Trout

Species of trout used to be geographically circumscribed: rainbow trout on the western edges of North America; brook trout in the Great Lakes region; brown trout in Europe. No more. Such has been the extent of global introduction for food and sport that these three main species – there are dozens altogether, subspecies included – can now be found in most latitudes. Breeding came early and energetically. As far back as the 1870s, in a novel instance of multipurposing public buildings, trout were reportedly being hatched from eggs in the basement of San Francisco City Hall. (The Great Earthquake and fire of 1906 killed 3 000 people and left City Hall in ruins. What happened to the fish, assuming any were left, history doesn’t tell us.)

In the wild, trout live primarily in lakes and rivers. Depending on species and habitat, they can measure just 30 centimetres or up to four times that. Their weight might vary by a factor of 20. They’ll run silver to gold in colour, or grey streaked with pink. You may find them covered in black or bright red dots. The alarmingly named cutthroat trout (Oncorhynchus clarkii) is stained crimson around its jaw and gills.

Remarkably, given this natural variety and global reshuffling, trout species remain distinct. Hybridization does occur in captivity, but far less in the wild, where it’s been shown to curb reproductive fitness. Diversity within species can meanwhile be high. The brown trout swimming in British rivers alone are thought to be genetically far more diverse that the entire human race. Some brown trout may go to sea for a while, in which case they’re called, intuitively enough, sea trout; most don’t. And much like some human communities who’d sooner identify with brethren across the border, brown trout will snub other trout, but happily interbreed with salmon.

The salmon-trout kinship is well established: both belong to the Salmonidae family. Salmon is predominantly oceanic; trout, largely riverine. Consequently, trout’s flavour echoes that of salmon as semi-skimmed milk echoes full-fat: substantially of a piece but subtler, as if holding back. At its best, trout tastes almost floral. Mild yet characterful, its flesh is a blueprint for versatility. Tomato, which features in two of our recipes, is a frequent partner: its acidity sets off the sweetness of the fish. Yet trout will easily accommodate more adventurous companions. In the French city of Reims, in Champagne country, Chef Kazuyuki Tanaka has been known to pair the Arctic char (Salvelinus alpinus) – a trout found in the cold lakes of Europe and Canada – with fermented fennel or cocoa. Indeed, something about trout seems to incite flights of fancy. One contemporary source has the nineteenth-century composer Franz Schubert improvising his most famous lied, Die Forelle (The Trout), after partaking liberally of Hungarian red wine. In Schubert’s song, the frolicky trout, exhilaratingly free in the first two stanzas, is subdued by a ruthless angler in the third. Musical audiences may squirm at this turn of events. Gourmands, though, will rejoice: for them, trout’s most beguiling note is the one struck post-mortem.