science
The Amount of Fish in the Sea Has Halved
The amount of fish in the sea areas outside of Norway has halved since peaking in 2013. There are many variables, but the most important thing we can do is adjust how much we fish and when we fish, says researcher Geir Huse at the Institute of Marine Research.
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Earlier this month, the Norwegian Institute of Marine Research presented the Resource Overview 2026.
The report provides an updated status of Norway's most important marine resources and ecosystems. This year's version makes it clear that several fish stocks are struggling and that the biomass of fishery resources in the sea has nearly halved since the peak year of 2013, from 35 million tons to 17 million tons in 2025.
This is the lowest number measured in the time series from 2000 to 2025.
"The largest decline was in the pelagic stocks, but the whitefish is also impacted," says researcher Geir Huse at the Institute of Marine Research to High North News.
He explains that the researchers examined three elements for each stock: recruitment, biomass, and fishing pressure.
Recruitment is poor for several stocks, especially mackerel, cod, and pollock.
"It is important to be aware of how much we fish and when we start fishing," says Huse about what can be done to preserve the important stocks.
This is due to concerns about how large the fish should be allowed to grow before being caught. In Norway, 55 centimeters is the minimum size for coastal cod, while it is 44 centimeters outside 4 nautical miles from the baselines.
Fish stocks in the North
For the commercially important stocks in the North, the decline has been steady over several years.
But Huse says that the trend may be about to turn for the northeast Arctic cod, also known as skrei.
"We expect a slight increase in stock size towards next year," he says.
As with wine, there are good and less good vintages of fish. And these have a significant impact on stock size.
"It varies greatly between years how many cod are born and survive. The class born in 2021, now five years old, is larger than the previous three years. They are now just reaching the minimum size for cod, so they have started making their presence felt in the fisheries," says Huse, adding:
Higher quotas
In recent years, the cod quota in the Barents Sea has been significantly reduced. The cod quota for 2026 is the lowest since 1991.
It appears that the foundation is laid for an increase in stock, and there is talk of higher quotas already from next year. Can the cod handle it?
"If the advice is followed, it will at least be sustainable. It is important to adopt something close to that level," replies Huse.
This year, the quota was slightly higher than the scientists recommended.
"If the advice is followed, there will be further growth in the stock. That is something all parties want," adds the researcher.
Especially vulnerable to warming
The resource overview points out that high latitudes are especially vulnerable to climate change. Small temperature changes can have major ecological impacts on Arctic systems. The ocean is getting warmer and species are moving further north.
"Climate change impacts the stocks in different ways. One is the distribution of stocks. It has become warmer further north, and the coldest water is much further north than before," says Huse and continues:
"This means that the habitat for Arctic species has become much smaller.
"In addition, climate change affects the distribution of important prey, such as zooplankton."
"The amount of plankton has decreased in both the Norwegian Sea and the Norwegian Sea, and that is not good for fish stocks. We see this as a climate effect. Several of the important plankton species, such as Calanus finmarchicus, thrive in colder temperatures," explains Huse, and adds:
"The cod has timed its entire spawning process for the cod larvae to reach the zooplankton when it is available in the right size. This timing can be affected by the climate, in addition to how the entire plankton process takes place."
The researcher says they see climate change in the North Sea, the Norwegian Sea, and the Barents Sea, but that the Barents Sea is among the fastest-warming areas in the world, and an area where climate change has the most significant effects.
"For example, we have to start our cod survey in Hammerfest, Northern Norway, this year. This is the first time we have started so fo far north and it is due to the cod spawning further north and east along the coast," says the researcher.
Extensive surveys
But how can you measure the amount of fish in the sea?
Huse says that the method has been the same since 2000 and that the data are therefore comparable.
Collects data and calculates an index of how much cod there is in the sea.
The institute conducts a winter survey in January-March in collaboration with the marine research institute PINRO in Russia. The survey covers demersal fish stocks in the Barents Sea. Later, the institute conducts a cod survey in March/April, which provides an acoustic measure of the cod spawning stock.
In September, they conduct an ecosystem survey that covers the entire Barents Sea. This also happens in collaboration with PINRO.
"On these surveys, we collect data and calculate an index of how much cod there is in the sea."
"We compare over time how much we catch in the trawl with standardized hauls, and we use the otoliths to determine the age of the fish. The variation in the survey index is assumed to reflect the amount of cod in the sea. If there is a lot of cod, we get much more per-quarter trawl haul than before."
"We also look at the fisheries, that is, how much is caught there. We combine this in a statistical model that estimates how many cod per age and size there are at this point and in the past. We also have another model that looks forward, how the stock will develop given different amounts of fishing," concludes the researcher.
