Chemical methods for fractionation of odorants produced by char smolts and tentative suggestions for pheromone origins.

Chemical procedures for fractionation of fish material containing odorants are described. These methods were developed with the aim of retaining the odorous activity of the material. Some of these methods were used to fractionate the intestinal contents of 1 1/2 year old smolts of a population of anadromous char (Salmo alpinus L.). The fractions were prepared, (a) for behavioural experiments to study possible attraction effects on mature char of the same population during the migration season, and (b) for testing in physiological experiments to elucidate the olfactory potency of the different fractions. The nature and origin of the attractive substances are discussed.