Encyclopedia and the net until we found you. I'm not surprised that you haven't found a great deal of information on this matter. I don't have much background on that topic myself. Here are some items.
Whales tend to excrete more frequently than land animals.
Excretions are marked by brown clouds often seen trailing whales, indicating the liquified state of the excretion. It is not known if excretion may at times be a form of communication among whales as with some land animals. Considering excretory systems as part of whole ecosystems, whale excrement is a vital organic nutrient for maintaining microorganic life of the oceans.