The Most Famous Food in England

You can’t get much meat for threepence, but you can get a lot of fish-and-chips.

—George Orwell, The Road to Wigan Pier

Cod are the heroes of this saga, but they are less than heroic in appearance, sluggish and rotund with off-putting twin tentacles dangling from the lower jaw. Their flanks are gray-green, painted with a thin white stripe, and mottled with pox-like burgundy spots. On a plate, however, or wrapped in newspaper, they are unrivaled. Cod are flawless eating fish, yielding brilliant white fillets with thick flakes, a firm texture, and a delightfully mild flavor. Indeed, without cod there would be no such thing as fish and chips, arguably England’s most famous food. When steam-powered trawlers first exploited massive schools in the frigid waters of the North Atlantic and the Barents Sea, a few scattered chippies—shops selling battered fish, fried potatoes, and mushy peas—swelled into a national industry. Today, more than 10,000 fish and chip shops in the United Kingdom dish out nearly 400 million meals annually and contribute a sizzling billion and a half dollars to the economy.⁸ Cod habits and habitats, so different from those of coral reef fishes, have fashioned through evolution an animal profoundly well adapted to thrive in cold and deep waters, but also mouth-wateringly primed for commercial fisheries.

If you fillet a cod you will find it is nearly entirely composed of white meat. Unlike tuna, who rely on sustained high speeds to feed themselves, cod are a lethargic lot. They glide through frigid northern seas, restricted almost entirely to waters colder than 45 °F, where they conserve energy by moving slowly and deliberately.⁹ White muscle is the sluggish engine that powers such languid cruising. When a morsel of food dances in front of a cod, perhaps a tasty capelin (Mallotus villosus, the polar equivalent of a sardine), it lunges with a burst of speed. Since they sustain that high speed for only an instant, cod have little need for the brown muscle that dominates tuna, herring, and other nonstop speedsters. Only a narrow ribbon of dark meat colors their swimming muscles, like the center line on a highway. The precise hue of this ribbon reflects the behavior of different stocks. Schools migrating from Spitzbergen Island to the Norwegian coast for spawning, a distance of some 500 miles, bear a stripe of espresso-brown muscle; shorter distance commuters to the Faroe Islands show only a line of cappuccino-tan.¹⁰ Color even varies seasonally: in North Sea cod the stripe grows progressively darker as the spawning months of July and August approach, reflecting their intense hunting activity to fuel reproduction. Other than this narrow line, cod fillets are gleaming white, comprising 80 percent protein and almost no fat, and they are positively delicious.

Cod belong to a family of coldwater fishes called gadoids that includes pollock, haddock, whiting, and a few others. Their forms and behaviors are quite similar, though preferred ranges and depths vary. They swim in giant schools (though not as vast as those of herring and sardine), sometimes fittingly called herds, and rely on the impressive productivity of arctic seas to sustain them. Nearly all are important white-meat food fishes, caught by northern fisheries but distributed around the top of the globe. The most famous species, Atlantic cod, is divided into many populations: some around Newfoundland and the northeast coast of the United States; others around Iceland and Greenland, more in the North Sea waters around the British Isles and the Barents Sea above Norway and Russia. Across most of their range, cod are the apex predators within their favored, icy waters. Only minke whales and harp seals challenge them for this top spot. Despite their dominance, however, cod success and reproduction is famously sensitive. The slightest fluctuations in environmental variables can levy powerful effects that reverberate through the population, and all the way to fishery docks.

Fisheries science is an incredibly complex discipline, but at its heart lies a simple truth: you can’t take more fish out of the sea than the population can replenish. Because of this maxim, scientists work tirelessly to understand every step of fish reproduction, from eggs to larvae, to juveniles, immatures, and finally spawning-ready adults. Each graduation from one age-class to another affects recruitment, the number of fish that join the adult population every year. And each step is extremely susceptible to minor changes in temperature, salinity, acidity, and the availability of prey populations, upon whose recruitment that of cod also rests.

Bjarte Bogstad is a fisheries scientist who has studied cod for years at the Institute of Marine Research of Norway. Though he grew up in an industrial town with no fishing vessels, he was drawn to the science of fisheries. Sporting owlish glasses and an affable grin (and a t-shirt proclaiming “In Cod We Trust”), he speaks rapidly and enthusiastically about his favorite fish. His Norwegian accent charmingly reveals itself on words with doubled consonants: “bigger” is distinctly pronounced with two syllables, as “big-ger.” His institute’s research is responsible for understanding a fish that contributes much to his nation’s economy. For more than a thousand years, Norwegians have fished for cod, particularly in the spawning grounds of the Lofoten Islands, and dried them for storage and sale. “The spawning areas are so close to the coast that you could go out and have a good catch with a small boat. It was this fish that came close to the coast in big quantities, so it was fairly easy to catch with the old technology. In addition to the abundance, that was something that made it a good export.”¹¹ Dr. Bogstad’s institute is based in Bergen, a city practically built on cod. By the fourteenth century (and indeed until 1830), Bergen was the largest and richest city in Norway, thanks to an empire overseen by the Hanseatic League and founded on trading dried cod, a handy protein source that could be shipped all over Europe. Today, what cod eat and which environmental factors most affect their populations are central to Bogstad’s charge.

