The high cost of fish, caused by the El Niño weather phenomenon, has held back profits growth at fish-and-chips group Harry Ramsden's.
The El Niño effect has turned the deep waters off Norway and Iceland warm, pushing fish prices up to their highest level for seven years.
Harry Ramsden's chairman John Barnes said the changes in the water temperature had reduced trawlers' catches, causing prices to rise by 70%.
"If prices had not gone up we would have had better profits," he confirmed.
Many other restaurants fear that their customers will be put off by the higher prices they are being forced to charge for fish (Caterer, 25 June, page 14).
But Barnes was confident of better times ahead: "Apparently El Niño is usually followed by La Niña, which turns the waters cold and means more fish."
Pre-tax profits for the group for the six months to 29 March were up 14% to £229,816 against the same period last year, while sales almost doubled to £4.9m.