The spatial distribution of spawning activity can affect the reproductive success of certain fishes, and locating the key areas is critical to accurately assessing and managing their populations. We determined estuarine spawning locations for spotted seatrout Cynoscion nebulosus during the 2004 summer spawning season in Tampa Bay, Florida, using a passive acoustic survey. Sound production was evaluated at each of 754 randomly selected stations for the number of individuals calling and ranged from 1‐2 individuals to large aggregations. Spawning was identified by large aggregation sounds and was detected at 8% of the selected stations. There was seasonal variability in spawning, as spawning areas were inconsistently used throughout the season. Spatially, spawning occurred in all regions of the bay except for the Hillsborough Bay region. Most spawning took place in lower Tampa Bay and the eastern portion of the middle bay. Spawning occurred most frequently near the shoreline in areas of relatively high dissolved oxygen and in association with submerged aquatic vegetation. The variability in spawning habitat, as exhibited by both the disproportionate distribution of spawning sites across Tampa Bay and the inconsistent use of spawning sites, may serve to increase the resilience of the stock. As management directives evolve to encompass habitat‐focused strategies, surveys such as this one can supply data necessary for the creation of meaningful ecosystem‐based management plans.

Fish spawning populations are complex and affected by many factors acting over temporal, spatial, and demographic scales. To better understand these factors, we chose to study spotted seatrout Cynoscion nebulosus, which has closed populations over small spatial scales and a periodic life-history pattern. We used experimental gill nets and hook and line, within a spatially and temporally explicit sampling design, to collect 2034 spotted seatrout in lower Tampa Bay, Florida, USA, in 2001 and 2002. Ovarian development was evaluated histologically. Mature females did not all spawn throughout the spawning season, and first-time spawners (Age 1) had the lowest probability of doing so. Two reproductive behaviors were observed: fish moving in the late afternoon or evening to a high-intensity spawning site in an inlet and low-intensity spawning within the estuary. Larger, older female and male spawners were more abundant at the inlet site than at nearby estuarine sites. Both batch fecundity and the percentage of females spawning increased with age and size. Spatialtemporal interactions made it difficult to assess certain aspects of reproduction, such as spawning frequency.

Reproductive behavior affects spatial population structure and our ability to manage for sustainability in marine and diadromous fishes. In this study, we used fishery independent capture-based sampling to evaluate where Common Snook occurred in Tampa Bay and if it changed with spawning season, and passive acoustic telemetry to assess fine scale behavior at an inlet spawning site (2007–2009). Snook concentrated in three areas during the spawning season only one of which fell within the expected spawning habitat. Although in lower numbers, they remained in these areas throughout the winter months. Acoustically-tagged snook (n = 31) showed two seasonal patterns at the spawning site: Most fish occurred during the spawning season but several fish displayed more extended residency, supporting the capture-based findings that Common Snook exhibit facultative catadromy. Spawning site selection for iteroparous, multiple-batch spawning fishes occurs at the lifetime, annual, or intra-annual temporal scales. In this study we show colonization of a new spawning site, indicating that lifetime spawning site fidelity of Common Snook is not fixed at this fine spatial scale. However, individuals did exhibit annual and intra-seasonal spawning site fidelity to this new site over the three years studied. The number of fish at the spawning site increased in June and July (peak spawning months) and on new and full lunar phases indicating within population variability in spawning and movement patterns. Intra-seasonal patterns of detection also differed significantly with sex. Common Snook exhibited divergent migration tactics and habitat use at the annual and estuarine scales, with contingents using different overwintering habitat. Migration tactics also varied at the spawning site at the intra-seasonal scale and with sex. These results have important implications for understanding how reproductive behavior affects spatio-temporal patterns of fish abundance and their resilience to disturbance events and fishing pressure.

Marine fish movement plays a critical role in ecosystem functioning and is increasingly studied with acoustic telemetry. Traditionally, this research has focused on single species and small spatial scales. However, integrated tracking networks, such as the Integrated Tracking of Aquatic Animals in the Gulf of Mexico (iTAG) network, are building the capacity to monitor multiple species over larger spatial scales. We conducted a synthesis of passive acoustic monitoring data for 29 species (889 transmitters), ranging from large top predators to small consumers, monitored along the west coast of Florida, USA, over 3 yr (2016-2018). Space use was highly variable, with some groups using all monitored areas and others using only the area where they were tagged. The most extensive space use was found for Atlantic tarpon Megalops atlanticus and bull sharks Carcharhinus leucas. Individual detection patterns clustered into 4 groups, ranging from occasionally detected long-distance movers to frequently detected juvenile or adult residents. Synchronized, alongshore, long-distance movements were found for Atlantic tarpon, cobia Rachycentron canadum, and several elasmobranch species. These movements were predominantly northbound in spring and southbound in fall. Detections of top predators were highest in summer, except for nearshore Tampa Bay where the most detections occurred in fall, coinciding with large red drum Sciaenops ocellatus spawning aggregations. We discuss the future of collaborative telemetry research, including current limitations and potential solutions to maximize its impact for understanding movement ecology, conducting ecosystem monitoring, and supporting fisheries management.

Spawning site selection and reproductive timing affect stock productivity and structure in marine fishes but are poorly understood. Traditionally, stock assessments measure reproductive potential as spawning stock biomass or egg production and do not include other aspects of reproductive behavior. Red drum make an excellent case study to assess these other aspects, as (1) they are highly fecund, pelagic spawners, like most exploited marine fishes; (2) their life cycle is delineated between nursery (estuarine) and adult (coastal and offshore) habitat; and (3) they are managed at these two spatial scales. This study was conducted from August 2012 to December 2013 and integrates data from multiple methods and spatial scales. Aerial surveys were used for large-scale monitoring of aggregations off two known estuarine nursery areas, Tampa Bay and Charlotte Harbor, Florida, USA. Capture-based sampling in Tampa Bay coastal (n = 2581) and estuarine waters (n = 158) was used to assess reproductive state and to confirm coastal spawning. To assess spatial dynamics, we acoustically tagged two population components in the Tampa Bay system, subadults from the estuary (n = 20) and adults from the coastal spawning site (n = 60). Behavioral plasticity was seen in subadult recruitment to coastal habitat, with some subadults maturing and recruiting before or during the spawning season and others (14 of 20 acoustically tagged fish) recruiting at the end of the 2012 spawning season. Both adults and recruited subadults (n = 29) were consequently detected in the Charlotte Harbor array, 132 km to the south. Spawning-site fidelity to the Tampa Bay spawning site occurred at both the population and individual scales. Aggregations consistently occurred in Tampa Bay coastal waters during the spawning season, and approximately two-thirds of tagged adults returned in the 2013 spawning season. A similar proportion of subadults returned to the Tampa Bay spawning site, exhibiting natal homing. However, these first-time spawners arrived later than repeat spawners and were detected over shorter time periods. This study, and others like it, demonstrates how integrating data from individuals tracked over space and time with more traditional population-based sampling is changing our understanding of ecological processes that affect marine fish productivity and our ability to manage for sustainablity.