IntechOpen

Home > Books > Sharks - Past, Present and Future

Open access peer-reviewed chapter

Elasmobranchs in Tunisia: Status, Ecology, and Biology

Written By

Samira Enajjar, Bechir Saidi and Mohamed Nejmeddine Bradai

Submitted: 30 August 2022 Reviewed: 17 October 2022 Published: 12 November 2022

DOI: 10.5772/intechopen.108629

Sharks IntechOpen
Sharks Past, Present and Future Edited by Mohamed Nejmeddine Bradai

From the Edited Volume

Sharks - Past, Present and Future

Edited by Mohamed Nejmeddine Bradai, Samira Enajjar and Bechir Saidi

Book Details Order Print

Chapter metrics overview

124 Chapter Downloads

View Full Metrics
Advertisement

Abstract

The authors have compiled published information on taxonomy, distribution, status, statistics, fisheries, bycatch, biologic, and ecologic parameters mainly on food and feeding habits and reproductive biology of elasmobranchs along the Tunisian coasts. This bibliographic analysis shows that cartilaginous species, including sharks and rays are by far the most endangered group of marine fish, with 63 species, about 53% of all are critically endangered, endangered, or vulnerable. Overfishing, fishing practices, and habitat degradation are leading to dramatic declines of these species. Biologic parameters concern a few species primarily in the Gulf of Gabes. Therefore, recommendations to fill gaps in order to protect and manage elasmobranchs stocks are proposed in this chapter.

Keywords

  • status
  • elasmobranchs
  • Tunisia
  • bibliographic analysis

1. Introduction

The Mediterranean Sea is known to be an important habitat for elasmobranchs with at least 48 sharks and 38 batoids species [1]. However, the region is a hotspot of extinction risk [2]. It has been demonstrated that sharks in the Mediterranean Sea have declined by more than 97% in number and “catch weight” over the last 200 years [3]. This situation driven a regional and a global rising concern about shark conservation and management [4].

Tunisian coasts (Central Mediterranean Sea) are characterized by their sharks and rays diversity [5, 6]. The region is known to be an important habitat for this group and a breeding grounds for many species such as the sandbar shark (Carcharhinus plumbeus) [7, 8, 9]. Like the rest of the Mediterranean, Elasmobranchs in Tunisia are subject to an increasing pressure due to the anthropogenic activities mainly fisheries [10]. The emerging picture illustrates a decline of several elasmobranch populations [11]. Nevertheless, investigation on management and conservation on elasmobranch have received little attention [12].

Elasmobranchs are vulnerable to fishing mortality owing to their life histories characteristics, such as low fecundity, late maturity, and slow growth rates [1]. Accordingly, information on biology, ecology, fishery, distribution, and population structure is required for suitable management and conservation of this group. Unfortunately, the investigations research related to these creatures is quite recent, it started by the end of the 1990s when landings declined, and some species became threatened [6].

Along Tunisian coasts, research interested on elasmobranch has started in early 1970. Although the studies relating to this group of fish are maintained until today, several gaps still exist for an adequate management of catches and sustainable conservation.

The aim of the present chapter is to review and analyze the research publications relating to elasmobranch species along the Tunisian coasts in order to appreciate the main gathered information and gaps. In addition, this analysis will guide our future research in order to acquire the essential information indispensable for an adequate conservation of this group.

Advertisement

2. Study area

Tunisia, with 2290 km of coastline, constitutes a transition zone between the eastern and western basins of the Mediterranean [13]. The Tunisian marine coasts include the FAO-GFCM Geographical Sub Areas (GSA) 12, 13, and 14 (Figure 1).

Figure 1.

GFCM geographic subareas off Tunisian coasts.

The northern coasts (GSA 12) are characterized by a turbulent underwater morphology, an alternation of hard, and soft bottom and a steeply sloping continental shelf. This diversity of biotopes gives them a high biodiversity. Among the 327 fish species listed in Tunisian waters, 270 were recorded in the Northern coast [5].

The eastern region of Tunisia (GSA 13), corresponding to the Gulf of Hammamet, begins with a narrow continental shelf (the -50 m isobath is located quite far from the coast), bordered by the Siculo-Tunisian channel and gradually widening from north to south of this region. The seabed of the area provides a transition between the northern and southern Tunisia [14, 15].

The GSA14, corresponding sensu lato to the Gulf of Gabes, represents the southern part of the Tunisian coast [16]. This region is characterized by a significant tidal phenomenon and an extended continental shelf. The presence of extensive seagrass meadows and the ease of access to fishing areas rich in species of high commercial value makes this region one of the most important maritime fishing areas in Tunisia.

The area is a high spot for marine biodiversity of regional importance. It constitutes a preferential habitat for several emblematic vertebrates: a wintering and feeding area for the Loggerhead Sea Turtle (Caretta caretta) [17], a nursery for several species of elasmobranchs, some of which are threatened [9, 10, 11, 12], and a favorable area to several fish such as the groupers and tunas. Cetaceans, especially bottlenose dolphin (Tursiops truncatus) and the fin whale (Balaenoptera physalus), are regularly encountered [18, 19].

Advertisement

3. Elasmobranchs landing

In Tunisia, the elasmobranchs species are caught as bycatch. Nevertheless, some species such as the sandbar shark and the smooth hound are targeted by a small artisanal fishery in the southern coast of the country during the summer [20]. This fishery uses a specific gill nets locally called “Garracia” and “Gattatia”.

Elasmobranchs represent an average of 2% of the national landing [21]. According to FAO Statistic, a mean of 2370 tons’ year is landed during the last 20 years (2000–2020). The production shows an increasing trend, although some exceptional decrease is noted during 2012 and 2017 (Figure 2).

Figure 2.

Tunisian elasmobranchs production according to FAO statistics from 2000 to 2020.

The Gulf of Gabès region (GSA 14) is known to be the most important area for sharks and rays in Tunisia, contributing by more than 60% in the landing of elasmobranchs [10]. However, during the last years, the statistics data provided by the General Directorate for Fisheries and Aquaculture (GDFA) between 2008 and 2020 show an increase in landing of elasmobranch of the Eastern region (GSA 13) (Figure 3). This area contributed in 2020 by more than 49% in the Elasmobranchs national production.

Figure 3.

Tunisian elasmobranchs production by GSA according to GDFA statistics from 2008 to 2020.

Along the Tunisian costs, elasmobranchs are landed mainly by small-scale vessel using gillnets, trammel nets, and longlines followed by bottom trawl (Figure 4).

Figure 4.

Tunisian elasmobranchs production by fishing gear according to GDFA statistics from 2008 to 2020.

Advertisement

4. Diversity and status

The list of elasmobranchs species occurring in Tunisian waters is established mainly by the authors and bibliographic analysis over the last 20 years. Species are classified according to four categories: very common, common, rare, and very rare. The analysis of data shows the occurrence of 63 elasmobranchs species in the area: 37 sharks belonging to 17 families and 26 batoids belonging to eight families (Table 1). This number reflected the specific richness on species in the area (71.6% of species signaled in the Mediterranean Sea).

