Seafood on the Move: How Warming Seas Are Rewriting Shallow-Water Fisheries, Deep-Ocean Harvests and Global Trade

The catch is moving before many boats, ports, quotas, processors and consumers are ready.

A fisher may return to a familiar ground and find fewer of the species that historically supported the local fleet. The missing fish may not have vanished from the ocean. They may have moved farther north, deeper into cooler water, closer to another country or beyond the range of the vessel and gear that previously caught them.

Elsewhere, a harbour may suddenly receive large volumes of a warm-water fish that local buyers do not recognise. The species may be edible and abundant, yet sell cheaply because processors lack suitable equipment, wholesalers lack customers and households have no established recipe tradition for it.

The result is more complicated than the statement that warmer seas produce “more fish in cold countries and fewer fish in hot countries.”

Some populations move poleward.

Others move deeper.

Some alter their spawning season without abandoning the region.

Some become more variable rather than consistently more or less abundant.

Some warm-water species expand rapidly into new lagoons or coastal ecosystems and damage established shellfish, seagrass or nursery habitats.

Open-ocean tuna can move across national maritime boundaries. Coastal squid can create an emerging fishery hundreds of kilometres from its former commercial centre. A deep-water species may find a larger thermal habitat but remain too slow-growing to withstand increased fishing pressure.

Human behaviour adds another layer.

Fishers do not automatically follow every movement of fish. They are constrained by fuel, vessel size, safety, permits, port location, quota, knowledge, family commitments, processing contracts and the locations they have learned to trust.

Markets move differently again.

The United States imports large quantities of salmon, shrimp and tuna. China is simultaneously the world’s leading seafood exporter and one of its largest importers. Norway’s trade is dominated by farmed salmon. Peru’s anchoveta can become fishmeal used in Chinese aquaculture rather than fish sold directly for human meals.

The global seafood map is therefore being rewritten through several connected forces:

• Long-term ocean warming.
• Marine heatwaves.
• El Niño and other natural climate variability.
• Ocean acidification and deoxygenation.
• Changes in currents, plankton and prey.
• Fishing pressure and stock management.
• Aquaculture.
• Consumer demand.
• Processing capacity.
• Tariffs and trade policy.
• The physical ability of boats and ports to adapt.

The most important question is not simply where the fish are going.

It is whether the complete food system can move with them without exhausting the new stock, abandoning the old fishing community or turning an ecological change into another unsustainable boom.

The Ocean Entered 2026 With Record Heat Already Stored Beneath the Surface

The oceans do not respond only to the temperature measured at the beach.

More than 91 per cent of the excess heat accumulating in the climate system is stored in the ocean. Ocean heat content down to 2,000 metres reached its highest observed level in 2025, and each of the previous nine years had established a new record. The rate of ocean warming during 2005–2025 was more than twice the rate observed during 1960–2005. Around 90 per cent of the ocean surface experienced at least one marine heatwave during 2025.

That longer-term accumulation entered 2026 alongside further short-term extremes.

NOAA estimated that 33 per cent of the global ocean was experiencing marine-heatwave conditions in June 2026. Active regions included the eastern Pacific, the Sea of Japan and Kuroshio Extension, the Northeast Atlantic, the Norwegian Sea, the Mediterranean and the Tasman Sea. NOAA’s July forecast also indicated a high likelihood of continued heatwave conditions across several major fishing regions through the remainder of the year, although these remain probabilistic forecasts rather than guaranteed outcomes.

Chronic warming and a marine heatwave are not the same thing

Long-term climate warming gradually shifts the average conditions to which fish, plankton, kelp, corals and shellfish are exposed.

A marine heatwave is a period in which a particular body of water becomes unusually warm compared with its normal seasonal range.

The two processes interact.

Long-term warming raises the starting point. A short heatwave can then push a species beyond a biological threshold that it might otherwise tolerate.

El Niño adds another source of variation, particularly across the Pacific. It can rearrange currents, suppress nutrient-rich upwelling and redistribute prey. However, a strong El Niño should not be used as an explanation for every warm-ocean trend. Natural variability can intensify or temporarily weaken the long-term climate signal without replacing it.

This distinction matters for fisheries.

A stock that moves during one heatwave may return.

A stock responding to several decades of changing temperature, oxygen, prey and spawning conditions may not.

“Shallow Water,” “Offshore” and “Deep Sea” Describe Different Fisheries

The phrase deep-sea fishing is often used loosely for any vessel operating beyond sight of land.

That can blur very different ecological systems.

For this article, the fisheries are separated into four practical zones.

This distinction prevents two opposite errors.

The first is assuming that fish moving into deeper water have entered the true deep sea. A cod population shifting from 100 to 150 metres remains part of a shelf fishery.

The second is treating the deep sea as a climate refuge that can safely replace declining coastal catches.

Many deep-sea fish are long-lived, slow-growing and late-maturing. Some can sustain only low exploitation rates and recover very slowly after depletion. FAO describes high-seas deep-sea fisheries as operating roughly between 200 and 1,500 metres and often targeting species with limited capacity to withstand increased harvest.

Moving fishing effort deeper is therefore not automatically adaptation.

It can become a transfer of pressure from one stressed ecosystem to another that is even less capable of recovery.

Why Fish Move When the Water Warms

Fish do not normally read the sea-surface temperature and swim north in a straight line.

Their movement reflects several interacting biological needs.

Temperature affects metabolism

Fish are ectothermic. Their body temperature and metabolic demand are strongly influenced by surrounding water.

Within a suitable range, warmer water may increase feeding and growth.

Beyond that range, oxygen demand can rise faster than the animal’s ability to obtain oxygen. Growth, reproduction and survival can then decline.

