Whales Around Iceland: How Much Do They Eat, What Do They Eat, and How Many Are There?

An evidence-based review of whale food consumption, fish predation and cetacean abundance in Icelandic and adjacent waters

Executive summary

Whales and dolphins consume very large quantities of prey in the productive waters around Iceland, but three numbers must not be confused:

1. Total food consumed is not the same as fish consumed.

2. Fish consumed is not the same as commercially valuable fish removed from fisheries.

3. A survey-area abundance estimate is not a headcount inside Iceland's territorial sea or Exclusive Economic Zone at any one time.

The most detailed peer-reviewed calculation estimated annual cetacean consumption in "Icelandic and adjacent waters" at 6.26 million tonnes. Of this, 2.03 million tonnes (32%) was finfish, 1.31 million tonnes (21%) cephalopods, and 2.91 million tonnes (47%) crustaceans, mainly krill. The calculation used abundance data from the 1987, 1989 and 1995 North Atlantic Sightings Surveys and many assumptions about seasonal presence, body mass, diet and energy requirements. Its authors explicitly described it as an estimate of the possible order of magnitude, not a precise current total.[1]

In 2019, Iceland's Marine and Freshwater Research Institute (MFRI) published an updated calculation of 7.6 million tonnes of total food per year, including 3.3 million tonnes of fish. In that update, the three largest consumers were reported as fin whales (1.8 million tonnes), common minke whales (1.5 million tonnes) and humpback whales (1.1 million tonnes). MFRI also stressed that uncertainty could not be quantified adequately with the available data, especially for toothed-whale abundance, diet composition and the time migratory whales spend in Icelandic waters.[2]

The latest complete, comparable multi-species abundance table remains the 2015 Icelandic-Faroese NASS ship survey. Its ten reported point estimates sum to about 773,000 cetaceans, but approximately 635,000 of that total consists of pilot whales and two dolphin species. The sum must therefore not be described simply as "nearly one million whales around Iceland." The survey covered a broad Central North Atlantic area around Iceland and the Faroe Islands, and several estimates have very wide confidence intervals.[3]

NASS 2024 produced preliminary Icelandic estimates of 15,867 fin whales and 15,660 common minke whales, but the March 2026 NAMMCO status report labels both estimates uncorrected and not endorsed. Final estimates for non-target species are scheduled for review in October 2026. Until the review is complete, the preliminary 2024 figures should not replace the accepted 2015 multi-species table.[4]

How much food do cetaceans consume?

Two estimates answer different questions

Estimate	Total food	Finfish	Cephalopods	Crustaceans / krill	Status
Sigurjónsson & Víkingsson (1997), Method A	6.26 million t/year	2.03 million t (32%)	1.31 million t (21%)	2.91 million t (47%)	Peer-reviewed full species table; built on 1987-1995 abundance data
MFRI update (2019)	7.6 million t/year	3.3 million t (43%)	Not separately reported	Not separately reported	Newer institutional update; uncertainty not quantified

The 1997 estimate corresponds to an average of about 17,100 tonnes of total prey per day across the year. The 2019 update corresponds to about 20,800 tonnes per day, of which about 9,000 tonnes per day was estimated to be fish. These daily averages are only a way to express the annual totals. Feeding is strongly seasonal and geographically concentrated.

The most defensible headline is therefore:

Cetaceans in Icelandic and adjacent waters have been estimated to consume roughly 6-8 million tonnes of food per year, of which approximately 2-3.3 million tonnes may be fish.

This range combines a peer-reviewed historical estimate and a later MFRI update. It should not be presented as a precise measurement for 2026.

Historic consumption by species

The table below reproduces Method A for the smaller study area, "Icelandic and adjacent waters", from Sigurjónsson and Víkingsson (1997). It is valuable because it is the only published full breakdown by consumer and prey class, but it is a historical model based on old abundance and diet inputs.[1]

Species or group	Finfish (t/year)	Cephalopods (t/year)	Crustaceans / krill (t/year)	Total food (t/year)	Diet interpretation used in the model
Common minke whale	1,055,602	0	1,025,398	2,081,000	Mixed fish and krill
Fin whale	32,045	0	1,448,363	1,480,408	Predominantly krill
Long-finned pilot whale	154,943	619,771	0	774,714	Mainly cephalopods, with fish
Northern bottlenose whale	34,315	651,980	0	686,295	Predominantly cephalopods
Humpback whale	118,889	0	110,792	229,681	Mixed fish and krill
Blue whale	0	0	206,364	206,364	Krill
Atlantic white-sided dolphin	184,643	9,718	0	194,361	Predominantly fish
Unidentified dolphins*	138,728	7,301	0	146,029	Predominantly fish
Killer whale	139,342	0	0	139,342	Fish was assumed in this model
Sei whale	1,781	0	122,021	123,802	Predominantly planktonic crustaceans
Sperm whale	58,104	18,349	0	76,453	Fish and cephalopods
White-beaked dolphin	67,810	3,569	0	71,378	Predominantly fish
Harbour porpoise	45,823	2,412	0	48,235	Predominantly fish
Total	2,032,024	1,313,100	2,912,938	6,258,062

*The unidentified-dolphin row is a survey category, not a biological species.

