Local variation in the timing of reproduction and recruitment in a widely distributed diadromous fish

Īnanga (Galaxias maculatus) is a widespread freshwater fish, found around coastal New Zealand, Chatham Islands, southern Australia and South America, exhibiting both diadromous land-locked life history patterns. We assessed population size structure, at maturity, timing of reproduction, post-reproductive survival in the Waikouaiti Kakanui rivers, two regionally important G. maculatus populations Zealand. Size maturity varied between rivers sexes, with males generally maturing smaller sizes than females. The reproduction recruitment was observed to vary across relatively small spatial scale. Population length-frequencies indicated that exhibited annual dynamics, most individuals spawning their first year, then apparently dying soon afterwards (as by marked drop post-spawning abundance). However, few recently spent or resting gonads were present over winter months, indicating some survival. There lower frequency exceptionally large (putatively 1+) reported for other Zealand elsewhere, suggesting over-winter following varies. Based on variation characters scales, we suggest management should be based catchment level information.