As cod cruise toward shore for spawning, whether to the Lofotens or to the Newfoundland seaboard, they are gearing up for record-setting reproduction. “They are among the most fecund of all fishes,” says Bogstad. “A female cod has typically a couple of million eggs, and they can spawn several times.” Over her lifespan, a single female may release as many as 18 million eggs into the water; if every one were to survive, she would have given birth to more citizens than the combined populations of London and Chicago.¹² But they do not all survive; rather, losses at this life stage are catastrophic. Scientists from the Northeast Fisheries Science Center in the United States tracked egg numbers by dragging nets through the waters off Cape Cod. They found mortality reached a devastating 20 percent per day.¹³ At this calamitous rate, more than 90 percent of her eggs would vanish in the week and a half they need to hatch.

Given such heavy losses, it is in a cod’s best interest to release lots of eggs. A larger fish produces far more roe than a smaller fish, including one hefty female who shattered the records, according to Bogstad. “There was a fish of 54 or 55 kilos [121 lb.] recently landed off the coast in northern Norway,” he relates proudly, “and this fish had 14 kilos of roe in it.” That is 30 pounds of fish eggs, equivalent to the weight of a cocker spaniel. But there is a tradeoff: if the fish prioritizes growing to that stout size, then she may have to skip some breeding years in the process; alternatively, she can release fewer eggs earlier in life when she is more petite, although the effort will hamper her overall growth. Each cod population solves this equation differently (if one grants them the power of mathematical analysis). In the Irish Sea, for example, cod begin spawning early but release only a third of a million eggs in the first season. After four seasons, however, their total production can top 14 million roe. In contrast, Barents Sea and Icelandic cod have not even begun to spawn by the time their Irish cousins have reached their fourth mating season.¹⁴ These differences are due in part to water temperatures, as the warmer southern waters boost growth rates of each Irish cod.

Once the eggs hatch, defenseless larvae emerge and begin gobbling plankton; the race is on to grow as quickly as possible into hardier juveniles. At this stage, temperature and timing are all-important. One of the favorite foods of a larval Norwegian cod is a copepod (Calanus finmarchicus, among others), tiny crustaceans whose numbers explode when springtime conditions are ideal, but unusual water temperatures can shift that peak by a few fatal weeks. In extremely warm years like 1960, copepods were most abundant around the first of April, and late-hatching cod starved.¹⁵ But in the brutally cold year of 1981, the peak arrived in late May, and early hatching cod also starved. Cod’s prodigious fecundity is probably a response to these unpredictable odds: when larvae and weather and copepods are all finally in sync, only then will enough of a female’s 2 million eggs survive to guarantee the next generation.

As adults, northern Atlantic cod prefer capelin. In the Barents Sea alone, cod consume upward of 3 million tons of capelin every year.¹⁶ These small schoolers feed on plankton blooms along the edges of polar ice sheets, but during warm years the ice retreats. Capelin must relocate to eat, a shift that can re-route spawning migrations, displace populations, and diminish survival. Many marine species rely on capelin, like adorable Atlantic puffins and doe-eyed harp seals, who target the silvery schools as they travel to breeding sites on the coast of northern Norway. When capelin populations shrink, cod and the other predators can go hungry, suffer increased mortality, and face seasonal breeding failures. As a balancing effect, however, the collapse of capelin lessens their predation on zooplankton, which begin to rebound.¹⁷ Across the Atlantic in Newfoundland, capelin spawn on beaches where they hurl themselves onto pebbled shores with such vigor that they are often left stranded, much to the delight of voracious seabirds. Here, too, they are sensitive to the slightest of temperature changes: a mere 2 °F warming of surface waters can shift capelin distribution by hundreds of kilometers.¹⁸

Capelin make up some 60 percent of the annual energy budget of cod in some areas, so any change in the distribution of the former is bound to affect the latter.¹⁹ When capelin populations are booming, cod eat well and grow quickly; but when they are scarce, cod suffer from hunger pangs and turn to other foods. Herring, sprats, shrimp, and all manner of shellfish are gobbled up by ravenous herds. But famished cod resort to a feeding strategy that is taboo in all but the most extraordinary human cultures (just ask Captain Cook’s crew): cannibalism.

In a normal year, as many as two-thirds of all cod juveniles (up to two years of age) who die at sea are gobbled up by their very own brothers and sisters.²⁰ For a young adult cod, cannibalism may supply just 1 percent of their stomach contents, but in older fish that value swells to 5 percent or even 10 percent.²¹ As described by Bogstad, “they become more cannibalistic as they get big-ger. They can eat fish, including small cod, up to half their own length.” He pauses to recall the prize-winning cannibal: “We found once a cod of 107 centimeters who had a cod of 62 centimeters in the stomach.” The total amount eaten fluctuates with temperature and food availability. When capelin populations plummet, or shift their distribution, their scarcity prompts even more offspring-eating.²² During one particularly bad year for Barents Sea capelin, the cannibalism rate multiplied threefold.²³

Cod, like capelin, respond strongly to small changes in water temperature. They prefer cold waters, typically between 36 and 50 °F but can survive at 30 °F (sea water freezes at 28 °F, because of the salt).²⁴ Atlantic cod off Newfoundland, however, painstakingly avoid the subzero Labrador Current that creeps down the coast from the North Pole. Remarkably, they swim in waters that are beneath the current, but slightly warmer: differences in salinity float the colder Labrador stream atop Atlantic Ocean water that measures between 2 and 4 °F. According to Canadian cod researcher George Rose, the cod “don’t live in that cold water, it’s too cold for them. It can get down to minus 2 [Celsius, or 28 °F], which really hurts.”²⁵ By contrast, he calls the Atlantic’s 36–39 °F “very favorable for cod.” Over on the other side of the Atlantic, cod are avoiding water that is slightly too balmy: fishery data reveal the North Sea population has shifted to deeper, colder waters as ocean surface temperatures have risen.

