The shipping industry has spent years debating how to cut emissions without overhauling entire fleets or waiting for next-generation fuels that remain decades from commercial viability. A white paper released March 2, 2026, by the Institute of Marine Engineering, Science and Technology (IMarEST) in collaboration with Montreal-based AI company Whale Seeker and True North Marine suggests the answer may already be hiding inside every vessel’s bridge controls: the throttle.

The paper, titled Navigating with Nature: How Smarter Ship Routing Delivers Emissions Cuts and Biodiversity Gains, models a transatlantic route from Montréal, Canada, to Le Havre, France, and integrates ecological sensitivity layers, habitat vulnerability indices, and speed optimization algorithms into the voyage planning process. The results, based on a single route simulation, are striking: modest speed adjustments along the transit could avoid approximately 198 tonnes of CO₂, cut underwater radiated noise exposure by more than 50%, and reduce the risk of a fatal whale strike by up to 86%. The optimized route also yielded fuel savings of 61.7 metric tonnes per crossing.

Those numbers deserve context. A single transatlantic voyage producing nearly 200 fewer tonnes of carbon dioxide is not a rounding error. Multiplied across the thousands of commercial transits that cross the North Atlantic each year, the cumulative reduction potential is enormous, and it requires no new vessel construction, no experimental fuels, and no regulatory overhaul. It requires information and willingness.

The white paper builds on a growing body of research showing that the relationship between vessel speed and whale mortality is not linear; it is exponential. Studies published in Scientific Reports and cited by NOAA Fisheries have consistently demonstrated that the probability of a fatal collision increases dramatically above 10 knots. For the critically endangered North Atlantic right whale, which numbers roughly 380 individuals and is the subject of an ongoing Unusual Mortality Event declared in 2017, vessel strikes remain one of the two leading causes of death alongside fishing gear entanglement. NOAA data shows that 42 right whales have died and 40 have been seriously injured since 2017, with the vast majority of those casualties traced to human interaction.

What the IMarEST paper adds to this picture is an economic case. The conventional framing positions whale protection and commercial efficiency as competing interests: slow your ship to save whales, and you lose time and money. The Navigating with Nature model flips that assumption. By integrating real-time ecological data into route planning, the optimized voyage actually saves fuel. The speed adjustments are not uniform reductions across the entire crossing; they are strategic, applied in areas of high ecological sensitivity where whale density, calving grounds, or migratory corridors overlap with the shipping lane. In lower-risk stretches, the vessel can maintain or even increase speed to compensate, keeping overall transit time within commercially acceptable margins.

“What this case study shows is that smarter speed choices could cut costs and emissions now, while also reducing underwater noise and pressure on ocean biodiversity,” said Emily Charry Tissier, CEO and co-founder of Whale Seeker. Charry Tissier, a biologist with two decades of experience in coastal and Arctic ecosystems, founded the company in 2018 to use AI and aerial detection for marine mammal monitoring. Whale Seeker’s technology has since been deployed with Transport Canada to detect right whales in real time in the St. Lawrence corridor.

The underwater noise dimension is worth pausing on. Chronic noise pollution from shipping is one of the least visible but most pervasive threats to marine mammals. Whales and dolphins rely on sound for communication, navigation, and foraging. Elevated background noise from vessel traffic can mask their vocalizations, disrupt feeding behavior, increase stress hormone levels, and in extreme cases cause physical injury. The International Maritime Organization has recognized underwater noise as a significant environmental concern, but regulatory action remains voluntary and unevenly implemented. A 50% reduction in noise exposure through route and speed optimization, as the white paper models, would represent a meaningful improvement for cetacean populations along one of the world’s busiest shipping corridors.

Alasdair Wishart, IMarEST’s technical and policy director, framed the paper in regulatory terms. “This white paper illustrates how the landscape could look for vessel owners and operators should there be further legislation to protect marine mammals,” he said. The subtext is clear: the shipping industry can either adopt these practices voluntarily and capture the fuel savings, or wait for governments to mandate them and lose the first-mover advantage.

The paper was endorsed by the United Nations Decade of Ocean Science for Sustainable Development and produced through IMarEST’s Marine Mammal Special Interest Group, a technical body composed of experts from academia, industry, policy, and government. Strategic framing was supported by Fürstenberg Maritime Advisory.