Each species—and often each life stage—has a different thermal window.

Eggs, larvae and spawning adults may respond more sharply than mature fish feeding outside the breeding season.

Oxygen can decline as water warms

Warm water holds less dissolved oxygen than cold water.

Stratification can also reduce the mixing that carries oxygen to deeper layers.

A fish may therefore move not because the temperature itself is immediately lethal but because the combined temperature-and-oxygen environment has become less suitable.

Prey moves too

A predator cannot remain productive where its preferred prey has disappeared.

Warming can alter the timing, abundance and location of plankton, forage fish, squid and benthic organisms.

The commercially valuable species may follow those food sources—or suffer when the timing of its migration no longer matches the prey peak.

Currents change transport and spawning success

Currents carry eggs, larvae and nutrients.

A species can encounter suitable adult habitat while its eggs are transported away from nursery grounds or its larvae fail to encounter enough food.

This is why one warm year can produce a strong local catch while weakening the next generation.

Habitats can deteriorate

Kelp forests, seagrass, coral reefs, oyster beds and seaweed farms provide food, refuge and nursery space.

Warming can damage those habitats directly or increase grazing, disease and competition from warm-water species. Japan’s fisheries agency has connected higher temperatures with declining seaweed beds, shorter nori cultivation periods and increased feeding damage from fish expanding into new areas.

Acidification affects shell formation and food webs

The ocean has absorbed a substantial share of human carbon-dioxide emissions, lowering average surface pH.

Shellfish, corals and some plankton can be sensitive to changes in carbonate chemistry. The effect then moves through the food web, even when the commercial fish itself does not build a shell. WMO identifies ocean acidification as a growing risk to marine biodiversity, shellfish aquaculture and fisheries.

Shallow Waters Can Change Quickly

Nearshore waters often respond rapidly to atmospheric heat, river flow and seasonal weather.

They are also among the most economically crowded marine environments.

Coastal fishers, aquaculture farms, ports, tourism, shipping, wetlands and residential development all compete within the same relatively narrow space.

Warm-water species can establish new coastal populations

A new species may initially appear to be a commercial opportunity.

If it is highly invasive, the ecological and economic costs can exceed its sale value.

Italy’s recent blue-crab expansion demonstrates the problem.

In the Sacca di Goro lagoon, catches increased from approximately 90 tonnes in 2022 to 936 tonnes in 2023 and 993 tonnes during only the first half of 2024. Yet around 60 per cent of the catch was not marketed and was instead removed and destroyed. The volume needed for ecological containment exceeded the size and quantity that buyers could absorb profitably.

This produces a central lesson:

Catching more of a species does not mean the fishing community has developed a viable market for it.

Processors need consistent sizes.

Retailers need customers.

Restaurants need recipes.

Fishers need a price that covers fuel and labour.

An invasive catch can be simultaneously abundant, edible and commercially inadequate.

Shellfish are unable to swim away

Mobile fish can move towards more favourable conditions.

Mussels, oysters and farmed shellfish cannot relocate themselves.

They may experience heat stress, disease, reduced growth, harmful algal toxins or low oxygen where they are attached or cultivated.

Shellfish also filter large quantities of water and can accumulate natural marine toxins. These toxins are not reliably removed by ordinary cooking, which is why harvest-area closures must be respected.

Small pelagic fish may arrive in new northern waters

Anchovy and sardine respond strongly to temperature, plankton and currents.

The proposed fisheries-management plan for the Celtic Sea and western English Channel describes anchovy as a relatively new and highly variable fishery in the area. Warming may expand its range farther north and create greater interest from UK and EU vessels.

However, the evidence also shows why an emerging fishery should not be treated as guaranteed.

Anchovy biomass fell sharply in the 2024 survey after a strong 2023 observation. Prices between 2016 and 2023 were highly variable, and fishers described the catch as opportunistic rather than dependable.

The UK could catch more anchovy in some future years.

That does not yet make anchovy a stable replacement for every declining cool-water stock.

Continental-Shelf Fish Are Often Moving Deeper

Poleward movement receives the most attention because it changes the country or port associated with a fish.

Depth may be equally important.

A major 2026 study analysed 92,961 scientific bottom-trawl samples covering 607 fish species across the European continental shelf over four decades. Sixty per cent of the populations increased their average depth. Among populations with statistically significant depth changes, approximately 76 per cent moved deeper, at an average rate of about 24 metres per decade.

The same study found nearly balanced poleward and equatorward latitudinal movement.

That result challenges the simple expectation that every European fish moves north.

Fish can respond by:

• Moving deeper.
• Changing range width.
• Arriving earlier.
• Altering spawning grounds.
• Remaining in the same latitude but changing abundance.
• Following local currents rather than the compass.

Bottom heatwaves can be hidden from the surface

A calm or ordinary sea surface does not prove that conditions near the seabed are normal.

Research along North American continental shelves found that bottom marine heatwaves can last longer and become more intense than heatwaves measured at the surface. They can also occur without a strong surface expression.

This matters for:

• Groundfish.
• Scallops.
• Lobster.
• Bottom-associated shrimp.
• Benthic habitats.
• Survey interpretation.

A fishing fleet can encounter an abrupt change in catch composition without beachgoers experiencing an obvious heatwave.

Going deeper changes the economics of fishing

A deeper or more distant ground can require:

• More fuel.
• Longer trips.
• Different cable or net specifications.
• More powerful hauling equipment.
• Additional ice or refrigeration.
• Different safety planning.
• A larger vessel.
• A different licence.
• A port capable of handling the catch.

