Gulf of Mexico Science Volume 25 Article 3 Number 1 Number 1
2007 Recruitment and Essential Habitat of Juvenile Sand Seatrout (Cynoscion arenarius) in Four Estuaries Along the West Coast of Florida Caleb H. Purtlebaugh Florida Fish and Wildlife Conservation Commission
Kristin R. Rogers Florida Fish and Wildlife Conservation Commission
DOI: 10.18785/goms.2501.03 Follow this and additional works at: https://aquila.usm.edu/goms
Recommended Citation Purtlebaugh, C. H. and K. R. Rogers. 2007. Recruitment and Essential Habitat of Juvenile Sand Seatrout (Cynoscion arenarius) in Four Estuaries Along the West Coast of Florida. Gulf of Mexico Science 25 (1). Retrieved from https://aquila.usm.edu/goms/vol25/iss1/3
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Gulf of Mexico Science, 2007(1), pp. 15-32
Recruitment and Essential Habitat of Juvenile Sand Seatrout ( Cynoscion arenarius) in Four Estuaries Along the West Coast of Florida
CALEB H. PuRTLEBAUGH AND KmsnN R. RoGERS
The sand seatrout (Cynosciou m·marillS) is an ecologically and economically important species common to estuarine and nearshore waters of the Gulf of Mexico. Currently, comprehensive information on the essential habitat of juvenile sand seatrout is limited. We analyzed data from a long-term fisheries-independent monitoring program to assess the spatial and temporal distributions of juvenile sand seatrout relative to various habitat parameters in four estuaries (Apalachicola Bay, the Suwannee River estuary, Tampa Bay, and Charlotte Harbor) along the gulf coast of Florida. A total of 25,668 sand seatrout (oS100 mm SL) were collected during monthly stratified-random sampling from Jan. 1996 through Dec. 1997 and Jan. 2001 through Dec. 2003. Specimens were collected with 21.3-m bag seines and 6.1-m otter trawls; the majority of specimens were captured in trawls from water ~ 1.8 m deep. Juvenile sand seatrout primarily recruited into the estuaries from May through Oct., although recruitment began 1 mo earlier in Tampa Bay. Juveniles were most abundant over unvegetated mud bottoms, in mesohaline salinities, and near salt marsh vegetation. Highest abundances also occurred in small rivers, tidal creeks, and areas adjacent to the mouths of large rivers. Juveniles between 30 mm SL and 70 mm SL primarily occupied mesohaline salinities before shifting toward higher salinities as they approached 100 mm SL.
INTRODUCTION estuaries (Christmas and Waller, 1973; Warren and Sutter, 1982). Information on relative and seatrout ( Cynoscion arenarius) are one of abundance and habitat associations of sand S the most common sciaenid fishes within seatrout is limited and in most cases has been estuaries of the northern Gulf of Mexico ancillary to larger studies (Gunter, 1938; Christ (Rakocinski eta!., 2002). Although sand seatrout mas and Waller, 1973; Gallaway and Strawn, have historically been thought to range westward 1974; Chittenden and McEachran, 1976; Warren along the gulf coast from southwest Florida to and Sutter, 1982). The majority of studies on the Gulf of Campeche, Mexico (Moffet et a!., sand seatrout have been principally from the 1979), recent genetic analyses indicate that they northwestern gulf (Texas, Louisiana, and Mis also occur commonly throughout inshore waters sissippi) (Gunter, 1945; Christmas and Waller, of Florida's Atlantic coast (Tringali eta!., 2004). 1973; Gallaway and Strawn, 1974; Cowan and Sand seatrout support a substantial recreational Shaw, 1988), with only one study conducted on and commercial fishery along the gulf coast of juvenile sand seatrout along the gulf coast of Florida. From 2001 to 2003, annual recreational Florida (Peebles, 1987). landings from the gulf coast of Florida averaged In our study, we used a stratified-random 230 metric tons (mt) [approximately 1 million sampling design with standardized protocols to fish year (National Marine Fisheries Service, sample and estimate the relative abundance of 2004)], and commercial landings averaged juvenile sand seatrout in four estuaries along the 8 mt. Currently, recreational harvest of sand west coast of Florida. The objectives of this study seatrout is unregulated in Florida. were to document recruitment windows for and Despite the ecological and economical impor seasonal changes in abundance of juvenile sand tance of sand seatroul, little is known regarding the life history of this species. Information is seatrout in shallow and deepwater areas and to widely scattered and sometimes conflicting (Ditty identifY factors that are associated with juvenile eta!., 1991). For instance, Copeland and Bechtel sand seatrout spatial occurrences in these estu (1974) found no relationship between catch aries. ratios and observed salinities, and Trent et a!. (1969) reported that sand seatrout distribution MATERIALS AND METHODS within an estuary was not related to salinity. Other studies, however, have identified optimal Study sites.-Juvenile sand seatrout were collected salinity ranges for this species within specific from four estuaries along the gulf coast of
Published by The Aquila Digital Community, 2007 1 Gulf of Mexico Science, Vol. 25 [2007], No. 1, Art. 3 16 GULF OF MEXICO SCIENCE, 2007, VOL. 25(1)
86'0'0'W
Suwannee River Estuary-
Gulf of Mexico Tampa Bay
Charlotte Harbor
-==-=---o::::====---Kilometers 0 40 80 160 240 320
Fig. l. Locations of the four estuaries sampled for juvenile sand seatrout in Florida: Apalachicola Bay, Suwannee River estuary, Tampa Bay, and Charlotte Harbor.
2 Florida (Fig. 1). Apalachicola Bay (sampling area 575 km ), are not influenced by a single domi 2 approximately 411 km ) and the Suwannee River nant freshwater source, but only by numerous 2 estuary (sampling area approximately 731 km ) small rivers. Five such rivers with average annual 3 were the northernmost estuaries included in this discharges of 2-13 m s -I (USGS 2004) provide study; these areas were similar in that they are freshwater inflow into Tampa Bay, whereas two both characterized by substantial freshwater rivers, each with an average annual discharge of input (Livingston, 1983; Mattson and Rowan, 19m3 s- 1 (USGS 2004), flow into the Charlotte 1989) from the Apalachicola (mean annual Harbor estuary. 3 1 discharge 1,184 m s- ) and Suwannee rivers Bottom habitat throughout the four estuaries 3 (mean annual discharge 125 m s -I) (USGS consisted of cliiTering proportions of mud, sand, 2004), respectively. Additional sources of dis oyster bars, and seagrass. Salt marsh habitat (i.e., charge into these estuaries include the Carra SjJmtina. a.lternijlora and ]uncus roeme1ia.nus) was belle River (discharge data unavailable) in available in all four estuaries but was more Apalachicola Bay and numerous small, unme prevalent in Apalachicola Bay and the Suwannee tered tidal creeks in the Suwannee River estuary. River estuary than in Tampa Bay and Charlotte The southernmost estuaries, Tamra Bay (sam Harbor. Extensive mangrove habitat was sup pling area approximately 886 km ) and Char ported only in the Tampa Bay and Charlotte lotte Harbor (sampling area approximately Harbor estuaries. https://aquila.usm.edu/goms/vol25/iss1/3 2 DOI: 10.18785/goms.2501.03 Purtlebaugh and Rogers: Recruitment and Essential Habitat of Juvenile Sand Seatrout (Cyno PURTLEBAUGH AND ROGERS-JUVENILE SAND SEATROUT DISTRIBUTION 17
TABLE 1. Summary of sand seatrout (:5 100 mm SL) catch-and-effort data by gear type aud sampled area in Apalachicola Bay (Ap. = Apalachicola River and Cr. = Carrabelle River), Suwannee River Estuary (Su. = Suwannee River), Tampa Bay, and Charlotte Harbor estuaries, FL.
