Age and growth of dusky grouper (Epinephelus marginatus) (Perciformes: Epinephelidae) in the southwestern Atlantic, with a size comparison of offshore and littoral habitats.
The dusky grouper (Epinephelus marginatus) (Epinephelidae) inhabits shelter-rich, hard substrata on the continental shelf along the eastern coast of South America from Brazil to Argentina (Figueiredo and Menezes, 1980; Irigoyen et al., 2005), throughout the Mediterranean Sea, and from the British Isles around the southern tip of Africa (Heemstra and Randall, 1993) to southern Mozambique (Fennessy, 2006). Adults inhabit rocky bottoms, generally at depths up to 50 m, and they can be found occasionally at depths up to 250 m (Brusle, 1985; Heemstra and Randall, 1993), whereas juveniles are usually found in coastal tide pools (Azevedo et al., 1995). Like other epinephelids, the dusky grouper is a slow-growing protogynous hermaphrodite species with late sexual maturation and low natural mortality rates (Manooch and Mason, 1987), and it is also a highly valuable commercial fish (Heemstra and Randall, 1993). These combined characteristics make the dusky grouper highly vulnerable to overfishing. This species is classified as endangered by the International Union for Conservation of Nature (Cornish and Harmelin-Vivien, 2004), with a decreasing global population trend.
The dusky grouper is the only large epinephelid that is usually found along the extreme southern part of the Brazilian coast, where it is fished over inshore rocky bottoms (depths <5 m) and offshore banks (depths >10 m) by small-scale fisheries (Condini et al., 2007). Offshore populations of dusky grouper occasionally are targeted opportunistically by large-scale commercial fisheries that use hand lines, but the species is otherwise not a commercially targeted species. The most frequently visited site in the southwestern Atlantic for commercial offshore fishing of this species is Carpinteiro Bank.
The role of dusky groupers in the coastal ecosystems of South America is not completely understood. Given the likely importance of this species as a predator (Renones et al., 2002), it is imperative to understand the implications of any sort of commercial exploitation that may be involved. To prevent stock collapse, reef fishes should be fished carefully because slow-growing, late-maturing fish species are found frequently in coastal ecosystems and are vulnerable particularly to overfishing (Coleman et al., 2000; Sadovy et al., 2013). Quantifying the age and growth of dusky groupers is required, therefore, to support adequate conservation and management of this species at its southernmost region of occurrence.
Previous investigations have provided initial information on the age structure of the dusky grouper in South America and also revealed the absence of reproduction in a coastal population associated with littoral rocky jetties from extreme southern Brazil (Seyboth et al., 2011). Those authors adopted the classification developed by Craig and Hastings (2007) that placed the dusky grouper in Mycteroperca. For our study, we followed the most recent classification (Craig et al., 2011), in which the species was retained in Epinephelus, given the absence of conclusive studies to change the genus. Another study conducted in this region revealed that the dusky grouper reproduces at offshore Carpinteiro Bank (Condini et al., 2014).
In this study, we validated the timing of increment deposition in otoliths and examined the aging structure and growth parameters of dusky grouper in an offshore habitat (Carpinteiro Bank, at depths of 1525 m). Because we had access to the original data of Seyboth et al. (2011), we also aimed to test the hypothesis, previously reported by Seyboth et al. (2011), that offshore habitats (depths of 15-25 m) may constitute better habitats for growth and reproduction of dusky groupers than inshore habitats (depths <5 m).
Material and methods
Sampling, fish processing, and study area
Dusky grouper samples examined in this study (n=211) were identified according to Heemstra and Randall (1993). They were collected twice a month from landings in small-scale fisheries in Rio Grande, a port city in southern Brazil (Fig. 1), from 2008 to 2011. Fish were caught with hand lines, and their origin was evaluated through interviews with owners of fishing boats. Only fish caught specifically at the Carpinteiro Bank were considered. In the laboratory, the total length (TL) in millimeters and weight (WT) in grams of each specimen were measured, and sex was identified by a macroscopic examination of the gonads following Marino et al. (2001). Male and female gonadal differences are quite clear in macroscopic examination for this hermaphroditic grouper (Marino et al., 2001; Condini et al., 2014). The Carpinteiro Bank (32[degrees]16 S; 51[degrees]47 W) (Fig. 1) is a submersed reef, with depths ranging from 15 to 25 m, formed by beach rocks and is superficially colonized by bryozoans, sponges, crustaceans, polychaetes, and coralline algae (Buchmann et al., 2001). Located approximately 30 km offshore from the city of Rio Grande (32[degrees] S), this bank is likely the most austral region where the dusky grouper is commercially exploited.