Cod themselves are an important food source for two polar mammals—minke whales (Balaenoptera acutorostrata) and harp seals (Phoca groenlandica)—who are also affected by capelin abundance. Harp seals, also known as Greenland seals, tuck into some 100,000 tons of cod when capelin are abundant (by comparison, Brits fry just three-quarters of this amount into fish-and-chips).²⁶ But when capelin are scarce, cod are the next-best option, and the seals’ cod harvest triples.²⁷ Shifting between food sources adds further pressure to cod populations themselves reeling from a lack of capelin prey. This arctic food web can be self-stabilizing, though, if given a chance. Take the years 1984–1986, for example. Capelin populations nosedived because of overconsumption of their larvae by young herring and cod, perhaps exacerbated by shifting sea ice or poor years for plankton growth.²⁸ Because of the scarcity of everyone’s favorite food, whales and seals started eating more cod, and cod themselves began cannibalizing their own offspring. All this predation forced cod populations to decline and average adult weights to fall by half.²⁹ The smaller cod population in turn could no longer eat as many capelin as in pre-1984 years. And the capelin schools, freed from heavy cod predation, rebounded when their waters grew more productive, soon returning to the prodigious numbers that could again sustain an entire marine ecosystem.

If cod larvae survive starvation for lack of copepods, and cannibalism by hungry adults, they grow into juveniles and begin to change their ways. Eschewing the open waters where they spent their infancy, juvenile cod may migrate to inshore waters along the Newfoundland coast and the shores of Iceland and Norway. There they comb the shallows in a concerted effort to put on pounds and grow into adulthood, an eating contest that takes about three years. Until they reach adult size, cod juveniles are still at risk of being attacked by any number of hungry marine animals. Finding food while avoiding risk is a delicate balancing act, one that juveniles approach with a strategy referred to by marine researchers as “hunt warm, rest cool.”³⁰ When the sun rises, and light suffuses into the cold sea, cod juveniles begin to dive.³¹ Swimming toward the bottom, they slip into dark waters where they cannot readily be seen, biding their time in the relative safety of these cool depths. Their metabolism also slows, an added energetic benefit. Later, as the sun skids below the horizon and darkness cloaks the surface, juveniles ascend to shallower and more productive waters. All night long they feed, gobbling crabs and shrimp larvae and smaller fishes. Here, in the shallows, the warmer surface water heats up their small bodies and makes them faster, stronger, and more agile as they hunt their prey. Soon the sun has spun around the world (with apologies to Copernicus), the sea brightens, and juvenile cod descend to safe darkness and meditative cold, where they await the next night’s feast.

One of the great benefits of cold oceans is that they are rich in oxygen. Polar waters, in comparison to tropical seas, hold nearly twice the dissolved oxygen, at least at the surface. Nevertheless, a gallon jug filled with air contains about forty times the oxygen in an average gallon of seawater, so fishes must use less oxygen, and they must absorb it more efficiently. To achieve the former, cod are steadfastly cold blooded and sluggish, with delicate white fillets. For the latter, they rely on counter-current blood flow across their gills, and on a familiar molecule: hemoglobin. As in human blood, fish hemoglobin greedily seizes oxygen from the outside world (albeit from water sliding through the gills) and dutifully transports it to heart, brain, and muscles.

Not all hemoglobin molecules are created equal, however, and various forms differ in the temperature at which they bind oxygen most effectively. If the veins of a fish in a 40 °F sea throb with hemoglobin suited to 50 °F water, it will be outcompeted by better-oxygenated rivals with properly tuned blood chemistry. Juvenile Atlantic cod have the ability to express two distinct hemoglobin morphs within the same fish.³² When tested in a laboratory, the HbI1 type achieves peak oxygen stickiness at temperatures above 57 °F. A second morph, poetically named HbI2, hits its oxygen-binding stride in water below 50 °F. Such polymorphism can be found in fish species that travel great distances as they grow from larva to adult, to ensure their blood is well suited for the temperatures found in both environments.³³ But cod do not undertake such expansive journeys. Instead, they seem to retain the genetic code for several hemoglobin types so the right form can be produced no matter where they are born. In the icy waters around Greenland, Norway, Iceland, and Canada, up to 99 percent of juvenile cod carry the cold-adapted hemoglobin HbI2. Juveniles swimming along Ireland and southern Norway, meanwhile, bear the warm-water HbI1 morph. Each population is precisely adapted to thrive, feed, and grow in its own thermal neighborhood.

To reach adulthood, juvenile cod—powered by their site-specific blood chemistry—must succeed in feeding themselves and avoiding predators. They head into deeper waters over the continental shelf, where they devour mid-water capelin and other prey. Here too, the effects of water temperature play an outsized role in their lives. When food is abundant, an adult cod stays in warmer waters (45 °F) and snacks on capelin within 100 feet of the surface. The modest increase in heat shifts its swimming muscles up a couple of gears, permitting the cod to pack on the pounds with more vigorous hunting. But when food is scarce, its warmed metabolism burns quickly through the gains just made; in response, the hungry cod will descend to depths below 250 feet, where the cold (39 °F) dampens its metabolism and spares hard-won fat stores.³⁴ This strategy looks like a slower-speed version of the “hunt warm, rest cool” approach of juveniles: gain weight quickly when the buffet line is booming, and limit weight losses when meals are scarce. Cod, in effect, are picking the temperature that maximizes their overall growth.