GFCM Sub areaIUCN Status
SpeciesGSA 12GSA 13GSA 14
Hexanchiformes
Hexanchidae
Heptranchias perlo (Bonnaterre, 1788)RRRDD **
Hexanchus griseus (Bonnaterre, 1788)RCRLC
Lamniformes
Lamnidae
Carcharodon carcharias (Linnaeus, 1758)RRRCR *
Isurus oxyrinchus Rafinesque, 1810CCCCR *
Odontaspididae
Odontaspis ferox (Risso, 1810)TRCR *
Carcharias taurus Rafinesque, 1810TRCR *
Alopiidae
Alopias vulpinus (Bonnaterre, 1788)RRREN **
Alopias superciliosus Lowe, 1841VREN
Cetorhinidae
Cetorhinus maximus (Gunnerus, 1765)VRVRVREN **
Carcharhiniformes
Pentanchidae
Galeus melastomus Rafinesque, 1810CCRLC
Scyliorhinidae
Scyliorhinus canicula (Linnaeus, 1758)VCVCCLC
Scyliorhinus stellaris (Linnaeus, 1758)RRVRNT
Triakidae
Mustelus asterias Cloquet, 1821RRRVU **
Mustelus mustelus (Linnaeus, 1758)VCVCVCVU **
Mustelus punctulatus Risso, 1827CCCVU **
Galeorhinus galeus (Linnaeus, 1758)RRRVU *
Carcharhinidae
Carcharhinus plumbeus (Nardo, 1827)RCVCEN **
Carcharhinus brevipinna (Müller & Henle, 1839)RRCNA
Carcharhinus melanopterus (Quoy & Gaimard, 1824)VRNA
Rhizoprionodon acutus (Rüppell, 1837)VRNA
Carcharhinus falciformis (Bibron, 1839)VRNE
Carcharhinus limbatus (Valenciennes, 1839)VRDD
Carcharhinus obscurus (Le Sueur, 1818)VRDD
Prionace glauca (Linnaeus, 1758)CCRCR **
Sphyrnidae
Sphyrna zygaena (Linnaeus, 1758)VRVRCR
Squaliformes
Squalidae
Squalus acanthias LinnaeusEN
Squalus blainville (Risso, 1827)VCVCCDD
Squalus megalops (Macleay, 1881)RRCDD
Somniosidae
Somnosus rostratus (Risso, 1827)VRDD
Dalatiidae
Dalatias licha (Bonnaterre, 1788)VRVRVU
Etmopteridae
Etmopterus spinax (Linnaeus, 1758)RVRLC
Oxynotidae
Oxynotus centrina (Linnaeus, 1758)CCRCR *
Centrophoridae
Centrophorus cf. uyato (Rafinesque, 1810)RRVRNE **
Squatiniformes
Squatinidae
Squatina aculeata Cuvier, 1829RRRCR *
Squatina oculata Bonaparte, 1840RRRCR *
Squatina squatina (Linnaeus, 1758)RRRCR *
Rajiformes
Torpedinidae
Torpedo nobiliana Bonaparte, 1835RRLC
Torpedo marmorata Risso, 1810CCCLC
Torpedo torpedo (Linnaeus, 1758)VCVCVCLC
Rhinobatidae
Glaucostegu cemiculus Geoffroy St. Hilaire, 1817RCVCEN *
Rhinobatos rhinobatos (Linnaeus, 1758)RCVCEN *
Rajidae
Dipturus oxyrinchus (Linnaeus, 1758)CCRNT
Rostraraja alba Lacépède, 1803RRREN *
Leucoraja circularis (Couch, 1838)VRCR *
Leucoraja melitensis Clark, 1926RRRCR *
Raja asterias Delaroche, 1809VRNT
Raja clavata Linnaeus, 1758VCVCVCNT
Raja miraletus Linnaeus, 1758CCCLC
Raja montagui Fowler, 1910VRLC
Raja radula Delaroche, 1809VCVCCEN
Raja polystigma Regan, 1923RRLC
Raja brachyura Lafont, 1873VRVRNT
Dasyatidae
Dasyatis centroura (Mitchill, 1815)RRRVU
Dasyatis marmorata (Steindachner, 1892)VRVRCDD
Dasyatis pastinaca (Linnaeus, 1758)CCVCVU
Dasyatis tortonesei Capapé, 1975CCVCNA
Pteroplatytrygon violacea (Bonaparte, 1832)CCRLC
Taeniura grabatus (Geoffroy St. Hilaire, 1817CCCDD
Gymnuridae
Gymnura altavela (Linnaeus, 1758)RRCCR *
Myliobatidae
Myliobatis aquila (Linnaeus, 1758)RRRVU
Aetobatidae
Aetomylaeus bovinus (Geoffroy St. Hilaire, 1817CCVCCR
Mobulidae
Mobula mobular (Bonnaterre, 1788)RCREN *
Not observed
Very Rare: Species observed accidentally in the region. Cited no more than three times in the literature.
Rare: Species observed in the region but in a restricted group or in isolated specimens.
Common: Species captured in more or less abundant quantities in at least one sector of the region and during a period of the year.
Very common: Species caught very frequently throughout the region throughout the year
*Species listed in the annex II of the SPA/BD Protocol to the Barcelona Convention
**Species listed in the annex III of the SPA/BD Protocol to the Barcelona Convention

Table 1.

Diversity and status of elasmobranchs species occurring in Tunisian water during the last 20 years.

Four species cited in the literature are not considered in this list because their record seems to be doubtful or not observed during the study period: the cuckoo ray (Leucoraja naevus), the African ray (Raja Africana), the spiny dogfish (Squalus acanthias), and the porbeagle (Lamna nasus). However, three species were observed for the first time in the area during the study period: the shortnose spurdog (Squalus megalops) [22], the little sleeper shark (Somniosus rostratus) [23], and the bigeye thresher (Alopias superciliosus) [24].

The spinetail devil rays (Mobula japonica) signaled in the area in 2015 [25] are not considered in this list because it was assessed by many authors as a junior synonym of the devil fish (Mobula moblar) [26, 27]. No proofs to support the hypothesis of two different species were demonstrated.

Among elasmobranchs species occurring in Tunisian coast, only three species were very common in all sub-area; species caught very frequently throughout the region along the year; the smooth hound (Mustelus mustelus), the common torpedo (Torpedo torpedo), and the thornback ray (Raja clavata). Five species were common; species captured in more or less abundant quantities in at least one sector of the region and during a period of the year; the shortfin mako (Isurus oxyrinchus), the marbled electric ray (Torpedo marmorata), the brown ray (Raja miraletus), the round stingra (Taeniura grabatus) and the blackspotted smooth-hound (Mustelus punctulatus).

The southern waters of Tunisia were characterized by the presence of costal species: the blackchin guitarfish (Glaucostegus cemiculus), the common guitarfish (Rhinobatos rhinobatos), and the spiny butterfly ray (Gymnura altavela), whereas deep species were found mainly in northern zone: the Velvet belly (Etmopterus spinax), the kitefin shark (Dalatias licha), and the little gulper shark (Centrophorus cf. uyato).

The number of species recorded in each GSA are almost comparable: 51 species in GSA 12 and 14 and 52 in GSA 13.

According to IUCN red list, more than 52% of elasmobranch species observed in Tunisian waters were threatened (Critically endangered, endangered, and threatened). Thirteen species were data deficient, not evaluated, or not applicable (Figures 5 and 6).

Figure 5.

Species status according to IUCN red list classification.

Figure 6.

Some vulnerable species captured accidentally in Tunisia. 1: Isurus oxyrinchus; 2: Gymnura altavela; 3: Alpoias vulpinus; 4: Aetomylaeus bovinus; 5: Raja radula.

Advertisement

5. Available data on elasmobranchs (Bibliographic analysis)

Two hundred and fifty-four references concerning elasmobranch species off Tunisia were published between 1971 and 2022. The temporal distribution of publications indicated that attention on elasmobranch has started in 1970. However, there is a lack of studies in the area during the period from 1980 to 1999. Since 2000, an interest in research on elasmobranchs is noticed in the area (Figure 7), following the emergence of an international concern for the conservation of this group of fish. However, studies concern mainly species of the southern (GSA 14) and northern coasts of the country (GSA 12). Only 10 publications covered the Eastern coast (GSA12) (Figure 8). Some studies concern all Tunisian coasts because of the uses of samples from all the countries without distinction between GSA.

Figure 7.

Temporal distribution of the number of published papers dealing with elasmobranchs in Tunisia.

Figure 8.

Geographic distribution of elasmobranchs paper in Tunisia according to GFCM sub-area (1971–2022).

Studies concern essentially biology (sexual maturity size, reproductive cycle, size at birth fecundity, etc.), ecology (diet composition, frequency of prey, etc.), and growth (Von Bertalanffy growth parameters, age at maturity, , etc.). Recently, an attention to the impact of fishery, bycatch, and systematic were observed [11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 28, 29, 30] (Figure 9).

Figure 9.

Distribution of elasmobranchs paper by topic in Tunisia (1971–2022).

5.1 Available data on reproduction

Elasmobranchs are a vulnerable group because of their life histories including the late maturity, the low fecundity, and a long reproductive cycle [31]. Reproductive parameters are crucial to develop conservation strategies and management plan. In Tunisia, data on reproductive parameters are available for 39 species (Table 2). However, recent data concern only 16 species. Among them, six species are listed in annex II and III of the of the SPA/BD Protocol to the Barcelona Convention. Reproductive studies related to GSA 13 are scare. The main reproductive parameters are listed in Table 2.