2 Gear Years Location No. hauls No. fish 100 Ill SE %occur Apalachicola Bay 21.3-m seine 2001-2003 bay 720 1,043 1.03 0.23 9 Ap. River 348 0 0.00 0.00 0 Cr. River 144 13 0.13 0.09 <1 Subtotal 1,212 1,056 6.1-m otter trawl 2001-2003 bay 432 2,194 0.35 0.07 27 Ap. River 180 3,806 2.69 1.51 15 Cr. River 72 1,534 2.90 0.85 54 Subtotal 684 7,534 Total 1,896 8,590 Suwannee River Estmuy 21.3-m seine 2001-2003 bay 747 877 0.84 0.21 15 Su. River 175 27 0.22 0.17 3 tidal creeks 324 664 3.03 0.52 24 Subtotal 1,246 1,568 6.1-m otter trawl 2001-2003 bay 350 1,612 0.33 0.13 9 Su. River 175 396 0.32 0.11 26 Subtotal 525 2,008 Total 1,771 3,576 Tampa Bay 21.3-m seine 2001-2003 bay 928 56 0.04 0.01 3 rivers 2,195 1,689 1.09 0.24 9 Subtotal 3,128 1,745 6.1-m otter trawl 1996-1997 bay 364 2,710 0.62 0.23 20 rivers 404 2,985 1.01 0.17 38 Subtotal 768 5,695 Total 3,896 7,440 Charlotte Harbor 21.3-m seine 2001-2003 bay 884 549 0.45 0.37 3 rivers 288 513 2.62 1.32 10 Subtotal 1,172 1,062 6.1-m otter trawl 1996-1997 bay 250 1,130 0.33 0.23 12 rivers 230 3,870 2.40 0.64 54 Subtotal 480 5,000 Total 1,652 6,062
Data collection.-Juvenile sand seatrout [:::; 100 walls, and beaches. "Offshore" deployments mm standard length (SL)] were collected during sampled shallow waters in the bays at least 5 m monthly stratified-random sampling using a bag away from a shoreline and sampled vegetated and seine and otter trawl (see Table 1 for estuary unvegetated flats. "River" deployments sampled specific effort). Data collections were made the shorelines of tidal creeks and rivers. All seine during daylight hours and during all tidal stages. hauls were standardized among all estuaries with The bag seine was 21.3 m long X 1.8 m deep regard to amount of area covered in each haul. with 3.2-mm #35 knotless nylon delta mesh. The The area sampled with shoreline and offshore otter trawl was 6.1 m wide with 38-mm stretch deployments was 140m2 and for river deploy 2 mesh and a 3.2-mm knotless nylon Delta m.esh ments was 68m . Otter trawls were deployed in cod-end liner. The bag seine was used to sample both bay and riverine habitats. Tow distance and water depths ranging from 0.3 m to 1.8 m, and duration were generally twice as long in bays the otter trawl was used in waters 1.8-7.6 m deep. (0.20 nm ± 0.05 nm, 10 min) than in rivers (0.10 Three techniques were used in deploying ± 0.02 nm, 5 min). Trawl distances were shorter the bag seine to sample bay different habitats. in rivers to reduce the chance of entanglement. ''Shoreline'' deployments sampled bay shorelines Sand seatrout catches were standardized across all 2 with emergent vegetation, mangrove fringes, sea- gears as fish · 100m- .
Published by The Aquila Digital Community, 2007 3 Gulf of Mexico Science, Vol. 25 [2007], No. 1, Art. 3 18 GULF OF MEXICO SCIENCE, 2007, VOL. 25(1)
Apalachicola Bay
.------, 40,------, 00 ~ M Jul so n=O 21.3-m seine 30 n=339 21.3-m seine 40 n=9 6.1-m otter trawl 2s n=3364 6.1-m otter trawl 20 30 15 20 10 10
0 25 50 75 100 0 25 50 75 100 100,------, 35,------, Feb 30 Aug 80 n=O 21.3-m seine 25 n=250 21.3-m seine n=2 6.1-m otter trawl n=1009 6.1-mottertrawl 60 20
40 15 10 20
0 25 50 75 100 0 25 50 75 100 100.------,25,------, Mru s~ 20 80 n=O 21.3-m seine n=186 21.3-m seine >. n=O 6.1-m otter trawl n=1253 6.1-m otter trawl u 00 15 c Q) 40 10 :::::l 20 0" ,_Q) Ll.. 0 25 50 75 100 0 25 50 75 100 +- 100,------, 30,------,
c Apr 25 Oct Q) 80 n=O 21.3-m seine n=73 21.3-m seine ~ 60 n=2 6.1-m otter trawl n=329 6.1-m otter trawl Q) 15 40 a.. 10 20 ...... ······ 0 25 50 75 100 0 25 50 75 100
~------,100.------, 30 May Nov 25 n=46 21.3-m seine eo n=2 21.3-m seine n=696 6.1-m otter trawl n=292 6.1-m otter trawl 20 00 15 40 10 20
0 25 50 75 100 0 25 50 75 100 25,------. 100 .------, Jun Dec 20 n=159 21.3-m seine 80 n=1 21.3-m seine n=563 6.1-m otter trawl n=15 6.1-m otter trawl 15 00
10 40
20
0 25 50 75 100 0 25 50 75 100 Standard Length (mm) 21.3-m seine ··········· 6.1-m otter trawl Fig. 2. Monthly length-frequency distributions for sand seatrout collected in 21.3-m seines and 6.1-m otter trawls fi·om Apalachicola Bay, FL, 2001-2003 (n = number of sand seatrout captured monthly in each gear type).