Japan’s fisheries agency reports that shifting grounds are already increasing fuel costs and disrupting highly specialised fleets. Some operations are adopting new fishing methods or targeting more accessible species, while others are combining capture fishing with aquaculture to reduce income volatility.

Fishers Do Not Automatically Follow the Fish

A biological range shift is not the same as a fishing-fleet shift.

A study of Norway’s Northeast Arctic cod fishery compared changing spawning suitability with 14.6 million landing observations from 2001 to 2021.

More suitable habitat predicted higher catch per trip. It did not reliably predict how many vessels would fish in that location once persistent characteristics of the area were considered.

The strongest predictors of present vessel activity were often where vessels had operated the previous week or the previous year. Fishers displayed considerable site fidelity even within a technologically capable industrial fishery.

This behaviour is not necessarily irrational.

A familiar fishing ground contains accumulated knowledge about:

• Weather exposure.
• Currents.
• Safe approaches.
• Seabed conditions.
• Gear loss.
• Port distance.
• Buyer expectations.
• Other vessels.
• Where the fisher has legal access.

A theoretically productive new ground may be farther from fuel, repair facilities and family life.

This creates an adaptation lag.

The fish can move before the fleet.

The fleet can move before the processor.

The processor can move before the consumer.

Each delay affects whether a new catch becomes a successful food industry or a short-lived ecological surprise.

Country and Regional Case Studies

The United States: California Lost Squid While Oregon Built a Fishery

Market squid had long been one of California’s largest commercial fisheries by volume.

During the Northeast Pacific marine heatwave known as the Blob, followed by the strong 2015–2016 El Niño, the species shifted north.

California landings dropped by more than half from 2014 to 2015.

Oregon went in the opposite direction.

Its squid landings rose from effectively none in 2015 to nearly three million pounds worth more than US$1 million in 2016, and they continued growing through 2020. Processors expanded capacity, vessels found a new target as other fisheries weakened and Oregon managers introduced the state’s first squid regulations.

This was not merely an ecological movement.

It required an entire commercial response:

• Boats capable of catching squid.
• Night-lighting and purse-seine knowledge.
• Ports able to receive the catch.
• Buyers and freezing capacity.
• State regulation.
• New relationships between fishers and processors.

Oregon’s gain did not cancel California’s loss.

The two states experienced opposite sides of the same redistribution.

The example also shows why national statistics can hide local disruption. The United States may still harvest market squid while the historical centre of that harvest changes substantially.

Japan: Yellowtail Moves North While Familiar Fisheries Decline

Japan provides one of the clearest examples of fishing culture and marine distribution becoming misaligned.

The country’s coastal waters have experienced major changes in temperature and currents. Catches of Pacific saury, Japanese flying squid and salmon have fallen markedly. Fishing grounds have moved farther offshore, increasing fuel costs and undermining specialised operations.

At the same time, warmer-water fish have expanded north.

Yellowtail catches in Hokkaido began rising around 2011. Yet the local price remained significantly below the national average because Hokkaido consumers did not have the same established habit of eating yellowtail as communities farther south.

The response included:

• Yellowtail cutlets.
• Canned products.
• School-led product development.
• New branding.
• Promotion to local consumers.

Japanese Spanish mackerel has produced a similar issue. More fish can arrive in a region whose consumers and wholesalers do not yet value it. Quality standards, on-board handling and regional branding are being used to prevent the new catch from entering the market as a low-value substitute.

Some squid vessels have shifted from declining Japanese flying squid towards neon flying squid in the central Pacific. That catch is now used increasingly in processed food and raw applications such as sushi, but the more distant fishing ground introduces additional fuel and efficiency pressures.

Japan demonstrates that climate adaptation can require a culinary transition as well as a fishing transition.

The public may need to learn how to buy and cook a species that previous generations rarely encountered locally.

The United Kingdom: Anchovy May Become More Available, but Not Predictable

Warming waters could increase the future presence of anchovy across parts of the English Channel and Celtic Sea.

This creates an apparent opportunity for UK fishers, particularly because Britain imports more anchovy than it exports.

Between 2021 and 2023, just over half of UK anchovy supply was destined for the domestic market, and the country imported substantially more by value than it exported. Local fishers and buyers have expressed interest in developing a higher-value market for locally sourced anchovy.

The biological and commercial evidence remains uncertain.

Anchovy:

• Is not currently covered by a complete local stock assessment.
• Shows sharp annual fluctuation.
• Has been caught largely opportunistically.
• Can vary substantially in price.
• May mix between northern and Bay of Biscay populations.
• Requires monitoring before fishing pressure expands.

A warming-driven range expansion could therefore create a new domestic ingredient.

It should not create a race to establish catch volume before the stock, spawning system and market are understood.

Italy: The Blue-Crab Catch Exceeds the Market

The rapid blue-crab increase in northern Italian lagoons is frequently presented as an invitation to “eat the invader.”

Developing a food market can support removal.

It cannot necessarily control the population by itself.

The catch volume rose so quickly that a majority could not be sold. Small individuals and inconsistent supply specifications created limited commercial value, while the ecological need for removal exceeded consumer demand.

This creates several difficult questions:

• Should public funding support removal where the catch has no market?
• Can processors develop frozen meat, stock or prepared products?
• Would building a premium market encourage dependence on a species managers hope to suppress?
• Can fishers receive a viable price without reducing ecological removal?
• How should traceability and handling be controlled across a rapidly expanding fishery?

An invasive species can become a useful food.

It should not automatically be branded as a climate-friendly solution.

Commercial success, ecological control and culinary value are three separate objectives.