Scientific nameGSASize at maturity (cm)Gestation (months)FecunditySize at Birth (cm)References
Heptranchias perlo12M:81TL/ F: 85 TL102–18—[32]
Mustelus mustelus12M:108TL /F: 123 TL11–124–2234–42[33]
14M: 97 TL/F:118 TL11–124–1830–40[8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38]
Mustelus punctulatus12M: 87 TL /F: 100 TL125–3040–43[39]
14M: 81 TL/F: 95 TL1212–2740–43[8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40]
Mustelus asterias12M: 75 TL/F: 96 TL1210–3528–32[41]
Galeorhinus galeusTNM: 126 TL/ F:140 TL8–368–3024–32[42]
Carcharhinus brevipinnaTNM: 172TL/ F: 176TL13–146–1061–69[43]
Carcharhinus limbatusTNM: 167TL/ F: 178 TL126–861–65[44]
Carcharhinus plumbeus14M: 160TL /F: 172 TL12–14750–65[7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45]
Oxynotus centrina12M: 60 TL/F: 65 TL1210–1521–24[46]
Squalus blainvillei12M: 55TL/F: 60 TL122–620–23[47]
14M: 52 TL/F: 62 TL121–623–24[48]
Squalus megalops14M: 44 TL/F: 56 TL121–618–23[49]
Etmopterus spinax12M: 28 TL/F: 34 TL—5–189–11[50]
Squatina aculeata12M:120 TL/ F:137 TL128–1230–35[51]
Squatina oculata12M: 70 TL/F: 90 TL—5–8—[52]
Squatina squatina12M: 80TL/F: 128 TL—7–18—[52]
Rhinobatos rhinobatos14M:75 TL/ F: 887 TL84–1231[53, 54]
Glaucostegus cemiculus14M:112 TL/F:138 TL84–1239[54, 55]
Dasyatis centrouraTNM: 80/F: 100DW—2 to 6—[56]
Dasyatis pastinaca12M: 32DW/F:38DW43 to 612[57]
14M:33 DW/F:40DW121011–13[58]
Dasyatis tortonesei12M:30 DW/F:32DW43 to 8—[59]
14M:38DW/F:46DW123 to 1015.7[60]
Dasyatis marmorata14M:30 DW/F:32DW3 to 42–411.8[61]
Pteroplatytrygon violaceaTNM: 42DW/F:45DW4 to 52–7—[62]
Torpedo nobiliana12M: 55 TL/F: 90 TL12—17–22[63]
Torpedo torpedo12M: 19 TL/F: 19 TL41–98–9[64]
14M: 23 TL/F: 23 TL67.15—[65]
Torpedo marmorata12M: 26 TL/F: 40 TL362–17—[66]
14M:27.5 TL/F: 34 TL—8—[54]
Aetomylaeus bovinus12M:80 DW/F:90DW82–6—[67]
Myliobatis aquila12M:50 DW/F:70DW128–1221–29[68]
Gymnura altavela12M:78DW/F:108DW96–829[56]
Scyliorhinus canicula12M: 40 TL/F: 35 TL—38–190—[69]
13M: 35 TL/F: 35 TL——[70]
Scyliorhinus stellaris12M: 77 TL/F: 82 TL—77–109—[71]
Galeus melastomus12M: 36TL/F: 49 TL—15–29—[72]
Raja alba12M:91DW/ F:98 DW———[73]
14M:94DW/ F: 95DW—6–16—[74]
Raja asterias12M: 51TL/F: 56 TL——[75]
Raja miraletus12M: 54 TL/F: 57 TL———[76]
14M: 34TL/F: 41 TL—12–60—[77]
Raja melitensis12M: 40/F: 40—10–56—[78]
Raja radula12M: 68 TL/F: 71 TL——[79]
14M: 47TL/F: 57 TL—120—[80]
Raja clavata12M: 75 TL/F: 85 TL—108–262—[81]
14M: 65 TL/F: 79 TL—36–144—[82]
Raja polystigma12M: 53/F: 63——[83]

Table 2.

Reproductive parameters of elasmobranch species in Tunisia. TL: Total length, disk width.

5.2 Available data on age and growth

The age and growth parameters of a population are very important for conservation and management plans [34]. The parameters are used for the determination of natural mortality and longevity and, ultimately for the calculation of vital rates in demographic models [35].

For age determination of elasmobranchs in Tunisia, vertebral sections and dorsal spines are used (Figure 10). These structures tend to accumulate calcified growth material as they age, thus producing concentric areas that often have characteristics reflecting the time of year in which this material is being deposited [36].

Figure 10.

A thin-section of a longnose spurdog spine and a blackchin guitarfish vertebra from the Gabes Gulf (GSA 14).

The age and growth studies in Tunisia are recent. They concern the south coast of the country (GSA 14). Age and growth data presented in this section include parameters of the Von Bertalanffy growth model (VBGM) (von Bertalanffy 1938) of eight species: three viviparous species and five oviparous species (Table 3).

SpeciesGSAsSexVBGM parameterstmaxAmatReferences
L∞ (cm)Kt0
Squalus blainvillei14M91.10.14−1.42154.97[84]
F105.70.11−1.12197.44
Squalus megalops14M68.550.08−4.65268.39[85]
F82.310.06−3.892915.38
Rostroaja alba14M177.60.06−1.283219.69[74]
F199.60.04−1.473523.47
Raja radula14M76.350.22−0.1693.39[80]
F97.940.14−0.35125.52
Glaucostegus cemiculus14M181.60.272−0.71102.89[55]
F2000.202−0.81145.09
Raja clavata14M100.80.14−1.13125.3[82]
F114.60.11−1.23157
Raja miraletus14M670.22−1.0172.7[77]
F69.20.18−0.1194.41
Dipturus oxyrinchus14M102.10.12−1.182211.95[86]
F123.90.08−1.262513.96

Table 3

Von Bertalanffy growth model (VBGM) parameters: L∞: cm (TL), k: (year-1), t0 (years); tmax: oldest fish (years), Amat: age at maturity (years).

5.3 Available data on food and feeding habits

Studies of feeding habits are essential to understand the functional role of fish in the ecosystem. Data on feeding can provide information on species distribution and its position in food webs.

Sharks are considered top predators and have an important role in the marine ecosystems. Information about the food habits is essential to appreciate the species biology and ecology, since the quality and quantity of food directly affect species maturation and growth.

In Tunisia, available data on food and feeding habits concern 24 species. Among them 16 species were subject of recent studies mainly in Gabes Gulf (GSA 14). Information on diet composition are summarized in Table 4.

SpeciesGSAsFrequency of PreyReferences
FishCrMolChonAn
Heptranchias perlo12xxxxxxx[37]
Squalus blainvillei14xxxxxxx*[87]
Centrophorus granulosus12xxxxx[88]
Galeus melastomus12xxxxx**[89]
Carcharhinus plumbeus14xxxxxxx*[90]
Mustelus mustelus14xxxxxx*[91]
Mustelus punctulatus12/14xxxxxx*[40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92]
Scyliorhinus canicula12/13xxxxxx*[93, 94]
Scyliorhinus stellaris12xxxxxx*[95]
Rhinobatos rhinobatos14xxxxxxx*[96, 97]
Glaucostegus cemiculus14xxxxxxx*[96, 97]
Dasyatis pastinaca12/14xxxxxxx[60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98]
Dasyatis tortonesei12/14xxxxx*[60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99]
Dasyatis marmorata14xxxxxx[100]
Torpedo torpedo12/14xxxx—*[54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101]
Pteromylaeus bovinus14xxxxxxx*[102]
Myliobatis aquila12——xxx*[103]
Raja alba12/14xxxxxx[104, 105]
Raja asterias12xxxxxx*[106]
Raja miraletus12/14xxxxx*[107, 108]
Raja melitensis12xxx[109]
Raja radula12/14xxxxx*[107, 108, 109, 110]
Raja clavata12/14xxxxxx**[111, 112]
Raja polystigma12xxxxxxx[113]

Table 4.

Diet composition of elasmobranch species from Tunisia.

xxx: Main preys, xx: Secondary preys, x: Accessory preys, *: Accidental preys, fish: Teleost fishes, chon: Chondrichtyens, Mol: Mollusks, an: Annelids, Cr: Crustaceans, other: Other invertebrates.

5.4 Available data on fishery and by catch

The studies on fisheries and bycatch of elasmobranchs in Tunisia are recent. The first study back to 2003 [113] (Figure 11). The low economic value of this group's products compared to bony fishes, crustacean, and mollusk has resulted in a lower priority for research and conservation of these species in Tunisia. It is to highlight that some other projects studying bycatch are currently in execution in Tunisia as the “Medbycatch” project.

Figure 11.

Temporal distribution of published papers dealing with fishery and bycatch of elasmobranchs in Tunisian coast.

In Tunisia, elasmobranchs are caught accidentally by all fishing gear (trawl, trammel net, longline, purse senne, etc.) and as a targeted species during the summer by a specific gill nets in the southern coast (GSA 14).

