The Sea Trout of Devon’s Rivers
On the rivers of Devon — the Tamar and its tributaries, the Dart, the Teign, the Torridge and the Taw — the sea trout goes by an older, local name: peal. It is one of the most enigmatic fish an angler can pursue, and the source of that mystique lies in its biography. The peal is not a separate species at all but a brown trout, Salmo trutta, that has chosen a different life: one that carries it from a gravel redd high on Dartmoor or Bodmin, down through estuary and tide, out into the sea to feed and grow, and back again to spawn in the very water where it hatched. Understanding that journey is the closest thing an angler has to understanding the fish.
Eggs in the gravel
The cycle begins in late autumn and winter, when adult fish run the upper reaches of the river to spawn. The hen cuts a nest, or redd, in clean gravel, fanning out a depression with her tail before depositing her eggs to be fertilised by an attendant cock fish. She covers them over, and the ova lie buried through the cold months, incubating slowly. The colder the water, the longer they take. Sometime between mid-March and early May the eggs hatch into alevins — tiny, yolk-sac fry that remain hidden among the stones, living off their own reserves until they are ready to wriggle up into the current and begin feeding.
The spent adults, known as kelts, have a harder time of it. Many are exhausted by spawning and a proportion will die. But — and this is the first great distinction between sea trout and salmon — a substantial number survive, drop back downstream, and recover at sea to spawn again. The sea trout is iteroparous, meaning it can repeat the whole cycle several times over a long life, rather than dying after a single spawning as most Atlantic salmon do.
Years in fresh water
Once feeding, the young fish are called fry in their first year and parr thereafter. Through this stage they are, to the eye, ordinary little brown trout, dark-flanked and spotted, holding station in the riffles and runs and taking the same diet of nymphs, caddis larvae and drifting insects as their resident cousins. Indeed, at this point there is no telling apart the fish that will stay in the river for life from the fish that will go to sea. The two forms are the same species in a kind of dynamic equilibrium, and whether an individual migrates is determined by a mixture of genetics and environment — chiefly, it is thought, the availability of food. Where the river is poor, the pull of the richer sea is stronger.
This freshwater apprenticeship lasts, in West Country rivers, somewhere between one and three years, and occasionally longer. During it the young fish learns the river and builds the size it needs to survive the transition ahead.
Becoming a smolt
The change that readies a trout for salt water is called smoltification, and it is a genuine physiological transformation rather than a simple growth spurt. As the fish reaches roughly 13 to 18 centimetres, its body remodels itself: the gills develop special cells able to excrete salt, the kidney and gut adapt to conserve water rather than shed it, the camouflaging spots fade, and the flanks turn a bright migratory silver. The fish is now a smolt.
Triggered largely by lengthening spring days, and helped along by river flow and temperature, smolts gather into loose shoals and slip downstream to the sea, usually under cover of darkness. On most Devon rivers the peak of this run falls in March, April and early May, though some fish leave in autumn instead — a hedging of bets that spreads the population’s risk across the seasons.
Out to sea
At sea the trout feeds voraciously on sandeels, sprats, shrimps and small fish, and grows far faster than it ever could in the river. This is why a sea trout is so much heavier than a resident brown trout of the same age and parentage. Unlike salmon, which range across the North Atlantic, sea trout tend to stay relatively local, often patrolling within a few hundred metres of the coast — though some populations are now known to travel surprising distances.
How long they remain at sea varies. Some return after only a few months, before their first winter, as small immature fish; in the West Country these little first-returners are the school peal, the shoals of modest fish that historically carpeted river beds from late June into early September. Others stay out for one, two or more years before coming back as larger adults. The biggest specimens are generally the older fish that enter the river early in the season.
The return
The Devon season has a recognisable shape. The first and largest fish tend to push in from mid-May, with the great clouds of school peal arriving from late June into July.
A long and repeating life
Having spawned, the survivors return to sea to feed and recover, then run again the following year. Scale-reading has shown West Country and Border fish spawning as many as four or five times across their lives, which is how sea trout can reach the ages — up to around nine or ten years — and the double-figure weights that make them such a prize.
It is a life of remarkable plasticity, and a fragile one: it depends on clean spawning gravel, healthy nursery streams, passable estuaries and a productive sea. The recent slump in school peal on rivers such as the Dart is a reminder that this elegant cycle, repeated in Devon’s rivers for millennia, holds together only as long as every stage of the journey remains intact.
.