Juveniles

We have been working in mangrove creeks of Charlotte Harbor since early 2002 to determine (1) habitat use patterns and survival, and (2) effects of habitat degradation on juvenile snook. We are using PIT (Passive Integrated Transponder) tags, and a remote antenna that reads the PIT tags, to estimate of juvenile snook survival. It's the same technology as automatic toll-booth systems: the PIT tag we put into the snook is the same as the toll transponder you place in your car, and the antenna, which is stretched across the creek, is like the tollbooth. From the tag and recapture data, we can estimate snook movements and abundance. So far, it appears that degradation of mangrove creeks causes a decline in juvenile snook abundance. In related research, we're determining whether abundances of other fishes (like killifishes and mojarras) differ among creeks. In ongoing research we're examining whether juvenile snook diet differs among the creeks.

Adults

Southwest Florida frequently experiences a toxic algal bloom (red tide) caused by a naturally occurring dinoflagellate, Karenia brevis. This organism has been causing red tide blooms for knwon history, but it is unclear whether recent human coastal impacts have increased the frequency and severity of red tides. Unfortuntaely, red tide occurs mostly during the summer, which is when snook are along Gulf Coast beaches for spawning season. Although snook is an important recreational species in Florida, we don't yet know the effect of red tide on snook spawning behavior. We are using PIT tags and sonic tags to track snook movements during spawning season during years without red tide and years with red tide to determine how red tide impacts their spawning success. Observational data from biologists and fishing guides suggest that red tide causes snook to change their distribution, which may force them to move to areas that are not conducive to spawning or result in higher larval mortality, thus resulting in recruitment failure (i.e., no juveniles next year).  Our ongoing work aims to determine the extent red tide impacts spawning snook.

All material copyright Aaron Adams 2007, 2008, and beyond, unless noted.