When adults have bulked up sufficiently, to a satisfying length of 24 inches or more, they are finally ready to mate. This is no small undertaking, given the astronomical number of eggs involved. A female cod must abandon growth and direct all her energy to producing roe, not to mention migrating to the spawning grounds. Cod from Norway and Iceland quit their deeper feeding grounds and swim more than 500 miles to mate in nearshore waters. In part, they are driven to find water conditions that will accelerate egg hatching: in water of 47 °F, eggs will hatch in ten days, but they require four additional days at 43 °F, and more than twenty days when the watery cradle is a frosty 38 °F.³⁵ The less time an egg is bobbing helplessly in the water column, the greater its chances of survival, so migrating before spawning can be well worth the cost. Cod who live in less frigid seas, like those around Ireland, enjoy warm water without lengthy migrations, and the energy saved may explain why Irish cod are able to mature and spawn earlier in life.

Spawning itself begins with courtship, in which males display their readiness to egg-bearing females (disturbingly referred to as “ripe” in literature of a certain age). Males make low-frequency grunting sounds and flex their fins while crossing the female’s path. Populations from different parts of the world even have different dialects: cod from the Americas make repetitive banging sounds, while their European brothers favor a lusty growl.³⁶ If aroused by these vocal enticements, a female cod follows her singing suitor as he inverts himself, and they swim belly-to-belly while simultaneously releasing sperm and eggs. Cameras on remotely operated submersibles show cod packed so tightly that water can scarcely be seen between them. Amazing patterns emerge from the twisting tangles of mating fish. Acoustic imaging of massive spawning grounds off Newfoundland revealed enormous columns of cod, broad and dense pillars stacked side by side like chips on a poker table, each formed by thousands of fish.³⁷ When seen from the surface, these breeding columns can carpet the sea for miles.

Such abundance even now is breathtaking to behold. Several hundred years ago, before fishing took its toll, the spectacle must have been mesmerizing. Even the most highly respected scientists could mislead themselves into believing that cod represented an inexhaustible resource. One was no less a luminary than Thomas Henry Huxley, a brilliant biologist known as “Darwin’s Bulldog” for vigorously championing his friend’s theory of natural selection in stuffy Victorian England. Huxley firmly embraced the idea that the natural world was inherently balanced, and imperturbable. With regard to Canadian cod fisheries, which already were sending back whispers of declining catches, he made a fatal pronouncement. “I believe, then, that the cod fishery, the herring fishery, the pilchard fishery, the mackerel fishery, and probably all the great sea fisheries, are inexhaustible; that is to say, that nothing we do seriously affects the number of the fish.”³⁸ A report prepared by the Canadian Ministry of Agriculture, went further: “I say it is impossible, not merely to exhaust them, but even noticeably to lessen their number by the means now used for their capture … For the last three hundred years fishing has gone on in the Gulf of St. Lawrence and along the coast of our Maritime Provinces, and although enormous quantities of fish have been caught, there are no indications of exhaustion.”³⁹ The two could not have been more wrong.

Crash and Burn: A Tale of Two Fisheries

Any attempt to regulate these fisheries seems consequently, from the nature of the case, to be useless.

—Thomas Henry Huxley, Inaugural Address to the London Fisheries Exhibition

More than any other, cod is the fish that built the New World. Dried cod fed the Vikings on epic journeys to Greenland and Canada over a thousand years ago. Salted cod were a mainstay of the first-century Basque economy, although they had to dodge the ruthless Hanseatic League in northern European waters. At some point in the mid-1600s, Basque fishing boats established secret routes across the Atlantic and began exploiting fantastically rich cod fishing grounds on the doorstep of North America. A century later, when the French explorer Jacques Cartier became the first European to map the St. Lawrence seaway, he found more than a thousand Basque boats anchored there; unimpressed, he claimed the region for France. After the Mayflower pilgrims arrived, a hundred years after Cartier’s declaration, they survived on the generosity of the continent’s native peoples but also on the vast abundance of cod. Great fortunes were later amassed in what is now Newfoundland and Massachusetts, where treasured cod was commemorated on stamps and even currency. To this day in Boston, a lifelike cod sculpted of wood hangs in the State House of Representatives and casts an unblinking eye over the (only infrequently fishy) politics of that august chamber.

Early fishing boats in New World waters used lines and small nets suited to shallow seas, and they stayed near shore where young cod and columns of spawners could be fished. But things began to change with the industrial revolution. Coal and steam engines permitted boats to be larger, and they powered winches that could haul massive trawling nets. Trawls are either weighted to reach the bottom and dragged along on wheel-like bobbins, or pulled through the open ocean if the trawler’s captain has located a midwater school. Motorized vessels could also travel much farther in search of their catch. Prior to the application of steam, cod in New England were harvested by picturesque schooners from Gloucester and elsewhere. Schooners were notoriously unstable, however, and accidents were legion: in one year more than 1600 Gloucester hands were lost at sea.⁴⁰ Once steam trawlers with their larger nets and indefatigable power began landing sixfold more fish than traditional boats, the iconic schooners were hastily retired.