5.4.1 Bycatch of elasmobranchs by longline

In the frame of ACCOBAMS-GFCM Project on mitigating interactions between endangered marine species and longline fishery in Zarzis (GSA 14), developed with the collaboration of the RAC/SPA and a substantial financial support from the MAVA foundation, results show that 46% of the production of the bottom longline targeting groupers are elasmobranchs. Eight sharks and nine batoids are caught by bottom longline. Among elasmobranchs species captured the blackchin guitarfish (Glaucostegus cemiculus), the hound sharks (Mustelus spp.), the Shortnose spurdog (S. megalops), the sandbar shark (C. plumbeus) and the stingray (Dasyatis spp.) were the most caught [114, 115] (Figure 12).

Figure 12.

Elasmobranchs catch rates in the bottom longline in Zarzis zone.

Elasmobranchs represent more than 90% of the capture of pelagic longline in the southern coast of Tunisia. Nine elasmobranch species were captured by this gear (Sandbar shark, spinner shark, shortfin mako shark, smooth hound, pelagic stingray, blackchin guitarfish, bull rays, round stingray, and thornback ray). The captures were dominated by the sandbar shark accounting about 82.5% of capture [11, 114, 115] (Figure 13).

Figure 13.

Catch composition of pelagic longline in Zarzis zone [33].

5.4.2 Bycatch of elasmobranchs by trammel nets

Landing monitoring of boat using shrimp’s trammel nets in Sfax port during May, June, and July 2009 shows that seven species elasmobranchs (M. mustelus, Mustelus punctulatus, Dasyatis pastinaca, Dasyatis marmorata, T. torpedo, C. plumbeus, and Carcharhinus brevipinna) were caught as by-catch in GSA 14. Elasmobranch by-catch was dominated by sharks (90.3%). The smoothhound sharks Mustelus spp. being by far the most important (88.9%) and reflecting their abundance in the area; 58% of the sets caught at least one specimen. Captures were composed essentially of neonate and juvenile sharks, while the batoids were dominated by mature individuals [28].

5.4.3 Bycatch of elasmobranchs by trawl

Monitoring of trawler fishery in the Gulf of Gabes during 2009 shows that Elasmobranchs are commonly caught as by-catch by bottom trawlers in the Gulf of Gabes (GSA 14). A total of 31 elasmobranch species was recorded in trawl captures, among them 14 sharks and 17 batoides representing 64.58% of elasmobranch species observed in the area. Elasmobranch bycatch averaged 5.42% of the total landing (1.7% sharks and 3.7% batoides). The CPUE was estimated at 0.8 Kg/haul for all elasmobranchs. Sharks represented 0.27 Kg/haul and batoides constituted 0.54 Kg/haul. Specimens caught were mainly juveniles [116].

5.4.4 Bycatch of elasmobranchs by purse seine

The purse seine caught a very low proportion elasmobranch especially pelagic sharks and rays. Mobula mobular, I. oxyrinchus, and Alopias vulpinus were the most reported species [117, 118].

5.4.5 Specific fishery

From March to August and between Jerba Island and Zarzis (Southern Tunisia, GSA14) adults of the blackchin guitarfish, the smouth-hound shark, and the sandbar shark are targeted by a little flotilla of small-scale vessel using specific gillnets called locally “Gattatia” and “Garracia”; “Gattatia” for smouth-hound sharks and “Garracia” for Blackchin guitarfish and sandbar shark. Gillnets are in polyamide monofilament netting with a stretched mesh size of 120–160 mm for the first one and 300–400 mm for the second gillnet type. These nets are used at 5–30 m depth. Size composition of captures varied by species, but usually mature, mainly gravid females were abundant [20] (Figure 14).

Figure 14.

Length-frequencies distribution of elasmobranch species caught by gillnet [20].

Advertisement

6. Critical area

Elasmobranch nurseries are areas characterized by the presence of neonates, small juveniles, and pregnant females. This area offers a better source of food and protection against predation; overall, they are located in coastal, shallow, and highly productive waters. At least four elasmobranch species were perceived use the coastal water of the southern coast of Tunisia (GSA 14) as nursery (Figure 15). C. plumbeus, M. mustelus, R. rhinobatos, and Rhinobatos cemiculus use the area as a year-round primary and secondary nursery, with juveniles remaining in it up to the size at maturity [7, 8, 9].

Figure 15.

Nursey area of some elasmobranchs in Gabes Gulf.

Advertisement

7. Regulations for the protection of elasmobranchs in Tunisia

Tunisia ratified many international conventions dealing with cartilaginous fishes and biodiversity in general (Table 5) and adopted the GFCM recommendations on the management and conservation of sharks and rays in the GFCM area of application (Rec. GFCM/36/2012/3; Rec. GFCM/42/2018/2).

ConventionAdoptionRatificationLoi n.°
CITES1973197474–12 du 11/05/74
Barcelone1976197777–29 du 25/05/77
CMS1979198686–63 du 16/07/86
Berne1979199595–75 du 07/08/95
CBD1992199393–45 du 29 /12/ 1994

Table 5.

International conventions ratified by Tunisia.

The protection of elasmobranchs species is ensured at the national level by the decree n° 94–13 on July 31, 1994 and the decree of September 28, 1995 of the Minister of Agriculture regulating the practice of fishing activities. The former one is currently being amended to mainly consider the conventions ratified by Tunisia and the recommendations of the CGPM.

Advertisement

8. Recommendations

Sharks and rays occupy a high level in the trophic webs and are characterized by a K-strategy. This determines a high sensibility to fishing pressure. To conserve the biodiversity of this emblematic groups, many actions should be ensured in Tunisia and in the Mediterranean as many species are migratory.

To overcome this situation, it is necessary to improve data collection at sea and at land for a global map of species distribution and for effective landing statistics in all Tunisian coast; statistic data must be done by species or at least by group of species. For this, it is necessary to focus on species identification trainings and to develop studies on systematic, launched a monitoring to delimit critical area for elasmobranchs in the area and to determine the discard quantity of elasmobranchs by different fishing gear. Experimentation of mitigation measures must be enlarged.

Developing of stock assessment studies; some knowledge on biologic parameters is now available and on fishery; at regional levels because of the urgent need for protection of these groups. Likewise, undertake studies on migration and exchange between populations by satellite tracking.

Advertisement

9. Conclusions

Elasmobranchs represent an average of 2% of the Tunisian national fish production. According to FAO statistics, a mean of 2370 tons per year is landed during the last 20 years. They are landed mainly by small-scale vessels using gillnets, trammel nets, and longlines followed by trawling.

Two hundred and fifty-four references, dealing with elasmobranchs in Tunisia, were analyzed in this chapter.

This analysis shows that 63 elasmobranchs occurred in the area during the last 20 years: 37 sharks belonging to 17 families and 26 batoids belonging to eight families. Three species were observed for the first time in the area during the considered period: S. megalops, S. rostratus, and A. superciliosus. The southern waters of Tunisia were characterized by the presence of costal species, whereas deep species were found mainly in northern zone. More than 52% of elasmobranchs species observed in Tunisian water were criterial endangered, endangered, or threatened. The Gabes Gulf represents an important area for elasmobranchs, four species use the coastal water of the area as a nursery.

In Tunisia, information on reproduction is available for 40 species. However, recent data concern 16 species. Studies on age and growth concerned only species from the south coast of the country (GSA 14). Von Bertalanffy parameters are available for eight species. Concerning food habits, recent data concern 16 species. Therefore, it is urgent to initiate the study of the age and growth of other species.

Bycatch has become one of the issues to be considered in any development of fisheries. Elasmobranchs which are considered mainly as bycatch are very sensitive given their particular biological characteristics. In Tunisia, trammel nets and trawl in the area cause the capture of juveniles while specific gillnets engender the capture of adults and mainly pregnant females.