The sagittal otoliths were dissected from all samples and stored dry. The otoliths were then embedded in epoxy resin and sectioned through the core with an Isomet (1) low speed saw (Buehler, Lake Bluff, IL) coupled to a diamond watering blade to obtain sections 0.4-0.6 mm thick. These sections were glued to histological glass slides, polished with fine sandpaper (grits of 2000-8000), embedded in Entellan mounting medium (Merck KGaA, Darmstadt, Germany), covered with thin glass slides, and, finally, examined under a stereomicroscope coupled to a computerized imaging system. All sections were photographed under transmitted light so that translucent and opaque bands in the otoliths could be appear as white and dark bands in the digital photographs, respectively. Each otolith was read 3 times at intervals of one month by an experienced reader with no prior knowledge of either fish size or previous reading results. Only those otoliths with at least 2 corresponding increment numbers were used in our study.
The precision of otolith readings was evaluated through analysis of average percent error (APE; Campana, 2001) with the following equation:
APE = 100% x 1/R [[summation].sup.R.sub.i=1] [absolute value of [x.sub.ij - [x.sub.j]]/[x.sub.j], (1)
where [x.sub.ij] = the ith age determination of the jth fish;
[x.sub.j] = the mean age estimate of the jth fish; and
R = the number of times that each fish is aged.
Validation and growth
The timing of otolith incremental deposition was estimated through marginal increment analysis (MIA) following Manickchand-Heileman and Phillip (2000), with the extra growth expressed as a proportion of the previous year's growth:
MIA = ([R.sub.t] - [R.sub.t]-1)/([R.sub.t] - 1 - [R.sub.t]-2), (2)
where [R.sub.t] = the distance measured from the core to the otolith's edge;
[R.sub.t-1] = the distance between the core and the distal margin of the last opaque band; and
[R.sub.t-2] = the distance between the core and the distal margin of the penultimate opaque band.
Growth increment measurements were conducted with otolith images by using the free software ImageTool (University of Texas Health Science Center, San Antonio), which was calibrated with a micrometric scale glass. For MIA, 188 otoliths (from fish of sizes from 277 to 1160 mm TL) were used. During summer, autumn, winter, and spring, 91, 48, 10, and 39 otoliths, respectively, were obtained,. Marginal increment values were averaged over the summer (January-March), autumn (April-June), winter (July-September) and spring (October-December). These averages were compared by using the nonparametric Kruskal-Wallis and Mann-Whitney tests (Zar, 1999) because the data were not normally distributed.
To estimate average growth, the number of otolith increments was modeled against TL by fitting a von Bertalanffy (Eq. 3) curve and by using a nonlinear least squares method (Ricker, 1975).
[MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] (3)
where TL = the TL corresponding to age I;
[L.sub.[infinity]] = the mean theoretical maximum TL;
[t.sub.0] = the theoretical age at zero length; and
K = the growth coefficient, the rate at which the curve approaches the asymptote.
These parameters were estimated both on the basis of all samples (male+female) and on the basis of females only. Growth parameters were not estimated for males because of their small sample size (n=11).
Data on sea-surface temperatures (SSTs) were analyzed from a 40-year time series measured in the region neighboring the Carpinteiro Bank (specifically, between 32-32[degrees]50'S and 50-52[degrees]W) made available by the Coastal and Estuarine Oceanography Laboratory of Rio Grande Federal University. SST data were averaged by season. Data on subsurface temperature were not available for this site.
