Stock discrimination of Chelidonichthys obscurus (Triglidae) in the central Mediterranean Sea using morphometric analysis and parasite markers

2019 ◽  
Vol 94 ◽  
Author(s):  
L. Boudaya ◽  
M. Feki ◽  
N. Mosbahi ◽  
L. Neifar
Keyword(s):  
Fisheries Management ◽  
Morphometric Analysis ◽  
Body Height ◽  
Future Research ◽  
Central Mediterranean ◽  
Gulf Of Gabes ◽  
Morphometric Characters ◽  
Mahalanobis Distances ◽  
Gulf Of Gabès ◽  
Fin Length

Abstract Assessing fish stocks has important implications for fisheries management and conservation biology. Gurnards are marine demersal fish that commonly occur in the Mediterranean, but their population in this region remains to be quantified. This study examines the population structure of the longfin gurnard Chelidonichthys obscurus (Walbaum, 1792) in waters off eastern Tunisia, using morphometry and parasite assemblages. A total of 134 fish are investigated from two studied zones – the Gulf of Hammamet and the Gulf of Gabès. Discriminant analysis is used to compare gurnard populations in the two studied zones using 13 morphometric characters and the infection parameters of seven parasites. Morphometric analysis reveals strong spatial variations between the studied zones, providing evidence for the existence of an ecological differentiation along the eastern Tunisian coast. Mahalanobis distances show that body height, pectoral fin length and first dorsal fin length are the most salient morphometric characters for determining the position of samples from the Gulf of Gabès. The effectiveness of using parasites to study longfin gurnard stocks is uncertain. The use of short-lived parasites as biological tags is questionable, at least in the present case. Future research, based on complementary approaches such as otolith microchemistry and genetics, may improve our understanding of the global stock structure of longfin gurnard to suitably inform regional organizations involved in fisheries management.

First data on the age, growth and sexual maturity of the piked spurdog, Squalus megalops (Chondrichthyes: Squalidae), in the Gulf of Gabès (central Mediterranean Sea)

2016 ◽  
Vol 67 (5) ◽  
pp. 578 ◽  
Author(s):  
Sondes Marouani ◽  
Hasna Kadri ◽  
Mohamed Nejmeddine Bradai
Keyword(s):  
Mediterranean Sea ◽  
Growth Parameters ◽  
Natural Mortality ◽  
Central Mediterranean ◽  
Gulf Of Gabes ◽  
Band Formation ◽  
Mortality Estimation ◽  
Gulf Of Gabès ◽  
Central Mediterranean Sea ◽  
Males And Females

The occurrence of the piked spurdog (Squalus megalops) in the Gulf of Gabès (Tunisia, central Mediterranean Sea) was recently confirmed. The present study is the first to report the age, growth, longevity, natural mortality and size and age at maturity of this species in the Mediterranean Sea, precisely in the Gulf of Gabès. Marginal increment and edge analysis suggested annual band formation. Age estimates ranged from 0 to 26 and from 0 to 29 years for males and females respectively. Von Bertalanffy growth parameters derived from length-at-age data were: the theoretical asymptotic length L∞=82.31±1.55cm, the growth-rate coefficient k=0.06±0.003 years–1, the theoretical age at length zero t0=–3.89±0.25 years for females; and L∞=68.55±0.98cm, k=0.08±0.003 years–1, t0=–4.65±0.25 years for males. Males and females reached maturity at 44.36- and 56.41-cm total length, corresponding to 8.39 and 15.38 years respectively. Longevity estimates were 32.85 and 46.11 years for males and females respectively. On the basis of life-history parameters, natural mortality estimation M ranged from 0.14 to 0.17.

Diet and feeding strategy of thornback ray, Raja clavata (Chondrichthyes: Rajidae) from the Gulf of Gabes (Tunisia—Central Mediterranean Sea)

2014 ◽  
Vol 94 (7) ◽  
pp. 1509-1516 ◽  
Author(s):  
Hasna Kadri ◽  
Sondes Marouani ◽  
Mohamed Nejmeddine Bradai ◽  
Abderrahmen Bouaïn
Keyword(s):  
Feeding Strategy ◽  
Stomach Contents ◽  
Ontogenetic Changes ◽  
Central Mediterranean ◽  
Gulf Of Gabes ◽  
Gulf Of Gabès ◽  
Thornback Ray ◽  
Raja Clavata ◽  
Food And Feeding ◽  
Quantitative Analyses

Food and feeding strategy of the thornback ray, Raja clavata, were studied from stomach contents analysis of specimens caught monthly in the Gulf of Gabes. The data were analysed according to sex, size and season. At total of 1280 stomachs was examined, from specimens ranging from 14 to 110 cm total length (TL), of which 1076 (83.98%) contained food. Thornback ray feed mainly on teleosts, crustaceans and cephalopods, whereas gastropods and polychaetes are occasionally consumed. Significant differences were found between the diets of males and females; however, ontogenetic changes were also detected, with crustaceans constituting the greatest proportion of the diet of smaller rays. Both teleosts and cephalopods increased in importance with growth of the skates. Prey diversity increased with size; large and mobile prey species were more commonly found in the diet of larger skates. Diet composition showed seasonal variations. Quantitative analyses and graphical methods indicate that the thornback ray is a generalist feeder.

