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MEPS prepress abstract   -  DOI:

New evidence for the establishment of coastal cod (Gadus morhua) in Svalbard fjords

Lisa Spotowitz*, Torild Johansen, Agneta Hansen, Erik Berg, Christoph Stransky, Philipp Fischer

*Corresponding author:

ABSTRACT: The Arctic is facing increasing water temperatures leading to a northward shift of Atlantic species into Arctic waters. Arctic marine ecosystems are therefore subject to substantial changes in species distribution and occurrence due to anthropogenic climate change. Atlantic cod is one of the commercially most important fish species in the Northern Seas. The largest known stock is the migrating Northeast Arctic cod (NEAC) that is distributed along the Norwegian coast, the Barents Sea, and off Svalbard. By literature Atlantic cod in Svalbard waters is generally known to belong to the NEAC ecotype. The more stationary coastal cod (CC) spawn together with NEAC at the Lofoten and at several separate areas along the Norwegian coast. The aim of this study was to investigate the population structure of Atlantic cod in Svalbard waters. The results are, among others, discussed in relation to increased water temperature and possible on-going borealization processes. This study used single nucleotide polymorphic (SNP) markers, the locus Pantophysin (Pan I), and otolith structure to categorize the two cod ecotypes collected in Svalbard fjords between 2017 and 2019. Our results showed that both NEAC and CC appear in Svalbard fjords and revealed that 0-group and adult CC individuals caught in Svalbard fjords differ genetically from those along the Norwegian coast, indicating a separation into a local Svalbard coastal cod population. The establishment of coastal cod in Svalbard fjords might be another keystone of an ongoing borealization of the Arctic, with consequences for the local Arctic fjord ecosystem.