Common snook Centropomus undecimaliswere sampled monthly from the Jupiter–Lake Worth area of Florida's Atlantic coast during 1989 and 1991 (1452 fish) and from Tampa Bay on Florida's Gulf of Mexico coast during 1988 and 1989 (2090 fish). Group‐synchronous oocyte development was demonstrated. Ovarian maturation began during March or April on both coasts. Spawning was first detected histologically in April during 1989 and 1991 on the Atlantic coast and during May in 1988 and in April in 1989 on the Gulf coast. In each year, spawning ended during October on the Atlantic coast and during September on the Gulf coast. Ovarian histological evidence suggested that individual females may spawn every 1·1–2·5 days between 1400 and about 2000 hours. Final oocyte maturation occurred independently of either tidal cycle or lunar phase, and some common snook were observed in prespawning or spawning condition on every day sampled. Spawning occurred in or near major inlets to the Atlantic Ocean and the Gulf of Mexico, in secondary passes to larger inland bays and bayous, and around nearshore islands.

Abstract. For species that are closely managed, understanding population resilience to environmental and anthropogenic disturbances (i.e., recovery trajectories across broad spatial areas) can guide which suite of management actions are available to mitigate any impacts. During January 2010, an extreme cold event in south Florida caused widespread mortality of common snook, Centropomus undecimalis, a popular sport fish. Interpretation of trends using fishery-independent monitoring data in five south Florida estuaries showed that changes in catch rates of adult snook (>500 mm standard length) varied between no effects postevent to large effects and 4-yr recoveries. The reasons for the variation across estuaries are unknown, but are likely related to differences in estuary geomorphology and habitat availability (e.g., extent of deep rivers and canals) and differences in the proportions of behavior contingents (i.e., segments of the population that use divergent movement tactics) that place snook in different areas of the estuary during winter. Emerging awareness of the presence of behavior contingents, identification of overwintering sites, and improvements of abundance indices in remote nursery habitats should provide a better understanding of population resilience to disturbance events for snook. Given that changes in the frequency of short-lived, severe cold events are currently unknown, the findings and management actions described here for a tropical species living at the edge of its distribution should be useful to scientists forecasting the effects of climate change.

Data collected to determine specific reproductive traits, including spatial and temporal patterns, are an area of need for improved understanding of factors that contribute to productivity in fish populations. We used passive acoustic telemetry to study the movements of 271 common snook Centropomus undecimalis on the east coast of Florida from 2008 to 2011 to assess spatial dynamics during the spawning seasons. Common snook were detected in 6 inlets from Port Canaveral to Palm Beach Inlet during the summer months when water temperature exceeded 23°C, with peak densities between July and August. Individual residency times in an aggregation were over 7.5 times shorter than the spawning season which, together with asynchronous arrival dates and frequent migrations away from the aggregation, indicates high rates of turnover. Nearly half of the tagged common snook were observed at multiple (2 to 5) spawning sites during a single season and showed varying degrees of fidelity to a spawning site. Area of residence, sex and size are influential factors in spawning traits of common snook. Females migrated earlier, made more trips, and spent longer periods in aggregations compared to males. Larger fish showed greater site fidelity to a single aggregation site. Each year a portion of the population was not detected in an inlet, implying that some common snook skip spawning or that spawning may occur outside of inlets. Findings highlight the need for a combined approach to management that includes updating the stock assessment, using more accurate measures of spawning effort and the protection of spawning areas from physical disturbance. KEY WORDS: Acoustic monitoring • Fish spawning • Fisheries management • Reproductive patterns • Centropomus undecimalis Resale or republication not permitted without written consent of the publisher This authors' personal copy may not be publicly or systematically copied or distributed, or posted on the Open Web, except with written permission of the copyright holder(s). It may be distributed to interested individuals on request.

Mortality rates were determined for common snook Centropomus undecimalis that had been hooked and released in different localities throughout southern Florida. Researchers and cooperative anglers caught, tagged, and retained 470 common snook ranging from 205 to 1,120 mm total length in 23 experiments during June 1991–April 1995. Live bait was used to capture 421 snook; 49 were caught with artificial lures. All snook were held in pens (9.1 × 2.4 × 1.2 m) for at least 48 h; 20.4% were held for 96 h (4 d), 30.8% were held for 120 h (5 d), and 3.2% were held for 288 h (12 d). Ten fish, or 2.13%, died within 24 h of capture. Hook location was the only variable that significantly affected release mortality rates (P < 0.0001); snook hooked in the throat or stomach (5.1% of the time) accounted for 40% of the total mortalities. No fish died in two separate control trials that examined the effects of handling, tagging, and holding common snook. These results should encourage resource managers to continue to use bag and size limits and closed seasons as tools to manage common snook populations. However, spawning aggregations that are heavily fished during the closed (fish cannot be retained) summer season may require additional protection because increasing effort could adversely affect reproductive output.

Based on the high‐reward tagging method, we determined that reporting rates by recreational anglers for tagged common snook Centropomus undecimalis along the Atlantic coast of Florida were approximately 60–70%. Additionally, we found that angler reporting rates were influenced by the use of high‐reward tags. To estimate reporting rates, we tagged 989 common snook (range = 600–1,132 mm total length) with internal anchor tags that bore one of eight variable‐reward messages (the word “Reward” with or without a specified monetary amount from US$5 to $200) during the summer closed‐harvest season of 1995. Approximately equal numbers and sizes of fish were tagged in each reward group. The $200 reward was assumed to be sufficient to elicit a reporting rate of 100%. Return rates during the first year were quite variable and ranged from 13.7% for $5 tags to 25.0% for $25 tags, while the $200 tags had a return rate of 18.7%. Return rates generally increased with increasing reward amount, reaching an asymptotic value at approximately $75 in year 1 and $100 in year 2, above which return rates did not change. In subsequent years, angler behavior appeared to change, as indicated by decreases in the reporting rate of unspecified “Reward” message tags and an increase in the asymptote of the reward level–return rate relationship. This may indicate that angler reporting behavior changed due to the use of high‐reward tags. The results from this experiment will facilitate the deconstruction of total mortality into fishing and natural mortality components derived from tagging programs. They also provide insight into angler behavior related to the design and use of high‐reward tagging programs to elicit tag returns.