As fish are poikilothermic (i.e. 'cold-blooded'), the onset of winter leads to a dramatic slowing of metabolic processes and feeding activity. To conserve body reserves, which will see them through the winter, fish typically seek refuge from the elements (e.g. currents, wind and wave action) in deeper, slower water or around the littoral margins where cover is provided within and above their water column by overhanging trees, stands of emergent vegetation and collections of submerged branches and decaying vegetation.