New article: Biology and conservation of Mediterranean sticklebacks
We first focused on growth, condition and reproduction of stickleback, using data from over 6000 measured fish that were captured along almost 100 fishing events throughout the year. We found that populations were strictly annual, with most adults dying immediately after their first reproduction and no evidence of survival up to the second reproduction season. Adult post reproduction mortality coincided with a period of extremely low somatic condition. Juveniles growth showed an almost complete stop during summer, when somatic condition was also low, but experienced a high and continuous growth during autumn, winter and early spring. This growth pattern differed from that of sticklebacks elsewhere, which usually stops in winter, and from that of other native species in Mediterranean streams, which does not show the summer growth stop.
We then analyzed stickleback habitat use using fyke nets during spring and summer in 118 sites. Stickleback populations were detected in 50 sites, occupying mainly intermediate locations along fluvial gradients. The presence of abundant aquatic vegetation was the main factor related with both stickleback presence and the abundance of its populations. This could be related the fact that male sticklebacks build nests, mainly from vegetation material, where they guard eggs from one or several females. Stickleback abundance was also negatively related with that of invasive fish and crayfish species. Stickleback tended to occur in native-dominated fish communities, being almost absent from lower stream reaches, which bear high abundances of invasive fish species.
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