Tucked away at the end of Waitrose car park and next to the Hempstead Meadows Nature Reserve in Uckfield is a structural feature which you may not have noticed.
It is a fish pass, or fish ladder, built, says ecologist Martyn Stenning, to enable migrating fish to by-pass the Roller Mill.
The fish pass looked particularly striking on a frosty morning earlier this week and Martyn, now semi-retired from his role at the University of Sussex, tells its story here.
He says the late Jim Smith, also known as ‘Jim the Fish’ a water bailiff on the Ouse (and Uck) for many years and a well-known local character, claimed he had the fish pass built many years ago.
Before that the Roller Mill had prevented the migration of fish to breeding grounds near High Hurstwood where the Uck rises.
Martyn and Jim were both members of the Sussex Ouse Conservation Society, since renamed the Ouse and Adur Rivers Trust.
Martyn says: “The fact is, the Sussex Ouse and its catchment is an historic breeding ground for sea trout. These migratory forms of the brown trout migrate between the English Channel, where they grow, and the stream tributaries of the larger rivers where they breed.
“I used to take students to the Uck in Uckfield every year to survey the animals living in the water, and we often used to get baby trout in those samples.
“The fish pass is designed to allow the trout and other migratory fish such as eels, for example, to swim up to the headwaters.
“The migration up-river happens during the winter when rivers are at their highest flow.
“The trout then pair up and the female makes a nest in the gravel, this nest is called a redd; she then lays her eggs in the nest while the male fertilises them with his sperm.
“The adult trout then return to the sea until next year.
“The eggs hatch after from 60 to 97 days depending on water temperature. The baby fish spend some time growing in the river to about 12 – 18 cm when they are called ‘smolts’. They then slowly make their way to the sea where they continue to grow until they mature to breeding age and the cycle repeats itself.
“The Ouse and Uck are well known as sea trout rivers. Sea trout can grow larger than permanently river dwelling brown trout, but are very closely related.”
Some links shared by Martyn:
Read more about the brown trout on the Wild Trout Trust website.
The chairman of the Ouse and Adur Rivers Trust, Hew Prendagast, has recently written a book: Ouse and Uck 2019. A website about the book can be found here.
And here’s more about the late ‘Jim the Fish’ in an obituary carried in The Guardian.