Ronald G. Taylor

Catch-and-Release Mortality Rates of Common Snook in Florida

Abstract 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 t...

Age, growth, and mortality of spotted seatrout in Florida waters

Abstract Estimates of age, growth, and mortality of spotted seatrout Cynoscion nebulosus were made by analyzing fish from commercial and recreational catches in 1986–1988 in three estuarine areas of Florida: Apalachicola Bay, Charlotte Harbor, and Indian River Lagoon. Thin sections of sagittae were used to determine age; annulus formation occurred in November–May. The maximum observed age differed among areas, ranging from 5 to 9 years for males and from 6 to 8 years for females. Spotted seatrout reached 301–337 mm total length at the end of their first year. Females were generally larger at age than males, although growth was highly variable. After age 1, male growth slowed to an average of 34–51 mm/year and was modeled best by area-specific linear growth equations. Females showed asymptotic growth that slowed from 87–107 mm at ages 1–2 to 46–60 mm at ages 4–5 and that was modeled best by area-specific Gompertz growth equations. Males and females from Indian River Lagoon and Apalachicola Bay were general...

Reproductive Biology of Female Spotted Seatrout, Cynoscion nebulosus, in the Gulf of Mexico: Differences among Estuaries?

Although the reproductive biology of spotted seatrout, Cynoscion nebulosus, has been documented across the northern Gulf of Mexico, longitudinal comparisons across its range are not available. We evaluated aspects of female spotted seatrout reproduction in five estuaries ranging from Charlotte Harbor, FL (CHFL) to Redfish Bay, TX (TX). Seasonal temperature profiles were similar among the five estuaries, but spring salinities were lower in Apalachicola Bay, FL (AFL) and St. Louis and Biloxi Bays, MS (MS) (range 7.5–15.0‰) than in CHFL, Barataria Bay, LA (LA) and TX (range 16.6–31.7‰). The length of the spawning season varied among estuaries: five months in MS and AFL, six months in LA and TX, and seven months in CHFL. Peak gonodosomatic index (GSI) values varied from May to July among estuaries. The smallest sexually mature females captured ranged from 235 mm TL in LA to 285 mm TL in AFL. Mean relative batch fecundity (# eggs g−1 ovary-free body weight) was significantly higher (ANOVA, p < 0.5) in TX (390 ± 39) and LA (397 ± 26) than in MS (103 ± 10). Spawning frequency, determined by the percentage of females in the late developing ovarian class with postovulatory follicles, ranged from 4.2 to 7.7 d and was not significantly different when all months were combined. However, significant differences during March, April and September (χ2, p < 0.01) showed that spotted seatrout from CHFL and AFL spawned less frequently than those from other estuaries. Overall, MS and AFL fish have the shortest reproductive season, fewer number of spawns and appear to obtain sexual maturity at a slightly larger size. Five hypotheses to explain these differences are presented: variations in time of sampling, temperature, habitat structure, genetics and salinity. Differences in salinity profiles appears to be the most plausible explanation.

Gonadotropin-releasing hormones, including a novel form, in snook Centropomus undecimalis, in comparison with forms in black sea bass Centropristis striata

The molecular forms of gonadotropin-releasing hormone (GnRH) in brain-pituitary extracts were determined for snook Centropomus undecimalis and black sea bass Centropristis striata. The extracts were analyzed in both isocratic and gradient high performance liquid chromatography (HPLC) programs. Eluted fractions were tested in radioimmunoassays with 4 different antisera made against 3 distinct GnRH peptides. Results show that snook contain 3 forms of GnRH, all of which are present in males and females irrespective of the stage of the reproductive cycle. Larger quantities of these GnRH peptides are present in snook in the nonreproductive phase than in snook in the reproductive phase. One form of snook GnRH is immunologically and chromatographically similar to salmon GnRH, and a second form is similar to chicken GnRH-II. However, the third snook GnRH appears to be distinct from the 7 known forms of the vertebrate hormone. In contrast, sea bass contain only the salmon GnRH-like and chicken GnRH-II-like forms of GnRH and, hence, appear to match the more usual pattern of GnRH peptides in teleosts. We speculate that one of the GnRH genes was duplicated and then altered in a fish ancestral to snook but not sea bass, even though both species of fish are in the recently evolved Perciformes order.

Effect of Different Reward Levels on Tag Reporting Rates and Behavior of Common Snook Anglers in Southeast Florida

Abstract 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

Annual Reproductive Cycle of the Common Snook: Endocrine Correlates of Maturation

5 to

Notes: Direct Validation of Ages Determined for Adult Red Drums from Otolith Sections

200) during the summer closed-harvest season of 1995. Approximately equal numbers and sizes of fish were tagged in each reward group. The

Limits to the Use of Contemporary Genetic Analyses in Delineating Biological Populations for Restocking and Stock Enhancement

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

Preliminary Study of the Effect of Reward Amount on Tag-Return Rate for Red Drums in Tampa Bay, Florida

5 tags to 25.0% for

Economies of scale for juvenile production of common snook (Centropomus undecimalis Bloch)

25 tags, while the