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Article

Morphometric Relations Within Elasmobranch Species from the Amvrakikos Gulf (Central Mediterranean)

by
Martina Ciprian
1,2,
Ioannis Giovos
2,
Carlotta Mazzoldi
3 and
Dimitrios K. Moutopoulos
1,*
1
Department of Fisheries and Aquaculture, University of Patras, 30200 Mesolongi, Greece
2
iSea, Environmental Organisation for the Preservation of Aquatic Ecosystems, 54645 Thessaloniki, Greece
3
Department of Biology, University of Padova, Via U. Bassi 58/B, 35121 Padova, Italy
*
Author to whom correspondence should be addressed.
Diversity 2026, 18(1), 41; https://doi.org/10.3390/d18010041
Submission received: 16 December 2025 / Revised: 9 January 2026 / Accepted: 11 January 2026 / Published: 13 January 2026
(This article belongs to the Special Issue Integrating Biodiversity, Ecology, and Management in Shark Research)
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Abstract

Despite their ecological and conservation significance, morphometric relations remain scarce for elasmobranch species in the Mediterranean. This study examined morphometric parameters of the eight elasmobranch species (one shark and seven batoids) presented in the Amvrakikos Gulf that has been designated as a National Park. A total of 1247 specimens were sampled between 2022 and 2025, caught by small-scale fishing vessels using trammel nets, gillnets or bottom longlines and collected through onboard surveys or landing sites monitoring. Linear regressions were applied to describe relations between total length and other body measures (disc length, disc width, fork length), and length measurements and body weight. Results showed strong relations across morphometric traits, with R2 values exceeding 0.655 for most relations. Growth patterns varied: four species (Aetomylaeus bovinus, Dasyatis pastinaca, D. tortonesei, Mustelus mustelus) exhibited positive allometry, one species (D. marmorata) displayed negative allometry and Gymnura altavela showed near-isometric growth. Sexual dimorphism was generally absent, although significant differences were found between sex in disc width slopes for D. marmorata, Myliobatis aquila and Torpedo torpedo, and in length–weight relations for M. mustelus. These findings substantially fill regional data gaps, offering new baseline estimates for rare and threatened elasmobranchs.

1. Introduction

Elasmobranch morphology is of fundamental importance for conservation and management, as these species are not generally targeted by fishing activities [1], creating significant knowledge gaps that hinder effective fisheries management and conservation efforts [2]. Key morphometric tools, such as length–length and length–weight relations, are essential for demographic modelling [3] and stock assessment [4], while also facilitating comparative growth studies [5] and reliable species identification [6]. Morphometric relations are widely used in fisheries research, and their importance has been well documented [7]. Relations between different types of lengths (length–length relations), for which information remains scarce for many Mediterranean species, including those examined in the present study, are particularly important for comparative growth analyses [5,7]. The aim of this study is to provide robust estimates of key morphological parameters of eight elasmobranch species found in the Amvrakikos Gulf. The gulf (Western Greece, Ionian Sea) (Figure 1) is characterized by a fjord-like hydrological regime and covers a surface area of approximately 400 km2 [8]. The gulf is protected under national and international regulations due to its rich biodiversity and wetland habitats [9], and it has recently been delineated as an important shark and ray area (ISRA) [10]. Only small-scale fisheries operate within the gulf, as, a century ago, the use of towing gears was prohibited all year round (i.e., 1924: trawling issued by Presidential Decree No2-3/9-5-1923 and 1931: purse seines issued by Presidential Decree 24-8-1932).
This study provides estimates of morphometric relations and examines sexual dimorphism in the following: (a) size frequency distributions; (b) length–length relations; and (c) length–weight relations parameters. The eight studied species include one shark (Mustelus mustelus (Linnaeus, 1758)) and seven batoids (Aetomylaeus bovinus (Geoffroy Saint-Hilaire, 1817), Dasyatis marmorata (Steindachner, 1892), Dasyatis pastinaca (Linnaeus, 1758), Dasyatis tortonesei (Capapé, 1975), Gymnura altavela (Linnaeus, 1758), Myliobatis aquila (Linnaeus, 1758) and Torpedo torpedo (Linnaeus, 1758)). Among the species examined, two Critically Endangered (Global Assessment) stingrays, A. bovinus and M. aquila, were frequently recorded. Published information on morphometric relationships within the above-mentioned elasmobranch species is extremely scarce from Mediterranean waters, and limited to D. pastinaca [11,12], G. altavela [13] and T. torpedo [14]. Length–weight relations (LWRs) for all the species are available for other areas of the Mediterranean Sea [13,15,16,17], while those that have been previously reported for the Greek waters included estimates based only on few samples [18].

2. Materials and Methods

Samples were collected from onboard fishing trips and landing site surveys (1247) using trammel nets (mesh sizes used from 21 mm to 45 mm), gillnets (mesh sizes used from 65 mm to 100 mm) and longliners (with hooks No 4) throughout the Amvrakikos Gulf (Figure 1) from February 2022 to August 2025. All the specimens that were previously not targeted by fishers were collected from the different fishing vessels operating in the area and collaborating in the data collection. Alive sampled specimens were released after capture and measurement, whereas dead individuals were preserved for further analyses (e.g., diet) and then discarded at sea. The data gathered corresponded to the protocol “Monitoring the incidental catch of vulnerable species in Mediterranean and Black Sea fisheries” [19], adapted to the needs of the area. In sharks, total length (TL), measured from the tip of the snout until the end of the tail, and fork length (FL), measured from the tip of the snout until the fork in the tail, were recorded. In batoids, total length, disc length (DL), measured from the tip of the snout to the posterior edge of the pectoral disc, and disc width (DW), measured from one pectoral fin tip to the other, were recorded. All lengths (straight line) were obtained using a measuring tape (error range: ±0.1 cm) and individuals with damaged or truncated tails (specifically batoids) were excluded from the analyses to avoid bias in length-based and morphometric relationships. Total weight (W) was obtained using a portable scale (load capacity: 50 kg, error range: ±0.01 kg), and the sex was determined by the presence or absence of claspers. Size comparisons between sexes were performed using Student’s t-test, while the length frequency distributions were analyzed using the Kolmogorov–Smirnov test (K-S) [20]. LWRs were described using the following equation: log W = log a + b × log L, where W is the weight in grams, L is the total length (TL), disc length (DL), disc width (DW) in cm (independent variable), a is the regression intercept and b is the regression slope. The coefficient of determination (R2) was used to assess the goodness-of-fit of the regression model. To test whether the estimated slope (b) differed significantly from the isometric value of 3, a Student’s t-test was applied following [21]: t = (b − 3)/SEb, where SEb is the standard error of the slope. The null hypothesis of isometric growth (b = 3) was rejected when t exceeded the critical t-value at α = 0.05. Slopes significantly greater than 3 indicated positive allometry (fish become relatively heavier as they grow), while slopes significantly less than 3 indicated negative allometry (fish become relatively lighter as they grow). Log-transformed data were plotted to confirm linearity and to identify outliers, which were removed following [6]. Residual diagnostics, including histograms, Q-Q plots and residual-versus-fitted plots, were examined to verify normality of residuals and homoscedasticity. Between-sex comparisons of the slopes of the relationships were performed using analysis of covariance (ANCOVA; [22]).

