The Bay of Biscay

The most transferable piece of intelligence in this record is the relationship between submarine topography and productivity, because it explains fisheries all over the world and it is at its clearest here.

THE OPEN OCEAN'S SURFACE IS NUTRIENT-POOR. Sunlight penetrates only the upper layer, so photosynthesis can only happen there, and the nutrients that photosynthesis consumes sink out of it continuously as material dies and falls. Deep water is nutrient-rich and dark; surface water is lit and impoverished. Production is limited by whatever brings the two together.

A CANYON IS A MECHANISM FOR BRINGING THEM TOGETHER. Where a submarine canyon cuts into the shelf edge, currents flowing along the slope are deflected and forced upward, and internal waves break against the canyon walls. Both processes drive mixing and localised upwelling, delivering deep nutrients into the lit layer.

AND A FOOD CHAIN ASSEMBLES ON TOP OF IT. Phytoplankton bloom where the nutrients arrive; zooplankton graze them; small pelagic fish — anchovy, sardine, sprat, horse mackerel — concentrate on the zooplankton; and large predators concentrate on the small pelagics. The whole structure is anchored to a piece of seabed topography that never moves, which is why particular canyons and shelf edges have reputations that persist across generations.

THE BAY OF BISCAY IS A GOOD TEACHER because the effect is unusually accessible. The Cap Breton canyon brings that machinery close enough inshore that a small boat from a coastal port can reach water that would normally require a long offshore passage, and the tuna fisheries of the Basque and Cantabrian coasts were built on precisely that accident of geology.

THE GENERAL LESSON FOR A READER is that offshore fishing is not conducted at random over a featureless surface. It is conducted at physical discontinuities — canyons, shelf edges, seamounts, fronts where water masses meet — and those are the marine equivalent of structure on a reef. Understanding that turns a chart into a map of where production happens.

The single most important safety fact about the Bay of Biscay is that its most dangerous condition is not generated locally and gives no local warning.

SWELL AND WIND WAVES ARE DIFFERENT THINGS. Wind waves are short, steep, disorganised and generated by the wind you can feel. Swell is what remains after waves leave the area that generated them: it sorts itself by wavelength as it travels, arriving as long, low, regular, organised undulations that may have crossed a thousand miles of ocean from a storm days earlier. It carries a great deal of energy and it looks like almost nothing in deep water.

WHAT SHOALING WATER DOES TO IT. As a long swell moves into shallowing water it slows, shortens and steepens, and the energy that was distributed through a deep column is concentrated into a shorter, taller wave that eventually breaks. A swell that was imperceptible offshore breaks heavily on a bar, a reef or a steep beach. The bay's geometry — open to the North Atlantic, narrowing and shallowing toward its south-eastern corner — funnels and concentrates that arriving energy.

SO THE DANGEROUS DAY LOOKS CALM. Sunny, windless, flat inshore, with a long swell running that produces a set of much larger breaking waves every few minutes. Anglers on rock platforms are swept off by a set wave after an hour of ordinary conditions; anglers wading on a sandy beach are knocked over by one; and a boat crossing a bar meets it at the worst moment.

WHICH IS WHY THE SWELL FORECAST IS THE DOCUMENT THAT MATTERS on this coast, and why reading only a wind forecast is reading the wrong half. Wave height, period and direction together are what describe the hazard: a two-metre swell at a long period carries far more energy than a two-metre wind sea at a short one, and it is the period that most people ignore.

AND THE BAÏNES ARE THE SANDY-COAST VERSION OF THE SAME ENERGY. Water pushed over a bar by breaking waves has to return seaward, and it does so through the gap in the bar as a concentrated, fast, seaward-flowing channel. That is a rip current, it is strongest at particular states of tide, and on this coast it is a documented and recurring cause of death.

The Bay of Biscay is a system record because its physical structure explains a fishery spanning two countries, and the structure has three components.

THE SHELF IS BROAD IN THE NORTH AND NARROW IN THE SOUTH. Off Brittany and the French coast the continental shelf extends a long way; along the northern Spanish coast it narrows sharply, so deep water comes close to shore. The same bay therefore offers a broad shallow shelf fishery at one end and a deep-water one at the other.