Seine data from all four estuaries were estuary were collected from Jan. 2001 through collected from Jan. 2001 through Dec. 2003. Dec. 2003 and Feb. 2001 through Dec. 2003, Trawl data were not available for all four respectively. estuaries during the same years. Trawl data for All sand seatrout collected were counted, and Tampa Bay and Charlotte Harbor were collected up to 40 individuals per sample were measured from Jan. 1996 through Dec. 1997. Trawl data to the nearest mm SL. Length measurements from Apalachicola Bay and the Suwannee River were then extrapolated to the unmeasured https://aquila.usm.edu/goms/vol25/iss1/3 4 DOI: 10.18785/goms.2501.03 Purtlebaugh and Rogers: Recruitment and Essential Habitat of Juvenile Sand Seatrout (Cyno PURTLEBAUGH AND ROGERS-JUVENILE SAND SEATROUT DISTRIBUTION 19
Suwannee River Estuary
too,------,--, w,------, •' Jan •' Jul 80 n=O 21.3-m seine ... . 40 n=260 21.3-m seine n=1 6.1-m otter trawl .. n=B3 6.1-m otter trawl 60 ... . 30 40 ... . 20 .. . . 20 . . 10 . . 0 25 50 75 100 0 25 50 75 100 ~------. 30,------. 30 Feb 25 Aug 25 n=O 21.3-m seine n=486 21.3-m seine n=O 6.1-m otter trawl 20 n=612 6.1-mottertrawl 20 15 15 10 10
0 25 50 75 100 0 25 50 75 100 60,------, w,------, Mar Sep n=O 21.3-m seine 40 n=309 21.3-m seine 40 n=O 6.1-m otter trawl n=68 6.1-m otter trawl ~30 30 c 20 Q) 20 ::J 10 10 0" ············· Q) .._ 0 25 50 75 100 0 25 50 75 100 UL_,_. 4o,------. 25,------. Apr Oct c 20 Q) 30 n=O 21.3-m seine n=127 21.3-m seine n=O 6.1-m otter trawl n=112 6.1-mottertrawl 2 15 Q) 20 10 c.. 10
0 25 50 75 100 0 25 50 75 100 4or------M--ay------~ so,------N-ov------, 25 30 n=144 21.3-mseine n=16 21.3-mseine n=521 6.1-m otter trawl 20 n=7 6.1-m otter trawl 20 15 10 10
0 25 50 75 100 0 25 50 75 100
25,------,,oo,------~~------, Jun Dec 20 n=226 21.3-m seine 80 n=O 21.3-m seine 15 ···. n=603 6.1-m otter trawl 60 n=1 6.1-m otter trawl
10 ',• 40
. . 0 25 50 75 100 0 25 50 75 100 Standard Length (mm) -- 21.3-m seine ...... 6.1-m otter trawl Fig. 3. Montly length-frequency distributions for sand seatrout collected in 21.3-m seines and 6.1-m otter trawls from the Suwannee River Estuary, FL, 2001-2003 (n number of sand seatrout captured monthly in each gear type).
portion of the sample. Collections contammg (psu), water temperature (0 C), water depth (m), more than 1,000 juvenile sand seatrout were and location (degrees, minutes, seconds) were subsampled with a modified Motoda box splitter recorded at all sample sites. Bottom type (mud, (Winner and McMichael, 1997), and the total sand, hard structure [rocks, oysters], and un number of individuals was estimated by fraction known), bottom vegetation (seagrass, algae, and al expansion of the subsampled portion. Salinity none), and shore type (emergent vegetation
Published by The Aquila Digital Community, 2007 5 Gulf of Mexico Science, Vol. 25 [2007], No. 1, Art. 3 20 GULF OF MEXICO SCIENCE, 2007, VOL. 25(1)
Tampa Bay
30 40 Jan 25 Jul n~o 21.3-m seine n~114 21.3-m seine 30 20 n~29 6.1-m otter trawl n~1053 6.1-m otter trawl 15 20 .. 10 10
0 25 50 75 100 25 50 75 100 100 40 Feb 35 Aug 80 n~o 21.3-m seine 30 n~59 21-m seine 6
0 25 50 75 100 0 25 50 75 100 40 30 May 25 Nov 30 n=226 21.3-m seine n=61 21.3-m seine n=447 6.1-m otter trawl 20 n=130 6.1-m otter trawl 20 15
10 10 ...... ··· 0 25 50 75 100 25 50 75 100 35 30
30 Jun 25 Dec 25 n=183 21.3-m seine n=69 21.3-m seine n=640 6.1-m otter trawl 20 n=36 6.1-m otter trawl 20 15 15 10 10 .... ···
0 0 25 50 75 100 0 25 50 75 100 Standard Length (mm)
21.3-m seine 6.1-m otter trawl Fig. 4. Monthly length-frequency distributions for sand seatrout collected in 21.3-m seines (2001-2003) and 6.1-m otter trawls (1996-1997) from Tampa Bay, FL (n = number of sand seatrout captured monthly in each gear type).
[principally salt marsh vegetation], overhanging type to identify the timing of sand seatrout vegetation, structure, and other) were also de recruitment in each estuary. Sand seatrout termined at each sample site. habitat associations were determined by using analysis of covariance (ANCOVA) for each Statistical analysis.-Only individuals :S 100 mm estuary. Only data collected during the estuary SL were included in analyses, which generally specific periods of sand seatrout recruitment represented fish less than 1 yr of age (Nemeth et were used in the ANCOVA models. Abundance 2 a!., 2006). Length-frequency histograms were estimates (fish · 100 m - ) used in the ANCOVA developed by month for each estuary and gear models were pooled across years for each gear https://aquila.usm.edu/goms/vol25/iss1/3 6 DOI: 10.18785/goms.2501.03 Purtlebaugh and Rogers: Recruitment and Essential Habitat of Juvenile Sand Seatrout (Cyno
PURTLEBAUGH AND ROGERS-JUVENILE SAND SEATROUT DISTRIBUTION 21
Charlotte Harbor ®,------,ro,------, Jul 50 60 21.3-m seine 50 n=32 21.3-m seine 40 6.1-m otter trawl n=849 6.1-m otter trawl 40 30 30 20 20 10 10
0 25 50 75 100 0 25 50 75 100
100 Aug 80 21.3-m seine n=28 21.3-m seine 6.1-m otter trawl 40 n=1760 6.1-m otter trawl
30 40 20
20 10
0 25 50 75 100 0 25 50 75 100 .------, 50,------, 60 Mar Sep 40 50 n=11 21.3-m seine n=14 21.3-m seine ~ 40 n=41 6.1-m otter trawl 30 n=515 6.1-m otter trawl 30 c 20 ().) 20 :::::l 10 0" 10 ().) ······· ··················· ...... LL o 25 50 75 100 0 25 50 75 100 +- 35~------. C 30 A~ ~ Oct
