Norwegian spring-spawning herring (Clupea harengus, norsk-íslensk vorgotssíld) were recorded at many stations to the north and east, continuing a familiar pattern. Icelandic summer-spawning herring (Clupea harengus, íslensk sumargotssíld) were also found on the continental shelf south and west of the country, as in previous years.
Blue Whiting in Higher Numbers
Blue whiting (Micromesistius poutassou, kolmunni) were found along the shelf edge east, south, and west of Iceland in greater densities than in recent summers. The species was also recorded at eight surface trawl stations off the east and south coasts, which researchers described as unusual. The average size of blue whiting sampled was 23 centimetres and 84 grams.
Capelin Observed Over Wide Area
Capelin (Mallotus villosus, loðna) were caught at eight trawl stations, including seven surface stations north of Iceland and south of Jan Mayen. Sizes ranged from 9 to 19 centimetres, with an average of 16 centimetres and 20 grams. Scientists noted that it is uncommon to record capelin across such a wide area, although there have been occasional records in the Greenland Sea in earlier surveys.
Higher Sea Surface Temperatures
Preliminary results also indicate that sea surface temperatures around Iceland were higher than in the summer of 2024. Calm weather during the survey allowed the surface layer to remain stable for extended periods, giving the sun a greater effect in warming the upper ocean.
Figure 1. Distribution and density according to surface trawls (red filled circles) of mackerel (top), herring (middle), capelin (bottom; red circles) and blue whiting (bottom; blue filled circles with deeper trawls) together with the vessel’s guide lines (black line). Surface trawl stations with no catch of the species in question are indicated by a black cross. Note that the scale for density varies between species. Also shown are depth lines for 200 m, 500 m and 1000 m. Image: Icelandic MRI
Implications for the Fishing Industry
The exceptionally low mackerel density raises questions over the availability of the stock to the Icelandic fleet in the coming seasons. If confirmed in the full survey analysis, the findings could undermine quota decisions and weaken the coastal state’s claims at the North-East Atlantic Fisheries Commission’s (NEAFC) negotiating table.
It has been a long-held belief by other coastal states that Iceland has been overfishing mackerel in International waters, whilst claiming it had reserves of the stock in its own waters.
The industry will now be watching closely to see if this represents a short-term shift in distribution or a more serious decline.