THE SHELF EDGE IS CUT BY CANYONS. Submarine canyons incise the shelf break, and they do two things: they channel deep water up towards the surface, and they concentrate life along their rims. The canyon systems here are among the most pronounced in the north-east Atlantic and they are a major reason the bay supports the pelagic fishery it does.

THE BAY IS A SWELL TRAP. Open to the west and north-west with a very long Atlantic fetch, and shoaling towards a concave coastline, Biscay concentrates swell generated by North Atlantic depressions. Its reputation among mariners is earned: a Biscay swell arrives with no local weather to explain it and breaks heavily on a coast that shoals.

UPWELLING OCCURS ALONG THE SOUTHERN AND WESTERN MARGINS, seasonally, adding nutrients to a system that is otherwise supplied by shelf mixing and river input.

MAJOR RIVERS DISCHARGE INTO IT, and their plumes stratify the surface layer and deliver nutrients and juveniles to the shelf.

AND THE WHOLE THING IS A NURSERY. The shelf waters of the bay are spawning and nursery ground for stocks fished across the north-east Atlantic, which is why what happens here matters well beyond it.

Biscay's species picture is dominated by pelagics and by the fact that this is nursery ground for a much larger area.

ALBACORE IS THE BAY'S SIGNATURE FISHERY. Summer-feeding albacore tuna move into Biscay in numbers and support a pole-and-line and trolling fishery of long standing on both the French and Spanish sides — one of the more selective tuna fisheries in Europe.

BLUEFIN TUNA PASS THROUGH AND FEED HERE, and the bay was historically a major bluefin ground; the stock's collapse and subsequent recovery under international management is one of the better-known fisheries stories in the Atlantic.

ANCHOVY IS THE STOCK THAT DEFINES THE BAY'S MANAGEMENT HISTORY. The Bay of Biscay anchovy fishery was closed entirely for several years in the twenty-first century after the stock collapsed, and its recovery and reopening under a management plan is a reference case in European fisheries. It is the clearest local demonstration that a closure can work.

SARDINE, MACKEREL AND HORSE MACKEREL make up the rest of the small pelagic biomass, and mackerel in particular use the bay heavily.

HAKE IS THE PRINCIPAL DEMERSAL FISHERY, and the northern hake stock's decline and rebuilding is another well-documented case.

SEA BASS SPAWN IN THE BAY, and the winter spawning aggregations there were the subject of a controversial pelagic pair-trawl fishery whose restriction was central to the bass measures that now govern angling across northern Europe.

AND THE SHORE AND INSHORE FAUNA IS THE ATLANTIC EUROPEAN ONE — bass, seabream, pollack, wrasse, conger, rays and flatfish — with the southern part of the bay showing an increasingly warm-temperate component as water temperatures have risen.

The disciplines around the Bay of Biscay span an industrial pelagic fishery and one of Europe's largest recreational sectors.

POLE-AND-LINE AND TROLLING FOR ALBACORE is the bay's distinctive commercial discipline. Summer tuna taken one at a time on poles or on trolled lines from small and medium vessels is a selective method with a long tradition on both coasts, and it survives alongside more industrial gears.

PURSE SEINING FOR SMALL PELAGICS is the volume fishery, and its management — particularly for anchovy — is where the bay's fisheries politics concentrate.

TRAWLING FOR HAKE AND DEMERSAL SPECIES works the shelf and the canyon edges.

RECREATIONAL BOAT FISHING IS ENORMOUS ON THE FRENCH SIDE. France has one of the largest recreational sea fishing populations in Europe, and small-boat fishing along the Biscay coast for bass, pollack, seabream and, offshore, tuna is a mass activity.

SURFCASTING ON THE LANDES BEACHES is a discipline in its own right. The long straight sand coast of south-western France produces a powerful surf and a genuine surfcasting culture, with heavy tackle and long rods, targeting bass, meagre, rays and flatfish.

ROCK AND SHORE FISHING ON THE BASQUE AND CANTABRIAN COAST works a completely different ground — steep rock, deep water, heavy swell — for bass, seabream and pelagics.