References

  1. 1. Serena F, Abella AJ, Bargnesi F, Barone M, Colloca F, Ferretti F, et al. Species diversity, taxonomy and distribution of Chondrichthyes in the Mediterranean and Black Sea. The European Zoological Journal. 2020;47(1):497-536. DOI: 10.1080/24750263.2020.1805518
  2. 2. Dulvy NK, Allen DJ, Ralph GM, Walls RHL. The conservation status of Sharks, Rays and Chimaeras in the Mediterranean Sea [Brochure]. Spain: IUCN; 2016
  3. 3. Ferretti F, Myers RA, Serena F, Lotze HK. Loss of large predatory sharks from the Mediterranean Sea. Conservation Biology. 2008;22:952-964
  4. 4. Musick JA, Burgess G, Cailliet G, Camhi M, Fordham S. Management of sharks and their relatives (Elasmobranchii). Fisheries. 2000;25:9-13
  5. 5. Bradai MN, Quignard JP, Bouaïn A, Jarbouï O, et al. Ichtyofaune autochtone et exotique des côtes tunisiennes : recensement et biogéographie. Cybium. 2004;28:315-328
  6. 6. Bradai MN, Saidi B, Enajjar S. Elasmobranchs of the Mediterranean and Black Sea: Status, ecology and biology. In: Bibliographic Analysis. Studies and Reviews. Rome: FAO; 2012. p. 91
  7. 7. Bradaï MN, Saidi B, Bouaïn A, Guelorget O, Capapé C. The Gulf of Gabès (Southern Tunisia, Central Mediterranean): A nursery area for sandbar shark, Carcharhinus plumbeus (Nardo, 1827) (Chondrichthyes: Carcharhinidae). Annales Series Historia Naturalis. 2005;15:187-194
  8. 8. Saidi B. Les requins du golfe de Gabès: Diversité et éco-biologie de trois espèces à importance économique Carcharhinus plumbeus, Mustelus mustelus & M. punctulatus [thesis]. Sfax: Sfax University; 2008
  9. 9. Enajjar S, Saidi B, Bradai MN. The Gulf of Gabès (Central Mediterranean Sea): A nursery area for sharks and batoids (Chondrichthyes: Elasmobranchii). Cahiers de Biologie Marine. 2015;56:143-150
  10. 10. Bradaï MN, Saidi B, Enajjar S, Bouaïn A. The Gulf of Gabès: A spot for the Mediterranean elasmobranchs. In: Başusta N, Keskin Ç, Serena F, Seret B, editors. The Proceedings of the International Workshop on Mediterranean Cartilaginous Fish with Emphasis on Southern and Eastern Mediterranean, Istanbul, 2005. Turkey: Turkish Marine Research Foundation; 2006. pp. 107-117
  11. 11. Saidi B, Enajjar S, Karaa S, Echwikhi K, Jribi I, Bradai MN. Shark pelagic longline fishery in the Gulf of Gabes: Inter-decadal inspection reveals management needs. Mediterranean Marine Science. 2019;20(3):532-541
  12. 12. Bradai MN, Saidi B, Enajjar S. Overview on Mediterranean shark’s fisheries: Impact on the biodiversity. In: Türkoğlu M, Önal U, Ismen A, editors. Marine Ecology Biotic and Abiotic Interactions. London, UK: INTECH; 2018. pp. 211-230
  13. 13. Apal. Vers une Gestion Intégrée du Littoral Tunisien. Ministère de l’Environnement et du Développement Durable Agence de Protection et d’Aménagement du Littoral; 2015
  14. 14. Azouz A, Ben OS. Les fonds chalutables de la région Est de la Tunisie (de Kélibia à Mahdia). Bulletin de l'Institut National Scientifique et Technique d'Océanographie et de pêche de Salammbo. 1975;4:49-59
  15. 15. Zaara C. Etude de la stabilité du littoral du Golfe de Hammamet, impact de la dynamique sédimentaire sur la morphologie côtière. Tunis Faculty of Science; 1995
  16. 16. Bradai MN, Ghobel M, Bouain A. Aperçu sur l’activité de pêche dans le gouvernorat de Sfax. Cahier de CERES Série géographique. 1995;1:211-236
  17. 17. Bradai MN, Bentivegna F, Jribi I, El Ouaer A, Maatoug K, El Abed A. Monitoring of a loggerhead sea turtle, Caretta caretta. In: Second Mediterranean Conference on Marine Turtles. 2009. p. 54
  18. 18. Bradai MN. Diversité du peuplement ichtyque et contribution à la connaissance des Sparidés du golfe de Gabès [Thesis]. Sfax: Sfax University; 2000
  19. 19. Karaa S, Bradai MN, Jribi I, Attia El Hili H, Bouain A. Status of cetaceans in Tunisia through analysis of stranding data from 1937 to 2009. Mammalia. 2012;76:21-29. DOI: 10.1515/MAMM.2011.100
  20. 20. Echwikhi K, Saidi B, Bradai MN, Bouain A. Preliminary data on elasmobranch gillnet fishery in the Gulf of Gabes, Tunisia. Journal of Applied Ichthyology. 2013;29:1080-1085. DOI: DOI: 10.1111/jai.12022
  21. 21. DGAP. Yearbook of fisheries statistics in Tunisia. 2020.
  22. 22. Marouani S, Chaâba R, Kadri H, Saidi B, Bouain A, Maltagliati F, et al. Taxonomic research on Squalus megalops (Macleay, 1881) and Squalus blainvillei (Risso, 1827) (Chondrichthyes: Squalidae) in Tunisian waters (Central Mediterranean Sea). Scientia Marina. 2012;76(1):97-109
  23. 23. Capapé C, Rafrafi-Nouira S, Diatta Y, Reynaud C. First record of little sleeper shark, Somniosus rostratus (Elasmobranchii: Squaliformes: Somniosidae), from the Tunisian coast, Central Mediterranean Sea. Acta Ichthyologica et Piscatoria. 2020;50(4):475-480. DOI: 10.3750/AIEP/02998
  24. 24. Bouzidi I, Enajjar S, Saidi B, Bradai MN. First record of the bigeye thresher shark Alopias superciliosus Lowe. In: (Elasmobranchii: Alopiidae) in Tunisian Water (Central Mediterranean Sea). 1841
  25. 25. Capapé C, Rafrafi-Nouira S, El Kamel-Moutalibi O, Boumaïza M, Reynaud C. First mediterranean records of Spinetail Devil Ray, Mobula japanica (Elasmobranchii: Rajiformes: Mobulidae). Acta Ichthyologica et Piscatoria. 2015;45(2):211-215. DOI: 10.3750/aip2015.45.2.13
  26. 26. Poortvliet M, Olsen JL, Croll DA, Bernardi G, Newton K, Kollias S, et al. A dated molecular phylogeny of manta and devil rays (Mobulidae) based on mitogenome and nuclear sequences. Molecular Phylogenetics and Evolution. 2015;83:72-85
  27. 27. White WT, Corrigan S, Yang L, Henderson AC, Bazinet AL, Swofford DL, et al. Phylogeny of the manta and devilrays (Chondrichthyes: Mobulidae), with an updated taxonomic arrangement for the family. Zoological Journal of the Linnean Society. 2017;182(1):50-75. DOI: 10.1093/zoolinnean/zlx018
  28. 28. Saidi B, Enajjar S, Bradai NM. Elasmobranch captures in shrimps trammel net fishery off the Gulf of Gabes (Southern Tunisia, Mediterranean Sea). Journal of Applied Ichthyology. 2016;32:421-426. DOI: 10.1111/jai.13061
  29. 29. Saidi B, Karaa S, Enajjar S, Echwikhi K, Jribi I, Bradai MN. Effects of fishing practice changes on shark pelagic longline captures of the Gulf of Gabes, Tunisia. Aquatic Conservation: Mar Fresh water Ecosystem. 2020;30:53-67. DOI: 10.1002/aqc.3226
  30. 30. Saadaoui A, Saidi B, Elglid A, Séret B, Bradai MN. Taxonomic observations on stingrays of the genus Dasyatis (Chondrichthyes: Dasyatidae) in the Gulf of Gabès (Southeastern Mediterranean Sea). Zootaxa. 2016;2:101-113. DOI: 10.11646/zootaxa.4173.2.1
  31. 31. Stevens JD, Bonfil R, Dulvy NK, Walker PA. The effects of fishing on sharks, rays and chimaeras (chondrichthyans), and the implications for marine ecosystems. ICES Journal of Marine Science. 2000;57:476-494
  32. 32. Capapé C. Nouvelle description de Heptranchias perlo (Bonnaterre.1788) (Pisces, Pleurotremata, Hexanchidae). Données sur la biologie de la reproduction et le régime alimentaire des spécimens des côtes tunisiennes. Bulletin de l'Office National des Pêches Tunisie. 1980;4(2):231-264
  33. 33. Saidi B, Bradaï MN, Bouaïn A. Reproductive biology of the smooth–hound shark Mustelus mustelus in the Gulf of Gabès (south–Central Mediterranean Sea). Journal of Fish Biology. 2008;72:1343-1354. DOI: 10.1111/j.1095-8649.2008.01801