Framework for habitat comparison
The hypothesis that offshore habitats may provide better environmental conditions for growth of dusky groupers than inshore habitats was tested by comparing mean sizes between fish from both sites. Specifically, the mean sizes at ages 3, 4, 5, 6, and 7 of fish collected offshore at the Carpinteiro Bank (depths of 15-25 m) were compared with the mean sizes of fish collected from the inshore rocky jetties of Rio Grande (depths <5 m) from 2007 to 2009 that were previously reported by Seyboth et al. (2011). These age groups were selected on the basis of the simultaneous availability of 10 or more individuals per age group at both sites. Leng-that-age data of inshore dusky groupers (Seyboth et al., 2011) were made available by those authors. Otoliths in this study and in Seyboth et al. (2011) were read by the same person. Statistical analysis was conducted through a one-way analysis of variance after verification of the assumptions of normality and homoscedasticity (Zar, 1999).
The TL of the dusky groupers sampled at Carpinteiro Bank ranged from 150 to 1160 mm TL (Fig. 2), and 80% of all samples measured between 300 and 700 mm TL. Females (n=200) accounted for the vast majority of samples, whereas males (n=11) composed only 5.5% of all samples. As expected, the mean TL for males (890.2 mm TL [standard deviation (SD) 122]) was larger than the mean for females (512.1 mm TL [SD 152.9]). The length-weight relationship was WT = 0.00001 x [TL.sup.3.094] (coefficient of determination [[r.sup.2]]=0.985), and the allometric coefficient was significantly different from 3 (t-test: P<0.0003), revealing that the species grows a little more in weight than in length.
The opaque and translucent growth bands in the otoliths of the dusky grouper were reasonably discernible, resulting in fine levels of precision during the process of otolith reading (APE=6.9%, n=211). Of the 211 examined otoliths, 22 were excluded from the analysis because of the absence of agreement among readings and 188 and 189 were used to validate the timing of deposition of growth increments and to estimate aging structure and growth, respectively.
The mean distribution of marginal increments in otoliths had significant differences among the fish collected during the 4 seasons (Kruskal-Wallis test: P<0.03; Fig. 3A). Marginal increment values were significantly lower during the winter than during the spring and summer (Mann-Whitney test: P<0.005 and P<0.018, respectively), and this pattern of differences was the same as the one observed for the proportion of opaque bands in the otolith edges (Fig. 3B). The same pattern was obtained for mean SST, where the proportion of opaque bands at the otolith edges was positively correlated with SST ([r.sup.2]=0.841).
Ages ranged from 1 to 40 years, and 85% of samples were aged between 2 and 8 years (Table 1). The mean ages for males and females were 26.7 years (SD 6.3) and 6.1 years (SD 4.9), respectively. The youngest sampled male was 20 years old and measured 760 mm TL, whereas no females were found at ages of more than 27 years or lengths greater than 933 mm TL. The von Bertalanffy parameters that were estimated for pooled sexes (n=189; [L.sub.[infinity]]=900.9 mm TL, K=0.129, [t.sub.0]=-1.45 years) showed smaller values for [L.sub.[infinity]] and larger values for K when males (n=ll) were removed from the analysis (n=178, [L.sub.[infinity]]=851.1 mm TL, K=0.153, [t.sub.0]=1.06 years). The von Bertalanffy curve had the typical exponential asymptotic shape and allowed us to estimate that 70% of the asymptotic length of a fish was achieved at approximately 8 years of age (Fig. 4; Table 1).
A comparison of fish sizes at ages 3-6 between littoral sites and offshore sites showed that dusky groupers from the offshore Carpinteiro Bank were significantly larger than fish from the inshore rocky jetties located at the mouth of Patos Lagoon in the Rio Grande (F=22.39, P<0.001; Fig. 5), with mean differences of 11.7%, 19.6%, 16.7%, and 11% per year, respectively. Significant differences, however, were not observed for age 7.
For otoliths to be used as reliable age indicators, they must display an internal structure of increments formed on a regular and predictable time scale. In dusky groupers, otoliths present well-defined growth increments that allow for age estimation at a relatively high precision. Translucent and opaque bands typically were formed during winter and summer, respectively, as determined through the analysis of marginal increments. Marginal increment analysis, however, is not considered the most trustworthy technique for validation of growth increments in otoliths (Campana, 2001), particularly where the temporal variation in environmental temperature is not strong enough to significantly influence fish metabolism. Therefore, to help increase confidence in validation, the seasonality of SST also was examined (Beckman and Wilson, 1995; Fablet et al., 2011). As expected, the results from marginal increment analysis closely followed the seasonal fluctuations in SST--a finding that supports the hypothesis that opaque and translucent increments in the otoliths of dusky groupers may be formed on an annual basis.