As early as the 1890s, still in the opulent dawn of the steam-trawler era, reports began to surface warning of declining cod stocks. Huxley’s optimistic pronouncements notwithstanding, the fact was that the fishing fleet could now catch cod faster than they could be replaced. In response to shrinking catches, the fleet scoured all known cod refuges, including the fabled Georges Bank. There, a shallow underwater platform extends out from Cape Cod, in places so near the surface that waves break upon its rocks at low tide. Georges Bank yielded some of the largest individual cod the world had ever seen, including a goliath measuring 6 feet in length and weighing more than 200 pounds. It beggars the imagination to think this giant was caught on a hand line. But as trawlers dragged nets repeatedly over the Bank and other productive cod grounds, they savaged the seafloor. Each net, as it rolled over the bottom, uprooted kelp, broke apart rock refuges, and inexorably, irreversibly destroyed the habitat that nurtured the great shoals of cod. Governments and ship owners refused to accept what was happening in front of their eyes: they were emptying the sea. From time to time, conditions would align, and huge catches would be landed. Everyone went on buying more and larger gear, and catching more fish, certain that the good times had returned. As Ralph Mayo, a US Fisheries Service biologist, remarked about their willful blindness: “You see some cod and assume this is the tip of the iceberg. But it could be the whole iceberg.”⁴¹

Dr. George Rose, who commented earlier about cod’s preference for cool waters, circles the decade of the 1970s as the end of cod in Canada. By that time fishing vessels from the collapsed Soviet Union and other postwar nations were “starved for protein” and desperate for new sources.⁴² They settled on the rich cod grounds off Newfoundland, forming by night a “city of lights of trawlers and mother ships and all the rest, just sitting over the overwintering and spawning grounds.” Previously, local fishing pressure had been constrained by what Rose wryly refers to as “berth control”: the number of boats was limited by the number of harbor slips where they could tie up, so the fleet never got overly large. But the new ships were massive enough to stay at sea for days on end, fishing with gigantic nets and without respite, and never returning to a harbor. During the heyday of the 1960s, Newfoundland waters were yielding well over a million pounds of cod each year.⁴³ But in the face of this industrialized onslaught, the fish that built the New World did not stand a chance.

Echoing decisions taken by Iceland, Canada in 1976 declared national control of waters within 200 miles of its coast, effectively halting foreign fishing. This move might have reduced fishing pressure on cod stocks and sidestepped the looming disaster. Heavily subsidized domestic fleets, however, quickly filled the void and continued the prodigious harvest levels. Lamentably for the fish, and the communities that relied on them, those 1960s harvests represented the high-water mark of the fishery. Just a decade later, catch levels had fallen below half their peak levels, and they continued to sink like a stone at sea. By 1992, the northern cod had plummeted to just 1 percent of their historical levels.⁴⁴ By any measure, after hundreds of years of bountiful harvests, the cod fishery had utterly collapsed. In the summer of that year the Canadian government issued a complete moratorium, ending a 600-year-old cod fishery, and the careers of some 30,000 fishers.⁴⁵

It did not have to be this way. As painful as catch reductions are for fishers, they should be less difficult to swallow than closure of an entire fishery. Overfishing and stock declines had happened elsewhere, but none were as catastrophic as in Newfoundland. In the 1980s cod populations nosedived in the Barents Sea, around the same time Bjarte Bogstad began studying the stock. “Cod is the most valuable fishery in Norway,” he states succinctly, “but we were definitely overfishing it. There was a situation in the late 80s, things were going quite bad, a combination of, say, climate issues and very hard fishing.” Faced with mounting evidence of a pending collapse, wise heads prevailed, and fishing communities swallowed the bitter pill. “Quite strong measures by the managers were taken [Norway and Russia manage the stock jointly], and the stock recovered quickly.” Bogstad seems pleased with the way the fishery is now managed, and his role in the process. “The last decade or so we’d gotten all those things in place, and also had a bit of help from mother nature … and it seems like it is stabilizing at a good healthy level. And that also means that if we fish it more lightly, then there are more fish that get older or bigger, so the average size of the fish caught gets bigger [‘big-ger’]. So when you fish more lightly then it’s more stable.”

Today, Bogstad and his fellow Norwegian scientists work diligently to detect declines in cod populations and rein in fishing pressure before the industry gets walloped by mother nature. To predict the future, they rely on harvest data, acoustical soundings, remote vehicle surveys, and advanced computer models. But they also rely on a humble instrument found in every home in Norway: a thermometer. Oceanographic research spearheaded by Bogstad revealed that cod responses to shifting temperature can be delayed by years, a startling discovery that permits long-range modeling of future cod abundance. “The temperature of currents in, say, south Norway or the Shetlands would translate into warm or cold conditions in the Barents Sea a few years later, which would then affect how the cod was doing,” he explains. “Then you get a different prediction horizon. If you can say that now it’s cold here, [you know] it will be cold up there in three, four years and there will be less cod in six years.” With disarming modesty, he notes that “expanding the prediction horizon is new.” New indeed, and extraordinarily valuable to one of the most important industries in Norway. If water temperatures today can help predict cod abundance years in the future, then quota reductions that trim the fishing fleet’s boats and crews can be planned well in advance and implemented carefully to minimize the hardship they might otherwise cause. Paying close attention to small shifts in temperature, it seems, can yield huge dividends for fish abundance and local livelihoods.

