Climate Change and New Potential Spawning Sites for Northeast Arctic cod

Anne Britt Sandø,Geir Odd Johansen,Angelika H H Renner,Jan Erik Stiansen,Asgeir Aglen

doi:10.3389/fmars.2020.00028

Anne Britt Sandø, Geir Odd Johansen + Show 3 more

Open Access

https://doi.org/10.3389/fmars.2020.00028

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Abstract

In this study we investigate both historical and potential future changes in the spatial distribution of spawning habitats for Northeast Arctic Cod (NEA cod) based on a literature study on spawning habitats and different physical factors from a downscaled climate model. The approach to use a high resolution regional ocean model to analyze spawning sites is new and provides more details about crucial physical factors than a global low resolution model can. The model is evaluated with respect to temperature and salinity along the Norwegian coast during the last decades and shows acceptable agreement with observations. However, the model does not take into consideration biological or evolutionary factors which also have impact on choice of spawning sites. Our results from the downscaled RCP4.5 scenario suggest that the spawning sites will be shifted further northeastwards, with new locations at the Russian coast close to Murmansk over the next 50 years, where low temperatures for many decades in the last century were a limiting factor on spawning during spring. The regional model gives future temperatures above the chosen lower critical minimum value in larger areas than today and indicates that spawning will be more extensive there. Dependent on the chosen upper temperature boundary, future temperatures may become a limiting factor for spawning habitats at traditional spawning sites south of Lofoten. Finally, the observed long-term latitudinal shifts in spawning habitats along the Norwegian coast the recent decades may be indirectly linked to temperature through the latitudinal shift of the sea ice edge and the corresponding shift in available ice-free predation habitats, which control the average migration distance to the spawning sites. We therefore acknowledge that physical limitations for defining the spawning sites might be proxies for other biophysically related factors.

Highlights

The recent warming of the oceans (Levitus et al, 2009; IPCC, 2013) has resulted in shifts in the geographical distribution of marine fish (Perry, 2005; Dulvy et al, 2008; Fossheim et al, 2015)
In this paper we define water masses along the Norwegian coast from a downscaled ocean model corresponding to the physical conditions temperature, salinity and depth characterizing the physical conditions of the spawning habitat of Northeast Arctic cod (NEA cod)
Thereafter we apply the same criteria on the results from the future projection to see how spawning sites may change in the future, given that there is a close link to the hydrographic properties

Summary

Introduction

The recent warming of the oceans (Levitus et al, 2009; IPCC, 2013) has resulted in shifts in the geographical distribution of marine fish (Perry, 2005; Dulvy et al, 2008; Fossheim et al, 2015). NEA cod has undergone distribution shifts involving most of its life history stages, parallel to the observed ocean warming during the last 3 decades (Kjesbu et al, 2014; Ingvaldsen et al, 2015; Fall et al, 2018). Considerable expansion of its distribution limits north- and eastwards in the Barents Sea has been observed following increased inflow of warm Atlantic Water into the region (Eriksen et al, 2011; Kjesbu et al, 2014; Fossheim et al, 2015). Further distribution shifts (Stenevik and Sundby, 2007; Drinkwater, 2011) and changes in total stock biomass (Årthun et al, 2018) in the NEA cod stock as a whole have been predicted due to continued ocean warming

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