3. Results

Overall, 1247 specimens were examined, with the number per species ranging from 87, for D. pastinaca, to 364, for T. torpedo. All the studied morphometric parameters exhibited no significant differences between sexes (Table 1). Similarly, no significant differences (K-S > 0.15, p > 0.05) were found in the TL frequency distribution of males and females (Figure 2). Highly significant (p < 0.001) linear regressions were estimated for the relations among TL, FL, DL and DW for each species, with R2 values being higher than 0.843. Most of the relations were not statistically different by sex (Table 2), apart for the slopes of the regression for TL–DW for D. marmorata and M. aquila, for TL–FL for M. mustelus and for the intercepts and slopes both between TL–DL and TL–DW for T. torpedo (Table 2). In all the cases, females presented more pronounced slopes than males (Table 2).
Highly significant LWRs were found for seven out of eight studied species, apart from T. torpedo, with R2 values being greater than 0.837 (Table 2). The estimated values of the exponent b of the relations ranged from 2.942, for males of D. marmorata, to 3.584, for t males for D. pastinaca. Six species, A. bovinus, D. marmorata, D. pastinaca, D. tortonesei, M. aquila and M. mustelus, exhibited significantly (t-test; p < 0.05) positive allometry, with b-values ranging from 3.024 to 3.584, apart from the relation of males for D. marmorata, M. aquila and M. mustelus, which presented a negative allometry for the first two species and an isometric growth for the latter. In contrast, G. altavela exhibited a non-significant (t-test; p < 0.05) difference from the isometric value 3 (Table 2). Both the intercept and the slopes did not differ significantly between sex (ANCOVA; p > 0.05), except for the LWRs for D. marmorata and M. mustelus, for which females presented higher b-values than males (Table 2).
The relations of DL and DW with the weight were provided for six studied batoids, apart from T. torpedo. All the other relations were highly significant (p < 0.001), with R2 values being greater than 0.863. The estimated values of exponent b for the DW–W relations ranged from 2.772 in males of A. bovinus to 3.227 in males of D. marmorata (Table 2). Both the intercept and the slopes did not differ significantly between sex (Table 2).

4. Discussion

The present study provided morphometric estimates for eight elasmobranch species, addressing critical data gaps that have historically hindered conservation efforts for data-deficient species in the Mediterranean [23]. Specifically, the study aimed to overcome the limitations associated with the small sample size and narrow length and weight distributions available for many species [6] by incorporating a substantially larger number of specimens across a broad range of lengths, thereby providing more robust and representative length–weight relations for rare batoids and sharks. In most of the previous studies, these species were represented by fewer individuals (from a minimum of 5, with an average of 108) (Table 1), compared with the present study for the same species (from 87 to 364, with an average of 177). Consequently, the results of this study provided new insights into these parameters, useful for modelling life history traits and fishery data of batoids and sharks in the Mediterranean Sea.
Sexual size dimorphism is widely documented across elasmobranch species [24]. Female-biased sexual size dimorphism is observed in viviparous shark species, whereas, in batoids, female-biased sexual size dimorphism tends to be present but less evident [24]. In our study, no significant differences in TL distributions were found. Several factors may explain this result. Size dimorphism is often more evident in mature individuals [25], while our sampling may have included a high proportion of juveniles (approximately 80%: Table 3 and Figure 2), due to the nursery nature of the area [9]. Furthermore, gear selectivity and sampling bias may have homogenized the observed size range, leading to the under-representation of the largest females or smallest males [5]. Population-level variation has also been documented in some elasmobranchs, with sex-specific size differences being less pronounced or even absent in certain regions, possibly due to ecological conditions or fishing pressure [23]. Nevertheless, some evidence of dimorphism emerged from the analyses between TL and DW in D. marmorata, M. aquila and T. torpedo. In these species, females become disproportionately wider as they grow compared to males. This pattern is consistent with findings from the North Aegean Sea, where females of D. marmorata exhibited larger disc width length than males (0.660 vs. 0.604, respectively) [26].
The b-values of the LWRs estimated for both sexes combined and for each sex separately, along with their 95% confidence intervals, fell within the expected range of 2.5–3.5 reported by [6]. In most of the LWRs examined (18 out of 21 cases) both males and females exhibited a positive allometry, indicating that body weight increased proportionally more than length. This pattern is consistent with findings from similar studies conducted in the Mediterranean (Table A1). Negative allometry was estimated for males of D. marmorata and M. aquila, for which no previous LWR estimates were found. For G. altavela, in most Mediterranean studies, LWRs presented a positive allometry (Table A1), whereas, in the present study, the species exhibited non-significant differences from the isometric value 3. Sexual dimorphism in LWRs was evident in M. mustelus, with females significantly gaining more weight (slope b) than males (Table 2). This result is consistent with a similar study in Saros Bay (North Aegean Sea) (females vs. males: 3.059 vs. 2.965, respectively) [33]. In contrast, the opposite pattern was reported in adjacent areas [34]; female vs. male: 3.301 vs. 3.392; [35]: 2.736 vs. 2.880, respectively) (Appendix A Table A1). Our findings also supported the hypothesis that males of M. mustelus exhibit a more isometric growth compared to females (3.024 vs. 3.205, respectively), meaning that a male’s body weight increases less relative to length than in females [36]. For M. aquila, the slope’s estimates of the disc width–total weight relations demonstrated a positive allometry for both sexes and combined sex data, in agreement with previous studies from the Turkish Aegean Sea (Table A1). Estimation of these relations is important for fisheries dynamics, as this species exhibits an exceptionally long tail that can vary in length due to breakage, injury or flexibility, making disc width a more reliable morphometric measure [37].
Differences in b-values among studies may be attributed to one or more factors, including the following [5,6,38,39]: (a) sample size; (b) spatial/seasonal effects; (c) gear selectivity; and (d) the measured length ranges and the type of length measurement used. Given that the Amvrakikos Gulf functions as a nursery ground for numerous fish species [9], the present results should not necessarily be considered valid for other Greek seas. Sexual size dimorphism typically becomes more pronounced in mature individuals; therefore, the nursery function of the gulf may have biased the sample towards life stages in which dimorphism is less evident. To better address the apparent lack of sexual dimorphism observed, future studies should focus on tracking potential ontogenetic migrations between the gulf and the adjacent open sea.
Considering that the relations presented in this study represented mean annual estimates, it should also be noted that the spawning and gonadal development may cause seasonal variations in the b parameter of the LWRs [38]. Our findings enable comparisons of morphometric patterns in elasmobranch species from the entire Mediterranean Sea, a region where these species are subjected to intense fishing pressure [40]. Moreover, this study also provided essential morphometric estimates derived from incidental catches, which are valuable inputs for demographic models and ecosystem-based fisheries management. Such information supports assessments for the recovery potential of these vulnerable elasmobranch populations within protected or partially protected areas, such as the Amvrakikos Gulf, and can be incorporated into multispecies ecosystem models to better define the ecological role of sharks and batoids in marine food webs [41].

Author Contributions

Conceptualization, I.G. and D.K.M.; methodology, D.K.M.; formal analysis, M.C. and D.K.M.; investigation, M.C. and D.K.M.; data curation, M.C. and D.K.M.; writing—review and editing, M.C., I.G., C.M. and D.K.M.; supervision, C.M. and D.K.M.; project administration, M.C.; funding acquisition, I.G. All authors have read and agreed to the published version of the manuscript.

Funding

This work was produced in the context of the By ElasmoCatch project 2022–2025 and funded by Ocean Care (Gerbestrasse 6, 8820 Waedenswil, Switzerland) and Shark Foundation (Blütenstrasse 4, 8057, Zurich, Switzerland).

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

The data collected in this study and published in this work are available upon request to the first author.

Acknowledgments

The authors would like to thank all professional fishers from the Amvrakikos Gulf for their significant collaboration.

Conflicts of Interest

The authors declare no conflicts of interest.