Moreover, the annual deposition of growth increments in otoliths has been reported previously for the dusky grouper (Fennessy, 2006; Renones et al., 2007) and other grouper species, such as the yellowedge grouper (E. flavolimbatus [Manickchand-Heileman and Phillip, 2000]), yellowmouth grouper (Mycteroperca interstitialis [Manickchand-Heileman and Phillip, 2000]), leopard grouper (M. rosacea [Dfaz-Uribe et al., 2001]), orange-spotted grouper (E. coioides [(Grandcourt et al., 2005)], and island grouper (M. fusca [Bustos et al., 2009]), indicating that it is an usual characteristic in epinephelids. The same pattern also was found for other long-lived fish species, such as the whitemouth croaker (Micropogonias furnieri [Haimovici and Umpierre, 1996]) and wreckfish (Polyprion americanus [Peres and Haimovici, 2004]), that inhabit the southwestern Atlantic.
The first finding on the growth of the dusky grouper in this study was the absence of males younger than 20 years or smaller than 760 mm TL--probably a result of protogynous hermaphroditism in this species (Heemstra and Randall, 1993; Andrade et al., 2003; Renones et al., 2010; Condini et al., 2013). Under that reproductive strategy, dusky groupers are expected to first mature as females (at approximately 5 years old) and then change sex into males after approximately 7 years old (Renones et al., 2010). Results from the few studies that have examined age and gonads simultaneously in dusky groupers indicate that males first appear in dusky grouper populations at diverse sizes and ages. For example, younger sampled males varied from 7 years (and ~580 mm TL) in the Mediterranean Sea (Renones et al., 2007) up to 9 years (and ~810 mm TL) off southeast Africa (Fennessy, 2006). We recognize that variables like sampling selectivity, environmental conditions, intraspecific competition, and fishing pressure may be related to the age and size at which sexual transition occurs. However, at this point, we have no further evidence to explain the very low abundance of male dusky groupers found in our study.
Examination of the von Bertalanffy parameters revealed that dusky groupers from Carpinteiro Bank grow slightly faster and attain slightly smaller theoretical maximum lengths than fish sampled from other areas in other studies. Although the von Bertalanffy model provided realistic estimates of growth parameters, [L.sub.[infinity]] (900 mm TL) was considerably smaller than the maximum length actually observed in this study (1160 mm TL) because fish older than 25 years were poorly represented. Given that the growth parameters were estimated by least squares fitting, the addition of more old individuals would most likely increase [L.sub.[infinity]] and decrease K because of the intrinsic antagonism of these parameters, and the revised set of parameters would be closer to the values reported in Table 2. Therefore, our results indicate that fitting a von Bertalanffy model to our actual data tends to slightly overestimate K and underestimate [L.sub.[infinity]] compared with a more realistic sampling size. Also, it may be possible that K estimated for the Mediterranean Sea (see Table 2) were higher than the values for other areas because of limited sampling.
Groupers are generally recognized as long-lived fishes capable of reaching maximum ages of more than 60 years (e.g., Renones et al., 2007). The maximum longevity of dusky groupers in this study was approximately 40 years, which is the second-highest longevity among the values observed worldwide (see Table 2). Currently, the most important factor influencing fish longevity most likely is fishing activity because fishing is expected to preferentially remove large, old fish from natural populations (King, 1995). According to local traditional fishermen, fisheries over the Carpinteiro Bank are known to have occurred since the 1960s, and fishing effort has been rising ever since. Additionally, fishing effort and the number of fishing boats operating in the region have increased during the last 3 decades (Cowx et al., 1998), and those changes could have resulted in the decreased availability of the older age classes of dusky grouper that we observed in this study. Another interesting finding was that approximately 40% of the fish captured offshore were immature ([L.sub.50]=496 mm TL, as estimated from Condini et al., 2014). Given the combined evidence of the low availability of old fish with the rising fishing effort over the last 3 decades and the large proportion of young adult individuals sampled here, it is reasonable to suggest that this offshore population may be undergoing overfishing. Unfortunately, there are no official fish landing records to allow an estimation of capture trends over time. These data would be necessary to objectively infer the population status of dusky grouper in southern Brazil.
