Long-term analysis of spatio-temporal patterns in population dynamics and demography of juvenile Pinfish (Lagodon rhomboides)

In estuarine systems, proximity to the ocean has the potential to directly and indirectly drive patterns of fish distribution and population dynamics. To test this hypothesis, we conducted a comprehensive analysis of fisheries-independent data and quantified patterns of density, biomass, and growth rates of juvenile Pinfish (Lagodon rhomboides) across spatial and temporal scales in Tampa Bay, Florida, USA. Spatially, the highest density and biomass were found in the outermost regions (closest to the Gulf of Mexico) of the Bay, and these patterns were generally consistent temporally. Inter-annually, Pinfish density and biomass were the highest during periods coinciding with favorable oceanographic conditions (e.g., anomalously intense and prolonged upwelling) for across-shelf transport of larvae from spawning grounds in the Gulf to Tampa Bay. Intra-annually, density and biomass were the highest during spring and summer likely due to the combined effects of spawning timing (and delivery of new settlers), and high somatic growth fueled by increased secondary and primary productivity. Declines in density and biomass during the late summer through early winter were possibly due to high post-settlement mortality and egress to offshore habitats. Pinfish increased predictably in size across the months of the calendar year, and tended to be larger and grew faster in the innermost regions of the Bay, which were located farthest from the Gulf. Pinfish density was related to the proximity to the Gulf of Mexico, with the outermost regions of the Bay having greater seagrass cover, higher salinity, and being closer to the offshore larval pool where spawning occurs. Thus, this study provided evidence that distance to the ocean was an important driver of biotic and abiotic factors that influenced Pinfish demographic rates across spatial and temporal scales in the largest estuary in Florida. (C) 2016 Elsevier Ltd. All rights reserved.