jb-b's brief notes about Seatrout
Sea Trout
Salmo trutta
Watercolor (14" x 4") by John Boyd-Brent. ©
Brief Description and life cycle
- Once thought of as a distinct species, Sea trout are now classified in the same family and with the same name as brown trout: salmo trutta
- Similar in looks to the brown trout, sea trout, like Atlantic Salmon, hatch from eggs deposited in fresh water.
- Hatching time is from one to three months depending on availability of food consequent to water temperature.
- The hatchling, known as an alvelin, has a yolk sac which has a store of food which can last for about a month.
- When the yolksac is exhausted, the fish, now known as a fry, begins to search for food. Often found in shoals it begins to acquire camouflage and looks almost indistinguishable from similar sized brown trout. At this stage it is known as a parr.
- As a parr it lives in the river on a diet of small insects, nymphs, caddis fly lavae, etc. until after about three years it begins to become more silvery than a brown trout.
- Now known as a smolt, it develops changes to the gills to enable it to cope with salt water.
- Its first migration usually takes place in early summer, and once at sea it feeds voraciously putting on weight in direct relationship to the amount of food available.
- Sometimes at the end of that summer, on reaching a size of about 1lb. or more, it will return to fresh water.
- In Scotland it is now known as a "Finnoch" or sometimes a "Herling".
- Often it will spend longer at sea, perhaps three or four years, before returning for the first time.
- On returning it may spawn, or sometimes go back down to the sea without spawning.
- A Sea Trout can live up to about twenty years (most live a lot less longer) during which time it may return to spawn almost every year.
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