SUFFOLK WILDLIFE TRUST: Delicious flatfish is a sensitive sole that suffers in the cold

Sole. Picture by Derek Haslam
Sole. Picture by Derek Haslam
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The Dover sole (Solea solea) has always been appreciated for its delicious taste but there is a lot more to this lively flatfish.

Among other things, it can live for over 30 years, has both eyes on its right side and dislikes cold water. It occurs on sandy sediments all along the Suffolk coast and is widely distributed from Denmark down to the Mediterranean.

Every spring, sole move inshore to breed. The eggs and larvae drift into shallow water and live their first year or more as juvenile fish in sandy bays and estuaries. The small larvae start out with eyes on each side of their head feeding on plankton. Then an amazing adaptation occurs. As the larvae grow their left eye migrates across until both eyes are on the right hand side of the head. At the same time, the little fish settle out on the seabed and live the rest of their lives as flatfish lying on their left side with just a pair of beady eyes showing above the sand. They develop their characteristic white underside and sandy coloured back as camouflage against predators such as shrimp, crabs and when bigger other fish.

As they grow, the small sole move into deeper water feeding mostly at night on small worms and shells dug out of the seabed. Over their lifetime they can grow to 40-50cm in length and 4kg or more in weight although most are caught when under five years old.

Sole are surprisingly sensitive to cold water. In winter, if the sea temperatures fall below 3-4C sole can die and in the very cold winters of 1947/48 and 1962/63 large numbers were killed off. Fortunately, the stock recovered and it remains an important predator in the ecology of sandy sediments as well as crucial to the economy of the local fishing industry.

For more information about Suffolk Wildlife Trust call 01473 890089 or visit www.suffolkwildlifetrust.org