Peru and China: Anchoveta Connects Ocean Conditions With Aquaculture

Peruvian anchoveta is one of the world’s most important inputs for fishmeal and fish oil.

Much of the catch does not appear directly on a household plate. It enters feed used in aquaculture.

During 2023, poor anchoveta catches associated with El Niño contributed to a 23 per cent decline in global fishmeal production and a 21 per cent fall in fish-oil output.

Conditions improved during 2024. Peruvian fishmeal exports recovered, while China imported approximately 771,000 tonnes from Peru during the first nine months of 2024, close to 90 per cent of Peru’s fishmeal exports for that period. China normally accounts for around 80 per cent of Peruvian fishmeal trade and about 40 per cent of global fishmeal imports.

This chain links several distant foods:

1. Ocean conditions affect anchoveta recruitment and catch.
2. Peru sets a quota and harvests the fish.
3. Anchoveta is processed into meal and oil.
4. China imports the ingredients.
5. Fishmeal enters shrimp, fish and other aquaculture feed.
6. Farmed seafood is sold domestically or exported.

A climate shock off Peru can therefore affect farmed-seafood costs in Asia.

It can eventually influence the price of shrimp, salmon or other farmed products in markets far from the original fishery.

Pacific Tuna: Fish Can Move Out of a Country Without Leaving the Ocean

Tuna are highly mobile open-ocean fish.

Their distribution follows temperature, oxygen, currents, productivity and prey rather than political boundaries.

A major modelling study projected that under a high-emissions scenario, tuna biomass in the combined waters of ten tuna-dependent Pacific small island states could decline by an average of approximately 13 per cent by 2050 as more fish occur farther east and in the high seas.

The associated purse-seine catch within those national waters could fall by an average of around 20 per cent without management measures preserving historical fishing rights.

This is not only a seafood-supply issue.

Pacific Island states earn substantial revenue by licensing foreign vessels to fish within their exclusive economic zones.

When tuna move into the high seas:

• The fish may remain available to industrial fleets.
• The coastal state may lose access-fee income.
• Processing plants may receive less local catch.
• Employment and government revenue can decline.
• Quota negotiations become more contentious.

The Pacific Islands Forum Fisheries Agency continued to emphasise regional cooperation in 2026 as warming alters tuna distribution.

This case demonstrates why a country can lose economic control of a fishery even when the total stock has not disappeared.

Aquaculture Does Not Escape Ocean Heat

Farmed seafood is frequently presented as protection from unstable wild fisheries.

Aquaculture reduces dependence on catching wild adult fish, but it remains exposed to water temperature, disease, oxygen, harmful algal blooms and feed costs.

In August 2024, northern Norway experienced an intense marine heatwave in which surface temperatures exceeded 18°C and were more than 4°C above the long-term average. Researchers linked the event with an unprecedented salmon-lice outbreak, increased mortality and economic loss at aquaculture sites.

Aquaculture adaptation may include:

• Moving sites.
• Deeper cages.
• Improved oxygen monitoring.
• Selective breeding.
• Different stocking dates.
• Stronger disease surveillance.
• Land-based stages.
• Diversifying species.
• Reducing dependence on marine feed ingredients.

None of these measures makes farmed seafood independent of climate.

The relevant comparison is not “wild is vulnerable, farmed is safe.”

Both are biological production systems exposed through different pathways.

Who Is Buying and Selling the Most Seafood Now?

The latest globally comparable trade data available in SOFIA 2026 describe trade during 2024.

These rankings reflect aquaculture, consumer income, processing, re-export activity, tariffs, geography and established commercial relationships as well as environmental change.

They should not be interpreted as a direct ranking of countries benefiting from ocean warming.

Leading exporters by value, 2024

Leading national importers by value, 2024

The European Union as a combined market imported aquatic animal products valued at approximately US$63.2 billion, including substantial trade between member states.

What species generate the most trade value?

Approximately 36 per cent of global aquatic-animal production was traded in 2024, generating an estimated US$186 billion. Aquaculture supplied 59 per cent of aquatic animal foods destined for human consumption.

China is now both exporter and net importer

China remains the leading exporter by value, yet it has also been a net importer of aquatic foods since 2022.

This is not contradictory.

China:

• Produces large volumes.
• Imports high-value seafood for domestic consumption.
• Imports products for processing.
• Imports feed materials.
• Re-exports processed seafood.
• Supports the world’s largest aquaculture sector.

A fish may therefore enter China frozen, be cut or processed, and leave for another market.

National trade rankings do not directly reveal where the original animal was caught, farmed or ultimately eaten.

Which Species Are Being Harvested More in New Places?

The strongest current evidence points towards several recurring patterns rather than one global replacement list.

Increasing or emerging in new northern areas

• Market squid in Oregon and Washington.
• Yellowtail in Hokkaido.
• Japanese Spanish mackerel in northern Japanese waters.
• Anchovy in parts of the English Channel and Celtic Sea.
• Warm-water crabs, including invasive blue crab in northern Mediterranean lagoons.
• Some tropical and subtropical pelagic fish appearing farther north during heat events.

Declining or becoming less dependable in traditional areas

• Japanese flying squid.
• Pacific saury.
• Salmon returning to parts of Japan.
• California market squid during major warm events.
• Some cold-water groundfish and shellfish populations.
• Reef and coastal fish in low-latitude habitats under prolonged warming.

Increasing because aquaculture and demand are expanding

• Salmon.
• Shrimp and prawns.
• Pangasius.
• Tilapia.
• Farmed marine fish.
• Species used for fishmeal and fish oil.

This final group cannot be explained primarily through wild species migration.

It reflects controlled production, feed availability, investment and international demand.

