1979 - 2005 Centre for Environment, Fisheries & Aquaculture Science (Cefas) Phenological changes in growth in cod as an indicator of climate change

Cod ( *Gadus morhua* ) stocks in the North Sea have declined to historically low levels of abundance and are considered to be suffering from a reduced ability to reproduce. In this situation there is considerable concern about the way in which climate change may affect the ability of these stocks to recover. Theoretical studies based on the effects of temperature on growth and spawning success or recruitment suggest that increases in temperature may result in the decline and subsequent disappearance of cod from the North Sea. Consequently it is useful to look at long time series data to see whether there is evidence for direct impacts of temperature changes on cod. Data includes otolith age, length and growth increment measurements, as well as high resolution photographs.