  34. 34. Cortés E. Life history patterns, demography, and population dynamics. In: Carrier JC, Musick JA, Heithaus MR, editors. Biology of Sharks and their Relatives. CRC Press. 2004. pp. 449-470
  35. 35. Goldman KJ. Age and growth of elasmobranch fishes. In: Musick JA, Bonfil R, editors. Elasmobranch Fisheries Management Techniques. Singapore: Asia Pacific Economic Cooperation; 2004. pp. 97-132
  36. 36. Cailliet GM, Smith WD, Mollet HF, Goldman KJ. Age and growth studies of chondrichthyan fishes: The need for consistency in terminology, verification, validation, and growth function fitting. Environmental Biology of Fishes. 2006;77:211-228. DOI: 10.1007/s10641-006-9105-5
  37. 37. Capapé C. Observations sur la sexualité, la reproduction et la fécondité de 8 sélaciens pleurotrèmes vivipares placentaires des côtes tunisiennes. Archives de l'Institut Pasteur de Tunis. 1974;51:329-344
  38. 38. Capapé C, Quignard JP. Contribution à la biologie des Triakidae des côtes tunisiennes. I. Mustelus mediterraneus Quignard et Capapé, 1972: répartition géographique et bathymétrique, migration et déplacement, reproduction, fécondité. Bulletin de l'Office National des Pêches Tunisie. 1977;1:103-122
  39. 39. Saidi B, Bradaï MN, Bouaïn A. Reproductive biology and diet of Mustelus punctulatus (Risso, 1826) (Chondrichthyes: Triakidae) from the Gulf of Gabès, Central Mediterranean Sea. Scientia Marina. 2009;73(2):249-258. DOI: 10.3989/scimar.2009.73n2249
  40. 40. Capapé C. Nouvelles données sur la biologie de la reproduction de Mustelus asterias Cloquet, 1821 (Pisces, Pleurotremata, Triakidae) des côtes tunisiennes. Vie et Milieu. 1983;33:143-152
  41. 41. Capapé C, Mellinger J. Nouvelles données sur la biologie de la reproduction du milandre, Galeorhinus galeus (Linné, 1758) (Pisces, Triakidae) des côtes tunisiennes. Cahiers de Biologie Marine. 1988;29:135-146
  42. 42. Capapé C, Hemida F, Secka AA, Diatta Y, Guelorget O, Zaouali J. Distribution and reproductive biology of the spinner shark, Carcharhinus brevipinna (Mueller and Henle, 1841) (Chondrichthyes: Carcharhinidae). Israel Journal of Zoology. 2003;49:269-286. DOI: 10.1560/DHHM-A68M-VKQH-CY9F
  43. 43. Capapé C, Seck AA, Diatta Y, Reynaud C, Hemida F, Zaouali J. Reproductive biology of the Blacktip shark, Carcharhinus limbatus (Chondrichthyes: Carcharhinidae) off West and North African coasts. Cybium. 2004;28(4):275-284
  44. 44. Capapé C. Nouvelles données sur la morphologie et la biologie de la reproduction de Carcharhinus plumbeus (Nardo, 1827) (Pisces, Carcharhinidae) des côtes tunisiennes. Investigaciòn Pesquera. 1984;48:115-137
  45. 45. Capapé C, Seck AA, Quignard JP. Observations on the reproductive biology of the angular rough shark, Oxynotus centrina (Oxynotidae). Cybium. 1999;23(3):259-271
  46. 46. Capapé C, Quignard JP. Recherche sur la biologie de Squalus blainvillei (Risso, 1826) (Pisces, Squalidae) des côtes tunisiennes: Relation taille–poids du corps, du foie et des gonades. Coefficients de condition. Rapports hépato et gonosomatique. Croissance embryonnaire. Archives de l'Institut Pasteur de Tunis. 1980;57(4):385-408
  47. 47. Marouani S, Bradai MN, Bouain A. Taille à la maturité sexuelle de Squalus blainvillei (Risso, 1826) du golfe de Gabès (Tunisie). Rapport de la Comité Internationale de la Mer Méditerranée. 2007;38:536
  48. 48. Marouani S, Kadri H, Bouain A, Bradai MN. Premières données sur la biologiede la reproduction de l’aiguillat au nez court Squalus megalops (Macleay, 1881) du Golfe de Gabès (Méditerranée centrale). In: Proceedings of the LRSE International Symposium on Biodiversity and Coastal Ecosystems (BEL03); 26-28 November 2013; Oran (Algerie); Chouikhi A, Boutiba Z, Moouffok S, Boudderbala M, edition; 2013. p. 566- 572
  49. 49. Capapé C, Bradai MN, Seck AA, Diatta Y, Tomasini JA, Quignard JP. Aspects of the reproductive biology of the velvet belly, Etmopterus spinax (Elasmobranchii: Squalidae). Bulletin de l’institut national des sciences et technologies de la mer de Salammbô. 2001;28:55-64
  50. 50. Capapé C, Diatta Y, Seck AA, Guélorget O, Ben Souissi J, Zaouali J. Reproduction of the sawback angelshark Squatina aculeata (Chondrichthyes: Squatinidae) off Senegal and Tunisia. Cybium. 2005;29:147-157
  51. 51. Capapé C, Quignard JP, Mellinger J. Reproduction and development of two angel sharks, Squatina squatina and S. oculata (Pisces: Squatinidæ), off Tunisian coasts: Semi–delayed vitellogenesis, lack of egg capsule and lecithotrophy. Journal of Fish Biology. 1990;37:347-356
  52. 52. Enajjar S, Bradaï MN, Bouaïn A. New data on the reproductive biology of the common guitarfish of the Gulf of Gabès (southern Tunisia, Central Mediterranean). Journal of the Marine Biological Association of the United Kingdom. 2008;88:1063-1068. DOI: 10.1017/S0025315408001550
  53. 53. Enajjar S. Diversité des Rajiformes et étude éco–biologique de Rhinobatos rhinobatos et Glaucostegus cemiculus (Famille des Rhinobatidae) du Golfe de Gabès (Tunisie) [thesis]. Sfax: Sfax University; 2009
  54. 54. Enajjar S, Bradai MN, Bouain A. Age, growth and sexual maturity of the blackchin guitarfish Rhinobatos cemiculus in the Gulf of Gabès (southern Tunisia, Central Mediterranean). Cahiers de Biologie Marine. 2012;53:17-23
  55. 55. Capapé C. Première données sur le cycle de la reproduction de Dasyatis centroura (Mitchill, 1815) et de Gymnura altavela (Linné, 1758) des côtes tunisiennes. Archives de l'Institut Pasteur de Tunis. 1974;51:345-356
  56. 56. Capapé C. Contribution à la biologie des Dasyatidae des côtes tunisiennes. I. Dasyatis pastinaca (Linne, 1758). Réparation géographique et bathymétrique, sexualité, reproduction, fécondité. Annali del Museo Civico di Storia naturale di Genova. 1976;81:22-32
  57. 57. Saadaoui A, Saidi B, Enajjar S, Bradai MN. Reproductive biology of the common stingray Dasyatis pastinaca (Linnaeus, 1758) off the Gulf of Gabès (Central Mediterranean Sea). Cahier de Biologie Marine. 2015;56:389-396
  58. 58. Capapé C. Contribution à la biologie des Dasyatidae des côtes tunisiennes. III. Dasyatis tortonesei Capapé, 1975: Répartition géographique et bathymétrique, sexualité, reproduction, fécondité. Bulletin de l’institut national des sciences et technologies de la mer de Salammbô. 1978;5:97-110
  59. 59. Saadaoui A. Statut Taxonomique, Pêche et Eco-biologie de deux pastenagues: Dasyatis pastinaca et D. cf tortonesei du golfe de Gabès (Tunisie). Thèse de doctorat en Sciences biologiques. [thesis]. Sfax: Sfax University; 2017. p. 192
  60. 60. Capapé C, Zaouali J. Reproductive biology of the marbled stingray, Dasyatis marmorata (Steindachner, 1982) (Pisces: Dasyatidae) in Tunisian waters (Central Mediterranean). Journal of Aquariculture and Aquatic Sciences. 1995;7:108-119
  61. 61. Hemida F, Seridji R, Enajjar S, Bradai MN, Collier E, Guélorget O, et al. New observations on the reproductive biology of the pelagic stingray, Dasyatis violacea (Bonaparte, 1832) (Chondrichthyes: Dasyatidae) from the Mediterranean Sea. Acta Adriatica. 2003;44:193-204
