Moncef Boumaïza

Production, maturity, reproductive cycle and fecundity of small-spotted catshark, Scyliorhinus canicula (Chondrichthyes: Scyliorhinidae) from the northern coast of Tunisia (Central Mediterranean)

Small-spotted catshark Scyliorhinus canicula (Linnaeus, 1758) is confronted since 2000 to a drastic decline of captures in Tunisian northern areas where it formerly was quantitatively and qualitatively very abundant. A study conducted in the area showed that males and females sexually matured between 400–478 mm and 364–471 mm total length (TL), respectively. The largest male and female were 521 mm and 531 mm TL, respectively and weighed 449 and 445.5 g, respectively. There was a not significant relationship total mass vs. TL between males and females. Conversely, the relationship of liver mass vs. TL significantly differed between sexes. Both HSI and GSI values did not present significant differences between males and females. There was a not significant relationship total mass vs. TL between males and females. Both male and female HSI reached high values in adults, significantly higher than those of sub-adults. Both male and female GSI values increased with TL of specimens; additionally, they showed significant differences between juveniles and sub-adults and also between sub-adults and adults. The OSI values were significantly different between juvenile and sub-adult females, and also between sub-adult and adult females. Monthly mean values of adult male and female HSI did not significantly vary throughout the year. Significant monthly changes were recorded in mean values of adult male however no significant changes were observed in monthly mean of GSI and OSI for adult females. Vitellogenic activity and production of egg cases permanently occurred throughout the year. The diameter of largest yolky oocytes ranged from 20.1 to 23.0 (mean = 21.43 ± 1.07) and weighed from 0.64 to 0.90 g (mean = 0.78 ± 0.09). Some measurements were taken on egg cases: length with horns ranged 42.5-55.7 mm with mean = 48.9 ± 2.9, width ranged 13.6–19.7 mm with mean = 16.50 ± 0.9, while the total mass of complete egg case ranged between 1.8 and 4.6 g, with mean = 2.4 ± 0.4. An annual fecundity estimation based on production of egg cases and oocytes during one year counted in adult females, enabled us to consider it between 40 and 240.

A CASE OF HERMAPHRODITISM IN TORTONESE'S STINGRAY, DASYATIS TORTONESEI (ELASMOBRANCHII: RAJIFORMES: DASYATIDAE) FROM THE LAGOON OF BIZERTE, TUNISIA

A normal hermaphrodite Tortoneses stingray, Dasyatis tortonesei Capape, 1975, captured in the brackish L agoon of Bizerte (north-eastern Tunisia) is described in this note. It was a large specimen measuring 685 mm total length, 350 mm disk width, and 2190 g of the total body mass. The specimen externally presented medial cuspidate tooth rows on both jaws, and two claspers were present, that were rigid and calcified although shorter than those observed in normal specimens. The dissection of the abdominal cavity revealed on each side, an ovary normally developed that contained y olked oocytes, a complete genital tract and an uterus less developed than in normal adult. Conversely the testes were rudimentary, both Leydigs glands were developed and a com- plete, slightly convoluted, male duct existed on the left side only. In all, 13 cases of normal (4) and abnormal (9) hermaphroditism, including the Tunisian D. tortonesei, have been found in batoid species, to date, confirming that the phenomenon is very rare among these chondrichthyan fishes.. K eywords: Dasyatis tortonesei, normal hermaphrodite, Lagoon of Bizerte, Tunisia, central Mediterranean

First record of the west African goatfish, Pseudupeneus prayensis (Actinopterygii: Perciformes: Mullidae), off the Tunisian coast (central Mediterranean)

Two specimens of the west African goatfish, Pseudupeneus prayensis (Cuvier, 1829), were found for the first time off the Tunisian coast, in northern area. They constituted the third Mediterranean record of this fish. Both specimens were studied and described, and some biological observations were reported. Same taxonomic charac- ters were concomitantly determined on two west African goatfish caught off the coast of Senegal, for comparison. The occurrence of Pseudupeneus prayensis in the area and the Mediterranean Sea is discussed and commented.

First Mediterranean records of spinetail devil ray, Mobula japanica (Elasmobranchii: Rajiformes: Mobulidae)

Captures of 11 spinetail devil rays, Mobula japanica (Muller et Henle, 1841), from the northern coast of Tunisian (central Mediterranean) are reported in the present paper. Of these 11 specimens, fi ve specimens were described. These captures constitute the fi rst records of the species in the Tunisian waters, but also in the Mediterranean Sea, extending its distribution. This unusual occurrence of M. japanica is probably due to a migration from the eastern tropical Atlantic into the Mediterranean Sea through the Strait of Gibraltar.

