsz132

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Abstract

Abstract Previous studies have identified changes in habitat temperature as a major factor leading to the geographical displacement of North Sea cod in the last decades. However, the degree to which thermal suitability is presently changing in different regions of the North Sea is still unclear, or if temperature alone (or together with fishery) is responsible for this displacement. In this study, the spatial distribution of different life stages of cod was modelled from 1967 to 2015. The model is fit point-to-point, spatially resolved at scales of 20 km. The results show that suitability has decreased south of 56°N (&gt;12% in the Southern Bight) and increased north of it (with maximum of roughly 10% in southern Skagerrak). Future changes to suitability were estimated throughout the century using temperature projections from a regional climate model under the Intergovernmental Panel on Climate Change scenario RCP8.5. The results show that southern Skagerrak, the central and northern North Sea and the edge of the Norwegian trench will remain thermally suitable for North Sea cod throughout the century. This detailed geographical representation of thermally suitable key zones for North Sea cod under climate change is revealed for the first time through the improved resolution of this analysis.

Highlights

Atlantic cod (Gadus morhua) is one of the most important and studied commercial fish species of the North Sea (Cohen et al, 1990). Hedger et al (2004), Engelhard et al (2014), and Nicolas et al (2014) have shown that over the last decades, the geographical distribution of North Sea cod has changed from the shallow south-western to deeper, north-eastern parts of the North Sea
The results show that southern Skagerrak, the central and northern North Sea and the edge of the Norwegian trench will remain thermally suitable for North Sea cod throughout the century
A species distribution model was developed for different life stages of cod based on generalized additive models (GAMs) fitted to data of the North Sea International Bottom Trawl Surveys (IBTS) spanning almost five decades (1967–2015)

Summary

Introduction

Atlantic cod (Gadus morhua) is one of the most important and studied commercial fish species of the North Sea (Cohen et al, 1990). Hedger et al (2004), Engelhard et al (2014), and Nicolas et al (2014) have shown that over the last decades, the geographical distribution of North Sea cod has changed from the shallow south-western to deeper, north-eastern parts of the North Sea. Hedger et al (2004), Engelhard et al (2014), and Nicolas et al (2014) have shown that over the last decades, the geographical distribution of North Sea cod has changed from the shallow south-western to deeper, north-eastern parts of the North Sea. Atlantic cod (Gadus morhua) is one of the most important and studied commercial fish species of the North Sea (Cohen et al, 1990). Hedger et al (2004), Engelhard et al (2014), and Nicolas et al (2014) have shown that over the last decades, the geographical distribution of North Sea cod has changed from the shallow south-western to deeper, north-eastern parts of the North Sea None of these previous studies has quantified the impact of temperature changes on the distribution of the suitable habitat for North Sea cod, spatially resolved at both long-term temporal and high-resolution spatial scales.

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