Filleted, Frozen, Flown, and Fried

In 1922, fifty years before Canada shuttered Newfoundland’s cod fishery, an American inventor established a pioneering seafood company that would revolutionize the industry.⁴⁶ He was struck by the twinkle of an idea while working as a trapper in Labrador, where he marveled at subzero temperatures that flash-froze fish which later tasted as fresh as the day they were boated. “The first winter, I saw natives catching fish in fifty below zero weather, which froze stiff as soon as they were taken out of the water. Months later, when they were thawed out, some of these fish were still alive.”⁴⁷ A native of New York, he soon realized this method could deliver fresh-tasting fish to the 6 million people living in his city, from as far away as northeastern Canada. His name was Clarence Birdseye, and Birdseye Seafoods would change the way the world ate fish. Soon the company, reconstituted as General Foods, would ship millions of pounds of frozen fish fillets—as well as berries, meat, and vegetables—across America, and around the planet. Now all they needed was a reliable source of fish, and they found it in haddock.

Haddock (Melanogrammus aeglefinus) is a close cousin of the Atlantic cod, and similar in many respects. Found from the Barents Sea to Iceland to Newfoundland, they overlap in depths and diets, though a few modest differences distinguish the two species. Haddock are much smaller, rarely reaching 3 feet in length, and are not as deep bodied: they look positively svelte next to a cod’s barrel-belly shape. The lateral line, pearly white on a cod’s flank, is replaced with a dark brown stripe in haddock. Between this line and the pectoral fin, they are marked with a distinctive dark blotch, like a thumbprint. Notably, haddock meat is more pinkish-tan than brilliant alabaster and has a slightly more fishy flavor, both traits making it decidedly secondary to cod as an eating fish. With the plunging decline in cod populations, however, fisheries turned to haddock. In England, the newcomer gradually replaced cod as the top seller in fish and chip shops. And after Clarence Birdseye’s company perfected fish freezing, the entire world would become acquainted with a new and wholly modern seafood: the fish stick.

Food fishes must be able to reproduce at a rate high enough to sustain their fishery, and in this regard, haddock absolutely excel. A large female can release up to 3 million eggs.⁴⁸ She lays them in batches on the ocean bottom, a few hundred feet below the surface, where they are fertilized by males. The eggs become buoyant thanks to oil droplets studding their exterior and float to the surface, where they bob vulnerably for a week or two until hatching. As with cod, vast numbers of floating eggs can be lost to predators large and small. The developing eggs also are extremely sensitive to pollution. Industrial chemicals from mines and other sources can stick to the eggs and make them sink, forcing larvae to hatch earlier, in fewer numbers, and suffer higher mortality once out of the egg.⁴⁹ Studies of cod larvae have shown the ocean’s rising acidity, a by-product of global climate change, also negatively impacts their early organ development and overall survival.⁵⁰ Oil spills, increasingly common in northern seas, further dampen the success of haddock reproduction. When floating eggs are exposed even briefly to raw oil, the larvae suffer skeletal deformations and damage to their heart that can be fatal.⁵¹ Here the natural buoyancy of the eggs works against them, as the raw oil droplets adhere to the gummy egg surface, so even a brief exposure to petroleum can lead to sustained exposure and danger.

Despite the risks, natural and human-induced, massive numbers of haddock larvae hatch on the high seas and develop into juveniles. They gradually make their way toward the continental shelf, where they feed as they grow into adulthood. In this they are aided by a built-in compass. Ingenious experiments carried out bravely in the North Sea showed that haddock larvae all oriented themselves to the northwest: when a floating chamber experimentally shifted the magnetic poles, all the larvae in the chamber turned accordingly to the new northwest.⁵² Their compass-following ability may help the larvae steer into favorable currents that transport them to their nursery grounds, northern seas where developing juveniles ravenously scour the rocky bottom for the clams and mussels, marine worms, sea stars, urchins, and brittle stars. When the myriad factors that affect hatching success, larval survival, and juvenile growth align favorably, haddock populations boom; when links in this reproductive chain are weakened, a crash can follow. Large fluctuations in haddock abundance are the result, which can span years or decades. Fishery catch data revealed colossal haddock schools in the 1920s plummeted just twenty years later, only to rebound dramatically by the 1950s.⁵³ For fishes like cod and haddock, conditions in the surface waters as well as on the bottom both affect the success of reproduction.

Haddock and their relatives are known to fishing boats as groundfish: they spend a substantial portion of their lives near the seafloor, where they forage and grow, court, and breed. Marine biologists call these fishes demersals, a term that encompasses rays and flounders, but also some of the world’s most important food fishes. Trawl nets hauled across the seafloor are designed to catch groundfish precisely because of their inclination for the bottom. Haddock are not found at great depths, typically less than 700 feet. When groundfishes like cod and haddock were fished with hand lines, it was nearly impossible to make a significant dent in their populations. But once trawlers began dragging the seafloor, the sluggish behavior of these animals meant one boat alone could scoop up thousands in a single net. Remote cameras reveal that cod will swim vigorously to escape an onrushing trawl but tire within a matter of seconds; once their pace flags, they are swallowed by the mouth of the net.

