usgs-cru-individual-data.s3.amazonaws.com... · web view50 is the length at which 50% of the fish...
TRANSCRIPT
Running Title: Tripletail Reproductive Status
Evaluation of reproductive status for tripletail, Lobotes surinamensis, nearshore Jekyll Island,
GA, USA1
R.T. Parr2
University of Georgia Warnell School of Forestry and Natural ResourcesAthens, GA 30602
C.A. JenningsUS Geological SurveyGeorgia Cooperative Fish and Wildlife Research UnitWarnell School of Forestry and Natural ResourcesUniversity of GeorgiaAthens, GA 30302
N. D. DenslowUniversity of FloridaDepartment of Physiological Sciences and Center for Environmental and Human ToxicologyGainesville, FL 32610
1 This draft manuscript is distributed solely for purposes of scientific peer review. Its content is deliberative and predecisional, so it must not be disclosed or released by reviewers. Because the manuscript has not yet been approved for publication by the U.S. Geological Survey (USGS), it does not represent any official USGS finding or policy.2 Current Address: 41 Park of Commerce Way Suite 303, Savannah, Georgia 31405
1
2
3
4
56789
101112131415161718192021
12345
K. J. KrollUniversity of FloridaDepartment of Physiological Sciences and Center for Environmental and Human ToxicologyGainesville, FL 32610
R.B. Bringolf3
University of Georgia Warnell School of Forestry and Natural ResourcesAthens, GA 30602
3 Author to whom correspondence should be addressed: Tel.: 1-706-542-1477; email: [email protected]
22232425262728293031
6
Evaluation of reproductive status for tripletail Lobotes surinamensis nearshore Jekyll Island, GA,
USA
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
Abstract
Tripletail (Lobotes surinamensis) aggregate nearshore off the Coast of Jekyll Island, Georgia,
United States from March through July. Why tripletail aggregate to these nearshore waters is
unknown, however anecdotal evidence has suggested the possibility of a spawning area. The
objective of the study was to evaluate the reproductive status of tripletail with a non-lethal
sampling method, plasma vitellogenin (VTG) analysis, concurrently with traditional lethal
sampling methodologies, gonadosomatic index (GSI) and histology. A total of 224 (122 males
and 102 females) tripletail were sampled for reproductive evaluation. Most of the male tripletail
(115 of 122) were in the spawning-capable reproductive phase. Female tripletail were found in
all reproductive phases, with few (10 of 102) in the spawning capable phase. The estimated
length at which 50% (L50) of females reached maturity was 459 mm at an approximate age of
1.17 years. The L50 for male tripletail could not be determined because of the lack of immature
fish within the study sample; however, the age at 50% maturity was estimated at 0.55 years.
Gonadosomatic index ranks for females were significantly higher than males (P <0.0001), as
well as among reproductive phases within females (P <0.0001). Females had significantly
higher VTG levels than males (P = 0.0006). Vitellogenin concentrations in spawning capable
females were higher than all phases except the developing phase. Linear regression demonstrated
a strong relationship (r2 = 0.873, n= 77) between VTG and GSI in females. The study indicates
that VTG levels in developing and spawning capable females may be distinguished from other
female reproductive phases and male tripletail; however, a greater sample size of spawning
capable females will be required to further evaluate the use of VTG as a non-lethal reproductive
status indicator.
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
Keywords: fish, reproductive assessment, non-lethal monitoring, GSI
INTRODUCTION
Tripletail Lobotes surinamensis (Bloch 1790) are medium-sized, deep-bodied fish that
occur in tropical and subtropical waters worldwide (Baughman 1941; Hardy 1978). The species
is the only member from the monophyletic family Lobotidae, which is found in the western
Atlantic Ocean (Hardy 1978). Tripletail are known to occur from Massachusetts, USA to
Argentina, including the Gulf of Mexico and the Caribbean Sea, with higher abundances south of
North Carolina, USA (Hardy 1978). Tripletail are migratory; however, detailed information
about their exact movement patterns is scarce or lacking (Merriner and Foster 1974; Franks et
al.1998; Streich et al. 2013).
Tripletail growth appears to be rapid during early life stages; wild-caught and captive fish
have demonstrated the ability to grow greater than 500 mm total length at age-1 (Armstrong et
al. 1996; Franks et al. 1998; Strelcheck et al. 2004; Parr 2011). Scale-based total length (TL) at
age of tripletail from North Carolina was: age-0 (n=1) 190 mm, age-1 (n=6) 445- 591 mm, age-2
(n=5) 562-706 mm, and age-3 (n=2) 568-706 mm (Merriner and Foster 1974). Spine-derived
ages of tripletail also show similar results (Franks et al. 1998; Strelcheck et al. 2004).
Peer-reviewed literature with tripletail reproductive data is scarce, and much of the
available information remains in unpublished agency reports. The size at which 50% of males
reach maturity has not been determined because of a lack of data for age-0 and immature males;
however, Brown-Peterson and Franks (2001) estimated that 50% of males reach maturity by at
least 290 mm. Estimates for female age-at-sexual maturity range from one to two years and
lengths from 350 – 500 mm TL depending upon criteria used for determination of maturity status
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
(Brown-Peterson and Franks 2001; Strelcheck et al. 2004). Brown-Peterson and Franks (2001)
and Strelcheck et al. (2004) estimate that 50% of females reach maturity at approximately one
year and approximately 490 mm TL. Strelcheck et al. (2004) note that size at 50% maturity for
females could change significantly if the presence of vitellogenic oocytes is used as the gauge for
maturity rather than presence of oocytes in the cortical alveolar stage.
Tripletail appear to be protracted multiple-batch spawners, with the ability to spawn once
every three to five days during the spawning season (Brown-Peterson and Franks 2001; Cooper
2002). Baughman (1941) documented gravid females during the months of July and August on
the Atlantic Coast, but other anecdotal reports of gravid females have not been
confirmed(Gudger, 1931, Baughman, 1941). In the Gulf of Mexico, running-ripe males have
been captured from May through September, and females in late ovarian maturation phases have
been found from June through August (Brown Peterson and Franks 2001; Strelcheck et al. 2004).
