ISRA FACT SHEETS
ISRA FACT SHEETS
MEDITERRANEAN AND BLACK SEAS REGION
Jerba-Zarzis
Summary
Jerba-Zarzis is located in the south-eastern side of the Gulf of Gabès, Tunisia. This area is characterised by shallow waters with a wide continental shelf. It is one of the most productive areas of the Western Mediterranean Sea, as this area contains the most extended and continuous Neptune Grass (Posidonia oceanica) meadow in this body of water. The area overlaps with the Le Golfe de Gabès Ecologically or Biologically Significant Marine Area, and partially overlaps with Côtes De L’île De Djerba Key Biodiversity Area. Within this area there are: threatened species (e.g., Blackchin Guitarfish Glaucostegus cemiculus); range-restricted species (Rough Skate Raja radula); and reproductive areas (e.g., Sandbar Shark Carcharhinus plumbeus).
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Jerba-Zarzis
DESCRIPTION OF HABITAT
Jerba-Zarzis is located in the Gulf of Gabès in south-eastern Tunisia. This area is situated on the south-eastern side of the gulf, next to Djerba island and the lagoon of El Bibane. The Gulf of Gabès is characterised by a semi-diurnal tide with a high amplitude (to 2 m), and a wide and shallow continental shelf (60 m depth occurs at 110 km from the coast), which are uncommon in the Mediterranean Sea (Ben Othman 1973). This area includes extensive seagrass beds of Neptune Grass (Posidonia oceanica) which support much of the benthic and demersal communities associated with this habitat in the Mediterranean Sea (El Lakhrach et al. 2012, 2019; Mabrouk et al. 2013).
Jerba-Zarzis is characterised by sandy-mud substrates with the Brown Algae (Arthrocladia villosa) and Neptune Grass well distributed and forming meadows to 27 m deep (El Lakhrach et al. 2019). These areas remain in good ecological condition and are considered critical habitats in the region (Sánchez-Jérez & Ramos-Esplá 1996; El Lakhrach et al. 2012, 2019).
The area is within the Le Golfe de Gabès Ecologically or Biologically Significant Marine Area (EBSA) (CBD 2023) and partially overlaps with the Côtes De L’île De Djerba Key Biodiversity Area (KBA) (KBA 2023).
This Important Shark and Ray Area is benthopelagic and is delineated from surface and inshore waters (0 m) to a depth of 40 m based on the bathymetry of the area and vertical distribution of the Qualifying Species.
CRITERION A
VULNERABILITY
Five Qualifying Species considered threatened with extinction according to the IUCN Red List of Threatened SpeciesTM regularly occur in the area. Threatened sharks comprise two Endangered species and one Vulnerable species; threatened rays comprise one Critically Endangered species and one Endangered species (IUCN 2023).
CRITERION B
RANGE RESTRICTED
This area holds the regular presence of the Rough Skate as a resident range-restricted species. The species is a regular bycatch of commercial fisheries (trawl, longline, and demersal gillnet) that operate in the area (Kadri et al. 2013, 2014). Rough Skate is restricted to the Mediterranean Sea Large Marine Ecosystem (LME).
CRITERION C
SUB-CRITERION C1-REPRODUCTIVE AREAS
Jerba-Zarzis is important for the reproduction of three shark and two ray species.
Pregnant Sandbar Sharks appear between March and July in the area. From July to October neonates and young-of-the-year are reported in the area. From January 2001 to May 2004, 932 animals were collected from commercial fisheries and embryos, neonates, juveniles, and adult females dominated catches. Adult females significantly outnumbered males (8.4:1.0) and parturition occurred in July (Saïdi et al. 2005). Between 2004–2008, of 1,114 Sandbar Sharks examined (50–218 cm total length [TL] with the highest frequencies between 60 and 90 cm TL), 82% were neonates and juveniles. Neonates were captured from July to October at depths between 10 and 30 m especially on sandy substrates. Pregnant females were caught through March to July and then disappeared from landings (Enajjar et al. 2015). From July to September in 2007 and 2008, 547 Sandbar Sharks were examined in which juveniles, including specimens with umbilical scars, dominated captures (Echwikhi et al. 2013). From May to July 2009, 11 Sandbar Sharks were examined with sizes ranging from 60.5 to 93 cm TL including neonates and juveniles (Saïdi et al. 2016).
Between 2004–2008, of 2,068 Common Smoothhounds examined (34–165 cm TL), 12% were neonates and 62% were juveniles. Neonates with unhealed umbilical scars were captured from April to July at depths between 10 and 30 m. Pregnant females were captured from February to April at depth between 10 and 30 m on sandy-muddy substrates (Enajjar et al. 2015). From May–July 2009, 706 Common Smoothhounds were sampled which were either neonates or young-of-the-year, with a dominance of neonates (Saïdi et al. 2016). This species has a defined annual reproductive cycle, based on the study of reproductive tracts (Saïdi et al. 2008). Mating occurred during May and early June, fertilisation occurred from early June to early July, and parturition occurred during late April and early May, after a gestation period of 10–11 months (Saïdi et al. 2008).
Between January 2002 and December 2005, 565 Blackspotted Smoothhounds were examined (24.5–122 cm TL) which included neonates with unhealed umbilical scars (n = 52) observed in June, and pregnant females with full-term embryos or post-partum females observed from mid-May to early June (Saïdi et al. 2009). From May to July 2009, 117 neonate Blackspotted Smoothhounds were examined (25–34 cm TL) with umbilical scars (Saïdi et al. 2016). In the Gulf of Gabès, the size-at-birth is of 24.5–30.5 cm TL (Saïdi et al. 2009). Mating occurred through late-May and June and parturition occurred from mid-May to early June, after a gestation period of 11 months, based on the reproductive cycle assessed by examining reproductive tracts (Saïdi et al. 2009).
Between 2004–2008, 2,292 Blackchin Guitarfish were examined (35–205 cm TL) and 60% were immature (Enajjar et al. 2015). In the Gulf of Gabès, the size-at-birth is of 35–38 cm TL (Enajjar 2009). Neonates (n = 95) were captured from September to November at depth <30 m (Enajjar et al. 2015). Pregnant females with eggs (n = 100) or embryos (n = 31) were observed from September to June at depths less than 50 m, while pregnant females with near-term embryos (n = 20) were observed in spring and summer (Enajjar et al. 2015). From July to September in 2007 and 2008, of 123 Blackchin Guitarfishes examined, 69% were pregnant females (with near-term embryos) or post-partum females (Echwikhi et al. 2013).
From September 2007 to August 2009, 1,250 Rough Skates were sampled with body sizes ranging from 15 to 80 cm TL; some of these individuals (n = 16) measured 15–18.4 cm TL and were determined to be young-of-the-year (Kadri et al. 2014). From January to December of 2007, 950 Rough Skates were sampled and of these 20 are considered young-of-the-year due to their body sizes (<20 cm TL); from the 550 females sampled, 155 were egg-bearing (Kadri et al. 2013). This species displayed a continuous reproductive cycle and females carrying developed oocytes and egg cases were observed year-around (Kadri et al. 2013).
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