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 lasts 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 days 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 May, and perhaps to mid-June in G. postvectis and G. argenteus (though data for the last two species are meager). The tendency for fish to be smaller at migration towards the end of the migration period is associated with their return to fresh water at a younger age (rather than being caused by slower growth). The semelparous, largely annual life cycle of G. maculatus, with its high relative fecundity, small eggs and larvae, is compared with the iteroparous, perennial life cycle of the other species, with lower relative fecundity, and larger eggs and larvae.
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Document Type: Research Article
Publication date: 1994-03-01
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