Ditty and Shaw (1994) captured larval tripletail in >100 m of water in plankton surface tows and
suggested that tripletail may use offshore spawning. Juvenile tripletail also have been captured in
offshore waters in the Gulf of Mexico in association with sargassum patches (Franks et al. 2001).
Histological analysis can yield accurate information on oocyte development and
reproductive phase; however, this analysis requires more time and expense compared to visual
staging based on macroscopic appearance of the gonads or calculation of gonadal somatic index
(GSI) values (West 1990). However, all of the aforementioned techniques require sacrifice of
the fish, and non-lethal alternatives for determining reproductive status are desired for species
such as tripletail, for which definitive population dynamics data are scarce or lacking completely.
Non-lethal methods have been used to determine reproductive status of other fish species
and often include evaluation of blood plasma for the egg yolk precursor, vitellogenin (VTG;
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
Heppell and Sullivan 2000; Ceapa et al. 2002; Wildhaber et al. 2007; Heise et al. 2009).
Vitellogenin is found at highest concentrations during the final oocyte maturation phase in most
fishes. Therefore, VTG can be an effective tool for determining sex, and in some cases,
reproductive phase -- although increased VTG levels are not always indicative of spawning
location (Heppell and Sullivan 2000; Ceapa et al. 2002; Wildhaber et al. 2007; Heise et al. 2009).
In Georgia (GA, USA), tripletail are found associated with structure in estuaries and
nearshore of some of the barrier islands. Tripletail are also found free-floating in the nearshore
Atlantic Ocean waters immediately east of Jekyll Island from March to July (Figure 1). Some
investigators (Brown-Peterson and Franks 2001; Cooper 2002; Strelcheck et al. 2004) have
suggested that this period coincides with the spawning season for tripletail. Atypically, many of
the fish near Jekyll Island are not associated with any structure, but rather are free swimming
near the surface of waters ranging from 2 to 4 meters deep. As tripletail angling pressure
increases in GA and elsewhere, additional information about their life history such as age,
growth, and reproduction data, is needed to inform fisheries managers to adequately protect this
species.
The lack of published tripletail data, particularly for the western Atlantic Ocean,
underscores the general scarcity of information on the life history of the species. The goal of the
current study was to describe reproductive characteristics of a nearshore tripletail aggregation in
the western Atlantic Ocean, specifically fish found near Jekyll Island, GA, USA. Specific
objectives were to compare results of non-lethal techniques with traditional lethal methods to
determine the gender and reproductive status of tripletail and to determine size at maturity to
inform fishery management actions. The current study represents the first attempt to evaluate
tripletail plasma VTG levels as a non-lethal method to determine gender and reproductive phase.
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
MATERIALS AND METHODS
Study Site
Tripletail sampling was conducted from March 30 to August 10, 2009 and March 14 -
August 6, 2010 in the Atlantic Ocean nearshore Jekyll Island, GA, USA. Tripletail were sampled
primarily around the northeast to central part of the island and on channel markers, range
markers, buoys, and other structures within St. Simons Sound, north and west of Jekyll Island
(Figure 1).
Field Sampling
This project was conducted under the auspices of the University of Georgia Animal Use
Protocol #A2009 02-030-R2. Sampling for tripletail and associated water quality variables was
performed on multiple dates during April to August during 2009 and 2010. On each sampling
trip, surface water temperature (ºC), salinity (ppt), and dissolved oxygen (mg/L) were measured
with an YSI 85 dissolved oxygen meter and recorded upon arrival at the sample site (Figure 1).
Hook-and-line methods from an open-cockpit fiberglass boat were used to sample tripletail. For
near shore sampling, the study area was searched visually for tripletail near the surface; when a
tripletail was spotted, they were directly targeted fish by casting a live white shrimp Litopenaeus
setiferus (Linneaus, 1758) or brown shrimp Farfantepenaeus aztecus (Ives, 1891)) or striped
mullet Mugil cephalus (Linneaus, 1758) with a spinning rod equipped with braided line (14 kg
test) attached to a popping cork rig with a Kahle™ live bait hook (size 1). Total numbers of
tripletail observed and captured were recorded and duration of the sampling event was recorded
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
to the nearest minute. The capture location for each fish was recorded with a global positioning
system (GPS).
Tripletail sampling also occurred around structures in the St. Simons Sound and adjacent
shipping channel. We used hook-and-line sampling methods to sample structures but with
different tactics than described for near shore (open water) sampling. We sampled approximately
two hours prior to, and post, slack tide. Heavier tackle was necessary to prevent line breakage
around the structure; we used a heavy-action spinning rod equipped with braided line (36.2 kg
test) with a slip float rig, a monofilament leader (36.2 kg), and a 7-g jig head hook baited with
live penaeid shrimp or striped mullet. We approached the structure by boat and fished the bait
throughout the water column next to the structure. Upon capture of a fish, data gathering
procedures were identical to the aforementioned sampling methodology. In 2009, we sampled
opportunistically on inshore structures when weather did not permit sampling nearshore. In 2010,
we began sampling the nearshore area and structures (in St. Simons sound) at a 50:50 ratio by
sampling day and allowed weekly catch success to determine where our effort was best allocated
the following week.
In addition to sampling with hook-and-line gear nearshore Jekyll Island, tripletail from
the aggregation were also sampled with a 12.2-meter fish trawl with 76.2-mm mesh (bar)
deployed from the GA-DNR Research Vessel (R/V) Anna. Vessel location (latitude and
longitude was determined with GPS), and heading of the R/V Anna was recorded at the
beginning of each tow, with trawl net--in, and at the end of each tow, with trawl net--out. Speed
was determined based on the amount of time required to get from the trawl net in GPS point to
the trawl net out GPS point. A maximum tow time of 10 minutes was used to minimize the risk
of lethal interactions with tripletail and other non-target species. The number of tripletail caught
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
was recorded, and procedures for handling the fish were identical to nearshore sampling
methodology by hook and line. Tripletail were also sampled opportunistically from local
tournaments and recreational anglers. As a result of the differing condition of the donations (i.e.,
carcass, fresh dead fish, live fish), not all fish sampled were included in all statistical analyses.
