AGE AT MIGRATION FROM THE SEA OF JUVENILE GALAXIAS IN NEW-ZEALAND (PISCES, GALAXIIDAE)

Daily growth rings begin to form in the otoliths of juvenile galaxiids several days before they hatch. These rings show that life at sea las ts for 103-202 days in Galaxias maculatus (N = 99), 93-128 days in G. fasciatus (N = 44), 110-155 days in G. brevipinnis (N = 70), 113-137 d ays in G. argenteus (N = 10), and 120-136 days in G. postvectis (N = 5 ). Return to fresh water takes place in the spring following spawning the previous autumn-winter. The peak spawning period for G. maculatus, G. fasciatus, and G. brevipinnis appears to be during April to mid Ma y, and perhaps to mid-June in G. postvectis and G. argenteus (though d ata for the last two species are meager). The tendency for fish to be smaller at migration towards the end of the migration period is associ ated with their return to fresh water at a younger age (rather than be ing caused by slower growth). The semelparous, largely annual life cyc le of G. maculatus, with its high relative fecundity, small eggs and l arvae, is compared with the iteroparous, perennial life cycle of the o ther species, with lower relative fecundity, and larger eggs and larva e.