It is worth noting what the paper does not claim. This is a case study based on a single simulated route, not a fleet-wide operational trial. Real-world implementation would face challenges including schedule pressures, port congestion, contractual obligations, and variable weather. The authors position the work as a starting point for integrating biodiversity intelligence into routing decisions, not a finished policy prescription.

Still, the fundamental insight is hard to argue with. In an industry under intense pressure to decarbonize, the notion that protecting marine life and reducing fuel costs can be pursued simultaneously, rather than traded against each other, is a compelling proposition. The ocean’s largest animals and the industry’s bottom line, it turns out, may have more aligned interests than decades of regulatory debate have assumed.

Source: IMarEST, Whale Seeker, True North Marine | Published March 2, 2026
White paper: Navigating with Nature: How Smarter Ship Routing Delivers Emissions Cuts and Biodiversity Gains | Available at imarest.org

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About the organization

The fishers of southern Tunisia called it “Daesh.”

The nickname, borrowed from the Arabic acronym for ISIS, was not chosen lightly. When the blue swimming crab first appeared in commercially significant numbers in the Gulf of Gabès around 2014, it behaved like an occupying force. The crustacean shredded traditional trammel nets with its powerful claws, devoured fish already caught in the mesh, and offered nothing in return. Coastal communities that had fished these shallow waters for generations watched their livelihoods unravel, one torn net at a time.

A decade later, that same crab has become one of Tunisia’s most valuable seafood exports. The transformation represents one of the most compelling case studies in adaptive marine resource management anywhere in the world: a nation that could not defeat an invader chose instead to monetize it.

The Mechanics of Invasion

The blue swimming crab, Portunus segnis, is native to the Red Sea and the western Indian Ocean. Its journey into the Mediterranean follows a phenomenon scientists call Lessepsian migration, named after Ferdinand de Lesseps, the French diplomat who oversaw construction of the Suez Canal. Since the canal’s completion in 1869, hundreds of marine species have drifted from the warmer Red Sea into Mediterranean waters. Most arrived quietly, filling ecological niches without disrupting local fisheries. P. segnis was different.

The Gulf of Gabès provided ideal conditions for explosive population growth. This vast, shallow continental shelf stretching along Tunisia’s southeastern coast had long supported the country’s most productive artisanal fisheries. Its warm, nutrient-rich waters now increasingly mimic the thermal regime of the crab’s native habitat as climate change pushes Mediterranean temperatures higher each year. Workshop outcomes from the 2025 “Blue Crab Management in the Mediterranean” conference confirmed what fishers already knew: the species has established a permanent, breeding population that now dominates the benthic ecosystem.

The ecological disruption extended beyond damaged fishing gear. The crab’s aggressive predation placed intense pressure on native biodiversity, particularly the autochthonous clam Tapes decussatus. This species forms the economic

The Policy Pivot

Eradication was never realistic. Once an invasive species establishes breeding populations across hundreds of kilometers of coastline, removal becomes biologically impossible without interventions that would devastate everything else in the ecosystem. Tunisian authorities, working alongside the Food and Agriculture Organization and the General Fisheries Commission for the Mediterranean, settled on a different strategy: commodification.

The approach required solving a practical problem first. Traditional trammel nets could not withstand the crab’s claws, but purpose-built crab pots could. These traps, constructed from durable materials and designed with selective entry points to minimize bycatch, allowed fishers to target crabs directly rather than losing their catch to incidental encounters. Government subsidies helped offset the cost of new gear, accelerating adoption across fishing communities.

The results exceeded projections. By 2021, Tunisia was exporting over 7,500 tons of blue crab annually, a figure that continued climbing through 2024 and 2025. Processing infrastructure expanded rapidly in southern cities like Zarzis and Sfax to meet demand from Asian markets, where blue crab commands premium prices. South Korea, Thailand, and Vietnam emerged as primary importers, joined increasingly by European buyers in Italy and Spain, along with growing interest from the United States.

Ripple Effects Across the Coast

The economic transformation reshaped coastal communities in ways that extend far beyond fishing boats.

For many fishers, blue crab provided income stability during a period when traditional target species like grouper and bream were declining due to overfishing and environmental degradation. The crab fishery operates on different rhythms than conventional fishing; traps can be set and checked on predictable schedules, reducing the uncertainty that has always characterized artisanal fishing.