0 25 50 75 100 0 25 50 75 100 35,------,40,------. 30 May 35 Nov 25 n=7 21.3-m seine 30 n=127 21.3-m seine n=971 6.1-m otter trawl 25 n=18 6.1-mottertrawl 20 20 15 15 10 10 0 25 50 75 100 0 25 50 75 100 60,------. 40,------, Jun 35 Dec 40 n=540 21.3-m seine 30 n=6 21.3-m seine 30 n=400 6.1-m otter trawl 25 n=32 6.1-m otter trawl 20 20 15 10 10 0 25 50 75 100 0 25 50 75 100 Standard Length (mm) -- 21.3-m seine ...... 6.1-m otter trawl Fig. 5. Monthly length-fi·equcncy distributions for sand scatroul collected in 21.3-m seines (2001-2003) and 6.1-m otter trawls (1996-1997) fi·om Charlotte Harbor, FL (n number of sand seatrout captured in each gear type). type (seine or trawl), and all analyses were gear applicable only to seine models. Covariates in the specific. Full ANCOVA models included the ANCOVA models were water temperature, salin following classification variables: month, year, ity, and depth. bottom type, bottom vegetation, shore type, and Abundance estimates and continuous variables deployment method (shoreline, offshore, and (i.e., water temperature, salinity, and depth) river). Deployment method and shore type were were log transformed (In (x + 1)) before analyses Published by The Aquila Digital Community, 2007 7 Gulf of Mexico Science, Vol. 25 [2007], No. 1, Art. 3 22 GULF OF MEXICO SCIENCE, 2007, VOL. 25(1) 30 12 Apalachicola Bay 25 20 6 15 3 0 F M A M A s 0 N D 12 Suwannee River Estuary 30 9 25 C\1 I- E 6 20 0 15 0 3 '7 ... r······f·······l······l· .. -1 .c .... ··· .... ···1· ...... (!) CJ) 0 3 .._.,;.;::::: F M A M A s 0 N D "0 (!) Q) ..... 0 c: ac: n1 ..... "0 12 (!) c: 30 ::J Tampa Bay 25 0 -0 ..c .._ <( 20 6 15 3 .... ·l······ ...... 0 F M A M A s 0 N D 12 30 Charlotte Harbor 25 20 6 15 3 0 F M A M A s 0 N D Months · · · • · · 21.3-m seine -<>- 6.1-m otter trawl _,_Temperature (°C) Fig. 6. Monthly abundance (fish· 100m-2 ± standard error) of juvenile sand seatrout collected in 21.3-m seines and 6.1-m otter trawls in Apalachicola Bay, Suwannee River estuary, Tampa Bay, and Charlotte Harbor, FL. Monthly mean water temperatures CC) calculated from samples collected in each estuary are also presented. to normalize the data. First-order interactions significant in order to avoid masking possible were included in the initial models. Class variables significant main effects during the stepwise and covariates that were not significant (P > 0.10) elimination process. All ANCOVA analyses were based on partial (type III) sum of squares were conducted using Proc GLM in SAS (SAS Institute sequentially removed, and the analysis was re Inc., 1989). Tukey's multiple comparison tests peated until all nonsignificant variables were were used to identify significant differences in removed unless they were associated with an mean abundance by pairwise comparison of the interaction. All significant interactions were re means associated with classification variables tained in the model regardless if main effects were found to be significant in the ANCOVA models. https://aquila.usm.edu/goms/vol25/iss1/3 8 DOI: 10.18785/goms.2501.03 Purtlebaugh and Rogers: Recruitment and Essential Habitat of Juvenile Sand Seatrout (Cyno PURTLEBAUGH AND ROGERS-JUVENILE SAND SEATROUT DISTRIBUTION 23 Apalachicola Bay Tampa Bay 5 5 -Seine -Seine ~Trawl 4 KilO!l T raw I 4 339 3 3 * * * 1048 2 2 * * * C\1 * 354 'E o 0 0 Mud Sand Non Veg Veg 0 Bottom Type Bottom Vegetation Bottom Type Bottom Vegetation ':"'" ..c (f) Charlotte Harbor u::: 5 * Suwannee River Estuary 5 376 -Seine -Seine fl!:ZSZ! Trawl 4 ~Trawl 4 * * 3 3 2 2 * * 93 4 512 3 0 0 Veg Veg Bottom Type Bottom Vegetation Bottom Type Bottom Vegetation Fig. 7. Abundances (fish · 100 m - 2 + standard error) ofjuvenile sand seatrout collected over mud versus sand bottom and vegetated versus unvegetated bottom in Apalachicola Bay, Suwannee River estuary, Tampa Bay, and Charlotte Harbor, FL, from 1996-1997 and 2001-2003. Numbers over bars represent the total number of samples collected over each habitat. Significant differences (P < 0.05) for Tukey's groupings within gear types are indicated with *. NS = Not significant. Additional analyses were conducted to investi REsuLTS gate the specific effects of salinity on juvenile 2 sand sea trout abundance (fish · 100 m - ). A total of 25,668 sand seatrout were collected Investigation into size-specific abundance of from Apalachicola Bay, the Suwannee River juvenile sand seatrout with regard to salinity estuary, Tampa Bay, and Charlotte Harbor was undertaken by calculating density-weighted (Table 1). Of these, 79% were collected with mean salinity at capture as described by McBride trawls; the remaining 21% were collected with eta!. (2001), incorporating both seine and trawl seines. The minimum size of individuals cap data. Density-weighted mean salinity at capture tured was 6 mm SL in trawls and 9 mm SL in was calculated for each 5 mm SL interval and for seines. each estua1y separately by using the weighted In Apalachicola Bay and the Suwannee River formula estuaty, juvenile sand seatrout were captured during all months except March in Apalachicola Bay and Feb.-Apr. in the Suwannee River estuary Yw= (LW;Y;II )/II LW;, (Figs. 2, 3).Juvenile sand seatrout were captured during every month in Tampa Bay and Charlotte where w; = the number of sand seatrout per Harbor (Figs. 4, 5). The primary recruitment 5 mm SL interval for collection i; Y; = the salinity period was May-Oct. in all estuaries except measured for collection i; and n = the total Tampa Bay, where recruitment began 1 mo number of collections with fish in that 5 mm SL earlier because of a shift in timing during the interval for that estua1y. 2001 recruitment year (Fig. 4). The primary Published by The Aquila Digital Community, 2007 9 Gulf of Mexico Science, Vol. 25 [2007], No. 1, Art. 3 24 GULF OF MEXICO SCIENCE, 2007, VOL. 25(1) TABLE 2. Reduced ANCOVA models of abundances of juvenile sand seatrout collected in Apalachicola Bay, Suwannee River estuary, Tampa Bay [(Apr. through Oct. 2001-2003) (seines) and 1996-1997 (trawls)], and Charlotte Harbor [May through Oct. 2001-2003 and 1996-1997 (Charlotte Harbor trawls)]. Estuary Source df Sum of squares F-value R' Apalachicola Bay 21.3-m seine Model 7 21.47 10.3*** 0.12 Bottom vegetation 2 6.58 11.05*** Shore type 3 11.67 13.07*** Deployment method 2 1.88 3.15** Error 529 157.48 Corrected total 536 178.95 6.1-m otter