Stained-glass language

At the LRB, Richard Hamblyn offers a delightful account of Richard Shelton's book on the Atlantic salmon:

‘Smolt’, ‘grilse’: as Richard Shelton observes, salmon are spoken of in a ‘stained-glass language’ of their own, their life stages marked by an ichthyological lexicon unchanged since Chaucer’s time. Born in a ‘redd’, a shallow, gravel-covered depression dug by the female in the days before spawning, newly hatched salmon begin life as ‘alevins’, tiny, buoyant creatures with their yolk sacs still attached. Once the yolk has been absorbed, the fast-growing fish, now known as ‘fry’, are able to feed for themselves, turning instinctively to face the current in order to graze on drifting insect larvae. Some months later, the juvenile salmon, now known as ‘parr’, move downstream to deeper water, where their markings grow darker and their shapes more distinctively salmonoid. By the following spring, most parr have begun the first of the transformations that will enable them to cross the hydrological boundary from the river to the sea: once their kidneys have been primed to reverse their usual function of taking in salts and excreting dilute river water, their skin colour brightens to reflective silver through a microscopic coating of guanine crystals, and their body shapes fill out in anticipation of the long voyage ahead. It is then that the ‘smolts’, as the fish are now known, are ready to head downriver to the sea.