SPEARFISHING IS STRONG ON BOTH SIDES and is separately licensed in both countries.

AND SHELLFISH GATHERING — pêche à pied on the French side, marisqueo on the Spanish — is a mass participation activity on the intertidal, subject to its own rules.

The bay's year is organised around the arrival of warm water and the departure of settled weather.

SUMMER IS THE PELAGIC SEASON. Albacore move into the bay as surface water warms, tuna fishing runs through the warmer months, and the small pelagic fishery is at its most active. This is when the bay's distinctive fisheries operate.

AUTUMN IS THE BEST INSHORE PERIOD. Water is still warm, bass and seabream feed hard, the first swells stir the ground, and shore and small-boat fishing is at its most productive.

WINTER IS SWELL SEASON AND IT IS SEVERE. North Atlantic depressions send very large ground swell into a bay that concentrates it, and the exposed coasts become unfishable and dangerous for extended periods. Biscay's reputation is a winter reputation.

BASS SPAWN IN WINTER IN OFFSHORE AGGREGATIONS in and around the bay, which is a biological fact with a substantial management history attached: the vulnerability of a spawning aggregation to a targeted fishery is precisely why the bass measures of the last decade exist.

SPRING IS THE UPWELLING AND RECRUITMENT PERIOD along the southern margins, with anchovy spawning and the shelf's productivity building.

RIVER FLOW IS A SEASONAL DRIVER on the French side, where the major rivers discharge, changing salinity and turbidity in the coastal zone and moving estuarine species.

AND THE MIGRATORY SALMONIDS RUN THE BAY'S RIVERS on their own calendar, at the southern edge of the Atlantic salmon's range, in systems whose runs are much reduced from historic levels.

The bay is shared, and its governance is a good illustration of how European fisheries management actually works.

TWO MEMBER STATES AND A COMMON POLICY. France and Spain each administer their own waters and fleets, within the European common fisheries policy, which sets quotas, technical measures and the framework for shared stocks. Regional advisory structures give the industry and other interests a formal route into that process.

STOCK ADVICE COMES FROM AN INTERNATIONAL SCIENTIFIC BODY, and quota decisions are political choices made against it, which is the structure a reader needs in order to follow any European fisheries argument.

THE ANCHOVY CLOSURE IS THE CASE TO KNOW. When the Bay of Biscay anchovy stock collapsed, the fishery was closed entirely for several years, and it was subsequently reopened under a management plan when the stock recovered. It is one of the clearest European demonstrations that a hard closure can rebuild a stock, and it was economically painful.

THE BASS MEASURES CAME OUT OF THIS BAY. Restrictions on targeting spawning aggregations, minimum sizes, bag limits for recreational anglers and gear restrictions were introduced across northern Europe following advice on a declining stock, and recreational anglers on this coast and far beyond feel them directly.

RECREATIONAL SEA FISHING IS LICENSED IN SPAIN AND NOT IN FRANCE, which is a striking difference across a single bay and a good illustration of why the framework question is national even where the fish are shared.

SHELLFISH GATHERING CARRIES SEPARATE PUBLIC HEALTH CONTROLS on both coasts, and local rules on pêche à pied and marisqueo differ substantially.

AND FISHINGHQ DOES NOT STATE WHAT ANY OF THIS CURRENTLY PERMITS. Quotas here are revised annually and bass measures have changed almost yearly.

The vocabulary of this bay is oceanographic and fisheries-scientific, because it is a sea area whose management is scientific.

SHELF AND SHELF BREAK NAME THE FUNDAMENTAL STRUCTURE. The continental shelf is the shallow submerged margin of the continent; the shelf break is where it drops away. Most of the bay's demersal fishing happens on the shelf and most of its pelagic fishing along and beyond the break.

SUBMARINE CANYON NAMES THE INCISIONS CUTTING THE SHELF BREAK. They channel deep water upward and concentrate life along their rims, and they are why particular positions along an otherwise featureless shelf edge fish consistently.