trawl Model 15 24.21 2.77*** O.ll Month 5 6.00 2.06* Year 2 7.32 6.29** Bottom type 2 1.78 1.53 MonthXbottom type 6 7.70 2.21** Error 325 189.ll Corrected total 340 213.32 Suwannee River Estuary 21.3-m seine Model 10 89.20 20.30*** 0.25 Year 2 7.82 8.90*** Bottom type 3 ll.46 8.70*** Bottom vegetation I 6.46 14.70*** Deployment method 2 29.30 33.34*** Salinity 15.52 35.33*** Temperature 5.44 12.38*** Error 619 271.99 Corrected total 629 361.19 6.1-m otter trawl Model 17 II .56 3.02*** 0.17 Month 5 4.28 3.81 ** Bottom type 2 1.84 4.09** MonthXbottom type 10 8.60 3.82*** Error 252 56.69 Corrected total 269 68.26 Tampa Bay 21.3-m seine Model II 98.43 45.31 *** 0.22 Year 2 4.70 11.91 *** Bottom type 3 2.72 4.59** Shore type 3 2.41 4.06** Deplo)~nent method 2 61.66 156.ll *** Salinity 1.83 9.25** Error 1759 347.4 Corrected total 1770 445.83 6.1-m otter trawl Model 5 23.64 13.07*** 0.13 Bottom type 2 10.43 14.43*** Salinity 4.43 12.25*** Depth 2.05 5.66** Temperature 4.82 13.33*** Error 427 154.39 Corrected total 4:l~ 178.02 Charlotte Harbor 21.3-m seine Model 18 35.89 11.03*** 0.26 Month 5 2.81 3.ll** Year 2 1.06 2.92* Bottom type 2 1.23 3.39** Bottom vegetation 0.60 3.29* Deplo~nent method 2 12.29 34.00*** MonthXbottom type 6 2.65 2.44** Error 557 100.67 https://aquila.usm.edu/goms/vol25/iss1/3 10 DOI: 10.18785/goms.2501.03 Purtlebaugh and Rogers: Recruitment and Essential Habitat of Juvenile Sand Seatrout (Cyno PURTLEBAUGH AND ROGERS-JUVENILE SAND SEATROUT DISTRIBUTION 25 TABLE 2. Continued. Estuary Source df Sum of squares F-value R' Corrected total 575 136.55 6.1-m otter trawl Model 4 43.17 19.01 *** 0.24 Bottom type 2 5.28 4.65** Salinity 20.91 36.83*** Depth 1.83 3.22* Error 235 133.41 Corrected Total 239 176.58 * p < 0.10; ** p < 0.05; *** p < 0.001. recruitment periods accounted for 95% or more seatrout were captured over unvegetated bot of the total catch from each estuary. Additional tom in seines at all four estuaries (P < 0.05) ly, the overall period of recruitment, as defined (Fig. 7). Differences in trawl abundance be by the presence of sand seatrout < 25 mm SL, ~veen vegetated and nonvegetated bottom was was broader in the ~vo southern estuaries not tested for significant differences. The (Figs. 2-5). sample size of collections from trawl deploy In Apalachicola Bay, monthly sand seatrout ments over vegetation was extremely small (n < abundance had a unimodal distribution in both 5) because of the small amount of seagrass in trawl and seine collections (Fig. 6). In the these areas (depth 2: 1.8 m). Seagrass that did Suwannee River estuary, monthly juvenile sand occur within areas sampled by the trawl was seatrout abundance was unimodal in seine often too difficult to confirm because of water catches, whereas low catches of sand seatrout in turbidity. Significantly more fish were captured the trawl during July resulted in a bimodal over mud than over sand or hard substrate in distribution (Fig. 6). Juvenile sand seatrout both types of gear in all estuaries, except for captured in seines from Tampa Bay had a bi Apalachicola Bay (P < 0.05) (Fig. 7). The seine modal distribution due to a second peak in captured significantly more fish in river deploy abundance during Sep. and Oct. However, trawl ments than shoreline or offshore deployments captured sand seatrout from Tampa Bay had in the same three estuaries (P < 0.05). a unimodal distribution (Fig. 6). Sand seatrout Although shore type was not a significant vari captured in both types of gear from Charlotte able in the Suwannee River estuary or Charlotte Harbor had well defined bimodal distributions Harbor models, abundance of sand seatrout was (Fig. 6). Months of peak abundance for sand highest along shorelines with emergent vegeta seatrout captured from Charlotte Harbor in tion (salt marsh vegetation) in all estuaries. seines were 1-2 mo behind those for sand Salinity was significant in two seine and ~vo seatrout captured from Charlotte Harbor in trawl models. Either month or year was signif trawls. This relationship may be because of a shift icant in the majority of models (Table 2). For in the timing of recruitment of seine-captured both types of gear, models for Apalachicola Bay fish (2001-2003) and trawl-captured fish (1996- explained the least amount of variance in sand 1997) because data from different years were seatrout abundance (Table 2). compared or it may be due to a legitimate lag. In Differences in the spatial distribution of Tampa Bay and Charlotte Harbor, seine data juvenile sand seatrout were apparent among from only 2001 through 2003 were used, whereas estuaries and appeared to be influenced by trawl data were from 1996 and 1997, making freshwater discharge. Highest sand seatrout abundance comparisons between gear types densities occurred in small rivers and tidal creeks difficult. In general, initial increase in abundance hut not in the much larger Apalachicola and of sand sealroul was associated with increasing Suwannee rivers. In Apalachicola Bay and the water temperatures, but sand seatrout abundance Suwannee River estuary, sand seatrout occurred be~veen months showed no clear synchronous in highest abundances adjacent to the discharge change with water temperature (Fig. 6). area (Figs. 8 and 9). The sampling areas within Within each estuary, final ANCOVA models the Apalachicola and Suwannee rivers had accounted for 12-26% of the variability in annual mean salinities of 1.0 psu and 3.6 psu, juvenile sand seatrout seine abundances and respectively. The small rivers that contained the 11-24% of the variability in trawl abundances highest densities of sand seatrout in Apalachi (P < 0.10) (Table 2). Significantly more sand cola Bay, Tampa Bay, and Charlotte Harbor had Published by The Aquila Digital Community, 2007 11 Gulf of Mexico Science, Vol. 25 [2007], No. 1, Art. 3 26 GULF OF MEXICO