The sampling target was a maximum of 10 fish ≤ 610 mm per week for histological
evaluation: five individuals <457 mm total length (TL) and five individuals ≥ 457 mm (TL). The
457-mm (18 inch) designation represents the minimum size limit for possession of tripletail in
Georgia, established by the Georgia Department of Natural Resources (GADNR). Based on the
literature, all tripletail ≥ 610 mm were assumed to be mature fish and therefore were sacrificed.
Any captured fish that exceeded the target number were measured to the nearest millimeter for
TL and standard length (SL), tagged with a uniquely numbered Hallprint™ PDS plastic dart tag
inserted behind the base of the third dorsal spine, and released.
Upon capture of tripletail within the sampling target size range, blood samples were
immediately obtained from the caudal vein with a heparinized 3-mL syringe equipped with a
Luer-lok 18-guage hypodermic needle. The blood samples were carefully expelled into
numbered 1.0-mL centrifuge tubes and immediately placed on ice. To minimize degradation of
VTG, blood samples collected in 2009 contained the protease inhibitor aprotinin, and 2010
samples were treated with a protease inhibitor cocktail (P2714, Sigma-Aldrich, St. Louis, MO,
USA). Specimens were then placed on ice and returned to the lab within six hours of collection.
Once blood samples were collected, fish were marked with a unique tag affixed to the fish
through their mouth and out of their operculum via a zip tie and placed on ice until processing
when researchers returned to the lab at the GADNR Coastal Regional Division (CRD)
headquarters in Brunswick, GA.
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
At the CRD lab, plasma was separated from blood cells by centrifugation (1500 x g) for
10 min and was then extracted with a micropipette, placed into a cryogenic vial and frozen in
liquid nitrogen. Samples were later transferred from liquid nitrogen to an ultracold (-80ºC)
freezer until VTG analysis. Sacrificed tripletail were measured for TL and SL (nearest mm) and
weighed (nearest 1.0 g) with an electronic platform scale (max 20 kg; Northern Industrial R-
2553). Gonads were dissected from the fish, weighed (nearest 0.1g), and preserved in 10%
buffered formalin until further processing for histological analysis.
Total length and total weight (TW) data were examined for normality with the Shapiro-
Wilk test. These data were not normally distributed; therefore, they were log10 transformed to
achieve normality. Levene’s test was used to evaluate homogeneity of variances. A 2 X 2
factorial analysis of variance (ANOVA) was used to determine if there were significant
differences among TL and TW of samples collected in 2009 and 2010, sexes, or the interaction
between capture year and sex. Data were pooled if the relationships were not significantly
different. A chi-square analysis was used to determine if monthly sex ratios varied from the
expected 50:50 ratio (α = 0.05). March samples were excluded from the chi-square analysis
based on insufficient data (< 5 samples) during this month.
Gonad Histology
A subsample of 15 males and 15 females was used to determine if development within
the gonads was uniform throughout the length of the gonad. Gonads were removed from 10%
buffered formalin and three sections (i.e., one each from the posterior, central, and anterior
portions of the gonads) were placed in tissue cassettes. Standard histological procedures
including dehydration, embedding in paraffin, thin sectioning (4 um), staining with hematoxylin,
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
and counterstaining with eosin, were performed at the University of Georgia Veterinary
Medicine Diagnostic Lab. Development of gametes was confirmed to be uniform throughout the
gonad and all subsequent gonad samples were collected only from the central portion of the
gonad. Reproductive phases for both males and females were evaluated based on criteria
described by Brown-Peterson et al. (2011) by examination of the mounted and stained gonad
sections with a compound microscope. Females were classified as immature, developing (sub-
phase: early developing), spawning capable (sub-phase: actively spawning), regressing or
regenerating. Immature females contained only oogonia and primary growth (PG) oocytes.
Females entered the developing phase with the appearance of cortical alveoli (CA) oocytes.
Primary vitellogenic and secondary vitellogenic oocytes are also present during the developing
reproductive phase. Primary, secondary, and tertiary vitellogenic oocytes are determined based
on the relative increase in yolk deposition (Lowerre-Barbieri et al. 2011). Males were classified
as immature, developing (sub-phase: early developing), spawning capable (sub-phase: early
germinal epithelium (GE), mid-GE, and late-GE), regressing or regenerating (Brown-Peterson et
al. 2011). A second reader evaluated the reproductive status of a randomly selected subsample (n
= 25) for both males and females for quality assurance and control.
Length at 50% Maturity
Length at which 50% of individuals reached maturity for male and female tripletail was
evaluated for TL and age, based on the equation described by Goncalves and Erzini (2000):
Pi=1
1+e−b¿¿¿
where Pi represents the proportion of mature adults in each 50-mm length bin, b represents the
slope of the maturity curve, L50 is the length at which 50% of the fish are mature, and length or
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
age class at 50% maturity (Li ). Ages for fish in this study were based on a concurrent tripletail
aging project (Parr 2011). All male and female tripletail that were not in the immature
reproductive phase were classified as mature for determination of length at 50% maturity. Non-
linear regression (PROC NLIN) was used to model the parameters for the length at 50% maturity
(SAS 9.1; Freund and Littell 1991).
Gonadosomatic Index
Gonadosomatic index (GSI) values were calculated based on the equation originally
described by Nikolsky (1963):
I g=(W g
W t)× 100
where, Ig represents the percentage of gonad weight to total body weight, Wg represents gonad
weight, and Wt represents total weight of the fish. Gonadosomatic index values were evaluated
for normality with the Shapiro-Wilk test. Data were not normally distributed and could not be
transformed to fit a normal distribution; therefore, the GSI values were ranked for further
(nonparametric) statistical analyses. As a result of the relatively small, annual sample sizes, data
were combined from the two years of the study. Sex, reproductive phase, and capture month
variables were analyzed individually with one-way ANOVA to evaluate their relationships with
the GSI values (α = 0.05). Small sample sizes in some months and reproductive phases precluded
the use of a factorial ANOVA design to evaluate the interaction and effects of month and
reproductive phase on GSI (Appendix A). Trends were examined for GSI values across the
reproductive phases and capture months.