Processing plants created thousands of jobs in communities where employment options had been limited. The work of picking crab meat from shells is labor-intensive and requires manual dexterity; machines cannot replicate the delicate extraction without destroying the product’s market value. Women from coastal communities filled these positions in large numbers, bringing household incomes into families that had previously depended entirely on what husbands and sons could catch at sea.

The “Blue Gold” rush also diversified Tunisia’s position in global seafood supply chains. The country’s fishing sector had historically depended heavily on fresh fish exports to the European Union. Blue crab opened new trade relationships with Asian buyers, reducing vulnerability to fluctuations in any single market.

The Shadow of Illegal Trawling

The crab story carries a darker subplot involving destructive fishing practices.

“Kiss” trawling, known locally as kys, is a form of mini-bottom trawling practiced in shallow coastal waters. The method drags weighted nets across the seabed, scouring everything in their path. It destroys Posidonia oceanica seagrass meadows, which serve as critical nurseries for marine life and significant carbon sinks. The practice is illegal precisely because of this environmental devastation, yet enforcement has proven difficult.

The explosion of blue crab populations initially drove more fishers toward illegal trawling. When crabs destroyed traditional nets, desperate fishers turned to gear robust enough to withstand the damage. Trawling equipment survives crab encounters better than trammel nets, even as it devastates the seabed. By 2022, an estimated 576 illegal trawlers were operating in the Gulf of Gabès.

The legalization and promotion of crab pot fishing offers a potential solution. By making legal trapping economically attractive, authorities aim to pull fishers away from destructive practices. Early reports suggest the strategy is gaining traction, though the immediate profitability of illegal trawling remains a significant barrier. Tunisia’s National Action Plan for Pollution Control explicitly links promotion of sustainable crab fishing to eradication of benthic trawling, treating the two issues as inseparable components of marine ecosystem recovery.

The Chitosan Frontier

Industrial processing of blue crab generates enormous quantities of solid waste. Shells constitute roughly fifty to sixty percent of each animal’s weight, and in the early years of the expanded fishery, this waste created new environmental problems. Discarded shells dumped back into the sea or piled in landfills produced odor and sanitation issues that strained relationships between processing facilities and surrounding communities.

Tunisia’s emerging blue biotechnology sector saw opportunity where others saw refuse.

Crab shells are rich in chitin, a biopolymer that can be converted into chitosan through chemical processing. Chitosan has high value across multiple industries: medical applications including wound dressings and drug delivery systems, agricultural uses as a natural pesticide and plant growth enhancer, and industrial applications in water treatment and bioplastics. The compound’s versatility makes it valuable enough that processed chitosan commands higher prices per kilogram than the crab meat itself.

Tunisian research institutes like the National Institute of Marine Sciences and Technologies have partnered with private ventures to develop industrial-scale chitin extraction. The country is positioning itself as a regional leader in what might be called third-order value creation: first the fishery revenue from meat exports, then the ecosystem service of removing an invasive predator, and finally the biotechnology input from shells that would otherwise become pollution.

The WestMED Initiative has cited Tunisia’s crab waste valorization as a best practice model for circular economy development across the entire Mediterranean basin. What began as a disposal problem has become a competitive advantage.

Lessons from the Laboratory

Tunisia’s blue crab story offers insights that extend well beyond this particular species or this particular coastline.

Climate change is accelerating species movements worldwide. Warming waters push marine life toward poles and into new habitats; the Suez Canal and other human-made corridors provide additional pathways for colonization. The Mediterranean, positioned between tropical and temperate zones and connected to warmer seas, will continue receiving new arrivals. How nations respond to these biological disruptions will shape coastal economies for decades.

The Tunisian model suggests that adaptation, rather than resistance, may offer the most practical path forward when eradication proves impossible. This requires institutional flexibility: regulatory frameworks that can pivot quickly, subsidy programs that can redirect fisher behavior, and research capacity that can identify commercial potential in unwanted species. It also requires honest assessment of what is achievable. The crabs are not leaving. The question becomes what to do with them.

For the fishers who once cursed “Daesh” while mending shredded nets, the answer has become surprisingly lucrative. The invader remains an invader, still altering the ecosystem in ways scientists are working to understand. But it is also now a livelihood, an export commodity, and a raw material for industries that did not exist in Tunisia a decade ago.