Appendix A

Table A1. Parameters of the length–weight relationships for the studied species, as reported in various studies in the Mediterranean Sea. N is number of individuals; a and b are the parameters of the length–weight relation; R2 is the coefficient of determination. * Disc width measurements and ** Disc length measurements. C for combined samples, M for males and F for females.
Table A1. Parameters of the length–weight relationships for the studied species, as reported in various studies in the Mediterranean Sea. N is number of individuals; a and b are the parameters of the length–weight relation; R2 is the coefficient of determination. * Disc width measurements and ** Disc length measurements. C for combined samples, M for males and F for females.
SpeciesnLength-RangeabR2Area/YearReference
Aetomylaeus bovinus12 *32.0–86.00.01942.9030.900Iskenderun Bay/2010–2011[42]
32 0.00903.0950.095Gulf of Trieste/2005 [43]
101 *28.0–171.00.02302.9190.880Northern Adriatic Sea/2006–2019[15]
Dasyatis marmorata2140.0–70.50.00203.2330.857Northeastern Levantine Sea/2009–2010[13]
21 *23.0–40.00.00403.5920.93Northeastern Levantine Sea/2009–2010[13]
21 **20.0–41.00.03403.0210.936Northeastern Levantine Sea/2009–2010[13]
14316.5–81.50.01202.7400.780Iskenderun Bay/2014–2015[16]
143 *9.9–41.50.04802.9400.883Iskenderun Bay/2014–2015[16]
Dasyatis pastinaca2937.3–74.20.01492.8100.850North Aegean Sea/March–July 2003[44]
4415.1–53.90.04982.9920.935Western Mediterranean/2000–2000[45]
417 *15.0–64.00.04193.3170.840Iskenderun Bay/2010–2012[42]
3119.0–43.20.01023.3700.984Izmir Bay/2005–2006[46]
1108.0–51.00.00093.4410.940Iskenderun Bay/1999–2000[47]
1644.2–138.00.00233.2490.986Izmir Bay/2005[48]
4820.5–66.00.01263.3030.990Saros Bay/2005–2006[49]
34614.7–64.90.00393.4920.961Cilician Basin/1999–2003[11]
1229.2–37.80.00303.2170.642Northern Aegean Sea/2004–2005[50]
14 C38.8–295.50.00852.9380.969North Aegean Sea/1999–2000[51]
334 C23.4–100.90.00203.2420.970Cilician Basin/1999–2003[34]
145 M23.4–69.50.00143.3380.950Cilician Basin/1999–2003[51]
189 F29.0–100.90.00253.1860.970Cilician Basin/1999–2003[47]
256 C7.0–88.00.00143.3100.940Iskenderun Bay/1999–2000[52]
297.0–34.00.00143.3110.910Iskenderun Bay/1999–2000[34]
Dasyatis pastinaca110 F20.5–88.00.00093.4410.940Iskenderun Bay/1999–2000[47]
349 C28.0–94.00.00223.1790.995Izmir Bay (Aegean Sea Coast of Turkey)/2018[32]
152 M28.0–62.00.00403.0090.865Izmir Bay (Aegean Sea Coast of Turkey)/2018[52]
172 F31.5–94.00.00173.2450.688Izmir Bay (Aegean Sea Coast of Turkey)/2018[34]
8 M38.8–295.50.00922.9330.978North Aegean Sea/1999–2000[51]
6 F39.2–175.00.01082.8570.981North Aegean Sea/1999–2000[47]
32 M40.0–110.00.00053.6090.940Saros Bay/2005–2008[47]
52 F37.5–114.00.00083.5080.960Saros Bay/2005–2008[32]
1431.5–97.00.00302.480 South of Sicily[52]
1318.5–65.00.44742.2930.807Northeastern Levantine Sea/2014–2016[53]
7227.4–93.40.00203.3130.911Iskenderun Bay/2014–2015[54]
72 *14.5–56.40.03902.9300.886Iskenderun Bay/2014–2015[16]
9217.9–95.20.02103.3970.956Eastern Adriatic Sea/1997–2001[16]
7137.5–114.00.00073.5500.957Saros Bay/2005–2007[55]
26 M40.0–110.00.00053.6400.951Saros Bay/2005–2007[56]
45 F37.5–114.00.00083.5400.956Saros Bay/2005–2007[56]
7833.4–138.00.00113.4600.968Central Aegean Sea/2008–2009[56]
36 M36.5–80.00.00213.2900.954Central Aegean Sea/2008–2009[57]
42 F33.4–138.00.97133.5100.971Central Aegean Sea/2008–2009[57]
39125.0–130.00.02302.7550.850Northeastern Levantine Sea[57]
391 *12.0–69.50.03702.9660.939Northeastern Levantine Sea[13]
391 **11.5–73.00.10002.7400.928Northeastern Levantine Sea[13]
1023.5–40.60.13062.1700.865Edremit Bay/2007–2009[13]
Dasyatis tortonesei712.0–44.00.02243.1600.999Israeli continental shelf/2008–2011[58]
5 M64.0–71.50.00013.9770.932Marmara Sea/May 2015[59]
19 F53.0–107.00.00263.2720.915Marmara Sea/May 2015[17]
Gymnura altavela17217.6–27.00.03102.9290.968Gulf of Antalya/2009–2010[17]
937.5–72.00.02682.9600.980North Aegean Sea/March–July 2003[13]
631.5–68.00.01093.2150.861Izmir Bay/2021[44]
Gymnura altavela104 *30.0–127.00.01702.7950.730Iskenderun Bay/2010–2011[52]
1737.6–95.0 0.04492.8410.986Izmir Bay/2005[42]
631.5–68.00.01093.2160.861Izmir Bay/2018[48]
947.1–88.30.00253.2170.970Izmir Bay/2005–2006[54]
947.1–88.30.00253.2700.970Izmir Bay/2005–2006[46]
107 C83.5–360.50.00903.2340.980Cilician Basin/1999–2003[46]
38 M83.5–360.50.00573.3580.970Cilician Basin/1999–2003[51]
69 F79.8–450.10.00113.2080.970Cilician Basin/1999–2003[51]
1251.5–82.30.00593.0320.556Northeastern Levantine Sea/2014–2016[51]
Myliobatis aquila1447.5–76.50.00083.3400.930North Aegean Sea/March-July 2003[54]
3923.5–54.50.00583.2800.986Izmir Bay/2005–2007[44]
1421 *15.0–130.00.03102.8400.815Northern Adriatic Sea/2006–2019[46]
105 *M24.0–120.00.07602.5540.805Northern Adriatic Sea/2006–2019[15]
242 *F18.0–102.00.08802.5540.805Northern Adriatic Sea/2006–2019[15]
13112.9–129.00.00163.1340.909Eastern Adriatic Sea/1997–2001[15]
1241.5–58.50.00143.1800.874Edremit Bay/2007–2009[55]
6629.5–121.00.00033.5600.918Saros Bay/2005–2007[58]
33 M29.5–90.50.00143.1500.934Saros Bay/2005–2007[56]
33 F41.0–121.00.00013.8900.916Saros Bay/2005–2007[56]
5441.1–179.50.00053.4200.946Central Aegean Sea/2008–2009[56]
14 M41.1–87.50.00093.2900.776Central Aegean Sea/2008–2009[57]
40 F43.5–179.50.00043.5000.963Central Aegean Sea/2008–2009[57]
Torpedo torpedo164 *C6.9–30.10.11202.8440.990South-east coast of Sicily/2019[57]
101 *M6.9–26.20.10402.8250.980South-east coast of Sicily/2019[14]
63 *F7.9–30.10.11202.8370.990South-east coast of Sicily/2019[14]
914.8–31.80.04542.6890.980Algarve/1997–1999[14]
918.7–49.20.01403.0500.993Algarve/1997–1999[60]
289.3–38.50.01333.0460.980Gulf of Lions/2011–2013[61]
2810.5–35.50.01503.130 South of Sicily[3]
Mustelus mustelus3538.3–97.50.00113.2500.970North Aegean Sea/March–July 2003[53]
1638.0–75.00.00632.7590.937Eastern Adriatic/1991–1994[44]
7434.9–101.70.00532.8450.989Southern Aegean Sea/2009–2010[62]
1751.4–95.50.00442.9130.982Izmir Bay/2005[63]
7046.8–152.20.00342.9800.988Saros Bay/2005–2008[48]
20827.5–135.00.00303.0280.990South-western coast of Sicily/2012–2019[33]
14825.6–125.10.00273.0510.979Izmir Bay/2005–2006[64]
11525.7–148.30.00213.0690.963Eastern Adriatic Sea/1997–2001[46]
24 C116.4–3170.00.00083.3260.975North Aegean Sea/1999–2000[55]
311 C 38.6–117.50.00632.8000.846Alexandria coast/2020–2023[34]
14 M116.4 -1988.00.00063.3920.983North Aegean Sea/1999–2000[35]
10 F200.0–3170.00.00083.3010.964North Aegean Sea/1999–2000[34]
157 M38.6–106.80.00462.8800.868Alexandria coast/2020–2021[34]
154 F38.6–117.50.00812.7360.827Alexandria coast/2020–2022[35]
46 M46.8–148.30.00362.9650.987Saros Bay/2005–2008[35]
24 F49.0–152.20.00253.0590.991Saros Bay/2005–2008[33]
68520.0–180.00.03502.4710.914Northern Adriatic Sea/2006–2019[33]
150 F40.0–165.00.00902.7630.916Northern Adriatic Sea/2006–2019[15]
446 M32.0–180.00.03502.4600.916Northern Adriatic Sea/2006–2019[15]
6039.4–75.00.11392.7090.977Edremit Bay/2007–2009[15]
4141.8–113.30.00103.2700.971Central Aegean Sea/2008–2009[58]
28 M41.8–91.50.00063.3900.981Central Aegean Sea/2008–2009[57]
13 F42.0–113.30.00173.1600.971Central Aegean Sea/2008–2009[57]
13 F42.0–113.30.00173.1600.971Central Aegean Sea/2008–2009[57]