A New Catch Can Have the Wrong Price

Climate-driven redistribution can create an economic mismatch.

A species may be plentiful but poorly valued because:

• The local market does not recognise it.
• Existing machinery is designed for another fish.
• The flesh has a different fat or bone structure.
• Boats land inconsistent sizes.
• There is no established wholesale category.
• Restaurants do not have familiar dishes for it.
• Regulations were written for another species.
• Cold-storage or freezing capacity is insufficient.

Japan’s yellowtail and Spanish-mackerel initiatives show that branding, quality grading and recipe development can raise the value of a newly abundant species.

Italy’s blue-crab experience shows the opposite: catch volume can expand faster than the market’s ability to use it.

The adaptation task therefore extends beyond fishing.

Chefs, food manufacturers, wholesalers and educators may need to explain:

• What the fish tastes like.
• Whether it is oily or lean.
• Whether it contains fine bones.
• Whether it holds together in curry or stew.
• Whether it suits grilling, frying, smoking or canning.
• How it should be stored.
• Which familiar fish it can replace.
• Whether the supply is likely to remain stable.

Culinary knowledge becomes part of fisheries resilience.

There Will Be Winners, Losers and False Winners

A country receiving more of a warm-water species may appear to benefit.

The benefit can be temporary or incomplete.

Possible winners

• Northern ports receiving a commercially valuable new species.
• Flexible vessels able to switch target and gear.
• Processors with multi-species equipment.
• Aquaculture farms capable of changing production.
• Consumers gaining a wider seafood range.
• Regions with strong monitoring and adaptive quota systems.

Possible losers

• Small vessels unable to travel farther.
• Ports designed around one dominant species.
• Coastal communities losing culturally important fish.
• Low-latitude countries with high seafood dependency.
• States losing migrating tuna from their exclusive economic zones.
• Processors unable to handle the new catch.
• Workers whose skills are tied to one fishery.
• Ecosystems invaded by aggressive warm-water species.

False winners

A port may record a dramatic catch increase that is not sustainable.

The increase may represent:

• A short marine heatwave.
• A stock concentrated into a smaller area.
• An invasive population.
• A fishery exploiting a stock before assessment.
• A deep-sea species vulnerable to rapid depletion.
• A low-value catch that does not cover harvesting costs.

A larger landing number is therefore not enough.

Managers must ask whether the population is productive, whether the market is viable and whether the ecosystem can tolerate the new pressure.

Fisheries Management Was Built Around More Stable Maps

Many quota and access arrangements assume that a stock’s geography changes within a familiar range.

Climate change weakens that assumption.

A fish may move:

• Between coastal districts.
• Between national waters.
• Between an exclusive economic zone and the high seas.
• Into an area with no established quota.
• Into the range of a new fleet.
• Away from a port whose economy depends on it.

Research published in 2025 estimated that a substantial share of straddling fish stocks could shift their presence between exclusive economic zones and high-seas areas under future warming.

The management response may require:

Faster monitoring

Annual surveys may be too slow for short-lived anchovy, squid or rapidly changing heatwave conditions.

Electronic monitoring, acoustic surveys, satellite data and fisher observations can help identify movement sooner.

Adaptive quotas

A quota that moves automatically with one country’s landings can reward whoever catches the stock first.

A more stable agreement may need to consider biomass, historic dependence, conservation and climate-driven redistribution together.

Flexible licences

Fishers may need permission to target a new species or use different gear.

Flexibility must remain controlled so that adaptation does not create unassessed bycatch or overfishing.

Port and processor investment

A changing catch may require different:

• Grading.
• Filleting.
• Freezing.
• Storage.
• Packaging.
• Waste handling.
• Marketing.

Transboundary agreements

Fish do not stop at maritime borders.

Data-sharing and agreed allocation become more important as stocks move between countries.

Protection for true deep-sea ecosystems

Declining shelf catches should not justify uncontrolled expansion into deep water.

Slow-growing fish and vulnerable coral or sponge habitats require precautionary limits, impact assessment and effective monitoring.

Professional Statement

RecipeWanted approaches changing fisheries as a combined environmental, economic, cultural and culinary subject.

This article distinguishes between:

• A long-term climate trend.
• A short marine heatwave.
• El Niño or another natural climate cycle.
• An observed catch change.
• A modelled future range shift.
• A trade change.
• A change caused primarily by aquaculture or demand.

Those categories must not be collapsed into one claim.

A country importing more shrimp does not prove that warming caused its demand.

A northern fish appearance does not prove that a permanent commercial stock has formed.

A strong catch can reflect abundance, temporary concentration or increased fishing effort.

A species that expands under warmer conditions is not automatically sustainable to harvest.

Seafood sustainability also depends on stock management, bycatch, habitat impact, traceability, labour conditions and food loss—not temperature alone.

RecipeWanted’s wider editorial and food-safety position is available at:

Seafood Education: How to Buy, Store and Cook a Changing Catch Responsibly

Consumers and professional kitchens can support adaptation, but purchasing an unfamiliar species requires more than choosing whatever is newly available.

1. Ask for the exact species

Common market names can cover several biologically different fish.

Ask for:

• Common name.
• Scientific name where available.
• Wild or farmed status.
• Catch or farming area.
• Fishing gear or production method.
• Fresh or previously frozen status.

“Sea bass,” “snapper” and “tuna” are broad labels.

The exact species can change sustainability, allergen, mercury and cooking considerations.

2. Do not treat “local” as automatic proof of sustainability

Local seafood may reduce transport and support nearby fishing communities.