  62. 62. Capapé C. Note préliminaire sur la biologie de Torpedo (Torpedo) marmorata Risso, 1810 et de Topedo (Tetronarce) nobiliana Bonaparte, 1835 des côtes Tunisiennes. Archives de l'Institut Pasteur de Tunis. 1974;51:257-267
  63. 63. Quignard JP, Capapé C. Recherches sur la biologie d’un sélacien du golfe de Tunis, Torpedo torpedo Linné, 1758 (Ecologie, sexualité, reproduction). Bulletin de l’institut national des sciences et technologies de la mer de Salammbô. 1974;3:99-129
  64. 64. Enajjar S, Bradaï MN, Bouaïn A. La reproduction de la torpille ocellée Torpedo (Torpedo) torpedo (Linnaeus, 1758) du Golfe de Gabès. Bulletin de l’institut national des sciences et technologies de la mer de Salammbô. 2002;7:40-43
  65. 65. La CC. torpille marbrée, Torpedo marmorata Risso, 1810 (Pisces, Rajiformes) des côtes tunisiennes: nouvelles données sur l’écologie et la biologie de la reproduction de l’espèce, avec une comparaison entre les populations méditerranéennes et atlantiques. Annales des Sciences Naturelles, Zoologie, Paris. 1979;13(1):79-97
  66. 66. Capapé C, Quignard JP. Contribution à la systématique et à la biologie de Pteromylæus bovinus (Geoffroy Saint–Hilaire, 1817), (Pisces, Myliobatidæ) des côtes tunisiennes. Bulletin du Museum National d’Histoire Naturelle, Paris. 1975;338(3):1329-1347
  67. 67. Capapé C, Quignard JP. Dimorphisme sexuel et observations biologiques sur Myliobatis aquila (L., 1758). Contribution à l'étude du genre Myliobatis, Cuvier, 1817. Annali del Museo Civico di Storia naturale di Genova. 1974;50:1-27
  68. 68. Capapé C, Mnasri-Sioudi N, El Kamel-Moutalibi O, Boumaïza M, Ben Amor MM, Reynaud C. Production, maturity, reproductive cycle and fecundity of small-spotted catshark, Scyliorhinus canicula (Chondrichthyes: Scyliorhinidae) from the northern coast of Tunisia (Central Mediterranean). Journal of Ichthyology. 2014;54(1):111-126. DOI: 10.1134/S0032945214010020
  69. 69. Saidi B, Bradaï MN, Bouaïn A. Taille à la maturité sexuelle de Scyliorhinus canicula des côtes Est et Sud–est de la Tunisie. Rapport de la Comité Internationale de la Mer. Méditerranée. 2004;37:433
  70. 70. Capapé C. Contribution à la connaissance de la biologie des Scyliorhinidae des côtes Tunisiennes. III. Scyliorhinus stellaris (Linné, 1758). Acta Adriatica. 1977;17:1-21
  71. 71. Capapé C, Zaouali J. Contribution à la biologie des Scyliorhinidae des côtes tunisiennes– VI–Galeus melastomus Rafinesque, 1810 – Répartition géographique et bathymétrique, sexualité, reproduction, fécondité. Cahiers de Biologie Marine. 1977;18:449-463
  72. 72. Capapé C. Contribution à la biologie des Rajidæ des côtes tunisiennes. Raja alba Lacépède, 1801: Répartition géographique et bathymétrique, sexualité, reproduction, fécondité. Annexe de l’Institut de Michel Pacha. 1976;9:23-47
  73. 73. Kadri H, Marouani S, Bradai MN, Bouain A, Morize E. Age, growth, mortality, longevity and reproductive biology of the White skate, Rostroraja alba (Chondrichthyes: Rajidae) of the Gulf of Gabès (Southern Tunisia, Central Mediterranean). Turkish Journal of Fisheries and Aquatic Sciences. 2014;14:193-204. DOI: 10.4194/1303-2712-v14_1_21
  74. 74. Capapé C. Contribution à la biologie des Rajidæ des côtes tunisiennes. IV. Raja asterias Delaroche 1809: répartition géographique et bathymétrique, sexualité, reproduction et fécondité. Bulletin du Muséum National d’Histoire Naturelle de Paris. 1977;435:305-326
  75. 75. Capapé C, Quignard JP. Contribution à la biologie des rajidae des côtes tunisiennes. I. Raja miraletus Linné, 1758: répartition géographique et bathymétrique, sexualité, reproduction, fécondité. Archives de l'Institut Pasteur de Tunis. 1974;51:39-60
  76. 76. Kadri H, Marouani S, Saidi B, Bradai MN, Ghorbel M, Bouain A, et al. Age, growth and reproduction of Raja miraletus (Linnaeus, 1758) (Chondrichthyes: Rajidae) of the Gulf of Gabès (Tunisia, Central Mediterranean Sea). Marine Biology Research. 2012;8:309-317. DOI: 10.1080/17451000.2011.619546
  77. 77. Capapé C. Contribution à la biologie des Rajidæ des côtes tunisiennes. VII. Raja melitensis Carck, 1926: sexualité, reproduction, fécondité. Cahiers de Biologie Marine. 1977;18:177-190
  78. 78. Capapé C. Contribution à la biologie des Rajidæ des côtes tunisiennes. II. Raja radula Delaroche 1809: Répartition géographique et bathymétrique, sexualité, reproduction et fécondité. Archives de l'Institut Pasteur de Tunis. 1974;51:211-228
  79. 79. Kadri H, Marouani S, Bradai MN, Bouaïn A. Age, growth and reproductive biology of the rough skate, Raja radula (Chondrichthyes: Rajidae), off the Gulf of Gabès (southern Tunisia, Central Mediterranean). Marine and Freshwater Research. 2013;64(6):540-548. DOI: 10.1071/MF12218
  80. 80. Capapé C. Contribution à la biologie des Rajidæ des côtes tunisiennes. III. Raja clavata Linné, 1758. Répartition géographique et bathymétrique, sexualité, reproduction et fécondité. Bulletin du Muséum National d’Histoire Naturelle, Paris, Zoologie. 1976;393(3):907-922
  81. 81. Kadri H, Marouani S, Saidi B, Bradai MN, Bouain A, Morize E. Age, growth, sexual maturity and reproduction of the thornback ray, Raja clavata (L.), of the Gulf of Gabe’s (south-Central Mediterranean Sea). Marine Biology Research. 2014;10(4):416-425. DOI: 10.1080/17451000.2013.797584
  82. 82. Capapé C, Quignard JP. Contribution à la biologie des rajidae des côtes tunisiennes. 14. Raja polystigma Regan, 1923: répartition géographique et bathymétrique, sexualité, reproduction, fécondité. Cahiers de Biologie Marine. 1978;19:233-244
  83. 83. Marouani S, Kadri H, Bradaï MN, Saidi B, Bouaïn A. Age, growth and age at sexual maturity of the longnose spurdog, Squalus blainvillei, in the Gulf of Gabès (Tunisia). Rapport de la Commission Internationale de la Mer Méditerranée. 2010;39:581
  84. 84. Marouani S, Kadri H, Bradai MN. First data on the age, growth and sexual maturity of the piked spurdog, Squalus megalops (Chondrichthyes: Squalidae), in the Gulf of Gabe’s (Central Mediterranean Sea). Marine and Freshwater Research. 2015;67(5):578-585. DOI: 10.1071/MF14356
  85. 85. Kadri H, Marouani S, Bradai MN, Bouain A, Morize E. Age, growth, longevity, mortality and reproductive biology of Dipturus oxyrinchus, (chondrichthyes: rajidae) off the Gulf of Gabès (southern Tunisia, Central Mediterranean). Journal of the Marine Biological Association of the United Kingdom. 2015;95(3):569-577. DOI: 10.1017/S0025315414000551
  86. 86. Marouani S, Bradaï MN, Saidi B, Bouain A. Contribution à l'étude du régime alimentaire du Squalus blainvillei dans le golfe de Gabès. Bulletin de l’Institut des Sciences et Technologies de la Mer de Salammbô. 2007;11:78-80
  87. 87. Capapé C. Nouvelle description de Centophorus granulosus (Schneider, 1801) (Pisces, Squalidae). Données sur la biologie de la reproduction et le régime alimentaire des spécimens des côtes tunisiennes. Bulletin de l’Institut des Sciences et Technologies de la Mer de Salammbô. 1985;12:97-141
  88. 88. Capapé C, Zaouali J. Contribution à la biologie des Scyliorhinidaedes côtes tunisiennes V. Galeus melastomus Rafinesque, 1810: Régime alimentaire. Archives de l'Institut Pasteur de Tunis. 1976;53:281-291