References

  1. Carpentieri, P.; Nastasi, A.; Sessa, M.; Srour, A. (Eds.) Incidental Catch of Vulnerable Species in Mediterranean and Black Sea Fisheries—A Review; Studies and Reviews No. 101; General Fisheries Commission for the Mediterranean: Rome, Italy; FAO: Rome, Italy, 2021. [Google Scholar]
  2. Giovos, I.; Pytka, J.M.; Barone, M.; Koehler, L.; Loth, C.; Lowther, J.; Moutopoulos, D.K.; Niedermüller, S.; Mazzoldi, C. Conservation and management of chondrichthyans in the Mediterranean Sea: Gaps, overlaps, inconsistencies, and the way forward. Rev. Fish Biol. Fish. 2024, 34, 1067–1099. [Google Scholar] [CrossRef]
  3. Mantzouni, I.; Somarakis, S.; Moutopoulos, D.K.; Kallianiotis, A.; Koutsikopoulos, C. Periodic, spatially structured matrix model for the study of anchovy (Engraulis encrasicolus) population dynamics in N Aegean Sea (E Mediterranean). Ecol. Model. 2007, 208, 367–377. [Google Scholar] [CrossRef]
  4. Barría, C.; Navarro, J.; Coll, M.; Fernandez-Arcaya, U.; Sáez-Liante, R. Morphological parameters of abundant and threatened chondrichthyans of the northwestern Mediterranean Sea. J. Appl. Ichthyol. 2014, 31, 114–119. [Google Scholar] [CrossRef]
  5. Moutopoulos, D.K.; Stergiou, K.I. Length–weight and length–length relationships of fish species from the Aegean Sea (Greece). J. Appl. Ichthyol. 2002, 18, 200–203. [Google Scholar] [CrossRef]
  6. Froese, R.; Tsikliras, A.C.; Stergiou, K.I. Editorial note on weight–length relations of fishes. Acta Ichthyol. Et Piscat. 2011, 41, 261–263. [Google Scholar] [CrossRef]
  7. Bobori, D.C.; Moutopoulos, D.K.; Bekri, M.; Salvarina, I.; Perandones, A.I. Length-weight relationships of freshwater fish species caught in three Greek lakes. J. Biol. Res. 2010, 14, 219–224. [Google Scholar]
  8. Georgiou, N.; Fakiris, E.; Koutsikopoulos, C.; Papatheodorou, G.; Christodoulou, D.; Dimas, X.; Geraga, M.; Kapellonis, Z.G.; Vaziourakis, K.-M.; Noti, A.; et al. Spatio-Seasonal Hypoxia/Anoxia Dynamics and Sill Circulation Patterns Linked to Natural Ventilation Drivers, in a Mediterranean Landlocked Embayment: Amvrakikos Gulf, Greece. Geosciences 2021, 11, 241. [Google Scholar] [CrossRef]
  9. Katselis, G.; Moutopoulos, D.K.; Dimitriou, E.N.; Koutsikopoulos, C. Long-term changes of fisheries landings in enclosed gulf lagoons (Amvrakikos gulf, W Greece): Influences of fishing and other human impacts. Estuar. Coast. Shelf Sci. 2013, 131, 31–40. [Google Scholar] [CrossRef]
  10. Rohner, C.A.; Richardson, A.J.; García-Rodríguez, E.; Charles, R.; Batlle-Morera, A.; Bortoluzzi, J.R.; Mouton, T.L.; Notarbartolo di Sciara, G.; Armstrong, A.O.; Everett, J.D.; et al. Important Shark and Ray Areas can inform conservation planning in the Mediterranean and Black Seas. iScience 2025, 28, 8. [Google Scholar] [CrossRef]
  11. Yeldan, H.; Avsar, D.; Manaþýrlý, M. Age, growth and feeding of the common stingray (Dasyatis pastinaca, L., 1758) in the Cilician coastal basin, Northeastern Mediterranean Sea. J. Appl. Ichthyol. 2009, 25, 98–102. [Google Scholar] [CrossRef]
  12. Yığın, C.Ç.; Işmen, A. Age, growth and reproduction of the rough ray, Raja radula (Delaroche, 1809) in Saros Bay (North Aegean Sea). J. Black Sea/Mediterr. Environ. 2014, 20, 213–227. [Google Scholar]
  13. Özbek, E.Ö.; Çardak, M.; Kebapçioğlu, T. Spatio-temporal patterns of abundance, biomass and length-weight relationships of Gymnura altavela (Linnaeus, 1758) (Pisces: Gymnuridae) in the Gulf of Antalya, Turkey (Levantine Sea). J. Black Sea/Mediterr. Environ. 2016, 22, 16–34. [Google Scholar]
  14. Tiralongo, F.; Messina, G.; Brundo, M.; Lombardo, B. Biological aspects of the common torpedo, Torpedo torpedo (Linnaeus, 1758) (Elasmobranchii: Torpedinidae), in the Central Mediterranean Sea (Sicily, Ionian Sea). Eur. Zool. J. 2019, 86, 488–496. [Google Scholar] [CrossRef]
  15. Colombelli, A.; Bonanomi, S. Length–weight relationships for six elasmobranch species from the Adriatic Sea. J. Appl. Ichthyol. 2022, 38, 328–332. [Google Scholar] [CrossRef]
  16. Yeldan, H.; Gundogdu, S. Morphometric relationships and growth of common stingray, Dasyatis pastinaca (Linnaeus, 1758) and marbled stingray, Dasyatis marmorata (Steindachner, 1892) in the Northeastern Levantine Basin. J. Black Sea/Mediterr. Environ. 2018, 24, 10–27. [Google Scholar]
  17. Yıldız, T.; Yemişken, E.; Karakulak, F.S.; Uzer, U.; Dalyan, C.; Oray, I.K. A new record of dasyatid fish from the Sea of Marmara: Tortonese’s stingray Dasyatis tortonesei Capapè, 1975. J. Appl. Ichthyol. 2016, 1, 3. [Google Scholar] [CrossRef]
  18. Tsikliras, A.C.; Dimarchopoulou, D. Filling in knowledge gaps: Length–weight relations of 46 uncommon sharks and rays (Elasmobranchii) in the Mediterranean Sea. Acta Ichthyol. Et Piscat. 2021, 51, 249–255. [Google Scholar] [CrossRef]
  19. Carpentieri, P. Monitoring the Incidental Catch of Vulnerable Species in Mediterranean and Black Sea Fisheries Methodology for Data Collection; FAO Fisheries and Aquaculture Technical Paper No. 640; FAO: Rome, Italy, 2019; pp. 1–81. [Google Scholar]
  20. Siegel, S.; Castellan, N.J. Nonparametric Statistics for the Behavioral Sciences, 2nd ed.; McGraw-Hill: New York, NY, USA, 1988. [Google Scholar]
  21. Pauly, D. Fish Population Dynamics in Tropical Waters: A Manual for Use with Programmable Calculators; ICLARM Studies and Reviews; International Center for Living Aquatic Resources Management: Manila, Philippines, 1984; Volume 8, 325p. [Google Scholar]
  22. Zar, J.H. Biostatistical Analysis; Prentice-Hall/Pearson: Upper Saddle River, NJ, USA, 2010; pp. 490–517. [Google Scholar]