It can still come from:

• An overfished stock.
• A damaging gear type.
• An unassessed emerging fishery.
• An invasive population requiring special management.
• A farm with poor environmental controls.

Local origin is useful information.

It is not the complete assessment.

3. Distinguish an emerging fishery from a stable one

A newly abundant species may fluctuate sharply from year to year.

Avoid designing a large permanent menu around it until supply consistency is understood.

Use flexible specials, frozen formats or seasonal menus where appropriate.

4. Substitute by texture and fat content

When a familiar fish becomes scarce or expensive, identify its culinary function.

A warm-water species may not behave like the cold-water fish it replaces.

5. Learn the new species before disguising it

Cook a small portion simply first.

Assess:

• Firmness.
• Fat.
• Bone pattern.
• Skin.
• Moisture loss.
• Flavour strength.
• Response to heat.

This provides more information than immediately covering it in a heavy sauce.

6. Match the heat method to the fish

Lean fish dries rapidly.

Oily fish can tolerate stronger grilling.

Squid is usually most tender when cooked very quickly or long enough for connective tissue to soften; the middle range can become rubbery.

Crab and shellfish require enough heat for safety without prolonged cooking that toughens the flesh.

7. Respect shellfish-harvest closures

Do not collect shellfish from an area merely because the water looks clean.

Naturally occurring marine toxins may be present without visible pollution. Cooking does not reliably neutralise every toxin.

Use approved suppliers and follow local closure notices.

8. Protect the cold chain

Fresh seafood should smell mild rather than strongly sour, rancid or ammonia-like.

Frozen seafood should remain hard and should not have damaged packaging or excessive ice suggesting repeated thawing.

Keep seafood cold during transport and refrigerate or freeze it promptly.

9. Separate raw seafood from ready-to-eat food

Use separate boards, knives, containers and utensils where practical.

Wash hands and surfaces after handling raw fish or shellfish.

Do not return cooked seafood to a plate that previously held it raw.

10. Cook seafood safely

US federal guidance recommends cooking finfish to 63°C / 145°F, or until the flesh is opaque and separates easily. Shrimp, lobster, crab and scallops should become firm and opaque. Shells of clams, mussels and oysters should open during cooking; unopened specimens should be discarded.

Local national guidance should take priority where it differs.

11. Treat raw and lightly cured seafood separately

Lemon, lime, vinegar and salt change texture.

They do not guarantee that parasites or harmful bacteria have been destroyed.

Raw or lightly cooked fish may require validated freezing and specialist handling. Pregnant people and other medically vulnerable diners should use particular caution with raw seafood.

12. Check mercury advice for large predatory fish

A shift towards new tuna, billfish, shark or other large predators can alter mercury exposure.

People who are pregnant or breastfeeding and young children should follow current national fish-consumption guidance and choose a variety of lower-mercury seafood.

13. Declare fish and shellfish allergens separately

Fish and crustacean shellfish are distinct major allergens.

A diner who can eat finfish may not be able to eat shrimp or crab.

Shared frying oil, stock, sauces and utensils can create cross-contact.

14. Use more of the catch where safe and appropriate

Frames and heads from suitable fish can produce stock.

Trim can be used in:

• Fish cakes.
• Dumplings.
• Soups.
• Pâté.
• Sauces.
• Croquettes.

This improves value from each harvested animal without increasing catch.

Food safety, species suitability and contaminant controls still apply.

15. Do not turn invasive-species consumption into a universal cure

Eating invasive blue crab, lionfish or another expanding species can support targeted removal.

It does not replace ecosystem management.

Demand must not create an incentive to maintain, transport or spread the species.

16. Freeze surplus before quality deteriorates

Freezing does not improve old fish.

Freeze seafood while it remains fresh, wrap it to limit air exposure and label it with the species and date.

RecipeWanted’s related guide is available at:

17. Use RecipeWanted’s seafood and regional routes

Seafood Preparation Visual Guides:

Storage and Food Safety:

Mediterranean Recipes:

Asian Recipes:

Scandinavian Recipes:

Tanzanian Mchuzi wa Samaki:

The Mediterranean, Asian, Scandinavian and Tanzanian recipe routes are live within RecipeWanted’s current archive.

Conclusion

The world is not simply running out of fish in one place and receiving more in another.

The marine food system is being rearranged.

Shallow waters can warm quickly, altering seaweed beds, shellfish farms, nursery areas and invasive-species pressure.

Continental-shelf fish may move deeper rather than north.

Open-ocean tuna can move between national waters and the high seas.

True deep-sea ecosystems are changing too, but their slow-growing species and fragile habitats make them dangerous candidates for uncontrolled replacement fishing.

The fishing fleet does not move as quickly as the fish.

A vessel is connected to a licence, gear, port, buyer, crew and body of local knowledge.

The market moves at another speed.

A new species can arrive before anyone has developed the processing line, wholesale grade or recipe tradition needed to give it value.

Trade can temporarily bridge the difference.

The United States buys salmon, shrimp and tuna from around the world.

China imports seafood and aquaculture inputs while remaining the leading exporter.

Peruvian anchoveta supports Asian fish farming.

Norwegian salmon reaches distant consumers while Norwegian farms themselves face warming-related biological pressure.

The strongest relationships are therefore:

• Temperature and metabolism.
• Oxygen and depth.
• Prey and migration.
• Fish and vessel.
• Vessel and port.
• Port and processor.
• Processor and consumer.
• Stock and national boundary.
• Wild capture and aquaculture.
• Climate signal and trade response.
• New opportunity and ecological restraint.

The future seafood table will not necessarily contain less variety.

It may contain different fish, from different waters, supplied through different countries.

