The UK's principal buyer and processor of seafood, Young's Bluecrest, is warning its catering customers to expect price increases of between 6 and 10% on fish products, as commodity and raw material costs continue to esculate. Worldwide consumer demand for fish continues to be buoyant and in the UK seafood sales were up by 8% in the 12 months to September 2001.  however, market prices on core species such as cod, haddock and pllack have risen by around 10% and - along with most other food manufacturers - Young's is also experiencing inflation on other key commodoties, such as flour, oil, dairy produce and potatoes.  Price increases are already starting to feed through to the trade.