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Postlarvae of the spiny lobster Panulirus argus migrate from offshore in the Florida Keys into their juvenile habitat in Florida Bay through interisland channels. The influx of postlarvae was monitored monthly over the new-moon period at Long Key and Whale Harbor channels (July 1997–June 1999). Although the channels were only 30 km apart, their influx patterns differed. At Long Key, influx peaked every 2–3 months, whereas at Whale Harbor the peaks were in winter and of higher magnitudes. The influx pattern at Long Key was highly correlated with the strength of coastal counter-current flow in the two-week period prior to sampling. Countercurrent flow was correlated with alongshore (upstream) wind stress, but the latter was not a significant predictor of postlarval influx. Coastal counter-current flow is hypothesized to indicate the presence of a cyclonic, mesoscale eddy offshore. Satellite imagery confirmed the presence of these eddies offshore of the Middle Florida Keys often when positive postlarval influx and counter-current anomalies were observed. These eddies can facilitate onshore larval transport, and their variable temporal and spatial properties can cause transport variability over a scale of several tens of kilometres along the Keys.

The pink shrimp Farfantepenaeus duorarum, one of the commercially important Penaeidae, reproduces offshore of the southwest Florida (SWF) shelf. Larvae migrate to nursery grounds in estuarine Florida Bay. Using a numerical approach, we investigated the role of spawning location, larval traits, and physical forces on the transport of pink shrimp larvae. First, the Regional Oceanic Modeling System that is based on tides, air–ocean fluxes, and freshwater flows was used to simulate the SWF shelf oceanography. The model replicates the tides, winds, salinity, currents, and seasonality of the shelf. Secondly, the Regional Oceanic Modeling System was coupled offline with the Connectivity Modeling System, in which virtual larvae were released near the surface from two spawning sites, Dry Tortugas and Marquesas, and tracked until the time for settlement (about 28–30 d). Virtual larvae moved vertically in the water column following ontogenetic behaviors previously observed in the field: diel vertical migration (DVM) and selective tidal stream transport (STST). Lagrangian trajectories indicated that migration paths changed radically between summer and winter during model years (1995–1997). Maximum settlements occurred in summer by larvae crossing the SWF shelf, while the lowest settlement occurred in winter by larvae moving through passes in the Florida Keys. Modeling results demonstrated an effective east‐northeast transport across the SWF shelf during summer as a result of the tidal currents, the subtidal currents, and the combined DVM and STST behaviors. The current phase captured during the initial DVM period was critical to determine the direction in which larvae move, favorable (east and northward) or unfavorable (south and westward), before the STST behavior captures the eastward tidal current that brings larvae to the nursery grounds. Unfavorable currents were driven by the summer easterlies and low salinities at the coast. Results indicated that Marquesas is the more effective spawning ground, with 4.5 times more likely settlement of originating larvae compared with Dry Tortugas. Model‐estimated seasonal settlement patterns concurred with postlarval influxes previously observed at Florida Bay boundaries. Received June 26, 2014; accepted December 7, 2014

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