By Courtney Saari, Dave Blewett, and Tim MacDonald
Fisheries scientists from FWRI’s Fisheries-Independent Monitoring (FIM) and Fish Biology section have been collaborating with scientists and managers from the Southwest Florida Water Management District (SWFWMD), Bonefish Tarpon Trust (BTT), Florida Department of Environmental Protection (FDEP) and FWC’s Habitat and Species division (HSC) to assess restoration techniques for fish nursery habitats in the Charlotte Harbor Estuary. This partnership formed almost a decade ago when SWFWMD was in the initial phase of the Coral Creek Ecosystem Restoration project and biologists observed large numbers of juvenile Tarpon in a small section of the relic man-made canal system that was next in line for restoration. After this discovery, fisheries scientists from BTT and FWRI and restoration scientists from SWFWMD all agreed that the next phase of restoration presented a unique opportunity to examine different restored habitat designs as they relate to juvenile sport fish habitat use.
The Coral Creek Ecosystem Restoration project is taking place in the Charlotte Harbor State Preserve on the Cape Haze Peninsula (cover image). The project consists of several phases of hydrologic and habitat restoration of approximately 2,600 acres of degraded and impacted wetlands within the preserve (SWFWMD 2010). One phase of this project converted six relic man-made canals into marsh ponds with varying degrees of connectivity to the open creek (Figure 2). A limited connection to the estuary is an important feature commonly observed in nursery habitat studies involving tarpon and common snook, where tidal flow and access is restricted seasonally (ex., rain flooded marshes meet summer high tides) or driven by weather events (ex. tropical storms and hurricanes). Restricted access seems to be important for recruitment and likely helps separate the juvenile fish from large predatory fish that cannot access these habitats or tolerate harsh wetland conditions. Therefore, the restoration of the canals used an experimental design with habitat connections in mind. Four of the canals were designed to be marsh ponds with an earthen sill at the entrance to limit tidal exchange and access by predatory fish, while the other two were designed as marsh ponds open to tidal flow. The constructed canal sills were augmented with bagged and loose fossilized shell to achieve desired elevations. In addition, within each connection type, the marsh ponds have varying depth contours, with the presence/absence of a deep hole habitat.
A 3-year project to follow up on these restoration efforts, made possible through Charlotte County’s RESTORE Act funding (Charlotte County 2015), is currently underway, where FIM staff are characterizing fish assemblages and juvenile sport fish use of 1) the restored marsh ponds, 2) natural marsh ponds in the nearby landscape, and 3) the associated tidal creek (Coral Creek) into which the restored ponds discharge and two adjacent reference creeks. Concurrently, our partners at BTT are tagging juvenile sport fish and tracking movements of these fish in and around the restored marsh ponds and FWRI is tracking juvenile sport fish movements in the natural ponds. Characterizing the physical attributes of these restore and natural marsh ponds (e.g., depths, frequency of tidal inundation) and the dynamics of fish use (e.g., fish density and movement between ponds) will inform future restoration and preservation efforts for juvenile sport fish habitat.
Charlotte County. 2015. RESTORE Act Advisory Board. https://www.charlottecountyfl.gov/boards-committees/raab/Pages/default.aspx
Southwest Florida Water Management District (SWFWMD). 2010. Peace River Basin Projects. https://www.swfwmd.state.fl.us/sites/default/files/calendar/others/peace_projects_dec.pdf