Demersal fish in Icelandic waters

• Main Author: Magnus Thorlacius
• Format: Conference Object
• Language: unknown
• Published: 2021
• Subjects: Iceland; North Atlantic; North Atlantic oscillation
• Online Access: https://zenodo.org/record/5575174; https://doi.org/10.5281/zenodo.5575174

A sudden increase in population size and distribution around Iceland took place in several species in 2000-2010. What they have in common is that Iceland is placed at the northern border of their geographic range making the susceptible to environmental fluctuations. Several studies have linked these changes with increasing temperature and long-term fluctuations in the North Atlantic Subpolar Gyre. Since then, we have observed a recruitment failure in many of these species which took place when temperatures were still high. There are some indications that salinity may have been reduced as well and seems more important for these species. Focusing on monkfish (Lophius piscatorius) for which I have data that demonstrates these changes very well, I used the VAST package (spatial delta generalized mixed models) to standardize the time series data and found a correlation with salinity and with the subpolar gyre index (though I have only found the time to use the old version (PC1)). I also compared the North Atlantic Oscillation Index which has been found to have an effect on fish stock sizes, but no correlation was found for monkfish. The (SPG) clearly being the most important factor, the question still remains whether the observed changes in distribution and density are caused by recruitment by means of migration and/or drift or if the warm, saline but nutrient deficient currents make local conditions more favourable for recruitment.