SCIENCE, 2007, VOL. 25(1) f5'1f!f!W 84'5[J[J\IV 84'3f!f!W Apalachicola Bay- Seine 23'5f!f!'N 23'5[J[J'N · site sampled 23'40CI'N 23'4f!O'N Catch Density High: 87.1 Gulf of Mexico Low: 0.7 N s -=~=--~===---Kilometers 0 3 6 '*'12 18 24 Apalachicola Bay- Trawl 23'500'N 23'5f!f!'N · site sampled 23'400'N 23'4CIO'N Catch Density Gulf of Mexico High: 264.3 Low: 0.06 El5'1[1(J\IV 84'500\IV 84'30(1\IV 2 Fig. 8. Density of juvenile sand seatrout (fish · 100 m- ) by gear type in Apalachicola Bay, FL, 2001-2003. mean salinities ranging from 10.6 to 16.4 psu. higher salinities and contain seagrass meadows, The tidal creeks in the Suwannee River estuary, such as St. George Sound in Apalachicola Bay, in which supported the highest sand seatrout the vicinity of the Cedar Keys in the Suwannee abundance in that estuary, had a mean salinity River estuary, and the lower bay areas near the of 12.8 psu. Large catches of juvenile sand Gulf of Mexico in Tampa Bay and Charlotte seatrout were absent from areas known to have Harbor (Figs. 8-11). https://aquila.usm.edu/goms/vol25/iss1/3 12 DOI: 10.18785/goms.2501.03 Purtlebaugh and Rogers: Recruitment and Essential Habitat of Juvenile Sand Seatrout (Cyno PURTLEBAUGH AND ROGERS-JUVENILE SAND SEATROUT DISTRIBUTION 27 83"200W 83"0'0'W Suwannee River Suwannee Estuary- Seine River 2l"15'0'N 2l"15'0'N Gulf of Mexico site sampled Catch Density High: 97.9 2l"S'O'N 2l"S'O'N Low: 0.7 N s Kilometers 0 3 6 "*'12 18 24 Suwannee River Suwannee Estuary - Trawl River 2l"15'0'N 2l"15'0'N Gulf of Mexico · site sampled ' •. Catch Density High: 27.1 '•, •'• 2l"5'0'N 2l"5'0'N .. · ·. ':. ', ',•:, Low: 0.05 . ·:. 83"200W 83"0'0'W 2 Fig. 9. Density ofjuvenile sand seatrout (fish · 100 m- ) by gear type in the Suwannee River estua1y, FL, 2001- 2003. Density-weighted mean salinities at capture in gradient at approximately 30-35 mm SL. Indi Apalachicola Bay, Tampa Bay, and Charlotte viduals in Charlotte Harbor consistently occu Harbor initially showed a trend toward lower pied lower salinities than those in Apalachicola salinity waters as fish increased in length Bay or Tampa Bay. Conversely, small juveniles in (Fig. 12). Juveniles from these three estuaries the Suwannee River estuary did not move toward then settled into a consistent mesohaline salinity lower-salinity areas; individuals 10-70 mm SL Published by The Aquila Digital Community, 2007 13 Gulf of Mexico Science, Vol. 25 [2007], No. 1, Art. 3 28 GULF OF MEXICO SCIENCE, 2007, VOL. 25(1) 83'15'CIW 82'45'CIW 82'15'CIW illsborough River 23'0'0'N 23'0'0'N Tampa Bay- Seine Palm River Alafia River '27'45'CI'N 27'45'CI'N Gulf of Mexico site sampled Catch Density High • 436.8 '27'3CICI'N 27'3CICI'N Low 0.7 -==-=----=====---Kilometers 0 5 10 20 30 40 Hillsborough River 23'0'0'N 23'0'0'N Tampa Bay- Trawl Palm River Alafia River '27'45'CI'N 27'45'CI'N Gulf of Mexico · site sampled : ,• Catch Density '' ·,· High • 79.2 ... ~ ,' '27'3CICI'N 27'3CICI'N Low • 0.05 IB'15'CIW 82'4SCIW 82'15'GW 2 Fig. 10. Density of juvenile sand seatrout (fish· 100m- ) by gear type in Tampa Bay, FL, 1996--1997 (trawls) and 2001-2003 (seines). consistently occupied upper-mesohaline and DISCUSSION lower-polyhaline waters. In all estuaries, as in dividuals >70 mm SL increased in length, they The abundance of sand seatrout captured in moved toward higher salinities. both types of gear indicated that the timing of https://aquila.usm.edu/goms/vol25/iss1/3 14 DOI: 10.18785/goms.2501.03 Purtlebaugh and Rogers: Recruitment and Essential Habitat of Juvenile Sand Seatrout (Cyno PURTLEBAUGH AND ROGERS-JUVENILE SAND SEATROUT DISTRIBUTION 29 f52'4SfJW f52'3r:Jr:JW f52'1SOW fQ'O'O'W 27'0'0'N 27'0'0'N Charlotte Harbor- Seine ::£'4SO'N ::£'4SO'N Gulf of Mexico · site sampled Catch Density I High 335.3 Low 0 7 N s -==-=----=====---Kilometersw*" 0 4.5 9 18 27 36 27'0'0'N 27'0'0'N Charlotte Harbor- Trawl Gulf of Mexico ::£'4SO'N ::£'4SO'N · site sampled Catch Density High: 108.7 Low: 0.06 f52'4SOW ff2'3aaw f52'1SCIW f52'0'0'W 2 Fig. 11. Density of juvenile sand seatrout (fish· 100m- ) by gear type in Charlotte Harbor, FL, 1996-1997 (trawls) and 2001-2003 (seines). peak abundance was similar in the four estuaries. findings elsewhere, where small numbers of We noted that sand seatrout < 25 mm SL were larval sand seatrout were captured in Dec. and captured in the two southern estuaries earlier Jan. (Peebles, 1987), suggesting some year-round (March) and later (Nov. and Dec.) than in the spawning may occur in southwest Florida. two northern estuaries. This was consistent with Spawning locations are likely determined by Published by The Aquila Digital Community, 2007 15 Gulf of Mexico Science, Vol. 25 [2007], No. 1, Art. 3 30 GULF OF MEXICO SCIENCE, 2007, VOL. 25(1) 40 40 Apalachicola Bay Tampa Bay 35 35 30 30 25 25 20 20 15 15 10 10 5 Apalachicola River 5 ,-, ------0 10 20 30 40 50 60 70 80 90 100 0 10 20 30 40 50 60 70 80 90 100 Vl ~= '-'c ...·a ~ -rJj 40 40 Suwannee River Estuary 35 35 Charlotte Harbor 30 30 Bay 25 25 20 20 15 15 10 10 5 ------Suwannee River 5 0 0 0 10 20 30 40 50 60 70 80 90 100 0 10 20 30 40 50 60 70 80 90 100 Standard Length (mm) Fig. 12. Density-weighted mean salinity at capture for juvenile sand sea trout collected in the 21.3-m seine and 6.1-m otter trawl from Apalachicola Bay, Suwannee River estuary, Tampa Bay, and Charlotte Harbor, FL. Error bars represent ± one standard error. The solid line represents the mean bay salinity, and the dashed line represents the mean river and tidal creek salinities. salinity, whereas the intensity of spawning events the high level of nutrients there (Grimes and is probably driven by water temperature (Pee- . Kingsford, 1996). The observed increased abun bles, 1987). Water temperatures in the southern dance of sand seatrout in these areas may be estuaries increased earlier in the year and a function of