The model's diet assumptions were necessarily simple. For example, examination of 1,609 fin-whale stomachs from Icelandic catches in 1967-1989 found krill alone in 96% of stomachs; the model therefore assigned 97% of fin-whale food to krill and 3% to fish. The original minke-whale assumption was 59% fish and 41% krill, while humpback whales were assigned 60% fish and 40% krill.[1]

Later research shows why these percentages cannot be treated as permanent constants. Minke-whale stomach samples collected in 2003-2007 contained less krill and capelin, but more gadoids and herring, than earlier Icelandic samples.[5] The broader Icelandic review by Víkingsson and colleagues also found major shifts in distribution and feeding ecology associated with changes in temperature, salinity and prey availability.[6]

What are the principal prey?

• Krill and other planktonic crustaceans: the dominant prey in the historic fin-, blue- and sei-whale calculations, and a major part of minke- and humpback-whale diets.

• Capelin: an important forage fish for humpback and minke whales and sometimes fin whales. Capelin distribution changes between Iceland, East Greenland and Jan Mayen, so predation can shift geographically from year to year.

• Herring: important to Icelandic killer whales and increasingly important in the documented minke-whale diet.

• Sandeel: a locally important prey for minke and humpback whales, especially in coastal feeding areas.

• Gadoids: cod-family fishes such as haddock, cod, saithe and blue whiting occur in the diets of several cetaceans, especially minke whales and dolphins.

• Cephalopods: a major prey category for long-finned pilot whales and northern bottlenose whales.

How many cetaceans are in the wider waters around Iceland?

The following are the corrected point estimates and 95% confidence intervals from the 2015 Icelandic and Faroese NASS ship surveys. They describe the survey area, not the number continuously present inside Iceland's EEZ.[3]

Species	2015 point estimate	95% confidence interval	Important interpretation
Long-finned pilot whale	344,148	162,795-727,527	Largest point estimate; exceptionally wide interval
White-beaked dolphin	159,000	49,957-506,054	Dolphin, not a large whale; wide interval
Atlantic white-sided dolphin	131,022	35,251-486,981	Dolphin; wide interval
Common minke whale	42,515	22,895-78,942	Iceland-Faroe survey estimate; other management-area estimates use different boundaries
Fin whale	36,773	25,811-52,392	Best-estimated abundant large baleen whale in this survey area
Sperm whale	23,166	7,699-69,709	Deep-diving species; wide interval
Northern bottlenose whale	19,975	5,562-71,737	Deep-diving species; wide interval
Humpback whale	9,867	4,854-20,058	Strong increase over the earlier NASS time series
Sei whale	3,767	1,156-12,270	Relatively few sightings
Blue whale	3,000	1,377-6,534	Concentrated especially west and north of Iceland
Sum of point estimates	773,233	Not a valid combined confidence interval	Includes whales and dolphins across a broad survey region

The lower and upper limits must be retained when the figures are published. Adding all lower bounds gives about 317,000 and adding all upper bounds gives more than 2 million, illustrating the very large uncertainty, but those sums are not a statistically valid combined confidence interval because uncertainty is species-specific and not necessarily independent.

MFRI notes that the NASS programme has documented substantial changes over time: fin whales increased markedly, especially between Iceland and Greenland; humpback whales multiplied; and minke-whale abundance fell on the Icelandic continental shelf after 2001, probably reflecting a northward distribution shift associated with reduced local prey availability.[7]

What do the preliminary NASS 2024 figures show?

NAMMCO's March 2026 project update lists the following Icelandic target-species estimates:

Species	Preliminary 2024 estimate	95% confidence interval	Correction and review status
Fin whale	15,867	11,399-22,088	Not corrected; not endorsed
Common minke whale	15,660	9,134-26,848	Not corrected; not endorsed

These figures are lower than the 2015 Iceland-Faroe point estimates, but a direct trend conclusion would be premature. The survey boundaries, realised coverage and correction status differ. Poor weather, ice, incomplete transects and the use of fishery-survey tracks complicated the 2024 analysis. NAMMCO states that the estimates must be corrected and reviewed before final use.[4]

Does whale consumption reduce fisheries yield?