Whether that transition becomes resilient or destructive will depend on how quickly science, management, infrastructure and culinary culture learn to move together.

Key Takeaways

• Ocean heat content reached another record in 2025, and 33 per cent of the global ocean experienced marine-heatwave conditions in June 2026.
• Fish do not only move poleward. A 2026 European study found deepening to be the dominant movement among many continental-shelf populations.
• Shallow-water systems can change quickly. Lagoons, seaweed beds, shellfish areas and nursery habitats are highly exposed to warming and marine heatwaves.
• True deep-sea fisheries are not a safe replacement by default. Many target species grow slowly and recover poorly from depletion.
• Fishers often respond more slowly than fish. Fuel, knowledge, permits, vessel size and port location can reinforce established fishing habits.
• Oregon gained a major market-squid opportunity after squid shifted north, while California’s landings fell sharply.
• Japan is catching more yellowtail and Spanish mackerel in northern areas, but local consumer habits and prices have taken time to adjust.
• UK anchovy could become more available, yet the stock remains variable and insufficiently assessed for automatic expansion.
• Italy’s blue-crab catch rose far faster than its market, proving that harvest volume and commercial value are not equivalent.
• China is both the largest seafood exporter and the second-largest importer. Its trade position reflects aquaculture, domestic demand, processing and re-export activity.
• Aquaculture remains climate-exposed. Heat, disease, oxygen, feed supply and harmful blooms can all affect farmed seafood.
• Culinary adaptation is part of fisheries adaptation. New species need suitable handling, processing, pricing and recipes before they can support a stable local market.

Frequently Asked Questions

1. Are fish really moving north because the seas are warming?

Many species are shifting towards cooler latitudes, but northward movement is not universal.

In the Northern Hemisphere, poleward movement often means north. In the Southern Hemisphere, it generally means south. Some species move deeper instead. Others alter their season, abundance or range width.

A 2026 analysis of European shelf fish found nearly equal numbers moving poleward and equatorward, while deeper movement was much more consistent. Ocean currents, prey, oxygen, spawning habitat and fishing pressure can all modify the temperature response.

2. Does deeper water protect fish from climate change?

Not necessarily.

Deeper water may remain cooler during some surface heat events, allowing mobile species to find temporary thermal refuge. Bottom marine heatwaves can nevertheless occur independently, persist longer and become more intense than surface events.

Long-term ocean heat also penetrates below the surface. Oxygen and food supply can change with depth, while moving deeper may place fish in less suitable spawning habitat or expose them to another fishery.

3. Which countries are harvesting more fish because of warming?

The clearest current examples are regional rather than whole-country totals.

Oregon developed substantial market-squid landings after squid shifted north from California. Hokkaido is receiving more yellowtail, and other northern Japanese regions are seeing more Japanese Spanish mackerel. Parts of the UK may see more anchovy, while northern Italian lagoons have experienced a major blue-crab increase.

These changes should not be interpreted as guaranteed long-term gains. Each species remains affected by natural variability, fishing pressure and stock management.

4. Which countries currently export the most seafood?

According to 2024 trade data published by FAO in 2026, the leading exporters by value were China, Norway, Viet Nam, Ecuador and Chile.

Their strengths are not based mainly on climate-driven wild-fish movement. Aquaculture is central: Norwegian salmon, Vietnamese shrimp and pangasius, Ecuadorian shrimp and Chilean salmon contribute heavily to the rankings. China combines large domestic production, processing and re-export systems.

5. Which countries currently import the most seafood?

The five largest national importers by value in 2024 were the United States, China, Japan, Spain and Italy.

The United States imported large values of salmonids, shrimp, prawns and tuna. China imported particularly large quantities of shrimp, crab and lobster while also supporting a major processing industry.

The European Union, treated as a combined market, remained larger than any individual country.

6. Could Britain replace imported anchovy with locally caught anchovy?

Local supply may become more significant, but it is not yet dependable enough to promise a full replacement.

Anchovy is appearing more widely in the Celtic Sea and western English Channel, and buyers have expressed interest in a locally sourced product. However, annual biomass and landings remain volatile, no complete local stock assessment is available and current fishing is largely opportunistic.

A careful market could develop alongside improved monitoring. Large rapid expansion would be premature.

7. Will eating invasive seafood solve ecological problems?

It can help, but rarely solves the problem by itself.

Commercial demand can support the removal of blue crab, lionfish and other invasive species. Yet the catch may include sizes that processors cannot use, and demand may never reach the volume needed for ecological containment.

A profitable market can also create pressure to maintain supply. Consumption should therefore operate within a wider removal, monitoring and habitat-recovery strategy.

8. Is farmed seafood safer from climate change than wild seafood?

Farmed seafood avoids some uncertainties of locating and catching wild adults, but farms remain exposed to water temperature, oxygen, disease, parasites, harmful algal blooms and storm damage.

They also depend on feed, seed stock, energy and transport.

The 2024 northern Norway marine heatwave contributed to an unprecedented salmon-lice outbreak and economic losses, illustrating that aquaculture cannot be separated from ocean conditions.

9. Why do some newly abundant fish sell cheaply?

Local buyers may not recognise the species, processors may lack suitable machinery and households may have no established recipes for it.

Size, fat content, bone pattern and shelf life can also differ from the fish the industry normally handles.

Hokkaido’s growing yellowtail catch initially remained below the national average price partly because local consumers had no strong tradition of eating it. Branding, new products and culinary education were needed to develop demand.

10. What should consumers do as familiar fish become less available?

Choose by culinary function rather than insisting on one exact species.

Ask the seller for the species, origin, production method and current sustainability information. Learn whether the fish is lean, oily, delicate or firm before choosing a recipe.