Diet composition and food habits of Diplodus puntazzo (Sparidae) from the Gulf of Gabès (Central Mediterranean)

2013 ◽  
Vol 93 (8) ◽  
pp. 2257-2264 ◽  
Author(s):  
Houda Chaouch ◽  
Olfa Ben Abdallah-Ben Hadj Hamida ◽  
Mohamed Ghorbel ◽  
Othman Jarboui
Keyword(s):  
Food Source ◽  
Feeding Habits ◽  
Feeding Strategy ◽  
Stomach Contents ◽  
Important Food ◽  
Central Mediterranean ◽  
Gulf Of Gabes ◽  
Diplodus Puntazzo ◽  
Gulf Of Gabès ◽  
Important Food Source

The diet and feeding habits of the sharpsnout seabream, Diplodus puntazzo, from the Gulf of Gabès were investigated using stomach contents of 490 specimens ranging from 12.6 cm to 26.1 cm total length in size and from 29.95 g to 230.83 g in weight collected from commercial catches between April 2008 and March 2009. Of the total number of examined stomachs, 279 were empty (%VI = 56.94). This percentage varied significantly with months, attaining a maximum in spring (74.88%) and a minimum in autumn (37.38%). Eight major taxa were identified (Plantae, Spongia, Tunicata, Echinodermata, Crustacea, Annelida, Mollusca and Teleostei) in stomach contents of D. puntazzo. Plants were the most important food source, constituting 89.88% of the total Index of relative importance. The other groups, such as teleosts, molluscs, crustaceans and annelids represented accessory food. Significant differences in diet were observed in relation to season. Plants were the most important food source item in all seasons, especially during the autumn. The estimation of trophic level gave an average of 2.57 ± 0.2 for the whole population of D. puntazzo in the Gulf of Gabès. Based on the composition of its diet, this species may be considered as an omnivorous fish with a preference for vegetable material, and showing specialist feeding strategy.

Feeding behaviour of greater amberjackSeriola dumerili(Risso, 1810) from Central Mediterranean (Gulf of Gabes, Tunisia)

2016 ◽  
Vol 96 (6) ◽  
pp. 1229-1234 ◽  
Author(s):  
Ayda Sley ◽  
Aymen Hadj Taieb ◽  
Othman Jarboui ◽  
Mohamed Ghorbel ◽  
Abderrahmen Bouain
Keyword(s):  
Stomach Contents ◽  
Frequency Of Occurrence ◽  
Central Mediterranean ◽  
Gulf Of Gabes ◽  
Seriola Dumerili ◽  
Gulf Of Gabès ◽  
Important Prey ◽  
Significant Difference ◽  
Opportunistic Predator ◽  
Greater Amberjack

The diet of greater amberjackSeriola dumerili(Carangidae) in the Gulf of Gabes (Tunisia, Mediterranean) was described from analysis of stomach contents of 290 specimens fished between June 2004 and May 2006. The index of vacuity (%VI) was relatively low (37.9%) and differed significantly across size classes.Seriola dumeriliis an opportunistic predator that consumes mostly pelagic organisms; benthic prey were also examined in small proportion. The diet was quantified using the frequency of occurrence (%O), numerical abundance (%N), weight (%W) and the index of relative importance (IRI and %IRI) for each prey taxa. The most important prey were teleosts (%IRI = 99.61); molluscs and crustaceans were found occasionally (%IRI, 0.38 and 0.01%, respectively). Among teleosts, Clupeidae were also the dominant food items in number (%N = 36.06%) and then in frequency of occurrence (%O = 36.7%). In term of weight, Sparidae were the most abundant prey (%W = 36.5%). There is no significant difference between male and female diets. Seasonal differences in the diet components were observed.

Age, growth and reproductive biology of the rough skate, Raja radula (Chondrichthyes: Rajidae), off the Gulf of Gabes (southern Tunisia, central Mediterranean)

2013 ◽  
Vol 64 (6) ◽  
pp. 540 ◽  
Author(s):  
Hasna Kadri ◽  
Sondes Marouani ◽  
Mohamed Nejmeddine Bradai ◽  
Abderrahmen Bouaïn
Keyword(s):  
Reproductive Cycle ◽  
Growth Parameters ◽  
Age And Growth ◽  
Age At Maturity ◽  
Central Mediterranean ◽  
Gulf Of Gabes ◽  
Vertebral Centra ◽  
Gulf Of Gabès ◽  
Southern Tunisia ◽  
Significant Difference

Age, growth and reproductive parameters were estimated for Raja radula from the Gulf of Gabes (southern Tunisia, central Mediterranean Sea), collected monthly during 2007 from commercial fisheries. In total, 550 females (18.5–80.0 cm TL) and 400 males (13.4–65 cm TL) were examined to study the reproductive cycle. A subsample of 272 specimens (140 females and 132 males, ranging from 15.5 to 80 cm in total length, TL) was used for age and growth estimation derived from vertebral centra. The marginal-increment and edge analysis showed annual deposition of growth bands. The oldest female in the study was 12 years old and 80 cm in TL, whereas the oldest male was 9 years old and 65 cm in TL. The von Bertalanffy growth parameters were L∞ = 76.36 cm, K = 0.22 year–1 and t0 = –0.16 years for males. There was no significant difference in growth between the sexes. The size-at-maturity was 47.05 cm for males and 56.48 cm for females. The age-at-maturity was estimated to be 4.47 and 5.89 years, respectively, for males and females. There was no significant difference of size- and age-at-maturity between the sexes. Females carrying egg cases occurred throughout the year. Variations in the gonadosomatic and hepatosomatic indices showed a continuous reproductive cycle throughout the year.

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