Plasma Vitellogenin
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
Tripletail plasma samples were shipped on ice via overnight express courier to the
University of Florida for VTG analysis. Vitellogenin was purified from plasma of estrogen
treated males by anion exchange chromatography with the BIOCAD Sprint Perfusion system
(Perseptive Biosystems) as described by Denslow et al. (1999). Briefly, plasma was diluted in
running buffer (10mM bis-tris propane, 50 mM NaCl, pH 9.0) and loaded onto a strong anion
exchange resin (POROS 20 HQ). Vitellogenin was eluted from the column with a linear gradient
of NaCl (50→1000 mM). The VTG fractions were pooled, pH adjusted to 7.0, and were then
concentrated with a 30,000 MWCO Centricon (Amicon) filter. Protease inhibitor, (Aprotinin, 10
KIU/ml), bacteriocide (azide, 0.02%), and cryprotectant (glycerol, 1:2) were added to the
purified VTG. The standard stored in this form is stable for 1-2 years (-20°C) and circumvents
freeze/thaw protein fracture.
Concentrations of plasma VTG were determined by direct enzyme-linked immunosorbent
assay (ELISA) with a monoclonal antibody, 3G2 (HL1393), that was developed for striped bass
VTG. Plasma samples were diluted 1:100, 1:10,000, and 1:100,000 with 10 mM phosphate, 150
mM NaCl, 0.02% azide, 10 KIU/mL Aprotinin, pH 7.6 (PBSZ-AP). Tripletail VTG standards (0,
0.005, 0.01, 0.02, 0.04, 0.06, 0.08, 0.1, 0.2, 0.4, 0.6, 0.8, 1.0 µg/mL) containing 1:100, 1:10,000
and 1:100,000 male plasma (in PBSZ-AP) were used to make a species-specific standard curve.
Male plasma was added to the standards to account for matrix effect found in direct ELISAs.
Samples and standards were loaded onto a 96-well ELISA plate in triplicate and stored overnight
at 4 ºC in a humidified Tupperware® container. The following day the plates were washed four
times with phosphate buffered saline solution and were then blocked with 1% bovine serum
albumin in 10 mM Tris, 150 mM NaCl, 0.05% Tween, 0.02% azide, 10 KIU/mL Aprotinin, pH
7.6 (1% BSA/TBSTZ-AP) for 2 hr at room temperature. The plates were rewashed with PBSZ (4
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
times) and the 1° monoclonal antibody, 3G2, was loaded into wells on each plate. The lowest
dilution (1:100) was probed with 1µg/mL of the monoclonal antibody and dilution > 1:10,000
with 0.1 µg/mL. After the addition of the monoclonal antibody, the plates were stored at 4 ºC
overnight in the humidified container. The following day the plates were washed and the
biotinylated secondary antibody, goat anti-mouse IgG-biotin (Pierce) was added to each well at
1:1,000 dilution in 1% BSA/TBSTZ-AP and incubated at room temperature for 2 hr. The plates
were washed and a strepavidin-alkaline phosphatase conjugate (Pierce) was added at 1:1,000
dilution in 1% BSA/TBSTZ-AP and incubated for 2 hr at room temperature. After a final wash
of the plates, the color was developed by adding 1 mg/ml p-nitro-phenyl phosphate in carbonate
buffer (30 mM carbonate, 2 mM MgCl2, pH 9.6) and the color was measured with an ELISA
plate reader (SpectraMax Plus384, Applied Biosystems) at 405 nm. Concentrations of the
unknowns were determined from the standard curves by using SoftMax® Pro analysis program.
The limit of detection for tripletail VTG was 1ug/mL. All assays were performed in triplicate
and reported as the mean of the three measurements. The coefficient of variation was <10% for
all samples analyzed. Inter- and intra-assay variability were measured by analyzing positive
controls on several plates and were <10%, and <5%, respectively.
Plasma VTG data was evaluated for normality with the Shapiro-wilk test and evaluated
for equality of variances with Levene’s test. Results of these tests indicated the data were not
normally distributed and their variances were unequal; therefore, VTG concentration levels were
ranked to facilitate further (nonparametric) statistical evaluation with a Kruskal-Wallis test. A t-
test was used to evaluate differences between male and female VTG ranks. Similar to GSI data,
VTG data from the two years were combined because of the small sample size. A one-way
ANOVA was performed for each sex to evaluate differences between the VTG ranks between
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
reproductive phases and capture month. As with GSI evaluations, some capture months and
reproductive phases did not contain a sufficient minimum sample size and restricted the use of a
factorial design. Linear regression was used to evaluate relationships between VTG and GSI for
males and females.
All statistical analyses were conducted with program SAS 9.1(SAS Institute, Inc; Cary,
NC). Duncan's multiple range test was used to evaluate significant differences among means for
all one-way ANOVAs (α = 0.05).
RESULTS
Field Sampling
The project included 177 sampling events with a total of 385 hours of ‘near shore’
sampling, 95 hours of ‘structure’ sampling, and 9 hours of ‘trawl’ sampling. Average water
temperature was 25.6 ºC, with a range of 13.7 – 33.0 ºC. Average salinity was 30.5 ppt, with a
range of 14.5 to 38.7 ppt. Dissolved oxygen averaged of 6.18 mg/L and ranged from 3.34 – 9.02
mg/L. A total of 432 tripletail were captured during the study, and 224 (122 males and 102
females) were sampled for reproductive evaluation. The remaining 208 fish were tagged and
released. Tripletail TL ranged from 241 to 822 mm and TW ranged from 265 to 14,152 g.