  23. Dulvy, N.K.; Forrest, R.E. Life histories, population dynamics, and extinction risks in chondrichthyans. In Sharks and Their Relatives II: Biodiversity, Adaptive Physiology, and Conservation; Carrier, J.C., Musick, J.A., Heithaus, M.R., Eds.; CRC Press: Boca Raton, FL, USA, 2010; pp. 639–679. [Google Scholar]
  24. Gayford, J.H.; Seamone, S.G.; Irschick, D.J.; Chin, A.; Rummer, J.L. Sexual Size Dimorphism in Rays and Skates (Elasmobranchii: Batoidea). Ecol. Evol. 2025, 15, e71858. [Google Scholar] [CrossRef] [PubMed]
  25. Neer, J.A.; Thompson, B.A. Life history of the cownose ray, Rhinoptera bonasus, in the northern Gulf of Mexico, with comments on geographic variability in life history traits. Environ. Biol. Fishes 2005, 73, 321–331. [Google Scholar] [CrossRef]
  26. Yığın, C.Ç.; Işmen, A. Age, growth and reproduction of the common stingray, Dasyatis pastinaca from the North Aegean Sea. Mar. Biol. Res. 2012, 8, 644–653. [Google Scholar] [CrossRef]
  27. Başusta, N.; Aslan, E. Age and growth of bull ray Aetomylaeus bovinus (Chondrichthyes: Myliobatidae) from the Northeastern Mediterranean coast of Turkey. Cah. De Biol. Mar. 2018, 59, 107–114. [Google Scholar]
  28. Saadaoui, A.; Saidi, B.; Enajjar, S.; Bradai, M.N. Reproductive biology of the common stingray Dasyatis pastinaca (Linnaeus, 1758) off the Gulf of Gabès (Central Mediterranean Sea). Cah. De Biol. Mar. 2015, 56, 389–396. [Google Scholar]
  29. Alkusairy, H.; Ali, M.; Saad, A.; Reynaud, C.; Capape, C. Maturity, reproductive cycle, and fecundity of spiny butterfly ray, Gymnura altavela (Elasmobranchii: Rajiformes: Gymnuridae), from the coast of Syria (Eastern Mediterranean). Acta Ichthyol. Et Piscat. 2014, 44, 229–240. [Google Scholar] [CrossRef]
  30. Capapé, C.; Guélorget, O.; Vergne, Y.; Quignard, J.P. Reproductive biology of the common eagle ray, Myliobatis aquila (Chondrichthyes: Myliobatidae) from the coast cf Languedoc (Southern France, Northern Mediterranean). Vie Et Milieu/Life Environ. 2007, 57, 125–130. [Google Scholar]
  31. Consalvo, I.; Scacco, U.; Romanelli, M.; Vacchi, M. Comparative study on the reproductive biology of Torpedo torpedo (Linnaeus, 1758) and T. marmorata (Risso, 1810) in the Central Mediterranean Sea. Sci. Mar. 2007, 71, 213–222. [Google Scholar] [CrossRef]
  32. Riginella, E.; Correale, V.; Marino, I.A.; Rasotto, M.B.; Vrbatovic, A.; Zane, L.; Mazzoldi, C. Contrasting life-history traits of two sympatric smooth-hound species: Implication for vulnerability. J. Fish Biol. 2020, 96, 853–857. [Google Scholar] [CrossRef] [PubMed]
  33. Işmen, A.; Cigdem Yigin, C.; Altinagac, U.; Ayaz, A. Length-weight relationships for ten shark species from Saros Bay (North Aegean Sea). J. Appl. Ichthyol. 2009, 25, 109–112. [Google Scholar] [CrossRef]
  34. Filiz, H.; Mater, S. A Preliminary Study on Length-Weight Relationships for Seven Elasmobranch Species from North Aegean Sea, Turkey. E.U. J. Fish. Aquat. Sci. 2002, 19, 401–409. [Google Scholar]
  35. Ahmed, A.M.M.; Azab, A.M.; Khalaf-Allah, H.M.M.; El-Tabakh, M.A.M. Growth and mortality rates for management of the common smooth-hound shark, Mustelus mustelus in the Egyptian Mediterranean waters. Egypt. J. Aquat. Biol. Fish. 2022, 26, 773–793. [Google Scholar] [CrossRef]
  36. Fola-Matthiews, O.O.; Souinka, O.O.; Lawal-Are, A.O. Length-Weight Relationsip and condition factor estimation of the common smooth-hound shark, Mustelus mustelus off the Southwestern coast of Nigeria. Ethiop. J. Environ. Stud. Manag. 2023, 16, 474–489. [Google Scholar]
  37. Francis, M. Morphometric minefields—Towards a measurement standard for chondrichthyan fishes. Environ. Biol. Fishes 2006, 77, 407–421. [Google Scholar] [CrossRef]
  38. Moutopoulos, D.K.; Ramfos, A.; Mouka, A.; Katselis, G. Length-weight relations of 34 fish species caught by small-scale fishery in Korinthiakos Gulf (Central Greece). Acta Ichthyol. Et Piscat. 2014, 43, 57–64. [Google Scholar] [CrossRef]
  39. Moutopoulos, D.K.; Chouli, M.; Dogrammatzi, A.; Papadopoulou, K.-N.; Smith, C.J.; Karachle, P.K. Biology and morphology of Bothus podas (Delaroche, 1809) in the Heraklion Bay, Crete. Turk. J. Zool. 2018, 42, 90–98. [Google Scholar] [CrossRef]
  40. Dulvy, N.K.; Fowler, S.L.; Musick, J.A.; Cavanagh, R.D.; Kyne, P.M.; Harrison, L.R.; Carlson, J.K.; Davidson, L.N.; Fordham, S.V.; Francis, M.P.; et al. Extinction risk and conservation of the world’s sharks and rays. eLife 2014, 3, e00590. [Google Scholar] [CrossRef]
  41. Ricci, P.; Sion, L.; Capezzuto, F.; Cipriano, G.; D’Onghia, G.; Libralato, S.; Maiorano, P.; Tursi, A.; Carlucci, R. Modelling the trophic roles of the demersal Chondrichthyes in the Northern Ionian Sea (Central Mediterranean Sea). Ecol. Model. 2021, 444, 109468. [Google Scholar] [CrossRef]
  42. Başusta, A.; Başusta, N.; Sulikowski, J.A.; Driggers, W.B., III; Demirhan, S.A.; Çiçek, E. Length–weight relationships for nine species of batoids from the Iskenderun Bay, Turkey. J. Appl. Ichthyol. 2012, 28, 850–851. [Google Scholar] [CrossRef]
  43. Dulčić, J.; Lipej, L.; Orlando Bonaca, M.; Jenko, R.; Grbec, B.; Guélorget, O.; Capapé, C. The bull ray, Pteromylaeus bovinus (Myliobatidae), in the Northern Adriatic Sea. Cybium 2008, 32, 119–123. [Google Scholar] [CrossRef]
  44. Filiz, H.; Bilge, G. Length–weight relationships of 24 fish species from the North Aegean Sea, Turkey. J. Appl. Ichthyol. 2004, 20, 431–432. [Google Scholar] [CrossRef]
