The temperature of North Sea waters in October averaged 14.2 degrees Celsius (57.6 Fahrenheit) -- or 2.4 degrees higher than the average calculated for the same month from the beginning of the measurements in 1968, and 1993, according to the study by Germany's Federal Office of Maritime Transport and Hydrography.

The reading was also almost one degree higher than the last water temperature record, set last year, according to the Hamburg-based office.

North Sea water rose 4.1 degrees Celsius during a July heatwave in Germany, and exceptionally warm weather in September and October prevented the sea from returning to its usual temperature, the study said.

The milder waters are part of a longer North Sea heating trend registered since 1988 -- the longest and most intense since sea samples were first tested in 1873.

Nor has the warming trend been offset by a subsequent cooling one, according to the report, a phenomenon that worries researchers.

Among other potential fallouts, plants and fish native to warmer regions of the Atlantic Ocean, such as the Bay of Biscay, may migrate to the North Sea.

All rights reserved. � 2005 Agence France-Presse. Sections of the information displayed on this page (dispatches, photographs, logos) are protected by intellectual property rights owned by Agence France-Presse. As a consequence, you may not copy, reproduce, modify, transmit, publish, display or in any way commercially exploit any of the content of this section without the prior written consent of Agence France-Presse.