Herring

Even as the Cold War was winding down in the 1980s, suspicious subaquatic noises in the waters off southern Sweden suggested persistent enemy submarine activity. Soviet incursions were nothing new. But this time, no detection system could pick up any vessels. For a decade and a half, the mysterious acoustic phenomena remained an irritant in relations between Stockholm and Moscow. “It sounded like someone frying bacon,” said Marcus Wahlberg, an academic who in 1996, was brought in to study the bubbling sounds. He was the first civilian to hear them – and identify them. They weren’t submarine noises: they were herring farts.

Herrings are oily, cold-ocean creatures, with dozens of Atlantic and Pacific subspecies. Like most fish other than sharks and fellow cartilaginous species, they have swim bladders. These function like internal balloons: by storing or releasing gas, they help regulate the creature’s buoyancy. Herrings, however, have one unique feature: their swim bladder connects directly to their anus. Gas is also expelled under stress – for example, when schools, which may count millions of individuals, brush past potential predators. It was, quite simply, herring flatulence that stumped the Swedish defence establishment. The herrings’ sudden presence in the area exemplified a pattern of abrupt appearances and disappearances that has spurred talk of miracles through the ages. One theory has it that as a new age cohort matures and becomes dominant in a herring group, it sets the direction of travel. How the cohort communicates this, assuming the hypothesis is correct, remains unknown. Then again, almost everything about how fish communicate – and they do, amply – has yet to be revealed.

Moving as it does in million-strong packs, the herring resembles its relative, the anchovy. Gastronomically and culturally too, the analogy stands: the former is to the north what the latter is to the Mediterranean. Economically, the herring, somewhat larger than the anchovy and richer in fat, has been even more significant. A staple source of calories throughout the upper part of the northern hemisphere, it was fiercely fought over by the English (later British) and Dutch navies in the seventeenth and eighteenth centuries. And unlike the anchovy, which has gentrified in recent decades, herring has remained a people’s fish. Take the French harengs pommes à l’huile, which consists of just that: herring fillets, boiled potatoes and warm oil, plus raw onions. The most you’d get as a bourgeois concession is a little parsley. In Germany, folk wisdom associates the rollmop, where the pickled fillet is tightly rolled around a gherkin, with hangover cures. Over in Poland, the traditional way of serving herring is just lightly salted, or perhaps with cream.

While such austerity may seem quaint, it still tends to define herring. The lack of accoutrement may reflect an empirical understanding that the fish is densely nutritious in its own right, an onslaught of vitamin D and fatty acids. In Alaska, and in what is now Canada and the northwestern US states, First Nation tribes rendered herring for its oil. So did, an ocean and a continent away, the Swedes, who also burned the oil for lighting and used it to fertilize the land. On the plate, because of herring’s oleaginous intensity, garnishes that work best are either starchy flavour absorbers such as potatoes, or else sharp, acidic competitors. In northern Europe, accompaniments may involve tomato, horseradish or hovmästarsås, a dill and mustard sauce. Sour apple is another great pairing, and so is rémoulade, a loose mustardy mayonnaise with shredded celeriac and chopped gherkins.

Few fish are quite as versatile as herring: it can be grilled, pickled, marinated, smoked and so forth. Beyond the diversity of experience, there’s a health aspect to this extent of processing. Herrings are prone to nematodes, a type of parasitical roundworm that can cause anaemia and debilitating gastro-intestinal illness in humans. These days, nematodes are killed by freezing the fish to 45° C below zero; in the past, the job was done by brining or other cures, or by heat treatments. The most notorious method may be the one involved in surströmming, a months-long fermentation treatment perfected in (yet again) Sweden: the result is, to many outsiders, evocative of a putrid stink bomb.

Oddly enough, it’s the one upper-class incarnation of herring, as cold-smoked breakfast kippers for the English gentry, that involved only light brining and was thus insufficient to eradicate the roundworm. Or, who knows, it may have been a subconscious way to invite the unforeseen into the regulated setting of the stately home – an aristocratic form of dicing with discomfort.