The sampling conducted in the our study was restricted to Carpinteiro Bank, and that limit may cause concern because it is shallower (15-25 m) than the depths (up to 40-50 m) where larger groupers usually live (Heemstra and Randall, 1993). It is, therefore, plausible to argue that ontogenetic migration, which is usual in epinephelids (Dahlgren and Eggleston, 2000), could be withdrawing large-size (>90 cm) fish from the examined population because of their emigration toward waters with depths of 40-50 m. However, we posit that this notion is not the case for two main reasons. First, the continental shelf at the extreme southern part of Brazil basically is formed by sand bottoms, where reefs and rocks are scarce (Calliari and Klein 1993). There are just a few rocky banks that may provide habitat for groupers, and they are found specifically between the 20- to 30-m isobaths (Cardoso and Haimovici, 2011). Among these banks, Carpinteiro, Solidao, and Torres are the most visited by fishing boats (Cardoso and Haimovici, 2011). Second, reproduction has been observed for dusky grouper in Carpinteiro Bank (Condini et al., 2014), supporting the idea that the whole life cycle of the examined population occurs in this bank. Given these arguments, we believe that the relatively low abundance of older (>15 years) individuals is an intrinsic feature of the studied population rather than a sampling effect related to emigration toward deeper offshore habitats.
Dusky groupers from Carpinteiro Bank were older (mean age=7.4 years; maximum observed age=40 years) than fish from the inshore rocky jetties located in the mouth of Patos Lagoon in Rio Grande (mean age=5.0 years; maximum observed age=12 years; Seyboth et al., 2011). Our study provides compelling evidence that younger (<7 years) dusky groupers from Carpinteiro Bank are also significantly larger than similar-age fish from the rocky jetties. Specifically, the sizes of offshore groupers at ages 3-6 are 11-19% larger than inshore dusky groupers--a finding that leads to the hypothesis that environmental quality at the deeper offshore habitat may be better than that at the shallow inshore habitats.
In this study, we assume that differences on mean size-at-age between fish from the inshore and offshore habitats may be associated with differences in environmental quality between both sites, and several types of evidence support this hypothesis. For example, freshwater runoff from the Patos Lagoon estuary is, perhaps, the most important physical factor that influences the studied population, particularly during El Nino events, when freshwater discharge into the lagoon increases and pushes the estuarine plume over the inshore zone (Garcia et al., 2003), decreasing salinity and disturbing fish communities (Garcia et al., 2003; Garcia et al., 2004). The large variations in salinity periodically experienced by the inshore population may cause osmotic stress, increasing the energy outlay required to maintain fish homeostasis (Schmidt-Nielsen, 2002). In contrast, the salinity variation at the offshore bank usually ranges from 26.8 to 36.6 (Moller (2)), a level that is roughly a third of the salinity variability measured at the inshore habitat (10.6 and 35.1 during winter and summer, respectively) (A. Garcia, unpubl. data). In fact, faster growth was reported in dusky groupers reared under a salinity of 35 compared with dusky groupers reared under mixohaline treatments with salinities of 20 and 27 (Gracia-Lopez and Castello-Orvay, 2003), indicating that less energy may be expended for body homeostasis in more salinity-stable marine waters than in more salinity-variable estuarine conditions. This evidence supports the hypothesis that salinity regimes may play a significant role in controlling the differential growth rates of dusky groupers observed in inshore and offshore habitats.
An additional environmental factor capable of influencing fish growth in our system is food availability. The diet of groupers from the rocky jetties of Rio Grande consisted mostly of small crabs (Condini et al., 2011), whereas groupers from the Carpinteiro Bank were found to feed mostly on fish (Condini, in press). Given that fish are known to be a higher-energy food resource than crustaceans (Renones et al., 2002), food quality also may partially explain the faster growth observed in dusky groupers sampled at the Carpinteiro Bank.