  45. Morey, G.; Moranta, J.; Massutı, E.; Grau, A.; Linde, M.; Riera, F.; Morales-Nin, B. Weight–length relationships of littoral to lower slope fishes from the Western Mediterranean. Fish. Res. 2003, 62, 89–96. [Google Scholar] [CrossRef]
  46. Ilkyaz, A.T.; Soykan, G.; Metin, O.; Kinacigil, H.T. Length-weight relationship of 62 fish species from the Central Aegean Sea, Turkey. J. Appl. Ichthyol. 2008, 24, 699–702. [Google Scholar] [CrossRef]
  47. Işmen, A. Age, growth, reproduction and food of common stingray (Dasyatis pastinaca L., 1758) in Iskenderun Bay, the Eastern Mediterranean. Fish. Res. 2003, 60, 169–176. [Google Scholar] [CrossRef]
  48. Özaydin, O.; Uçkun, D.; Akalin, S.; Leblebici, S.; Tosunoglu, Z. Length-weight relationships of fishes captured from Izmir Bay, Central Aegean Sea. J. Appl. Ichthyol. 2007, 23, 695–696. [Google Scholar] [CrossRef]
  49. Işmen, A.; Ozen, O.; Altinagac, U.; Ozekinci, U.; Ayaz, A. Weight-length relationships of 63 fish species in Saros Bay, Turkey. J. Appl. Ichthyol. 2007, 23, 707–708. [Google Scholar] [CrossRef]
  50. Karakulak, F.S.; Erk, H.; Bilgin, B. Length–weight relationships for 47 coastal fish species from the Northern Aegean Sea, Turkey. J. Appl. Ichthyol. 2006, 22, 274–278. [Google Scholar] [CrossRef]
  51. Yeldan, H.; Avşar, D. Length–weight relationship for five elasmobranch species from the Cilician Basin shelf waters (Northeastern Mediterranean). J. Appl. Ichthyol. 2007, 23, 713–714. [Google Scholar] [CrossRef]
  52. Taylan, B.; Bayhan, B.; Sağlam, C.; Babaoğlu, A.O.; Kara, A. The length-weight characteristics of five Elasmobranch species (Pisces: Chondrichthyes) from Izmir Bay (Aegean Sea Coast of Turkey): Spring 2018. Turk. J. Agric.-Food Sci. Technol. 2022, 10, 368–373. [Google Scholar] [CrossRef]
  53. Geraci, M.L.; Ragonese, S.; Scannella, D.; Falsone, F.; Gancitano, V.; Mifsud, J.; Gambin, M.; Said, A.; Vitale, S. Batoid Abundances, Spatial Distribution, and Life History Traits in the Strait of Sicily (Central Mediterranean Sea): Bridging a Knowledge Gap through Three Decades of Survey. Animals 2021, 11, 2189. [Google Scholar] [CrossRef]
  54. Yemișkeni, E.; Eryilmaz, L.; Megalofonou, M.; Yildiz, T. Length-weight relationships of nine common demersal Elasmobranch species from the Eastern Mediterranean. Cah. Du Biol. Mar. 2019, 60, 293–297. [Google Scholar] [CrossRef]
  55. Pallaoro, A.; Jardas, I.; Santic, M. Weight-length relationships for 11 chondrichthyan species in the Eastern Adriatic Sea. Cybium 2005, 29, 93–96. [Google Scholar]
  56. Yığın, C.Ç.; Işmen, A. Length–weight relationships for seven rays from Saros Bay (North Aegean Sea). J. Appl. Ichthyol. 2009, 25, 106–108. [Google Scholar] [CrossRef]
  57. Eronat, E.G.T.; Özaydin, O. Length-weight relationship of cartilaginous fish species from Central Aegean Sea (Izmir Bay and Siğacik Bay). Ege J. Fish. Aquat. Sci. 2014, 31, 119–125. [Google Scholar] [CrossRef]
  58. Türker, D.; Zengin, K.; Tünay, Ö.K. Length-weight relationships for Nine Chondrichthyes fish species from Edremit Bay (North Aegean Sea). Turk. J. Fish. Aquat. Sci. 2019, 19, 71–79. [Google Scholar] [CrossRef]
  59. Edelist, D. New length-weight relationships and Lmax values for fishes from the Southeastern Mediterranean Sea. J. Appl. Ichthyol. 2014, 30, 521–526. [Google Scholar] [CrossRef]
  60. Borges, T.C.; Olim, S.; Erzini, K. Weight–length relationships for fish species discarded in commercial fisheries of the Algarve (Southern Portugal). J. Appl. Ichthyol. 2003, 19, 394–396. [Google Scholar] [CrossRef]
  61. Veiga, P.; Machado, D.; Almeida, C.; Bentes, L.; Monteiro, P.; Oliveira, F.; Ruano, M.; Erzini, K.; Gonçalves, J.M.S. Weight–length relationships for 54 species of the Arade estuary. South. Port. J. Appl. Ichthyol. 2009, 25, 493–496. [Google Scholar] [CrossRef]
  62. Dulčić, J.; Kraljevic, M. Weight-length relationship for 40 fish species in the Eastern Adriatic (Croatian waters). Fish. Res. 1996, 28, 243–251. [Google Scholar] [CrossRef]
  63. Bílge, G.; Yapici, S.; Fíliíz, H.; Cerím, H. Weight-length relationshions for 103 fish species from the Southern Aegean sea, Turkey. Acta Ichthyol. Et Piscat. 2014, 44, 263–269. [Google Scholar] [CrossRef]
  64. Falsone, F.; Geraci, M.L.; Scanella, D.; Gancitano, V.; Maio, F.D.; Sardo, G.; Quattrocchi, F.; Vitale, S. Length-weight relationships of 52 species from the South of Sicily (Central Mediterranean Sea). Fishes 2022, 7, 92. [Google Scholar] [CrossRef]
Diversity 18 00041 g001
Figure 1. Map indicating the sampling area. Blue dots indicate location of elasmobranch catch. The arrow indicates the study area.
Figure 1. Map indicating the sampling area. Blue dots indicate location of elasmobranch catch. The arrow indicates the study area.
Diversity 18 00041 g001
Diversity 18 00041 g002
Figure 2. Size frequency distribution divided by species and sex (females are indicated in orange, while males are indicated in light blue). Size at maturity is indicated for females by a dotted orange line and for males by a dottle light blue line. Specimens were caught in the Amvrakikos Gulf during February 2022–August 2025.
Figure 2. Size frequency distribution divided by species and sex (females are indicated in orange, while males are indicated in light blue). Size at maturity is indicated for females by a dotted orange line and for males by a dottle light blue line. Specimens were caught in the Amvrakikos Gulf during February 2022–August 2025.
Diversity 18 00041 g002