feeding. During early-life stages, remained high for longer periods of time than sand seatrout prey heavily upon mysids, cope in the northern estuaries. Therefore, it was not pods, and larval fishes (Reid, 1954; Darnell, surprising that recruitment of juvenile sand 1958; Springer and Woodburn, 1960; Sheridan, seatrout in the southern estuaries began earlier 1979; Byers, 1981). Increased feeding is thought and lasted longer than in the northern estuaries. to lead to faster growth, decreased predation, Overall, the timing and duration of the observed and increased survival of fish larvae (Gillanders recruitment period in all four estuaries was and Kingsford, 2002). Juveniles in the Suwannee consistent with the previously reported spawning River estuary were also caught in high densities period of March-Sep., with limited spawning around the shoreline areas far from the Suwan possible as late as Dec. (Gallaway and Strawn, nee River. The shoreline areas in this estuary are 1974; Copeland and Bechtel, 1974; Shlossman influenced by numerous tidal creeks and have and Chittenden, 1980; Warren and Sutter, 1982; lower salinities than do open gulf waters by an Cowan et al., 1989). average difference of 10 psu and consist of Juvenile sand seatrout were almost exclusively unvegetated muddy substrate and salt marsh found within and adjacent to rivers or other shoreline. Most nonshoreline areas of the freshwater influences in areas with unvegetated Suwannee River estuary, particularly areas mud bottom, often associated with salt marsh around the Cedar Keys, were characterized by vegetation. Areas near freshwater input often expanses of seagrass beds, sand, and mud support increased densities of phytoplankton, substrates. This habitat also characterized areas zooplankton, larval fishes, and nekton because of in the other three estuaries that were close to https://aquila.usm.edu/goms/vol25/iss1/3 16 DOI: 10.18785/goms.2501.03 Purtlebaugh and Rogers: Recruitment and Essential Habitat of Juvenile Sand Seatrout (Cyno PURTLEBAUGH AND ROGERS-JUVENILE SAND SEATROUT DISTRIBUTION 31 passes leading to the open gulf. These areas had This paper benefited from reviews by Jered higher salinities because of the lack of freshwater Jackson, Chuck Cichra, Doug Adams, and Ted influences and close proximity to the Gulf of Switzer. Valuable comments on earlier drafts Mexico and were devoid of juvenile sand seatr were provided by Doug Nemeth and Bob out. In the rivers, higher sand seatrout densities McMichael. Editorial assistance was provided by were found farther up-river in the trawl samples Judy Leiby and Jim Quinn. This project was than in the seine samples. This difference was supported in part by proceeds from the sale of likely related to the presence of a salt wedge State of Florida fishing licenses and in part by the along the bottom of the rivers, which created Department of the Interior, U.S. Fish and ideal salinity ranges (i.e., higher salinity) at Wildlife Service, and Federal Aid for Sportfish trawled depths. Restoration, Project Number F-43. Juvenile sand seatrout in all four estuaries followed a similar sequence of size-specific move ments with respect to salinity. Sand seatrout LITERATURE CITED apparently sought an optimal reduced salinity BYERS, S. M. 1981. Trophic relationships of two range when they reached a length of approxi sympatric sciaenid fishes, Cynoscion arenarius and mately 30-70 mm SL and then moved into Cynoscion nothus, in the northcentral Gulf of Mexico. higher salinities as they grew toward 100 mm Master's Thesis, Univ. Southern Mississippi, Hatties SL. Details of these movements deserve further burg, MS. investigation. Variations in salinity ranges in CHITTENDEN, M. E., JR., AND j. D. McEACHRAN. 1976. combination with available suitable habitat in Composition, ecology, and demersal fish communi all four estuaries likely contributed to the ties on the northwestern Gulf of Mexico continental shelf, with a similar synopsis for the entire GOM. apparent selection for specific areas within each TAMU-SG-76-208, Texas A & M Univ., College estuary. It is well known that estuarine species Station, TX. often select a particular range along an environ CHRISTMAS, j. Y., AND R. S. WALLER. 1973. Estuarine mental gradient (particularly salinity gradients) vertebrates, Mississippi, p. 320-434. In: Cooperative that mrmmizes metabolic costs, optimizes Gulf of Mexico estuarine inventory and study, growth, and facilitates survival (Wohlschlag, Mississippi. ]. Y. Christmas (ed.). Gulf Coast Res. 1978; Moser and Gerry, 1989; Cyrus and Blaber, Lab., Ocean Springs, MS. 1992; Whitfield, 1999; Nelson and Leffler, 2001). CONNER, j. C., AND F. M. TRUESDALE. 1972. Ecological It is likely that the observed salinity ranges, in implications of a freshwater impoundment in a low conjunction with unvegetated, mud-bottom hab salinity marsh, p. 259-276. In: Proceedings of the coastal marsh and estuary management symposium. itat, convey one or more of these benefits to sand Louisiana St. UniY., Baton Rouge, LA. seatrout during their juvenile life stage. CoPELAND, B. J., AND T. ]. BECHTEL. 1974. Some Information on the preferred habitat identi environmental limits of six gulf coast estuarine fied in this study may be beneficial to ensure the organisms. Contrib. Mar. Sci. 18:169-204. survival of juvenile sand seatrout. Within each CowAN,]. H., JR., R. F. SHAw, AND]. G. DITTY. 