Differences in mean TL (F1,216 = 0.87, P = 0.3517) and TW (F1,216 = 0.89, P = 0.3476) were not
significant between the years; therefore, the data for both years were pooled. Mean female TL
(489 mm) was not significantly different from mean male TL (455 mm) (ANOVA: F1,216 = 3.85,
P = 0.0512). Mean female TW (3,116 g) was significantly heavier than mean male TW (2,314 g)
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
(ANOVA: F1,216 = 4.96, P = 0.00270). Ratio of males and females was not significantly different
than the expected 1:1 ratio (X2 = 2.3937, P = 0.0828).
Gonad Histology
Nearly all (115 of 122, 94%) of the male tripletail captured were in the spawning-capable
phase (Table I). Only one male (0.8 %) was in an immature reproductive phase. Female tripletail
were captured in all reproductive phases (Table II), but only two (2.0 %) of the 102 females were
classified in the ‘actively spawning’ sub-phase of the spawning-capable category. One actively
spawning female captured in June 2009 was 615 mm and contained oocytes that were
undergoing lipid coalescence, which is indicative of final oocyte maturation. The other actively
spawning female was 355 mm and was captured in April 2010; the ovaries contained hydrated
oocytes and post-ovulatory follicles, which indicated ovulation had occurred within 48 hours.
Length at Maturity
The estimated length at which 50% of females reached maturity (L50) was 459 mm with a
slope (b) of 0.02, and the age at which 50% of females reached maturity was estimated at 1.17
years with a slope of 4.21 (Figures 2 and 3). Length at which 50% of males reached maturity
could not be estimated by regression techniques because of a lack of convergence caused by the
lack of immature fish in the sample (Figure 2); however, the age at which 50% of males became
mature was 0.55 years with a slope of 9.74 (Figure 3).
Gonadosomatic Index
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
Gonadosomatic index values for female tripletail (n = 101) ranged from 0.07 to 10.9%
with a mean of 1.1% (Figure 4). Male (n = 116) GSI values ranged from 0.04 to 0.22% with a
mean of 0.11% (Figure 4). Females had significantly higher GSI ranks than males (T-test, DF =
210, t-value = -3.518, P <0.0001), and female GSI values in March were significantly higher
than May and June values (ANOVA: F5, 95 = 2.98, P = 0.0153). Significant differences were not
detected for male GSI ranks among sample months (ANOVA: F4,111 = 1.51, P = 0.2040)
Female GSI values were significantly different among reproductive phases (ANOVA:
F4,96 = 25.21, P = <0.0001). Gonadosomatic Index values for females in the immature
reproductive phase were lower than all other phases, and values for the regenerating phase were
higher than the immature phase and lower than all other reproductive phases. Differences were
not detected among the developing, spawning-capable, and regressing female reproductive
phases but were higher than all other reproductive phases. Significant differences were not
detected among male reproductive phases for GSI values (ANOVA: F3,111 = 1.89, P = 0.1357).
Vitellogenin
Plasma VTG concentrations for female tripletail (n = 77) ranged from below detection
(1.0 µg/ml) to 4000 µg/ml with a mean of 209 µg/ml and a standard deviation of 696 µg/ml
(Figures 5 and 6). Male tripletail (n = 98) VTG levels ranged from below detection to a
maximum of 170 μg/ml with a mean of 36 μg/ml and a standard deviation of 28 μg/ml (Figures 5
and 6). A t-test indicated that females had significantly higher VTG concentrations than males
(DF = 173, t-value = -3.49, P = 0.0006). Vitellogenin did not differ among months for males
(ANOVA: F4,92 = 0.64, P = 0.6351). Significant differences were detected among months for
female VTG concentrations (ANOVA: F4,73 = 3.33, P = 0.0146). May female VTG concentration
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
was lower than April and August but was not different from June and July. Mean VTG in
immature females was lower than all other phases except the regenerating phase (ANOVA: F4,73
= 9.09, P < 0.0001). Differences were not detected among females in developing, regressing, and
regenerating phases. Mean VTG concentration in spawning-capable females was higher than all
phases except the developing phase. Vitellogenin concentrations did not differ among male
reproductive phases (ANOVA: F3,93 = 0.24, P = 0.8684).
Plasma VTG and GSI values showed similar trends across the reproductive phases for
males and females (Figure 7). Male tripletail did not exhibit any peaks in GSI or VTG during our
sampling period, and linear regression analysis of VTG and GSI for males showed a very weak
relationship (r2=0.186; n = 94). Female tripletail in the spawning capable phase increased in
VTG and GSI values, but VTG and GSI across all other reproductive phases were similar. Linear
regression demonstrated a strong relationship (r2 = 0.873, n= 77) between VTG and GSI in
females.
DISCUSSION
Male tripletail captured near Jekyll Island, GA from March to August were in a
spawning-capable reproductive phase; however, most female tripletail in this aggregation were
not in spawning condition. Plasma VTG analysis was unable to decisively distinguish males and
females, although spawning-capable females were distinguishable from all other reproductive
phases. A larger sample size than was available in the present study, particularly of females >525
mm, is needed to provide more conclusive evidence for the utility of VTG to differentiate sexes.
Increased sampling of females >500 mm is needed to determine if the variability in the GSI and
VTG data occurring during the year is natural or is an artifact of the small data set. The
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
limitations of this data set required us to evaluate relationships between GSI and VTG with one-
way ANOVA based on ranks instead of actual data, which increased uncertainty in interpreting
our results.
Based on histology in the present study, 50% of male tripletail reached maturity at
approximately 0.5 years old, although our estimate is limited by the lack of age-0 fish (Figure 3).
The lack of immature males precluded calculation of L50 for males; however, the smallest male
tripletail found in a spawning-capable phase was 261 mm. The only immature male was 336 mm
and our data suggests that the L50 for males is < 261 mm (Figure 2). Brown-Peterson and Franks
(2001) and Strelcheck et al. (2004) reported that all males in their studies were sexually mature
and suggested that length at which 50% of the males were mature would likely be ≤290 mm.
Male GSI data remained relatively constant throughout the sampling period, mean value of
0.11% and a range of 0.04 to 0.22%, as would be expected from the primarily spawning capable
male population. Overall, male tripletail captured in the present study near Jekyll Island, GA
were spawning capable through the size range (261- 714 mm) and through the entire sampling
period.