Table 1. Descriptive and statistical analyses of the total length (TL, cm), disc length (DL, cm), disc width (DW, cm) and total weight (W, g) for the eight studied elasmobranch species caught in Amvrakikos Gulf during February 2022–August 2025 by sex and combined data. F-ratio indicated the Student–Newman–Keuls (SNK) test in case of non significant (ns) (ANOVA; p > 0.05) comparisons by sex.
Table 1. Descriptive and statistical analyses of the total length (TL, cm), disc length (DL, cm), disc width (DW, cm) and total weight (W, g) for the eight studied elasmobranch species caught in Amvrakikos Gulf during February 2022–August 2025 by sex and combined data. F-ratio indicated the Student–Newman–Keuls (SNK) test in case of non significant (ns) (ANOVA; p > 0.05) comparisons by sex.
ParametersnMin–MaxMean (SD)F-Ratio nMin–MaxMean (SD)F-Ratio
Aetomylaeus bovinusTL12058.5–186.086.4 (27.9) Dasyatis marmorata19914.0–84.044.1 (12.1)
Female5258.5–186.087.9 (31.4)0.230 ns9815.0–84.045.1 (13.9)1.380 ns
Male6859.0–157.085.4 (25.0)10114.0–67.043.1 (10.1)
W151315–15,0002307.3 (2805.9) 22940.0–3720.0569.1 (539.5)
DL13316.5–74.030.3 (11.2) 2249.0–40.520.8 (6.1)
Female5716.5–74.030.1 (12.1)0.020 ns1149.0–40.521.8 (7.2)6.060 ns
Male7619.0–61.530.4 (10.6)11010.5–33.519.8 (4.6)
DW14818.5–125.049.8 (18.7) 22911.0–40.023.2 (6.5)
Female6426.0–125.050.6 (21.6)0.220 ns11711.0–40.024.3 (7.5)7.950 ns
Male8418.5–90.049.2 (16.3)11213.0–36.021.9 (4.9)
Dasyatis pastinacaTL8328.0–71.043.7 (9.9) Dasyatis tortonesei11624.0–104.048.3 (16.1)
Female4129.0–71.044.9 (11.1)1.080 ns5724.0–104.046.4 (17.7)1.500 ns
Male4228.0–65.042.6 (8.6)5927.5–73.050.1 (14.3)
W8775.0–3020.0607.2 (510.8) 14240.0–10,0001136.3 (1417.1)
DL8712.0–38.521.0 (5.7) 13710.5–45.523.1 (8.4)
Female4313.5–38.521.6 (6.3)1.080 ns7010.5–45.523.0 (9.6)0.020 ns
Male4412.0–35.020.3 (5.1)6711.5–38.523.2 (7.1)
DW8714.8–205.024.7 (6.5) 14112.0–67.027.9 (10.3)
Female4315.8–45.025.6 (7.2)0.300 ns7112.0–67.028.3 (12.3)0.190 ns
Male4414.8–205.028.0 (27.9)7014.0–43.527.5 (8.0)
Gymnura altavelaTL16820.0–71.033.1 (9.2) Myliobatis aquila8615.0–134.064.7 (26.9)
Female8121.0–63.032.5 (7.4)0.680 ns3337.0–134.064.4 (29.8)0.010 ns
Male8720.0–71.033.6 (10.6)5315.0–108.064.9 (25.3)
W177200.0–13,0001263.3 (1943.1)
DL14514.0–60.024.8 (7.9) 7210.5–45.519.3 (8.3)1.220 ns
Female7215.5–60.024.9 (8.0)0.060 ns3511.0–45.520.4 (9.8)
Male7314.0–50.524.6 (7.8)3710.5–34.018.3 (6.6)
DW17827.0–121.048.9 (16.1) 9319.0–80.037.3 (16.0)0.750 ns
Female8827.0–121.049.3 (17.1)0.100 ns3819.0–80.039.1 (20.2)
Male9029.0–103.048.6 (15.1)5519.0–64.036.1 (12.2)
Torpedo torpedoTL36411.0–40.524.4 (5.9) Mustelus mustelus18333.0–142.061.4 (29.4)
Female19311.0–40.524.8 (6.6)0.710 ns8837.0–142.059.2 (29.6)0.940 ns
Male17113.5–34.024.0 (5.1)9533.0–125.063.4 (29.2)
W 18385.0–13,0002584.5 (1515.2)
DL3336.5–21.012.8 (3.1)
Female1796.5–21.013.0 (3.2)0.700 ns
Male1547.0–17.2012.5 (3.1)
DW3647.5–26.015.3 (3.5)
Female1937.5–26.015.6 (4.0)0.080 ns
Male1718.5–21.014.9 (2.9)
Table 2. Estimated parameters of the relations between total length (TL, cm) with disc length (DL) and disc width (DW, cm) and TL and DL with weight (W, g) for the eight studied elasmobranch species caught in Amvrakikos Gulf during February 2022–August 2025 by sex and combined data. Comparisons of the estimated parameters between sexes are shown, for nonsignificant (ns) (ANOVA; p > 0.05) and * significant cases (ANCOVA, p < 0.05). N indicates the sample size.
Table 2. Estimated parameters of the relations between total length (TL, cm) with disc length (DL) and disc width (DW, cm) and TL and DL with weight (W, g) for the eight studied elasmobranch species caught in Amvrakikos Gulf during February 2022–August 2025 by sex and combined data. Comparisons of the estimated parameters between sexes are shown, for nonsignificant (ns) (ANOVA; p > 0.05) and * significant cases (ANCOVA, p < 0.05). N indicates the sample size.
RelationsNaSEabSEbR2ANCOVA
Aetomylaeus bovinus
DL = a + bTL
   Females48−0.3560.9540.3390.0100.960a = 0.925 ns
  Males640.1341.2340.3340.0140.905b = 0.768 ns
 Total112−0.1190.7790.3370.0080.935
DW = a + bTL
   Females51−0.7640.9750.5600.0110.983a = 0.901 ns
  Males68−2.0531.4750.5760.0170.948b = 0.492 ns
 Total119−1.3510.8900.5670.0100.966
W = a*TLb
   Females520.00090.1223.1930.0640.981a = 0.415 ns
  Males680.00140.1233.1030.0640.972b = 0.319 ns
 Total1200.00110.0873.1480.0450.976
W = a*DLb
   Females570.10260.1432.8180.0980.938a = 0.665 ns
  Males760.11000.1362.8030.0930.925b = 0.914 ns
 Total1330.10630.0982.8110.0670.931
W = a*DWb
   Females640.02650.1332.8020.0790.953a = 0.117 ns
  Males840.03160.1252.7720.0750.943b = 0.778 ns
 Total1480.02930.0912.7850.0540.947
Dasyatis marmorata
DL = a + bTL
   Females96−0.6060.3510.4580.0080.942a = 0.801 ns
  Males990.9180.3510.4230.0030.904b = 0.062 ns
 Total195−0.1050.3510.4470.0090.930
DL = a + bTL
   Females980.1780.9800.5000.0220.950a = 0.083 ns
  Males1011.6790.7980.4580.0180.583b = 0.020 *
 Total1990.5760.3980.4880.0090.943
W = a*TLb
   Females980.00150.1393.2810.0840.941a = 0.365 ns
  Males1010.00530.2742.9420.1300.837b = 0.027 *
 Total1990.00240.1223.1560.0740.901
W = a*DLb
   Females1140.05190.0912.9950.0690.944a = 0.057 ns
  Males1100.03550.1273.1020.0980.902b = 0.376 ns
 Total2240.04380.0733.0420.0560.929
W = a*DWb
   Females1170.02170.0843.1520.0610.958a = 0.808 ns
  Males1120.01710.1283.2270.0960.911b = 0.503 ns
 Total2290.01990.0703.1790.0520.943
Dasyatis pastinaca
DL = a + bTL
   Females41−2.8881.2720.5440.0280.909a = 0.730 ns
  Males42−3.2401.0390.5490.0220.865b = 0.915 ns
 Total83−3.0800.6960.5470.0150.893
DW = a + bTL
   Females41−3.2401.4880.5490.0340.865a = 0.291 ns
