Our clean rivers are home to many different fish including salmon and trout. Salmon lay their eggs in the upper parts of rivers in gravel beds where there is lots of oxygen in the water.
When the eggs hatch the tiny fish live in the river for a couple of years growing bigger until they change into a ‘smolt’ with silver scales and head off to sea. They have to change the way their body deals with water as they move from fresh to salt water.
Watch a journey through the year in North Northumberland, showing some of the things you can expect to see and enjoy in each of the seasons including Salmon leaping.
In the sea they feed for 2 or more years and then incredibly return to the river they were born in. They change the way their metabolism again to cope with coming back to fresh water and swim upstream to mate and start the cycle all over again.
You can see these adult fish swimming upstream in late summer and autumn when they have to leap to get up waterfalls and over obstructions. Some trout (sea trout) also make this change and swim out to grow and feed in the sea before returning. Others of the same species (brown trout) stay in their home rivers all their life.
We are not totally sure what triggers some to become sea trout. Both salmon and trout are bony fish, but we also have a much more ancient type of fish with cartilage instead of bone. Lamprey look a bit like eels and have no jaws but a sucker for a mouth. They live as immature larvae (ammocetes) in mud and fine gravels until they turn into adults. They are rare and protected and are found in the rivers in the Cheviots.