Through histological analysis it was determined that 50% of female tripletail in GA
reached maturity at 449 mm or 1.17 years (Figure 2 and 3). Previous studies have reported that
50% of female tripletail in the Gulf of Mexico reached maturity at approximately 490 mm
(Brown-Peterson and Franks 2001; Strelcheck et al. 2004). Similarly, Brown-Peterson and
Franks (2001) reported that all females >525 were mm sexually mature. Our study indicates that
the L50 for females (449 mm) was slightly below the current minimum size limit (457 mm) for
tripletail caught in Georgia waters.
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
Female tripletail had a wider range of GSI values than males, 0.07 - 10.9%, with a mean
of 1.1%; female GSI generally increased from April to August. The high GSI value in March is a
result of a two females captured in 2009 and could be indicative of a protracted spawning period
of tripletail or could be an artifact of small sample size. The asynchronous oocyte maturation and
relatively low mean GSI values throughout the sampling period is consistent with previous
tripletail studies (Brown-Peterson and Franks 2001; Cooper 2002), as well as other multiple-
batch spawning species such as wahoo Acanthocybium solandri (Brown-Peterson et al. 2000).
Plasma VTG concentrations were significantly greater in female tripletail than in males
as expected; however, the difference appears to be heavily influenced by high VTG
concentrations in a few spawning-capable females. Statistical interpretations of the data were
limited by the small sample size, but the trend of higher GSI and VTG for females in the
spawning-capable phase suggests that a more robust dataset than the one used in this study could
provide the ability to differentiate spawning females from other female reproductive phases and
from males (Figures 5 and 6). The relationship between VTG and GSI was strong (r2= 0.873) but
should be interpreted with caution because of the small sample size of high VTG and high GSI,
which may have disproportionately affected the coefficient of determination. The VTG
concentration in females also appears to increase into August, which suggests that peak
spawning may occur in August or later into the year (Figure 6). It should be noted that increased
VTG levels are not always clear indicators of temporal and spatial distribution of spawning fish,
but can be used as a line of evidence for elucidating reproductive activities (Ceapa et al. 2002).
Plasma VTG in spawning capable females was similar to those reported in other fish species
including spawning stellate sturgeon Acipenser stellatus (Ceapa et al. 2002), gag grouper
Mycteroperca microlepis (~3000 µg/ml;Heppell and Sullivan 2000), and presumed spawning
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
female Gulf sturgeon Acipenser oxyrinchus desotoi (> 1000 µg/ml;Heise et al. 2009). Tripletail
VTG levels were greater (~ 400 µg/ml) than concentrations found in spawning shovelnose
sturgeon Scaphirhynchus platorhynchus (Wildhaber et al. 2007).
Previous estimates of length and age at which 50% of the population is mature and those
of the present study are based on the premise that females in a developing stage during the
predicted spawning season are mature fish. Other investigators (Strelcheck et al. 2004) have
warned that if fish in the developing phase do not spawn in that season, length- and age-at-sexual
maturity may be underestimated. Strelcheck et al. (2004) further suggested that if early
vitellogenic oocytes were used as the minimum qualification for maturity status, length at which
50% of the females are mature would increase from 494 to 594 mm, which corresponds to an age
of 1 or 2 years. In the present study, classification of immature and developing females as
immature and all other female reproductive phases as mature resulted in an increase in length at
50% maturity from 449 to 491 mm, which corresponds to an age of 1.17 to 1.47 years of age.
This change in maturity classification indicates that a more conservative approach of classifying
maturity status yields only slightly higher length and age estimates; however, the increase to
491mm does raise the length at 50% maturity above Georgia’s current minimum size restriction,
of 457 mm, meaning less than 50% of female fish are mature when they become vulnerable to
harvest.
Preliminary tagging data (Streich et al. 2013) indicates that tripletail remain near the
Georgia coast as late as October; therefore, spawning in the Atlantic could occur later in the year
than previously reported for fish captured in the Gulf of Mexico and represents a possible bias in
the study design. Cooper (2002) suggested that spawning could occur year-round in tropical
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
waters, although spawning seems to occur primarily between April and September off the eastern
coast of Florida.
Currently the state of Georgia’s recreational fishing harvest regulations require a
minimum size limit of 457 mm and a creel limit of two fish per person per day. This level of
harvest seems to allow 100% of the males and approximately 50% of the females to reach sexual
maturity prior to vulnerability of harvest. An increase in the minimum size would allow a
greater percentage of females to reach sexual maturity. In the present study, only one female
tripletail greater than 500 mm (1 of 39) was in an immature reproductive phase; therefore, an
increase in the Georgia minimum size limit to 500-525 mm may allow nearly all females to reach
maturity prior to susceptibility to exploitation by anglers. Currently, fisheries managers do not
have sufficient data to understand the effects of fishing mortality on tripletail populations.
The inability to use entanglement gear to capture tripletail in their primary habitat
presents researchers with a challenge when attempting to obtain representative samples across all
size ranges. The use of hook-and-line sampling presents the most cost effective method for
sampling tripletail; however, the use of these sampling methodologies can bias sampling, often
leading to the disproportionate capture of fish in the lower end of the size range, a trend evident
in this and other tripletail studies (Brown-Peterson and Franks 2001; Cooper 2002; Strelcheck et
al. 2004). The lack of imminently spawning females in the present study could be attributed to
the possibility that imminently spawning females may not actively feed; therefore, other methods
to capture tripletail must continue to be explored. Future research should expand the sampling to
a larger temporal and spatial scale and use tagging information to better understand migratory
patterns for more cost-effective sampling. A larger spatial scale should include more inshore and
nearshore locations on the Atlantic coast but should also include an offshore component. A large
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
offshore effort may be cost prohibitive because of the random distribution of tripletail and
association with non-stationary floating debris.