Food and feeding habits of black scorpionfish, Scorpaena porcus (Osteichthyes: Scorpaenidae) from the northern coast of Tunisia (Central Mediterranean)

Food and feeding habits of black scorpionfish Scorpaena porcus Linnaeus, 1758 were carried out from 715 specimens collected off Ras Jebel, city located in northern Tunisia. Diet was studied in relation to fish size, sexes and seasons. The relationship total length (TL) versus total body mass (TBM) showed a positive allometry, suggesting that S. porcus found favourable environmental parameters and available preys in its habitat. Vacuity index (VI) values were high for the total sample and also related to size classes, sexes, and seasons. Stomach contents of S. porcus revealed a very large diversity of preys; a total of 79 taxa were recorded, 3 osteichthyan, 69 crustacean, 2 annelid and 2 gastropod species, while angiosperma, alga, were rare. Crustaceans were the most abundantly found followed by osteichthyes. The troph value of S. porcus from the north-eastern coast of Tunisian reached 3.48 ± 0.58. S. porcus did not display significant changes in the diet related to sizes and/or seasons. S. porcus should be included among the carnivorous species which play a major role in regulation of marine food webs.

Maturity, reproductive cycle and fecundity of common torpedo, Torpedo torpedo (Chondrichthyes, Torpedinidae) from the Lagoon of Bizerte (Northeastern Tunisia, central Mediterranean)

Common torpedo Torpedo torpedo (Linnaeus, 1758) is widely distributed in the Mediterranean Sea, especially in southern and northern regions. The species is known throughout the Tunisian coast and entered brackish areas, such as the northeastern Lagoon of Bizerte, where it is commonly captured. Investigations conducted in this latter area showed that males and females sexually matured between 234–285 mm and 245–280 mm total length (TL), respectively. The largest male and female were 403 mm and 435 mm TL, respectively and weighed 721.5 and 1273.5 g, respectively. There was a not significant relationship total mass versus TL between males and females. Conversely, the relationship of liver mass versus TL significantly differed between sexes. The diameter of the largest yolky oocytes ranged between 43 and 47 mm (mean 45.08 ± 0.98)}, while the mass ranged between 29.5 and 37.4 g (mean 31.79 ± 2.20). Near term embryos ranged from 19.34 to 31.28 mm TL (mean: 24.60 ± 4.12) and weighed from 3.9 to 9.0 g (mean 5.97 ± 1.41). Ovarian fecundity ranged from 4 to 36 (mean = 11.60 ± 5.96). Uterine fecundity or litter size ranged from 3 to 13 (mean = 6.36 ± 2.67). Both fecundities showed a positive relationship with TL of females. A chemical balance of development based on mean dry masses of yolky oocytes and near-term embryos was 0.75 and suggested that T. torpedo could be considered as a pure lecithotrophic species. Hepatosomatic index (HSI) and gonadosomatic index (GSI) calculated for females presented significant higher values than those of males. HSI values of males significantly differed differences between juveniles, sub-adults and adults, and in females, HSI values were not significantly different between juveniles and sub-adults and significantly different between sub-adults and adults. The values of male GSI increased with TL of specimens; additionally, they showed significant differences between juveniles and subadults, but not between sub-adults and adults. Monthly mean values of adult male and female HSI significantly varied throughout the year. Monthly mean of females GSI showed significant changes especially from January to April, due to a high vitellogenic activity, GSI decreased from May to August, during this period all yolky oocytes were ovulated, then GSI increased progressively from September. The reproductive cycle lasted one year approximately and gestation period 4 months, while near-term females were captured in August. Vitellogenesis did not proceed in parallel with embryonic development: during ovarian vitellogenic activity, the uteri were empty and in an appearent resting phase, conversely during gestation, the ovaries did not exhibit an appearent activity, by contrast other specimens exhibited a vitellogenic activity during gestation. With special regard to the latter case, it remains difficult to state if these small yolky oocytes were not ovulated, or if they were new oocytes produced immediately after ovulation, both hypothesis remaining suitable.

Additional and unusual captures of elasmobranch species from the northern coast of Tunisia (central Mediterranean)

The present paper reports occurrences of six elasmobranch species previously considered as rare and/or unknown in northern Tunisian waters. Captures of sharpnose seven-gill shark, Heptranchias perlo (Bonnaterre, 1788) and bluntnose six gills shark, Hexanchus griseus (Bonnaterre, 1788) showed that both species although they are threatened are not totally exctincted in the area. A new record of a juvenile great white shark, Carcharodon carcharias (Linnaeus, 1758) confirms one again that the central Mediterranean could be considered as a possible nursery area for this species. Additionally, captures of sandbar shark, Carcharhinus plumbeus (Nardo, 1827) and blackchin guitarfish Rhinobatos cemiculus E. Geoffroy Saint-Hilaire, 1817 are due to migrations from southern toward northern areas as a consequence of the warming of the latter areas. It may be also the case for blue shark, Prionace glauca (Linnaeus, 1758), from Algerian waters where the species is rather abundant.

Unusual captures of teleost species from the northern Coast of Tunisia (central Mediterranean)

A survey conducted off the northern Tunisian coast allow to collect specimens belonging to species rarely captured in the area, such as longjaw snake eel Ophisurus serpens (Linnaeus, 1758), bluntsnout snake eel Echelus myrus (Linnaeus, 1758), Mediterranean parrot fish Sparisoma cretense (Linnaeus, 1758) and sharksucker Echeneis naucrates (Linnaeus, 1758). All specimens are shortly described in the present paper, including morphometric measurements and meristic counts. Their distribution in the area and the Mediterranean Sea is commented and discussed.