Cod and haddock may be closely related, but they are not free from sibling rivalry. Their distributions largely overlap, although haddock prefer more northern waters. Where they occur together, they compete. Larvae of both species share the same feeding habits of gulping down copepods, particularly just before sunset.⁵⁴ Like siblings grabbing cookies from the same jar, the more voracious the larvae of one species, the less food there is for the other. Cod tend to take the lion’s share of copepods, often forcing larval haddock to seek other food. In adulthood, that rivalry can be even more extreme. As Barents Sea cod grow larger, they graduate from capelin to demersal fishes, and their proclivities range from cannibalism to familial homicide: haddock can make up an astonishing quarter of the daily diet of large cod.⁵⁵ To some extent, a good year for cod is a poor year for haddock, and vice versa. The same applies to the effects of seawater temperature. When the surface waters of northern oceans warm, cod populations swell, but at the expense of haddock, which decline in numbers.⁵⁶ In the northwest Atlantic, however, neither population was able to resist the intense fishing pressure unleased in Newfoundland and New England: from a peak in the 1990s of more than 2 million tons landed every year, haddock and cod numbers nosedived to just 5 percent of those record harvests. In the case of cod, they have yet to recover. In the case of haddock, Clarence Birdseye’s frozen fish empire had to look elsewhere, and they turned to pollock.

Several fish in the sea are known as pollock, though all are members of cod’s clan. Haddock, whiting, hake, cod, and all pollock species are in a family (Gadidae) so important to global fisheries that its total landings are second only to the family of sardines, herring, and anchovies. The annual catch of Alaskan pollock (Gadus chalcogramma, also known as walleye pollock) from the Bering Sea alone routinely exceeds 3 million tons, bested only by 6 million tons of Peruvian anchovies.⁵⁷ True pollock is another fish so nice they named it twice, Pollachius pollachius, but its aliases include Atlantic pollock, European pollock, lythe, or even pollack. A close relative is Pollachius virens, itself known as a coley, coalfish, saithe, or even Boston blue. All three species (with their ten names!) resemble small haddock, with more or less speckling, and more or less pronounced lateral lines. They lack the haddock’s distinctive dark thumbprint but have a similar underslung jaw, triple dorsal fins, and moderately deep belly. They grow quickly, reaching reproductive age in as little as three years, and lay huge clutches of eggs. On the high seas, pollock larvae pursue their own version of “hunt warm, rest cool” to accelerate their growth. When food is abundant, they stick to warmer surface waters and feed voraciously; when plankton abundance dips, however, they descend into colder depths where the icy chill slows their metabolism until plankton blooms return.⁵⁸ The result is a fast-growing fish that multiplies rapidly and plentifully.

Initially passed over by fisheries in favor of cod, pollock’s stupendous powers of reproduction have made them a prime target of late. Their flaky, white meat is more strongly flavored than cod but still makes for excellent eating. Now one of the world’s largest fisheries, total North Pacific pollock harvests can reach 7 million tons yearly, valued in the hundreds of millions of dollars.⁵⁹ The catch from the Bering Sea represents one-fifth of all fishery landings in the United States.⁶⁰ Today, most of the fish sticks, fish fingers, frozen fillets, and fast-food fish sandwiches sold are pollock, while imitation crab meat and minced fishmeal known as surimi are made from processed pollock. Their roe and rendered fish oil are widely sold. Medical uses for pollock have been investigated as well, including a promising adhesive spray manufactured from pollock gelatin that helps seal punctures in damaged lungs of people suffering from emphysema.⁶¹

Alaskan fisheries targeting wild-caught pollock are some of the best managed in the world. In the past, fishing boats could operate within a fixed season, a now-obsolete mode of stock management that inevitably provoked what is known as a “race to fish.” In this mad dash, boats and crew work round the clock, regardless of risk or weather, to land as many fish as possible during the brief season. Pollock landings exceeded the target levels year after year, and the stock declined steeply in the face of repeated overfishing. Boat crews also suffered terrible rates of injury and even death as they labored in staggeringly dangerous conditions, hauling nets and gutting fish while icy walls of water smashed over slippery decks. Finally, a new policy of “catch shares” was implemented, in which a fixed amount of fish was awarded to each boat regardless of the amount of time taken to land it. Injuries and overfishing dropped almost immediately, and today the pollock stock—and the fishery it sustains—is well on its way to recovery.

A Horse’s Tongue as Big as a Barn Door

He knew that at 50 below zero water from the mouth made a noise when it hit the snow. But this had done that in the air.

—Jack London, To Build A Fire

One of the finest examples of successful fishery management is the governance provided by the International Pacific Halibut Commission, which implemented a catch share system in 1995 for this gigantic fish. Pacific halibut is one of the largest fishes in the sea, with record-setters over 8 feet long sagging the scales at an incredible 500 pounds.⁶² Such giants are dubbed “barn doors” for good reason, and some of these leviathans can exceed fifty years of age. Halibut are closely related to tropical flounders, those sideways-turned flatfishes with one eye that migrates across their head. Specifically, halibut are known as right-eye flounders, since the migrating eye ends up on the right side, which turns dark and faces away from the bottom. Occasionally this genetic code develops a bug, however, and anywhere from one in 20,000 Pacific halibut to an estimated 40 percent of California halibut (Paralichthys californicus) develop in reverse, with the migrating eye moving to the left side.⁶³ Naming of these flatfishes also develops a coding bug, with appellations like sole and flounder and dab being applied in restaurants with little regard for their scientific identity. Regardless of their name tag, most flatfishes spend their lives skimming the bottom of frigid seas, top predators on crustaceans, mollusks, and unsuspecting fishes.

