Spawning Site Selection and Contingent Behavior in Common Snook, Centropomus undecimalis

Abstract

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.

More Than Just a Spawning Location: Examining Fine Scale Space Use of Two Estuarine Fish Species at a Spawning Aggregation Site

“…The focal inlet connects Tampa Bay with the Gulf of Mexico and falls between two less developed island preserves, Shell Key preserve on the North, and Fort Desoto County Park to the south. The inlet is 300 m across and 8.5 m deep (Lowerre-Barbieri et al, 2013. On the leeward side of Shell Key, an extensive seagrass meadow exists, which is a component of the 8,880 acres of seagrass coverage in the entire Boca Ciega Bay area.…”

“…Last, to track movement in and out of the seagrass habitat, 3 receivers were also placed in key channels that connect seagrass habitats on the leeward side of Shell key to the spawning site (Figure 1). Control tags were deployed to estimate variation in detection radii overtime and extensive range testing was conducted (Lowerre-Barbieri et al, 2014).…”

“…Fish were marked at a spawning aggregation site subject to comprehensive and long-term study. At this site, direct observations of spawning for both species (visual and acoustic) have been observed and females of both species have been captured with hydrated oocytes and fresh post-ovulatory follicles, indicating active spawning Lowerre-Barbieri et al, 2014). On the leeward side of the pass where spawning occurs, a productive seagrass meadow exists which could act as a key foraging habitat for spawning fish that would allow them to overcome body size constraints on egg production, which may result in different spawning behaviors than what would be expected from total spawners (i.e., Nassau Grouper Epinephelus striatus; Bolden, 2000).…”

“…To answer our research questions, we used two well-studied aggregating species as a model, Common Snook (Centropomus undecimalis), and Spotted Seatrout (Cynoscion nebulosus), in South Florida (U.S.). Both species can form spawning aggregations with individuals spending several weeks at spawning aggregation sites (Lowerre-Barbieri et al, 2013;Young et al, 2014). Importantly, the general spatial-temporal patterns of spawning are well-understood for both species, making these species ideal models to test hypotheses related to the foraging and reproduction at spawning aggregation sites.…”

“…Trout produce productive recreational fisheries and are highly managed where they occur (Saucier and Baltz, 1993). Though trout are often considered to form more resident spawning aggregations, at the focal site, previous research has shown that Seatrout migrate to the area from adjacent habitats to spawn (Lowerre-Barbieri et al, 2013). …”