1989. estuary, the location of low-salinity unvegetated, Occurrence, age and growth of two morphological mud-bottom habitats varied. Experimental stud types of sand seatrout ( Cynoscion arenarius) larvae in ies to confirm the optimal salinity for juvenile the winter and early spring coastal waters off west sand seatrout growth and survival may clarif)' Louisiana. Contrib. Mar. Sci. 31:39-50. whether they benefit by actively selecting low CowAN,]. H., AND R. F. SHAW. 1988. The distribution, abundance, and transport of larval sciaenids collect salinity habitats. This information would also ed during winter and early spring from the conti serve as a next step in defining essential habitat nental shelf waters off west Louisiana. U.S. Fish. Bull. for juvenile sand seatrout and for predicting the 86:129-142. effects of changes in estuarine salinity on the CYRUS, D. P., AND S. j. M. BLABER. 1992. Turbidity and fishery. salinity in a tropical northern Australian estuary and their influence on fish distribution. Estuarine Coast al Shelf Sci. 35:5,15-563. AcKNOWLEDGMENTS DARNELL, R. M. 1958. Food habits of fishes and larger We thank the staff of the Fisheries-Indepen invertebrates of Lake Ponchartrain, Louisiana, an dent Monitoring Program at the Florida Fish and estuarine community. Pub!. Inst. Mar. Sci., Univ. Texas 5:353-416. Wildlife Conservation Commission's Fish and DITrY,j. G., M. BouRGEOis, R. KASPRZAK, AND M. KoNIKOFF. Wildlife Research Institute, for their dedication 1991. Life history and ecology of sand seatrout and hard work collecting samples, particularly in Cynoscion arenmius Ginsburg, in the northern Gulf of Apalachicola, Cedar Key, Tampa Bay, and Mexico: a review. Northeast Gulf Sci. 12:35-47. Charlotte Harbor. We thank Anthony "Taj" GALLAWAY, B. J., ru'ID K. STRAWN. 1974. Seasonal Knapp for his assistance with figures and tables. abundance and distribution of marine fishes at Published by The Aquila Digital Community, 2007 17 Gulf of Mexico Science, Vol. 25 [2007], No. 1, Art. 3 32 GULF OF MEXICO SCIENCE, 2007, VOL. 25(1) a hot-water discharge in Galveston Bay, Texas. SHLOSSMAN, P. A., AND M. E. CHITTENDEN. 1980. Re Contrib. Mar. Sci. 18:1-137. production, movements and population dynamics of GuNTER, G. 1938. Notes on invasion of fresh water by the sand seatrout, Cynoscion arenmius. U.S. Fish. Bull. fishes of the Gulf of Mexico, with special reference to 79:649-669. the Mississippi-Atchafalaya River system. Copeia SPRINGER, V., AND K. WOODBURN. 1960. An ecological 1938:69-72. study of the fishes of the Tampa Bay area. Florida St. ---. 1945. Studies on marine fishes of Texas. Pub!. Bd. Consen•. (St. Petersburg) Mar. Lab., Prof. Pap. Inst. Mar. Sci., Univ. Texas 1:1-190. Ser. l. 1 04p. LlVINGSTON, R.]. 1983. Resource Atlas of the Apalachi SunER, F. C., AND T. D. McilwAIN. 1987. Species profiles: cola Estuary. Florida Sea Grant College Publication life histories and environmental requirements of No. 55, 64 pp. coastal fishes and invertebrates (Gulf of Mexico) MATTSON, R. A., AND M. E. RowAN. 1989. The Suwannee sand seatrout and silver seatrout. U.S. Fish Wild!. River estuary: an overview of research and manage Serv. Bioi. Rep. 82(11.72). U.S. Army Corps of ment needs. Special Publication 89-4:17-31. Ameri Engineers, TREL- 82-4, 15p. Available at: http:/ I can Water Resources Association, Bethesda, MD. www.nwrc.gov/wdb/pub/1045.pclf McBRIDE, R. S., T. C. MAcDONALD, R. E. .MATHESoN JR., D. TRENT, W. L., E.]. PuLLEN, R. 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Map of real-time 12:35-41. streamflow compared to historical stream flow for tl1e day of the year, Florida. Available at: http:/ /water. usgs. NATIONAL ~1AruNE FISHERIES SERVICE. 2004. Fisheries statistics and economics division. Available at: http:/ I govI cgi-bin/waterwatch?map_type =real&state= fl WARREN,]. R., AND F. C. SUTTER. 1982. Industrial bottom www.st.nmfS.gov/st1/recreationalandhttp:/h1~1w.stnmfs. govI stl/commercial fish-monitoring and assessment, p. II-1-1-II-1-69. In: Fishery monitoring and assessment, completion re NELSON, G. A., AND D. LEFFLER. 2001. Abundance, spatial port. T. D. Mcilwain (eel.). Gulf Coast Research Lab., distribution, and mortality of young-of~the-year spotted seatrout ( Cynoscion nebulas us) along the gulf Ocean Springs, MS. WHITFIELD, A. K. 1999. Ichthyofaunal assemblages in coast of Florida. Gulf Mex. Sci. 1:30-42. estuaries: a South African case study. Rev. Fish Bioi. NEMETH, D. ]., ]. B. JACKSON, A. R. KNAPP, AND c. P. Fish. 9:151-186. PURTLEBAUGH. 2006. The demographics of sand WINNER, B. L., AND R. H. McMICHAEL JR. 1997. Evalu seatrout ( Cynoscion arenarius) in the eastern Gulf of ation of a new type of box splitter designed for Mexico. Gulf Mex. Sci. 24:45-60. subsampling estuarine ichthyofauna. Trans. An1. PEEBLES, E. B. 1987. Early life history of the sand seat:rout, Fish. Soc. 126:1041-1047. Cynoscion arenmius, in southwest Florida. Master's WoHI.SCHLAG, D. E., AND M. WAKEMAN. 1978. Salinity Thesis, Univ. South Florida, St. Petersburg, FL. J stresses, metabolic responses and distribution of the RAKociNSKI, C. F., B. H. CoMvNs, M. S. PETERSON, AND G. coastal spotted seatrout, Cynoscion nebu/osus. Contrib. A. ZAPFE. 2002. Field growth responses of juvenile Mar. Sci. 21:171-185. white trout (Cynoscion arenarius) to continue variation in physical habitat conditions. Gulf and Caribbean Fisheries Institute. 53:623-635. (CHP) FLORIDA FisH AND WILDLIFE CoNSERVATION REm, G. K. 1954. An ecological study of the Gulf of CoMMISSION, FISH AND WILDLIFE REsEARCH INSTI Mexico fishes in the vicinity of Cedar Key, Florida. TUTE, SEN. GEORGE KIRKPATRICK FIELD lABORATO Bull. Mar. Sci. GulfCaribb. 4(1):1-94. RY, 11350 SouTHWEST l53RD CT, CEDAR KEY, SAS INSTITUTE INc. 1989. SAS/STAT Users Guide, FLORIDA 32625; AND (KRR) FLORIDA FISH AND Version 6, 4th eel., Volume 2. SAS Institute, Inc., \-\I'ILDI.IFE CONSERVATION COWv!ISSION, FISH AND Cary, NC. WILDLIFE RESEARCH INSTITUTE, 4005 SoUTH tvfAIN SHERIDAN, P. F. 1979. Trophic resource utilization by STREET, GAINESVILLE, FLORIDA 32601-9099. Sene! three species of sciaenid fishes in a northwest Florida reprint requests to CHP. Date accepted August estuary. Northeast Gulf Sci. 3:1-15. 7, 2007. https://aquila.usm.edu/goms/vol25/iss1/3 18 DOI: 10.18785/goms.2501.03