Iceland’s 2025 groundfish survey shows lower cod and haddock indices, rising saithe levels, and record biomass for tusk and ling. Image: Icelandic IMR
Annual Groundfish Survey Highlights Key Shifts in Icelandic Waters
The Marine and Freshwater Research Institute (Hafrannsóknastofnun) has published the findings of the 2025 bottom trawl groundfish survey, covering the period from 27 February to 23 March. The survey, now in its 41st year, monitors the condition of demersal stocks in Iceland’s exclusive economic zone and provides crucial data for fisheries management and quota setting.
Survey methods remain consistent with those used since 1985, allowing reliable year-on-year comparisons. This year, 47 survey hauls were conducted across all major fishing grounds, with additional biological sampling and diet analysis.
Cod Index Declines Slightly as Larger Fish Remain Stable
The cod biomass index, which peaked in 2017 after a steady rise from 2007, declined again this year. While the total biomass was slightly below 2024 levels, large cod over 70 cm remained above the long-term average. In contrast, the 25–45 cm size class — important for recruitment — was below average.
Cod stomach content analysis found capelin made up more than 50% of diet across all size classes, particularly in the Westfjords and Húnaflói regions. This reflects capelin spawning movements during the survey period.
Haddock Biomass Down from 2024 But Still Strong
The haddock index, which had recovered significantly from its low point between 2010 and 2016, also showed a decline compared to last year. Nonetheless, values between 2023–2025 remain among the highest seen since 2007.
Stomach analysis showed more capelin in medium-sized haddock (36–55 cm), but less in the largest size group (56–75 cm) compared to previous years. This reinforces capelin’s role as a dominant prey species during winter and early spring.
Saithe Stocks Recover to Near-Average Levels
The saithe (ufsi) biomass index increased from last year, reversing a decline that began in 2018. Fish in the 60–100 cm size class were particularly abundant. Capelin was again the dominant prey, especially off the Reykjanes Ridge and northwest shelf.
Redfish and Flatfish Show Mixed Results
The golden redfish (gullkarfi) index remained stable, with an above-average presence of juveniles in the 10–15 cm range. However, deepwater redfish (djúpkarfi) showed no significant changes.
Plaice (skarkoli) biomass appears to have plateaued following a period of recovery, though larger individuals are now more common. Greenland halibut and lumpfish indices remained low, consistent with recent years.
Tusk and Ling at Highest Levels on Record
The survey recorded the highest biomass indices for tusk (keila) and ling (langa) since the survey began. Abundance was up across all size classes, confirming long-term positive trends for both species.
This may reflect favourable feeding conditions or changes in distribution linked to sustained warmer sea temperatures.
Monkfish and Other Demersal Stocks
The monkfish (skötuselur) index has risen in recent years, though not dramatically. Wolffish (steinbítur) and megrim (skarkoli) indices remained largely unchanged.
Long-term shifts in species composition continue to reflect subtle ecosystem changes in Icelandic waters.
Temperature Data Confirms Long-Term Warming Trend
Bottom temperatures recorded during the survey remained high by historic standards, consistent with measurements over the past two decades. While eastern inshore areas showed slightly cooler temperatures, the overall picture remains one of long-term ocean warming — a trend with potential implications for species distribution and stock productivity.
Key Tool for Stock Management and Quota Setting
The March groundfish survey is a critical input into Iceland’s fisheries management framework, informing the setting of Total Allowable Catches (TACs) and harvest advice for the coming fishing year.
This year’s report reinforces the need for continued close monitoring, particularly of cod and haddock, where recruitment remains below average. At the same time, it signals strong stock health for tusk, ling, and saithe.
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