RIVER PLUME NAMES THE BODY OF FRESH OR BRACKISH WATER spreading over the sea surface from a river mouth. Plumes stratify the water column, carry nutrients and juveniles, and their edges are fishing features.

STOCK IS A MANAGEMENT UNIT RATHER THAN A BIOLOGICAL ONE, and understanding that distinction is essential to reading anything about this bay. A stock is the population unit assessed and managed; it may or may not correspond exactly to a biological population.

TOTAL ALLOWABLE CATCH NAMES THE QUOTA SET FOR A STOCK for a period, allocated between countries. It is the instrument every European fisheries argument is ultimately about.

SPAWNING AGGREGATION NAMES THE GATHERING OF ADULTS to reproduce, and here it names the specific bass behaviour whose exploitation drove a decade of management change.

AND PÊCHE À PIED — FISHING ON FOOT — NAMES THE FRENCH INTERTIDAL GATHERING TRADITION, a mass participation activity with no British equivalent in scale, and it is the term a visitor to the French side will meet first.

Biscay has one of the longest and best-documented fishing histories in the Atlantic, and it starts earlier than most.

THE BASQUE WHALE FISHERY IS THE OLDEST CHAPTER. Basque communities on both sides of the bay were hunting right whales from shore and then from vessels from the medieval period, and Basque whalers subsequently crossed the Atlantic to Newfoundland and Labrador. It is among the earliest documented commercial marine hunting industries in Europe.

THE COD FLEETS FOLLOWED. Basque and French vessels fished the Grand Banks for centuries, salting cod for the European market, and the bacalao and morue trades shaped the food cultures on both sides of the bay.

THE ANCHOVY AND SARDINE CANNING INDUSTRY built the modern coastal economy on both coasts, supported by the shelf's productivity.

THE ALBACORE POLE-AND-LINE FISHERY IS A CONTINUING TRADITION, and its survival alongside more efficient gears is a deliberate choice with a selectivity argument behind it.

THE ANCHOVY COLLAPSE AND CLOSURE IS THE MODERN EVENT. The stock's decline, the total closure of the fishery for several years, and its recovery and reopening under a management plan is the reference case in recent European fisheries history, and it is the reason the bay is cited in arguments about closures everywhere.

THE BASS STORY IS THE OTHER MODERN CHAPTER, in which a targeted fishery on winter spawning aggregations contributed to a decline that produced Europe-wide restrictions affecting recreational anglers a thousand kilometres away.

AND THE ERIKA AND PRESTIGE OIL SPILLS affected the bay's coasts within recent decades, with substantial consequences for inshore fisheries and for public attitudes to shipping in these waters.

Biscay is shared by two countries whose fishing cultures are genuinely different, and the contrast is instructive.

THE FRENCH SIDE IS A MASS RECREATIONAL CULTURE. France has one of Europe's largest populations of recreational sea anglers and an enormous small-boat sector, and the activity is treated as an ordinary leisure pursuit rather than a specialist one. Pêche à pied — gathering shellfish on foot at low water — is a family activity practised at very large scale on the Atlantic coast.

THE SPANISH SIDE IS A PROFESSIONAL AND LICENSED CULTURE. Recreational fishing is licensed by category, the professional inshore sector is organised through guilds, and the relationship between the two is more formally delineated.

THE BASQUE MARITIME IDENTITY SPANS BOTH SIDES and is distinct from either national one, with its own language, its own boat traditions, its own tuna fishery and a food culture built on cod, anchovy and tuna.

SURFING AND SURFCASTING SHARE THE LANDES COAST, and the long straight beaches of south-western France support both cultures in the same water with the usual mild friction.

THE TUNA FISHERY CARRIES REAL PRIDE on both sides, and the pole-and-line boats and their crews occupy a position in local esteem comparable to any craft fishery.

THE FOOD CULTURE IS PELAGIC. Anchovy, sardine, tuna and hake are central to the cuisines of both coasts in a way that reflects exactly what the shelf produces.

AND THE SEA'S REPUTATION IS SHARED. Biscay's name means rough weather to mariners across Europe, and the coastal cultures on both sides carry a respect for Atlantic swell that a visitor should adopt rather than test.