The transformation did not happen by accident. It required policy intervention, international cooperation, investment in processing infrastructure, and willingness among fishing communities to adopt new methods. Not every invasive species will offer similar opportunities; many will simply cause damage without redemption. But where commercial potential exists, the Tunisian experience demonstrates that crisis can become catalyst.

Blue gold, it turns out, was hiding in the claws of disaster all along.

Written by: Junior Thanong Aiamkhophueng

Attribution: This article draws on reporting from FAO and the General Fisheries Commission for the Mediterranean on blue crab fisheries management; El País coverage of the economic transformation; SPA/RAC technical workshop documentation; IW:LEARN and ARIJ reporting on community impacts; and WestMED Initiative blue economy research. Charfia photo via Wikimedia Commons; Portunus segnis photo via Wikimedia Commons CC0; fishing and crab trap photos ©FAO/Valerio Crespi. For further reading, visit The Guardian, Green Prophet, and Environmental Justice Foundation.

For generations, fishing along Tunisia’s coast has been both livelihood and identity. From the shallow tidal flats of the Gulf of Gabès to the small ports of Sfax, Kerkennah, and Mahdia, the sea once offered a reliable rhythm. Fishermen knew the seasons, the winds, and the species that would arrive and depart each year. That knowledge shaped not only income, but family life, food traditions, and entire coastal cultures.

Today, that rhythm is breaking down. Tunisian fishermen are facing a convergence of pressures that few communities are equipped to absorb. Climate change is altering weather patterns and sea conditions faster than local knowledge can adapt. Fish stocks are declining or shifting their ranges. At the same time, destructive bottom trawling has expanded into coastal waters, undermining both ecosystems and the economic viability of small scale fishing.

Together, these forces are eroding a centuries old relationship between people and sea.

A Coast Shaped by Small Scale Fishing

Tunisia’s fishing history is deeply tied to artisanal practices. With more than 1,300 kilometres of Mediterranean coastline, the country developed one of the largest small scale fishing fleets in the region. The vast majority of Tunisian fishing vessels are small boats operating close to shore, using nets, traps, and fixed gear designed to work with coastal ecosystems rather than against them.

In places like the Kerkennah Islands, fishing traditions such as the charfia system were refined over centuries. Wooden barriers and palm fronds guided fish into enclosures using tides and seasonal movements. These methods depended on healthy seagrass meadows, predictable spawning cycles, and intact coastal habitats. They also reflected a deep understanding of ecological limits.

By the early 2000s, fishing supported tens of thousands of Tunisian families directly and many more through processing, transport, and trade. Fish was both a staple food and an important export, especially to European markets.

That balance is now under strain.

Climate Change Reaches the Docks

The Mediterranean Sea is warming faster than the global ocean average. Rising sea surface temperatures have intensified marine heatwaves, altered currents, and increased the frequency of extreme weather events. For fishermen working in small boats, these changes are not abstract trends. They translate into lost days at sea, damaged equipment, and growing danger.

Fishermen across Tunisia report longer periods of bad weather and storms that arrive with little warning. Conditions that once followed seasonal patterns are now unpredictable. Autumn and winter storms are stronger and more erratic, making it harder to plan fishing trips or ensure safe returns.

Research by international fisheries and climate bodies shows that weather related disruptions already affect fishing activity for a significant portion of the year, particularly in northern and central Tunisia. The risks are highest for artisanal fishermen, whose boats lack the size, shelter, and safety systems of industrial fleets.

In some cases, these risks have been fatal. Storm related sinkings in recent years underscore how climate change is increasing the human cost of fishing in the Mediterranean.

A Sea Rich in Life, and Increasingly Fragile

Beneath Tunisia’s coastal waters lies one of the Mediterranean’s most ecologically important regions. The Gulf of Gabès is unique due to its shallow depth and tidal range, which support vast meadows of Posidonia oceanica seagrass. These underwater forests are among the most productive ecosystems in the sea.

Posidonia meadows act as nurseries for fish, feeding grounds for invertebrates, and carbon sinks that help regulate the climate. Hundreds of marine species depend on them at some stage of their life cycle, including species of commercial importance and others already considered threatened.