Although the role of near shore aggregations in the life history of tripletail in the western
Atlantic remains unanswered, the current study indicates that plasma VTG concentrations could
provide an effective non-lethal sampling technique for determining reproductive status of female
tripletail. The primary need for future research is an increased sample size of sexually mature
female tripletail (> ~525 mm) throughout the year. Increasing the sample size of large females
throughout the year could elucidate trends in GSI and plasma VTG concentrations. Future
laboratory studies of VTG and sex steroid hormone (e.g., testosterone, estradiol, progesterone)
concentrations in maturing tripletail may be a cost effective means for better understanding
tripletail reproductive biology.
Acknowledgements
This project was funded by the Georgia Department of Natural Resources, Coastal
Resources Division (CRD) and the Federal Sportfish Restoration Fund. D. Haymans and S.
Woodward helped all along the way to the project’s completion. C. Belcher provided critical
guidance and technical assistance. B. Warren provided insightful editorial comments to an
earlier draft of this manuscript. J. Franks provided invaluable technical advice on many aspects
of tripletail life history and biology. Staff at GADNR CRD including P. Geer, C. Kinstle,
C.Kalinowsky, G. Gaddis, S. Jordan, E. Robillard, D. McDowell, K. Herrin, L. Willis, K. Wolfe,
G. Meeks, J. Mericle, D. Guadagnoli, P. Medders, W. Hughes, J. Page, B. Readdick, R.
Flournoy, E. Butler and D.Varnadoe provided field and technical assistance with the project.
Anglers including those from the Coastal Conservation Association of Georgia and especially G.
Hildreth provided assistance with field sampling. The GA Cooperative Research Unit is jointly
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
sponsored by the GA Department of Natural Resources, the University of Georgia, the U.S. Fish
and Wildlife Service, the U.S. Geological Survey and the Wildlife Management Insitute. Any
use of trade, product, or firm names is for descriptive purposes only and does not imply
endorsement by the U.S. Government.
REFERENCES
Armstrong, M. P., Crabtree R. E., Murphy, M. D., & Muller, R. G. (1996). A stock assessment
of tripletail, Lobotes surinamensis, in Florida waters. Florida Department of
Environmental Protection, Florida Marine Research Institution Publication.
Baughman, J. L. (1941). On the occurrence in the Gulf Coast waters of the United
States of the tripletail, Lobotes surinamensis, with notes on its natural history. The
American Naturalist 75, 569-579.
Benson, N. G. (1982). Life history requirements of selected finfish and shellfish in the
Mississippi Sound and adjacent areas. US Fish and Wildlife Service Biological
Services Program Technical Report No. 81.
Breder, C. M. (1949). On the behavior of young Lobotes surinamensis. Copeia 4, 237-242.
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
Brown-Peterson, N. J., Overstreet, R. M., Lotz, J. M., Franks, J.S., & Burns, K. M.. (2000).
Reproductive biology of cobia, Rachycentron canadum, from coastal waters of the
southern United States. Fisheries Bulletin 99, 15-28.
Brown-Peterson, N. J. & Franks, J. S. (2001). Aspects of the reproductive biology of
tripletail, Lobotes surinamensis, in the northern Gulf of Mexico. Proceedings of the Gulf
and Caribbean Fisheries Institute 52, 586-597.
Brown-Peterson, N. J., Wyanski D. M., Saborido-Rey, F., Macewicz, B. J., &
Lowerre-Barbieri, S. K. (2011). A standardized terminology for describing reproductive
development in fishes. Marine and Coastal Fisheries 3, 52–70.
Ceapa, C., Williot, P., Le Menn, F., & Davail-Cuisset, B. (2002). Plasma sex steroids and
vitellogenin levels in stellate sturgeon (Acipenser Stellatus Pallas) during spawning
migration in the Danube River. Journal of Applied Ichthyology 18, 391-396.
Cooper, D. C. (2002). Spawning Patterns of Tripletail, Lobotes surinamensis, on the Atlantic
Coast of Florida. Master’s Thesis. Florida Institute of Technology, Melbourne, FL.
Denslow, N. D., Chow, M., Kroll, K. J., & Green, K. J. (1999). Vitellogenin as a biomarker of
exposure to estrogen or estrogen mimics. Ecotoxicology 8, 385-398.
Ditty, J. G. and Shaw, R. F. (1994). Larval development of tripletail, Lobotes surinamensis
(Pisces, Lobotidae), and their spatial and temporal distribution in the northern Gulf of
Mexico. Fishery Bulletin 92, 33-45.
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
Franks, J. S., Warren, J. R., Wilson, D. P., Garder, N. M. & Larsen, K. M. (1998). Potential of
fin spines and fin rays for estimating the age of tripletail, Lobotes surinamensis, from the
northern Gulf of Mexico. Proceedings of the Gulf and Caribbean Fisheries Institute 50,
1022-1037.
Franks, J. S., Ogle, J. T., Hendon, R., Barnes, D. N. & Nicholson, L. C. (2001). Growth of
captive juvenile tripletail Lobotes surinamensis. Gulf and Caribbean Research 1, 75-78.
Freund, R. J. & Littell, R. C. (1991). SAS system for regression, 2nd edition. SAS Institute,
Cary, North Carolina.
Goncalves, J. M. S. & Erzini, K.. (2000). The reproductive biology of Spondyliosoma cantharus
(L.) from the SW Coast of Portugal. Scienta Marina 64, 403-411.
Gudger, E. W. (1931). The triple-tail, Lobotes surinamensis, Its names, occurrence on our
coasts and its natural history. The American Naturalist 65, 49-69.
Hardy, J. D. (1978). Development of fishes of the Mid-Atlantic Bight: an atlas of egg,
larval and juvenile stages. U.S. Fish and Wildlife Service, Biological Service Program
FSW/BSP78/12.
Heise, R. J., Bringolf, R. B., Patterson, R., Cope, W. G. & Ross, S. T. (2009). Plasma
vitellogenin and estradiol concentrations in adult Gulf Sturgeon from the Pascagoula
River Drainage, Mississippi. Transactions of the American Fisheries Society 138, 1028-
1035.
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
Heppell, S. A & Sullivan, C. V. (2000). Identification of gender and reproductive maturity in the
absence of gonads: muscle tissue levels of sex steroids and vitellogenin in Gag
(Mycteroperca microlepis). Canadian Journal of Fisheries and Aquatic Sciences 57, 148-
159.
