Torquigener flavimaculosus, Hardy & Randall, 1983

Mutlu, Erhan, Meo, Ilaria de & Miglietta, Claudia, 2020, Spatio-temporal distribution of pufferfish (Tetraodontidae) along the Turkish coast of the Mediterranean Sea Abstract, Mediterranean Marine Science 22 (1), pp. 1-19 : 10-13

Torquigener flavimaculosus

The species T. flavimaculosus was found mostly in the eastern part of the study area. The species was not found in R4 located in front of the river. This species was distributed on the shelf without exceeding bottom depths of 75 m, the maximum biomass was 2 kg /km 2, and the abundance was 150 ind/km 2 in the other regions ( Fig. 11 ). The biomass of the species was not significantly different among regions, seasons, and bottom depths (p = 0.190, 0.306, and 0.077, respectively); however, the mean biomass was significantly higher in R3 (0.20 ± 0.06 kg /km 2) than in R1 (0.03 ± 0.06 kg /km 2). The seasonal biomass varied between 0.037 ± 0.08 kg /km 2 in August and 0.20 ± 0.07 kg /km 2 in May. The biomass decreased slightly with bottom depths of 50 m, and then was higher at 75 m (0.35 ± 0.08 kg /km 2) only than that at 25 m (0.10 ± 0.08 kg /km 2, Fig. 11A ) .

Results of ANOVA showed that abundance did not differ significantly among regions, seasons, and bottom depths (p = 0.160, 0.503, and 0.063, respectively). Nevertheless , the mean abundance was significantly higher in R3 (21.24 ± 5.65 ind/km 2) than in R1 (4.96 ± 5.54 ind/km 2). The maximum seasonal abundance was estimated to be 16.77 ± 6.14 ind/km 2 in May, and the minimum abundance was 4.18 ± 6.98 ind/km 2 in August. Similar to biomass distribution by bottom depth, abundance varied between 7.69 and 8.33 ind/km 2 at 25–50 m, 26.53 ind/km 2 at 10 m, and 25.14 ind/km 2 at 75 m ( Fig. 11B ) .

Dominance of females over males was not significant among regions, seasons, and bottom depths (p = 0.291, 0.094, and 0.081, respectively). The female:male ratio varied seasonally between 3.3×10 -16 ± 0.55 by male dominance in R1 and 1.16 ± 0.45 by female dominance in R2 . The ratio was significantly higher in February (1.81 ± 0.48) than in May (0.36 ± 0.37). In the other seasons, females were mostly absent with males present in high abundance. Greater bottom depths (75 m) had high- er abundances of females (1.55 ± 0.44) as compared to males .

The total length (TL) of T. flavimaculosus ranged from 3.6 to 11.1 cm in the study area. The optimum length class interval was estimated to be 1.07 cm for the length distribution; however, one cohort (3.6–11.1 cm in TL) was estimated. The length changed significantly with bottom depth and sex (p = 0.037 and 4.5×10 -5, respectively). Regional length distributions varied between 6.02 ± 0.80 cm in R 1 and 8.07 ± 0.62 cm in R 2. Seasonally, the maximum length was 7.95 ± 1.43 cm in August and the minimum length was 6.28 ± 0.72 cm in October. The specimens were significantly longer at bottom depths of 75 m (8.16 ± 0.50 cm) than at 10 m (6.27 ± 0.43 cm). Female individuals were significantly longer (8.94 ± 0.48 cm) than males (7.18 ± 0.33 cm). Specimens with lengths less than 5.0 cm could not be sexed.

Similar to length distribution, individual weights were significantly different with respect to bottom depth and sex (p = 0.010 and 0.001, respectively). There were no significant seasonal or regional differences in weight. There were light individuals in R1 (5.35 ± 2.82 g) and in October (5.76 ± 2.51 g) and heavy individuals in R2 (12.43 ± 2.18 g) and in May and August (~ 11 g). There were significantly heavier individuals at bottom depths of 25 m and 75 m (~ 13 g) than at 10 m (5.56 ± 1.44 g). Females were significantly heavier (15.74 ± 1.83 g) than males (8.25 ± 1.23 g). Individuals that weighed less than 3 g could not be sexed .

Length-weight relationships did not differ significantly by region, season, bottom depth, and sex (p = 0.050, 0.517, 0.803, and 0.342, respectively). Regression equations of L-W relationships are shown in Figure 12 for females, males, and total individuals pooled. The species showed significant isometric growth in length with the weights for the all individuals, males, and females (n = 33, t = 0.012; n = 22, t = -0.347, and n = 10, t = 0.101, respectively) at p <0.05.

Figures

Fig. 11: Distribution of (A) biomass, (B) abundance (circles square-rooted), and (C) percent sex composition of Torquigener flavimaculosus in time (months) and space (regions and depths). Seasonal colors on the figures are: blue = May 2014, green = August 2014, red = October 2014, and magenta = February 2015. Colors for sex composition are: females follow seasonal color scheme, males = black, and juveniles = white in seasons.

Fig. 12: Length-weight relationships of males (blue), females (pink), and unisex pooled data (red) of Torquigener flavimaculosus.