Use approved suppliers, maintain the cold chain, follow shellfish closures and cook seafood safely. Diversifying demand can help fishing communities adapt, but buying a new species should never be treated as proof that its fishery is automatically sustainable.

References and Further Reading

Current Ocean Conditions

1. World Meteorological Organization — State of the Global Climate 2025
   https://wmo.int/news/media-centre/earths-climate-swings-increasingly-out-of-balance
2. NOAA — Global Marine Heatwave Monitoring and July 2026 Forecast
   https://psl.noaa.gov/marine-heatwaves/
3. Copernicus — Global Climate Highlights for the First Half of 2026
   https://climate.copernicus.eu/

Fish Distribution and Depth

4. Nature Communications — Marine Fish Ranges Are Expanding and Shifting Deeper Across the European Continental Shelf
   https://doi.org/10.1038/s41467-026-74371-8
5. NOAA — Heat Waves Happen at the Bottom of the Ocean Too
   https://research.noaa.gov/heat-waves-happen-at-the-bottom-of-the-ocean-too/
6. Nature Communications — Bottom Marine Heatwaves Along Continental Shelves
   https://www.nature.com/articles/s41467-023-36567-0
7. npj Ocean Sustainability — Do Fishers Follow Fish Displaced by Climate Warming?
   https://www.nature.com/articles/s44183-024-00063-9
8. FAO — Cross-Sectoral Impacts on Deep-Sea Fisheries
   https://openknowledge.fao.org/handle/20.500.14283/cd3781en
9. FAO — Transformation of Deep-Sea Fisheries Management in the High Seas
   https://www.fao.org/in-action/commonoceans/newsroom/news-and-stories/news-detail/New-FAO-report-shows-profound-transformation-of-deep-sea-fisheries-management-in-the-high-seas-/en

Country and Regional Case Studies

10. NOAA Fisheries — West Coast Marine Heatwave and Market Squid
    https://www.fisheries.noaa.gov/feature-story/7-ways-el-nino-and-large-marine-heatwave-could-affect-west-coast-marine-species
11. Japan Fisheries Agency — Impact of Changes in the Marine Environment on Fisheries
    https://www.maff.go.jp/e/data/publish/White_Paper_on_Fisheries/White_Paper_on_Fisheries_Summary_FY2024_Trends_in_Fisheries_FY2025_Fisheries_Policy.pdf
12. DEFRA — Proposed Celtic Sea and Western Channel Pelagic Fisheries Management Plan
    https://consult.defra.gov.uk/fisheries-management-plans-1/copy-of-consultation-on-the-proposed-celtic-sea-we/supporting_documents/proposed-celtic-sea-and-western-channel-pelagic-fmppdf-1
13. Italian Ministry of Agriculture — Blue Crab Economic and Environmental Response
    https://www.masaf.gov.it/
14. Nature Sustainability — Pathways to Sustaining Tuna-Dependent Pacific Island Economies
    https://www.nature.com/articles/s41893-021-00745-z
15. Pacific Islands Forum Fisheries Agency — Pacific Power and Tuna Cooperation
    https://www.ffa.int/2026/06/pacific-power-how-regional-cooperation-transformed-the-worlds-largest-tuna-fishery/
16. Communications Earth & Environment — Northern Norway Marine Heatwave and Salmon Lice
    https://www.nature.com/articles/s43247-025-02618-1

Seafood Production and Trade

17. FAO SOFIA 2026 — Global Aquatic Food Trade
    https://www.fao.org/in-action/globefish/news-events/news/news-detail/global-aquatic-food-trade—the-latest-findings-from-sofia-2026/en
18. FAO GLOBEFISH — Fishmeal and Fish Oil
    https://www.fao.org/in-action/globefish/species-analysis/fishmeal-and-fish-oil/en
19. FAO GLOBEFISH — China Dominates Fishmeal Imports
    https://www.fao.org/in-action/globefish/news-events/news/news-detail/2024-fishmeal-exports-bounce-back–china-dominates-imports–fish-oil-trade-declines/en

Seafood Safety

20. FDA — Selecting and Serving Fresh and Frozen Seafood Safely
    https://www.fda.gov/food/buy-store-serve-safe-food/selecting-and-serving-fresh-and-frozen-seafood-safely
21. FoodSafety.gov — Safe Minimum Internal Temperatures
    https://www.foodsafety.gov/food-safety-charts/safe-minimum-internal-temperatures
22. FDA — Advice About Eating Fish
    https://www.fda.gov/food/consumers/advice-about-eating-fish
23. UK Food Standards Agency — Freezing Fish for Raw or Lightly Cooked Service
    https://www.food.gov.uk/business-guidance/freezing-fish-fishery-products-and-treatment-for-parasites

RecipeWanted Internal Routes

24. Cultural & Regional Cuisines
    https://recipewanted.com/category/cultural-regional-cuisines/
25. Seafood Preparation Visual Guides
    https://recipewanted.com/visual-guides/category/seafood-prep/
26. Storage and Food Safety
    https://recipewanted.com/education/storage-food-safety/
27. Freezing Cooked Fish
    https://recipewanted.com/education/storage-food-safety/freezing-cooked-meals/freezing-cooked-fish/
28. Mediterranean Recipes
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29. Asian Recipes
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30. Scandinavian Recipes
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31. Tanzanian Mchuzi wa Samaki
    https://recipewanted.com/recipe/tanzanian-mchuzi-wa-samaki/
32. Cooking Education
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33. Quality and Safety Standard
    https://recipewanted.com/quality-and-safety-standard/
34. Recipe Search
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