Accurate age and growth parameters of fish populations are important for the efficiency of environmental protection actions. In this study, we have shown that dusky groupers from their southernmost population present growth performance similar to that observed worldwide, with maximum size and age of about 900 mm TL and 40 years, respectively. We have also shown that younger individuals with ages between 3 and 6 years sampled offshore (depths of 15-25 m) are larger on average than fish of the same age sampled inshore (depths <5 m). These findings indicate that offshore banks may provide higher quality habitats for dusky groupers than do inshore rocky habitats. Therefore, the dusky grouper population that inhabits this offshore bank should be a preferable target for fishery management actions (e.g., catch monitoring and fishing quotas) to prevent increases in the level of overfishing of this endangered species at its southernmost distribution limit in southwestern Atlantic.
We thank B. Ferreira, L. Romano, and G. Velasco for their comments on this manuscript, J. Castello for helping with infrastructure to process samples, L. Madureira for providing the 3-D bathymetric map of Carpinteiro Bank, and Osmas Moller for providing salinity data for the offshore site. M. Condini and A. Garcia acknowledge fellowship support from Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq; 140570/2013-6 and 305888/2012-9, respectively). C. Albuquerque is currently a postdoctoral fellow (CAPES-PNPD 02907/09-7). This study received financial support from the Fundagao O Boticario de Protegao a Natureza (0753-20072).
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Manuscript submitted 18 June 2013.
Manuscript accepted 22 August 2014.
Fish. Bull. 112:311-321 (2014).
The views and opinions expressed or implied in this article are those of the author (or authors) and do not necessarily reflect the position of the National Marine Fisheries Service, NOAA.
Mario V. Condini (contact author) 
Cristiano Q. Albuquerque 
Alexandre M. Garcia 
Email address for contact author: email@example.com
 Instituto de Oceanografia
Universidade Federal do Rio Grande
Avenida Italia km 8, Carreiros
96201-900, Rio Grande
Rio Grande do Sul, Brazil
 Departamento de Oceanografia e Ecologia
Universidade Federal do Espfrito Santo
Espirito Santo, Brazil
(1) Mention of trade names or commercial companies is for identification purposes only and does not imply endorsement by the National Marine Fisheries Service, NOAA.
(2) Moller, O. 2012. Unpubl. data. Laboratorio de Oceano grafia Costeira e Estuarina, Institute de Oceanografia, Universidade Federal de Rio Grande, CP. 474, 96200-900, Brazil.
Table 1 Ages, number of specimens sampled (n), and means and ranges of total length (TL) and weight (WT) for dusky groupers (Epinephelus marginatus) caught at the Carpinteiro Bank in the southwestern Atlantic by small-scale fisheries from 2008 to 2011. Standard deviations of the means (SD) are provided in parentheses. Age n Mean TL (mm) TL Mean WT (g) (years) range (mm) 1 2 160.0 (14.1) 150-170 58.2 (14.6) 2 27 325.7 (38.0) 290-405 602.3 (196.6) 3 28 385.9 (38.0) 277-453 1081.2 (297.6) 4 28 464.1 (48.4) 365-561 1890.8 (661.5) 5 15 526.9 (44.4) 420-635 2806.0 (977.9) 6 22 563.9 (45.2) 485-680 3415.8 (1053.9) 7 21 587.3 (60.6) 475-671 4135.1 (1384.0) 8 12 658.1 (38.6) 606-713 5824.9 (1553.5) 9 1 532.0 532.0 3171.0 10 3 709.7 (57.6) 650-765 7213.3 (2725.1) 11 2 744.0 (50.9) 708-780 7137.5 (88.4) 14 3 748.3 (72.9) 665-800 7785.8 (2671.2) 15 2 774.0 (28.3) 754-794 9390.0 (3620.4) 17 2 729.5 (36.1) 704-755 6715.0 (792.0) 18 3 762.3 (87.9) 668-842 7746.7 (3225.9) 19 