Kelly, H. A. (1923). Triple-tail numerous in North Carolina. Copeia 124, 109-111.
Lowerre-Barbieri, S. K., Brown-Peterson, N. J., Murua, H., Tomkiewicz, J., Wyanski, D. M. &
Saborido-Rey, F. (2011). Emerging issues and methodological advances in Fisheries
Reproductive Biology. Marine and Coastal Fisheries 3, 32-51.
Merriner, J. V. & Foster, W. A. (1974). Life history aspects of the tripletail, Lobotes
surinamensis (Chordata-Pisces-Lobotidae), in North Carolina Waters. Journal of the
Elisha Mitchell Scientific Society 90, 121-124.
Nikolsky, G. (1963). The Ecology of Fishes. Academic Press, New York.
Parr, R.T. 2011. Age, growth, and reproductive status of tripletail (Lobotes surinamensis) in the
aggregation nearshore Jekyll Island, GA, USA. MS Thesis. University of Georgia.
Streich, M. K., C. A. Kalinowsky, & Peterson, D. L. (2013). Residence, habitat use, and
movement patterns of Atlantic tripletail in the Ossabaw Sound Estuary, Georgia. Marine
and Coastal Fisheries: Dynamics, Management and Ecosystem Science 5, 291-302.
Strelcheck, A. J., Jackson, J. B., Cowan Jr., J. H., & Shipp R. L. (2004). Age, growth,
diet and reproductive biology of tripletail, Lobotes surinamensis, from the north-central
Gulf of Mexico. Gulf of Mexico Science 22, 45-53.
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
West, G. (1990). Methods of assessing ovarian development in fishes: A Review. Australian
Journal of Marine and Freshwater Research 41, 199-222.
Wildhaber, M. L., Papoulias, D. M., DeLonay, A. J., Tillitt, D. E., Bryan, J. L. & Annis, M. L.
(2007). Physical and hormonal examination of Missouri River shovelnose sturgeon
reproductive stage: A Reference Guide. Journal of Applied Ichthyology 23,382-401.
615
616
617
618
619
620
621
622
623
Table I. Reproductive phases of individual male tripletail (n = 122) captured in 2009 and 2010 near Jekyll Island, GA, USA. All males
in this study in the regressing phase were spawning capable but were not undergoing active spermatogenesis. GE = germinal
epithelium.
Developing Spawning Capable
Month Immature Early Developing Early GE Mid GE Late GE Regressing Regenerating
March 0 0 0 0 0 0 0 0
April 0 1 0 0 2 1 1 0
May 0 1 4 6 9 6 8 0
June 1 0 0 5 20 21 3 0
July 0 0 0 3 12 12 1 0
August 0 0 0 0 2 2 1 0
30
624
625
626
627
628
629
630
631
632
633
Table II. Reproductive phases of individual female tripletail (n = 102) captured in 2009 and 2010 near Jekyll Island, GA, USA.
Developing Spawning Capable
Month Immature Early DevelopingSpawning Capable
Actively Spawning Regressing
Regenerating
March 0 1 0 1 0 0 0
April 7 6 0 0 1 0 2
May 14 2 0 0 0 2 5
June 18 0 0 0 1 2 15
July 4 0 3 5 0 0 9
August 0 0 0 2 0 1 1
31
634
635
Figure 1. Tripletail sampling location near Jekyll Island, GA, USA. Inset shows a map of the
southeast United States with the Jekyll Island area indicated by the arrow. Each point on the map
indicates that one or more tripletail were captured at that location from March to August 2009
and 2010.
32
636
637
638
639
640
641
Figure 2. Non-linear regression of sexually mature female tripletail in 50-mm length bins
captured near Jekyll Island, GA, USA from March to August 2009 and 2010. Closed data points
represent actual cumulative percent maturity of females, whereas males are represented by the
open data points. The dashed line denotes the length (459 mm) at which 50% of female tripletail
are mature. The dotted line represents the minimum size limit (457 mm) currently enforced by
the Georgia Department of Natural Resources. Non-linear regression models for males were
unable to converge and therefore were unable to be modeled; however, only one male captured
in this study was classified as immature.
33
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
Figure 3. Non-linear regression of sexually mature female and male tripletail by age class
captured near Jekyll Island, GA, USA from March to August 2009 and 2010. Closed data points
represent actual cumulative percent maturity of females; males are represented by the open data
points. The dotted line denotes the age at which 50% of males (0.55 years) and females (1.17
years) are mature.
34
657
658
659
660
661
662
663
664
665
666
667
668
Figure 4. Mean gonadosomatic index values for (A) female (n = 101) and (B) male (n = 116)
tripletail captured near Jekyll Island, GA, USA from March to August 2009 and 2010. Error bars
represent 95% confidence intervals.
35
669
670
671
672
673
674
675
Figure 5. Blood plasma vitellogenin concentrations of tripletail captured near Jekyll Island, GA,
USA from March to August 2009 and 2010. Females are represented by the triangles and males
are represented by open circles. Reproductive phases are represented by Imm- immature, Dev-
developing, SC- spawning capable, Regress- regressing, and Regen- regenerating.
36
676
677
678
679
680
681
682
683
684
685
686
687
688
689
Figure 6. Mean plasma vitellogenin concentrations (mug/ml) for (A) female (n = 77) and (B)
male (n = 98) tripletail captured near Jekyll Island, GA, USA from March to August 2009 and
2010. Error bars represent 95% confidence intervals.
37
690
691
692
693
694
695
696
697
Figure 7. Comparison of plasma vitellogenin and gonadosomatic index values across
reproductive phases for (A) female (n=77) and (B) male (n=98) tripletail captured near Jekyll
Island, GA, USA during March to August 2009 and 2010. Vitellogenin means are represented
by triangles and GSI mean values are represented by circles. Error Bars represent 95%
confidence intervals. Reproductive phases are represented by Imm- immature, Dev- developing,
SC- spawning capable, Regress- regressing, and Regen- regenerating
38
698
699
700
701
702
703
704