It’s December. After a cold, wet spell my thoughts turn to the rivers and to a very special event taking place just out of sight of our everyday lives; the peak of the sea trout’s return to their spawning grounds – a magical, shape-shifting journey.

The life cycle of sea trout is intriguing. Unless you are an angler, it is a little surprising to learn that here in Sussex we have a fish that migrates between fresh and saltwater just like the Atlantic salmon, to which they are closely related.

The cycle begins when trout hatch from piles of gravel called redds on the beds of inland streams. Redds are created by the adult female fish and are where she lays her eggs, which are then fertilized by the male.

Sea trout spend a couple of years in the rivers before their physiology changes and they become silver with black and red spots. They then head downstream to the sea where they become saltwater fish. The sea provides more food than the rivers so sea trout are able to grow much bigger than non-migratory brown trout. The latter make the rivers their home and do not go out to sea, although they are the same species as sea trout. After a year or two at sea, come November and December, sea trout begin to make their way back to the river where they hatched, using olfactory clues, in order to breed.

Various cultures revere the salmon, it has a reputation for being a magical fish. In Ireland it is associated with wisdom, knowledge and power. For Native Americans the fish symbolised determination, prosperity and renewal. I haven’t found any folklore or myths specific to sea trout, although there is a lovely Japanese myth about Ainu, a giant trout that carried the world on its back and caused the ebb and flow of the tides by sucking water into its mouth and then letting it go.

The Ouse and Adur Rivers Trust (OART) works to protect the rivers Adur and Ouse and their catchment areas to ensure they are healthy for sea trout and all the other wildlife that should thrive alongside them. Each year during the winter months as an OART volunteer, I go and survey some of the Sussex river tributaries for the presence of redds. If I am lucky I might occasionally see a few determined trout leap up a weir, which is always an exciting spectacle. The sea trout in Sussex are some of the largest in the country. I have also helped with tree planting with OART along the Adur on the Knepp Estate in West Sussex. OART also works with the Environment Agency, carrying out water testing for pollutants and agricultural run-off in the rivers.

For more information about the fascinating life story of these amazing fish and the important work of OART visit the OART website.