1 764.0 764.0 7025.0 20 1 850.0 850.0 10,000.0 21 1 770.0 770.0 8100.0 22 2 825.0 (7.1) 820-830 10,900.3 (423.8) 23 5 808.0 (118.3) 660-985 10309.0 (4650.2) 24 2 881.0 (12.7) 872-890 10657.5 (2605.7) 25 1 933.0 933.0 15,100,0 27 1 910.0 910.0 16,300.0 28 1 864.0 864.0 11,100.0 29 1 917.0 917.0 14,335.0 31 1 875.0 875.0 10,560.0 34 1 981.0 981.0 11,700.0 40 1 1160.0 1160.0 25,000.0 Age WT range (g) (years) 1 47.9-68.5 2 314.5-1227.9 3 400.0-1675.8 4 1015.0-3513.0 5 1284.0-5902.0 6 2108.7-6530.0 7 2103.3-7045.0 8 4080.0-8950.0 9 3171.0 10 4590.0-10030.0 11 7075.0-7200.0 14 4725.8-9651.5 15 6830.0-11,950.0 17 6155.0-7275.0 18 5100.0-11,340.0 19 7025.0 20 10,000.0 21 8100.0 22 10,600.6-11,200.0 23 6030.0-17,850.0 24 8815.0-12,500.0 25 15,100.0 27 16,300.0 28 11,100.0 29 14,335.0 31 10,560.0 34 11,700.0 40 25,000.0 Table 2 Study site, aging structure, range of total lengths (TLs), age range, number of specimens sampled (n), and von Bertalanffy growth parameters of dusky groupers (Epinephelus marginatus) examined in this study and in previous investigations. Ageing structures used were scales (Sc), sectioned otolith (So), and whole otolith (Wo). Von Bertalanffy growth parameters included [L.sub.[infinity]], the mean theoretical maximum TL; [t.sub.0], the theoretical age at zero length; and K, the growth coefficient or the rate at which the curve approaches the asymptote. Aging Reference Study site structure Rafail et al. (1969) (1) Mediterranean Sea Sc --Egypt Chauvet (1988) (2) Mediterranean Sea Sc/Wo --Tunisia Kara and Derbal (1995) (3) Mediterranean Sea Sc --Algeria Bouchereau et al. (1999) (4) Mediterranean Sea Sc --France Fennessy (2006) (5) Southern Western Indian So --FranceSouth Africa Renones et al. (2007) (6) Western Mediterranean So --Spain Seyboth et al. (2011) (7) Southern Western Atlantic So --Brazil Present study Southern Western Atlantic So --Brazil [L.sub.- TL range Age range [infinity]] Reference (mm) (years) n (mm) Rafail et al. (1969) (1) 166-475 1-7 251 800 Chauvet (1988) (2) 53-1180 0-36 270 1144 Kara and Derbal (1995) (3) 197-567 1-7 41 785 Bouchereau et al. (1999) (4) 200-1200 1-14 22 1359 Fennessy (2006) (5) 95-1020 1-16 215 1249 Renones et al. (2007) (6) 66-1056 0-61 358 955 Seyboth et al. (2011) (7) 260-800 2-12 108 1249 Present study 150-1160 1-40 190 900 K ([years.- [T.sub.0] Reference sup.-1]) (years) Rafail et al. (1969) (1) 0.112 -1.08 Chauvet (1988) (2) 0.090 -0.75 Kara and Derbal (1995) (3) 0.160 -0.73 Bouchereau et al. (1999) (4) 0.080 -0.80 Fennessy (2006) (5) 0.090 -1.43 Renones et al. (2007) (6) 0.087 -1.12 Seyboth et al. (2011) (7) 0.069 -1.49 Present study 0.129 -1.45 (1) Rafail S. Z., W. L. Daoud, and M. M. Hilal. 1969. Long line Mediterranean fisheries studies west of Alexandria. GPCM Stud. Rev. 42, 16 p. (2) Chauvet, C. 1988. Etude de la croissance du merou Epinephelus guaza (Linne, 1758) des cotes tunisiennes. Aquat. Living Resour. 1:277-288. (3) Kara M. H., and F. Derbal. 1995. Morphometrie, croissance et mortality du Merou Epinephelus marginatus (Serranidae) des cotes de l'est algerien. Cah. Biol. Mar. 36:229-237. (4) Bouchereau J. L., R Body, and C. Chauvet. 1999. Growth of the dusky grouper Epinephelus marginatus (Linnaeus, 1758) (Teleostei, Serranidae), in the natural marine reserve of Lavezzi Islands, Corsica, France. Sci. Mar. 63:71-77. (5) See Fennessy, 2006. (In literature cited section.) (6) See Renones et ah, 2007. (7) See Seyboth et al., 2011.
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|Author:||Condini, Mario V.; Albuquerque, Cristiano Q.; Garcia, Alexandre M.|
|Date:||Oct 1, 2014|
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