  89. 89. Saidi B, Bradaï MN, Bouaïn A, Capapé C. Feeding habits of the sandbar shark Carcharhinus plumbeus (Chondrichthyes: Carcharhinidae) from the Gulf of Gabès. Tunisia. Cahiers de Biologie Marine. 2007;48:139-144
  90. 90. Saidi B, Enajjar S, Bradai MN, Bouain A. Diet composition of smooth–hound shark, Mustelus mustelus (Linnaeus, 1758), in the Gulf of Gabès, southern Tunisia. Journal of Applied Ichthyology. 2009;25:113-118. DOI: 10.1111/j.1439-0426.2009.01306.x
  91. 91. Capapé C, Quignard JP. Contribution à la biologie des Triakidae des côtes tunisiennes II. Mustelus mediterraneus Quignard et Capapé, 1972: Régime alimentaire. Bulletin de l’Institut des Sciences et Technologies de la Mer de Salammbô. 1977;1:173-179
  92. 92. Capapé C. Contribution à la biologie des Scyliorhinidae des côtes tunisiennes II. Scyliorhinus canicula Linné, 1758: Régime alimentaire. Annales, Institut Michel Pacha. 1974;7:13-26
  93. 93. Saidi B, Bradaï MN, Bouaïn A. Régime alimentaire de la petite roussette Scyliorhinus canicula des côtes est et sud–est de la Tunisie. Bulletin de l’Institut National des Sciences et Technologies de la Mer. 2002;7:17-20
  94. 94. Capapé C. Contribution à la biologie des Scyliorhinidae des côtes tunisiennes. IV. Scyliorhinus stellaris (Linné, 1758). Régime alimentaire. Archives de l'Institut Pasteur de Tunis. 1975;52:383-394
  95. 95. Capapé C, Zaouali J. Etude du régime alimentaire de deux Sélaciens commune dans le golfe de Gabès (Tunisie) : Rhinobatos rhinobatos (linnaeus, 1758) et Rhinobatos cemiculus Geoffory Saint–Hilaire, 1817. Archives de l'Institut Pasteur de Tunis. 1979;56:285-306
  96. 96. Enajjar S, Bradaï MN, Bouaïn A. Feeding habits of Rhinobatos rhinobatos in the Gulf of Gabès. Rapport de la Commité International de la Mer Méditerrannée. 2007;38:468
  97. 97. Capapé C. Contribution à la biologie des Dasyatidae des côtes Tunisiennes. II. Dasyatis pastinaca (Linne, 1758). Régime alimentaire. Institut Michel Pacha. 1975;8:1-5
  98. 98. Capapé C. Contribution à la biologie des Dasyatidae des côtes tunisiennes. IV. Dasyatis tortonesei Capapé, 1975: Régime alimentaire. Archives de l'Institut Pasteur de Tunis. 1978;55:359-369
  99. 99. Capapé C, Zaouali J. Le régime alimentaire de la pastenague marbrée, Dasyatis marmorata (Pisces, Dasyatidae), des eaux Tunisiennes. Vie et Millieu. 1992;42:269-276
  100. 100. El Kamel-Moutalibi O, Mnasri N, Boumaiza M, Reynaud C, Capapé C. Diet of common torpedo Torpedo torpedo (Chondrichthyes: Torpedinidae) from the Lagoon of Bizerte (northeastern Tunisia, Central Mediterranean). Cahiers de Biologie Marine. 2013;54(2):209-220
  101. 101. Capapé C. Etude du régime alimentaire de la Mourine vachette, Pteromylaeus bovinus (Geoffroy Saint–Hilaire, 1817) (Pisces, Myliobatidae) des côtes tunisiennes. Journal du Conseil International pour l'Exploration de la Mer. 1977;37(3):214-220
  102. 102. Capapé C. Étude du régime alimentaire de l’aigle de mer, Myliobatis aquila (L., 1758) des côtes tunisiennes. Journal du Conseil International pour l'Exploration de la Mer. 1976;37(1):29-35
  103. 103. Capapé C. Contribution à la biologie des Rajidae des côtes tunisiennes. XII. Raja alba Lacepede, 1803: Regime alimentaire. Archives de l'Institut Pasteur de Tunis. 1977;54(54):85-95
  104. 104. Kadri H, Marouani S, Bouain A, Bradai MN. Régime alimentaire de Rostroraja alba, raie blanche, dans le Golfe de Gabès. Rapport de la Comité Internationale de la Mer Méditerranée. 2013;40:468
  105. 105. Capapé C, Quignard JP. Contribution à la biologie des Rajidae des côtes tunisiennes. 6 – Raja asterias Delaroche, 1809. Régime alimentaire. Bulletin de l’Institut National des Sciences et Technologies de la Mer. 1977;4(2–4):319-332
  106. 106. Capapé C, Azouz A. Etude du régime alimentaire de deux raies communes dans le golfe de Tunis: Raja miraletus Linné, 1758 et R. radula, Delaroche, 1809. Archives de l'Institut Pasteur de Tunis. 1975;52:233-250
  107. 107. Kadri H, Marouani S, Bradai MN, Bouain A. Food habits of the brown ray Raja miraletus (Chondrichthyes: Rajidae) from the Gulf of Gabe’s (Tunisia). Marine Biology Research. 2014;10(4):426-434. DOI: 10.1080/17451000.2013.797583
  108. 108. Capapé C. Contribution à la biologie des Rajidae des côtes tunisiennes. VIII. Raja melitensis Clark, 1926. Régime alimentaire. Archives de l'Institut Pasteur de Tunis. 1975;1(2):40-46
  109. 109. Kadri H, Saidi B, Marouani S, Bradai MN, Bouaïn A. Food habits of the rough ray Raja radula (Chondrichthyes: Rajidae) from the Gulf of Gabès (Central Mediterranean Sea). Italian Journal of Zoology. 2013;80:52-59. DOI: 10.1080/11250003.2012.697925
  110. 110. Capapé C. Contribution à la biologie des Rajidae des côtes tunisiennes. IV. Raja clavata (Linné 1758). Régime alimentaire. Annexe. Institut Michel Pacha. 1975;8:16-32
  111. 111. Kadri H, Marouani S, Saidi B, Bradai MN, Bouain A. Diet and feeding strategy of thornback ray, Raja clavata (Chondrichthyes: Rajidae) from the Gulf of Gabès (Tunisia-Central Mediterranean Sea). Journal of the Marine Biological Association of the United Kingdom. 2014;94(7):1509-1516. DOI: 10.1017/S0025315414000587
  112. 112. Capapé C. Contribution à la biologie des Rajidae des côtes Tunisiennes-Raja polystigma Regan, 1926. Regime alimentaire. Biljeske–Notes, Split. 1979;35:1-10
  113. 113. Saidi B, Bradaï MN, Bouaïn A. La pêche des requins dans la région du golfe de Gabès. Bulletin de l’Institut National des Sciences et Technologies de la Mer. 2003;8:84-87
  114. 114. Bradai MN, Saïdi B, Enajjar S, Karaa S. Pêcheries aux palangres de fond et de surface dans le Golfe de Gabès: Rapport final. MoU ACCOBAMS N°07/2016/LB6410. 2016.
  115. 115. Enajjar S, Saidi B, Karaa S, Chouikhi K, Bradai MN. Vulnerability of elasmobranchs as longline bycatch in the Gulf of Gabès (Southern Tunisia, central Mediterranean Sea). Deuxième Conférence Méditerranéenne «BIODIV » 28 au 30 octobre 2017 (Monastir; TUNISIE). Bulletin de l’Institut National des Sciences et Technologies de la Mer. 2018;45:61-64
  116. 116. Hamdaoui B. Les élasmobranches dans les débarquements des chalutiers au port de pêche de Sfax, golfe de Gabès. [Master]. Sfax: Sfax University; 2009
  117. 117. Bouzidi I. Les élasmobranches (Requins & Raies) dans les pêcheries de Kélibia [Master]. Sfax: Sfax University; 2020
  118. 118. Zammit Chatti M. Les élasmobranches, les tortues marines et les cétacés dans les pêcheries de Teboulba [Master]. Sfax: Sfax University; 2020

Written By

Samira Enajjar, Bechir Saidi and Mohamed Nejmeddine Bradai

Submitted: 30 August 2022 Reviewed: 17 October 2022 Published: 12 November 2022

© 2022 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution 3.0 License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Continue reading from the same book

View All
Chapter 2 Overview of the Genus Squalus in the Mediterranean...

By Sondes Marouani, Sami Karaa and Othman Jarboui

109 downloads

Chapter 3 Shark Fishing in Ghana: What We Ought to Know

By Samuel K.K. Amponsah, Rachael Ackah, William Dzise...

102 downloads

Chapter 4 Elasmobranches and Chimaeras in Syria: Past, Prese...

By Adib Saad and Hasan Alkusairy

88 downloads