MATURE MALES OF ARCTIC CHARR, SALVELINUS-ALPINUS, RELEASE F-TYPE PROSTAGLANDINS TO ATTRACT CONSPECIFIC MATURE FEMALES AND STIMULATE THEIR SPAWNING BEHAVIOR

We examined the behavioural and biological functions of prostaglandins (PG) of F-type as a chemosensory signal during spawning in Arctic cha rr. Immunoassay revealed F-type PGs in water inhabited by ripe charr o f both sexes performing spawning-related acts. High concentrations of immunoreactive PGFs seemed to coincide with male spawning activity. Ri pe isolated males were more odorous to other charr (as assayed by EGG) than either females or immature charr. When these males received chem ical cues from ovulated females, they increased their release of odora nts, including F-type PGs, into the water. PGF(2 alpha) at concentrati ons of 0.1 nM attracted ovulated females and ripe males. It also stimu lated digging behaviour in mature females. It is concluded that F-type PGs or their derivatives are released by ripe males on the spawning g rounds to attract females and elicit their spawning behaviour.