Tunisia’s waters also host migratory species, sea turtles, dolphins, and endemic organisms found nowhere else. This biodiversity has long supported artisanal fishing, allowing small scale gear to yield steady catches without exhausting stocks.

However, climate change is weakening this ecological foundation. Warmer waters affect reproduction, oxygen levels, and species distribution. Some fish are migrating north or into deeper waters. Others are declining as habitats degrade.

These changes alone would challenge fishermen. Combined with destructive fishing practices, they become devastating.

The Rise of Bottom Trawling in Coastal Waters

Over the past decade, bottom trawling known locally as kys fishing has expanded dramatically along Tunisia’s coast. Using heavy nets dragged across the seabed, these vessels capture everything in their path. The method is highly efficient in the short term and highly destructive in the long term.

Bottom trawling damages seagrass meadows, disturbs sediments, releases stored carbon, and destroys the complex structures that support marine life. It also tears through the nets and traps used by artisanal fishermen, causing direct economic losses.

Although bottom trawling is regulated under Tunisian law and Mediterranean fisheries agreements, enforcement has struggled to keep pace with its spread. Legal ambiguities, limited monitoring capacity, and misclassification of vessels have allowed trawlers to operate in areas where they are restricted or banned.

In regions such as Sfax and the Gulf of Gabès, the number of kys trawlers has increased sharply since the early 2010s. Many fishermen attribute this rise to declining catches from traditional methods and economic pressure following political and social upheaval after 2011.

The result is a vicious cycle. As trawlers degrade habitats and reduce fish stocks, artisanal fishermen see their catches fall. Some abandon fishing altogether. Others feel compelled to adopt destructive methods themselves, even as they recognise the long term damage.

Economic Stakes Beyond the Shore

Fishing remains economically significant for Tunisia. Annual production reaches well over one hundred thousand tonnes, with a substantial portion exported. European markets are particularly important, making sustainability and traceability critical for trade.

Illegal and indiscriminate fishing practices threaten that relationship. International partners have raised concerns about bottom trawling and enforcement gaps, warning that continued violations could jeopardise exports and reputational standing.

Tunisian authorities have increased inspections, seizures, and surveillance in recent years, and have acknowledged both progress and limitations. With a long coastline and limited resources, oversight remains uneven.

Meanwhile, coastal communities bear the consequences first.

Lives Caught in the Middle

On the docks, the impacts are deeply personal. Fishermen speak of species that once fed families now becoming luxuries. Octopus, once affordable and common, has become scarce and expensive. Younger fishermen hesitate to invest in boats or start families, unsure whether the sea can still provide a future.

Older fishermen recall a time when knowledge of tides, winds, and seasons was enough to make a living. Today, even experience cannot offset degraded ecosystems and unpredictable conditions.

The loss is not only economic. It is cultural. As fishing becomes less viable, traditions tied to food, language, and community risk fading with it.

An Uncertain Horizon

Tunisia’s fishermen are navigating a narrow passage between climate change and industrial pressure. Protecting their future will require more than enforcement alone. It will demand rebuilding marine ecosystems, supporting small scale adaptation, and recognising that artisanal fishing is not a problem to be replaced, but a solution worth preserving.

The sea still holds life. Whether it can continue to sustain those who have depended on it for generations depends on choices made now, before the tide turns further against them.

 

Sources and References

Arab Reporters for Investigative Journalism. Climate Change Deepens the Struggles of Tunisia’s Fishermen, as “Kys” Trawlers Boats Steal Their Livelihoods. 

Food and Agriculture Organization of the United Nations. Mediterranean fisheries assessments and Tunisia country profiles.

Intergovernmental Panel on Climate Change. Sixth Assessment Report. Mediterranean regional impacts.

Environmental Justice Foundation. Reports on bottom trawling and seafloor carbon release in Tunisia.

General Fisheries Commission for the Mediterranean. Technical regulations and Gulf of Gabès management measures.

UNEP Mediterranean Action Plan. Coastal ecosystems and climate vulnerability.

International Union for Conservation of Nature. Mediterranean biodiversity and Posidonia oceanica assessments.

Mongabay. Investigative reporting on illegal trawling and seagrass loss in the Gulf of Gabès.

Giacomo Abrusci, SEVENSEAS Media