During the winter, a female Pacific halibut will release up to 2 million eggs in moderately shallow waters over the continental shelf, avoiding the sea ice of the far north.⁶⁴ Prevailing currents, however, drag the floating eggs westward for two weeks until the larvae hatch, an aquatic conveyor belt transporting them hundreds of miles from the spawning grounds. About two months after hatching each larva has absorbed its yolk sac, and a month or so later the migrating eye arrives at its destination on the other side of the head.⁶⁵ It may take six months to a year for the fish to fully adopt its unique sideways stance; meanwhile, the developing juvenile begins swimming east, battling ocean currents all the while, just the beginning of a life that will be spent in perpetual motion. Despite its small size, the juvenile can log up to 2000 miles along the edge of the Aleutian Islands chain, and as far as northern Oregon.⁶⁶ An Atlantic halibut (Hippoglossus hippoglossus) can readily journey from Newfoundland all the way to the coast of Greenland. Along the way, the young halibut devours crabs and shrimp scooped from the bottom with its sideways mouth; by the time it reaches a couple feet in length, it will add juvenile pollock to its diet, as well as herring, capelin, cod, rockfish, and even octopus. Each winter, as sea ice advances and water temperatures plunge, young and old halibut alike move out into deeper, warmer water away from the continental shelf. Other flatfishes, like the winter flounder (Pseudopleuronectes americanus), are better protected in winter thanks to an antifreeze protein that courses through their blood.⁶⁷ But halibut, who lack such antifreeze, must flee the shallows when bottom temperatures approach freezing. In spring they stage a homecoming toward the shelf, re-dispersing over the flats that make for rich feeding grounds.

Halibut grow at a deliberate, unhurried pace. Juveniles spend three or four years mostly apart from adults, favoring shallow areas (less than 200 feet deep) with sandy bottoms that are well-defined nursery grounds. Around the age of five they can be considered young adults, though a few more years must pass before they even dream of mating. Males reach sexual maturity around eight years of age, while females do not begin reproducing until a full twelve years, practically the entire life span of an Alaskan pollock.⁶⁸ Given their leisurely development, halibut populations grow very slowly, a characteristic that mandates careful management of their fisheries. If too many are taken in a given year, the stock may require a decade or more to recover.

Commercial halibut fishing in the Pacific began in the 1880s, when the newly opened Northern Pacific Railway began shipping west coast fish to America’s populous east coast. Commerce overwhelmed judgment, and landings virtually collapsed just thirty years later, prompting Canada and the United States to join forces in managing the stock. The world’s first international effort to govern a fishery culminated in 1923, when the Pacific Halibut Commission was inaugurated, one year after Birdseye Seafoods was founded.⁶⁹ Careful consideration of stock size data, strict regulation of fishing effort, closure of nursery grounds, and the implementation of a catch shares program eventually stabilized the fishery and restored the population. Today, fishing for halibut is safer than ever, catch levels are sustainable, and prices are steady and high.

As in other groundfishes, the meat of a halibut is white and flaky, their muscles equally adapted for slow and steady swimming rather than high-speed dashes. Compared with a cod or pollock, however, the fillets are larger and more steak-like, reflecting the huge size of the fish and the added power needed to push a body of several hundred pounds through the water. Strong control of fishery landings combined with exceptional quality keeps prices high, and for the most part halibut is destined for affluent shoppers and expensive restaurants. Innovative products are being developed for the parts discarded by the fishery, however, to maximize the use and value of these majestic fishes. In Brazil, researchers at the University of Sao Paolo’s Food Engineering Department invented a technique for converting surplus Atlantic halibut skin gelatin into an edible film. Their goal is to replace the flimsy plastic used for shopping bags with a bio-polymer that will degrade safely rather than polluting the environment.⁷⁰ Given that plastic bags washing into the sea pose a dreadful threat for marine life, from whales to basking sharks to sea turtles, a biodegradable alternative would be a triumph for materials science and the planet.

Fifty years ago another engineering triumph helped propel pollock and haddock into the kind of widespread popularity that slow-growing halibut cannot match. Because pollock were frozen at sea in great blocks, the unwieldy fish bergs could not be separated into fillets. Some ingenious engineer realized that the frozen blocks could be sawed into narrow, rectangular bars of flaky, white fish meat. Employees of Birds Eye Foods were asked to name the new product, and “fish fingers” were introduced to the world. In England, where fish consumption had been on the decline for years, towns that relied on fishing were revitalized by the new frozen food.⁷¹ Fish fingers were launched in 1955, with the slogan “no bones, no waste, no smell, no fuss,” and 600 tons were sold in their very first year.⁷² Processing factories opened in the port towns of Grimsby and Hull, and jobs turning fish into fingers helped offset the collapse of employment caused by the cod wars. Today, as many as three-quarters of Brits get their first taste of seafood from a fish stick made from pollock, haddock, or even the venerated cod. Encouragingly, nearly all the fish that goes into these frozen delights is harvested sustainably, guaranteeing fish fingers will provide crunchy and flaky joy to hungry diners, and decent employment in traditional fishing towns, for years to come.⁷³