High consumption does not automatically equal an equivalent loss to fishing fleets.

Whales eat krill, cephalopods and non-commercial fish as well as commercially harvested species. They may prey on fish that would otherwise be caught, but they also consume predators and competitors of commercial fish. Their nutrient recycling and movement affect ecosystem productivity. The net effect depends on the food web, prey age and size, location, season, alternative prey, and the response of other predators.

MFRI's 1997 multispecies simulation explored possible long-term interactions among fin, minke and humpback whales and cod, capelin and shrimp. The results were highly dependent on assumptions about diet and future whale abundance. MFRI's 2019 review therefore concluded that existing knowledge was insufficient for a quantitative prediction of the effect of whale hunting on the yield of specific fish stocks.[2]

This distinction matters for economic analysis:

Tonnes eaten by whales are an ecosystem flow, not a direct estimate of tonnes lost to commercial fisheries.

A defensible fisheries-impact estimate requires whales and prey to be mapped in the same place and time, with species-specific diet and energy models. Annual national totals alone cannot provide that answer.

Data needed for a current Icelandic predation model

A modern assessment should combine:

1. Accepted NASS 2024 abundance estimates, with perception and availability corrections and full uncertainty distributions.

2. Seasonal spatial distributions, including coastal bays and fjords that broad offshore transects may not represent well.

3. Contemporary diet data, using stomach contents, DNA metabarcoding, stable isotopes and fatty-acid analysis.

4. Species-specific energetic requirements, including body size, reproductive state and seasonal feeding intensity.

5. Acoustic fish and zooplankton surveys, especially for capelin, herring, sandeel, mackerel, blue whiting and krill.

6. A spatially explicit ecosystem model, estimating overlap by species, grid cell and season.

7. Transparent uncertainty scenarios, rather than one headline point estimate.

This is a natural use case for integrating MFRI/NAMMCO survey data with spatial fisheries and environmental models: abundance indicates how many consumers may be present, while co-location, diet and energy demand determine what they may remove from a particular prey stock.

Conclusion

The evidence supports four robust conclusions:

• Cetacean food consumption around Iceland is measured in millions of tonnes per year.

• Only part of that food is fish: the published estimates are approximately 2.0-3.3 million tonnes of fish, not 6-8 million tonnes.

• The latest complete multi-species abundance picture is still based on NASS 2015, while the 2024 Icelandic fin- and minke-whale estimates remain preliminary.

• Current evidence does not justify converting total whale consumption directly into lost commercial catch.

The scientific priority is therefore not another single national headline number. It is a transparent, spatial and seasonal model linking whales, prey and fisheries with explicit uncertainty.

References

1. Sigurjónsson, J. & Víkingsson, G. A. (1997). "Seasonal Abundance of and Estimated Food Consumption by Cetaceans in Icelandic and Adjacent Waters." Journal of Northwest Atlantic Fishery Science, 22, 271-287. Article and abstract | Full paper (PDF) | DOI

2. Marine and Freshwater Research Institute (2019). "Um afrán hvala við Ísland og áhrif þeirra á afrakstur annarra nytjastofna." MFRI statement

3. Pike, D. G., Gunnlaugsson, T., Mikkelsen, B., Halldórsson, S. D. & Víkingsson, G. A. (2019). "Estimates of the Abundance of Cetaceans in the Central North Atlantic based on the NASS Icelandic and Faroese Shipboard Surveys Conducted in 2015." NAMMCO Scientific Publications, 11. Article and supplementary tables | DOI

4. NAMMCO (2026). "NASS 2024 Updates", document NAMMCO/33/14. Project status report (PDF)

5. Víkingsson, G. A. et al. (2014). "Recent changes in the diet composition of common minke whales (Balaenoptera acutorostrata) in Icelandic waters - A consequence of climate change?" Marine Biology Research, 10(2), 138-152. DOI and abstract

6. Víkingsson, G. A. et al. (2015). "Distribution, abundance, and feeding ecology of baleen whales in Icelandic waters: have recent environmental changes had an effect?" Frontiers in Ecology and Evolution, 3:6. Full article | DOI

7. Marine and Freshwater Research Institute. "Víðtækar hvalatalningar." MFRI survey overview

Editorial note: This report was prepared on 28 July 2026 from the local NASS and MFRI source collection, the peer-reviewed literature and current official NAMMCO/MFRI status information. Numbers are rounded only where clearly indicated. Scientific names can be added to the tables if required by the website's house style.