Otolith microstructure reveals consequences for juvenile growth of fractional spawning in an invasive goldfish Carassius auratus (Linnaeus, 1758) population

摘要

The consequences of fractional spawning on the early-life growth rates of invasive goldfish (Carassius auratus) from the Qinghai-Tibet Plateau were studied using the otolith microstructure of samples collected in June 2011. The effect of the estimated hatching date on the subsequent growth of individual fish was determined by back-calculating their number of growth days, daily growth rates and the onset of their second growth season. The number of growth days in the first growth season ranged from 93 to 186 days. Following hatching, daily growth rates increased rapidly to a maximum of 0.55 mm days(-1) before declining to 0.09 mm days(-1). The effect of the duration of the first growth season on individuals was significant (P 0.01), with later spawned fish having faster growth rates. These later spawned fish were, however, still significantly smaller in body length at the end of the first growth season (37 +/- 4 mm in late hatched fish vs 55 +/- 9 mm in early hatched fish). However, the smaller, later hatched fish started growing earlier in their second growth season than all other fish (P 0.01) and subsequently achieved larger growth increments (P 0.01), suggesting that the larger, early-hatched fish were investing more resources in gonadal growth than somatic growth in their second growth year. Thus, this invasive population revealed considerable plasticity in their early-life growth rates that were associated with the hatching date, potentially having substantial effects on their development in their second year of life.