The summer research cruise of the vessel Árni Friðriksson sails more than 5,000 nautical miles around Iceland and Jan Mayen.
On board, scientists tow nets, take ocean measurements, and collect samples. This year, the mackerel story takes a sharp turn.
The fish appears only east of Iceland, and in smaller numbers than ever since measurements began in 2010. Out of 46 standard towing stations, mackerel show up at just 13.
The catch is tiny — between half a kilo and 23 kilos per haul. The total catch is 97 kilos, only 164 fish. Each is large, averaging 40 cm and 590 grams.
Other Species Show a Different Picture
While mackerel retreats, Norwegian spring-spawning herring gathers to the north and east, and Icelandic summer-spawning herring holds its usual grounds to the south and west.
Blue whiting appears in substantial numbers along the continental slope in the east, south, and west — denser than recent summers. This species even turns up in places where it is not usually found.
Capelin Surprises in the North
Capelin shows up at eight towing stations, including seven in surface hauls. They stretch over a wide area north of Iceland and south of Jan Mayen.
This is unusual, as past cruises have only spotted them in a few stations in the Denmark Strait. These small fish range from 9 to 19 cm in length.
Calm Seas, Warmer Waters
Ocean surface temperatures run warmer than last summer around the entire country. Calm weather during the 26-day expedition keeps the surface layer stable, letting the sun warm the water for more extended periods. This may play a role in where and how fish gather.
Data from the other research vessels — from Norway, the Faroe Islands, and Denmark — will be combined in mid-August. The full international results will be ready by the end of the month.
For now, the early Icelandic data raises questions: why does the mackerel stay east, and why is it so few? Scientists look to changing ocean conditions for clues.