  Males42−3.8571.3940.6460.0320.910b = 0.874 ns
 Total83−3.6000.8330.6440.0190.937
W = a*TLb
   Females410.00140.1773.3830.1080.962a = 0.194 ns
  Males420.00060.3513.5840.2160.873b = 0.392 ns
 Total830.00090.1883.4810.1150.919
W = a*DLb
   Females430.09500.1342.8220.1010.950a = 0.262 ns
  Males440.06300.2302.9400.1770.868b = 0.554 ns
 Total870.07700.1282.8820.0980.911
W = a*DWb
   Females430.04200.1322.9260.0950.959a = 0.776 ns
  Males440.04300.2452.9160.1790.863b = 0.964 ns
 Total870.04200.1332.9250.0970.915
Dasyatis tortonesei
DL = a + bTL
   Females57−1.6551.1760.4840.0240.958a = 0.199 ns
  Males58−1.6091.3280.4930.0270.915b = 0.701 ns
 Total115−1.6160.5980.4880.0120.941
DW = a + bTL
   Females57−1.1301.0470.5690.0200.934a = 0.690 ns
  Males59−1.6781.0440.5770.0200.971b = 0.737 ns
 Total116−1.4730.8650.5740.0170.957
W = a*TLb
   Females570.00110.1623.4010.0980.957a = 0.725 ns
  Males590.00150.1733.3460.1030.949b = 0.469 ns
 Total1160.00120.1773.3870.0700.954
W = a*DLb
   Females700.05400.1123.0370.0830.951a = 0.978 ns
  Males670.05700.1303.0160.0960.938b = 0.876 ns
 Total1370.05500.0833.0290.0620.946
W = a*DWb
   Females710.02600.0963.0870.0680.968a = 0.375 ns
  Males700.02200.1173.1370.0820.955b = 0.642 ns
 Total1410.02500.0733.1050.0520.963
Gymnura altavela
DL = a + bTL
   Females692.3941.9590.6540.0590.944a = 0.367 ns
  Males731.2180.4920.6840.0140.972b = 0.218 ns
 Total1421.6470.3820.6740.0110.964
DW = a + bTL
   Females81−1.4792.3631.4830.0710.910a = 0.564 ns
  Males871.2531.0591.4070.0300.979b = 0.152 ns
 Total1680.3150.8291.4310.0240.955
W = a*TLb
   Females810.02000.1823.0340.1210.888a = 0.253 ns
  Males870.02370.1172.9870.0780.946b = 0.973 ns
 Total1680.02200.1023.0080.0680.923
W = a*DLb
   Females720.04000.1733.1100.1250.898a = 0.219 ns
  Males730.06600.1262.9700.0910.937b = 0.362 ns
 Total1450.05300.1053.0320.0760.917
W = a*DWb
   Females870.01300.1402.8680.0830.933a = 0.813 ns
  Males900.00700.1013.0150.0610.966b = 0.160 ns
 Total1770.01000.0872.9360.0520.948
Myliobatis aquila
DL = a + bTL
   Females330.8400.9370.2920.0130.940a = 0.240 ns
  Males351.5250.9020.2850.0130.942b = 0.779 ns
 Total881.2360.4610.2870.0070.961
DW = a + bTL
   Females330.3310.7330.5340.0120.983a = 0.699 ns
  Males533.3281.1480.4850.0190.971b = 0.006 *
 Total881.8130.6280.5090.0090.975
W = a*TLb
   Females330.00100.1163.1380.0650.987a = 0.948 ns
  Males530.00300.1622.9460.0900.955b = 0.113 ns
 Total880.00200.1073.0290.0600.968
W = a*DLb
   Females350.06000.1863.1040.1450.933a = 0.141 ns
  Males370.07100.1543.0200.1240.945b = 0.287 ns
 Total720.06200.1203.0800.0950.938
W = a*DWb
   Females380.00800.1213.1770.0780.979a = 0.733 ns
  Males550.00700.0773.2050.0500.987b = 0.763 ns
 Total930.00800.0693.1900.0450.982
Torpedo torpedo
DL = a + bTL
   Females1791.1300.0220.4780.0160.954a = 0.026 *
  Males1531.7650.2510.4410.0100.899b = 0.012 *
 Total3321.2780.1710.4670.0070.935
DW = a + bTL
   Females1930.8100.0220.5990.0160.960a = 0.001 *
  Males1711.6490.2510.5520.0100.912b = 0.003 *
 Total3641.0310.1910.5840.0080.942
Mustelus mustelus
FL = a + bTL
   Females31−0.4381.1510.8530.0170.988a = 0.996 ns
  Males502.2570.9470.8110.0110.991b = 0.042 *
 Total811.1700.7250.8260.0100.990
W = a*TLb
   Females880.00150.1093.2050.0620.968a = 0.000 *
  Males950.00290.0823.0240.0460.979b = 0.000 *
 Total1830.00220.0683.1020.0390.973
Table 3. Size at sexual maturity at which 50% of the population reaches maturity and rate of immature individuals per each sex for each elasmobranch species caught in Amvrakikos Gulf during February 2022–August 2025.
Table 3. Size at sexual maturity at which 50% of the population reaches maturity and rate of immature individuals per each sex for each elasmobranch species caught in Amvrakikos Gulf during February 2022–August 2025.
SpeciesNumber of FemalesNumber of MalesTL50 Females (cm) *TL50 Males (cm) *% Females Immature% Males Immature
Aetomylaeus bovinus5268162.1142.596.297.1
Dasyatis marmorata9810158.652.479.676.2
Dasyatis pastinaca414278.857.1100.095.2
Dasyatis tortonesei575982.159.693.071.2
Gymnura altavela818765.754.1100.093.1
Myliobatis aquila3353136.196.20.090.6
Torpedo torpedo19317125.824.956.555.6
Mustelus mustelus8895121.0108.089.883.2
Total643676 81.578.1
* Data for size at maturity were found for A. bovinus in [27], for D. marmorata and D. tortonesei in Ciprian M. (unpublished data), for D. pastinaca in [28], for G. altavela in [29], for M. aquila in [30], for T. torpedo in [31] and for M. mustelus in [32].
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Ciprian, M.; Giovos, I.; Mazzoldi, C.; Moutopoulos, D.K. Morphometric Relations Within Elasmobranch Species from the Amvrakikos Gulf (Central Mediterranean). Diversity 2026, 18, 41. https://doi.org/10.3390/d18010041

AMA Style

Ciprian M, Giovos I, Mazzoldi C, Moutopoulos DK. Morphometric Relations Within Elasmobranch Species from the Amvrakikos Gulf (Central Mediterranean). Diversity. 2026; 18(1):41. https://doi.org/10.3390/d18010041

Chicago/Turabian Style

Ciprian, Martina, Ioannis Giovos, Carlotta Mazzoldi, and Dimitrios K. Moutopoulos. 2026. "Morphometric Relations Within Elasmobranch Species from the Amvrakikos Gulf (Central Mediterranean)" Diversity 18, no. 1: 41. https://doi.org/10.3390/d18010041

APA Style

Ciprian, M., Giovos, I., Mazzoldi, C., & Moutopoulos, D. K. (2026). Morphometric Relations Within Elasmobranch Species from the Amvrakikos Gulf (Central Mediterranean). Diversity, 18(1), 41. https://doi.org/10.3390/d18010041

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