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Not just a huge collection of Shark Pictures: Elasmodiver.com contains images of sharks, skates, rays, and a few chimaera's from around the world. Elasmodiver began as a simple web based shark field guide to help divers find the best places to encounter the different species of sharks and rays that live in shallow water but it has slowly evolved into a much larger project containing information on all aspects of shark diving and shark photography.

There are now more than 10,000 shark pictures  and sections on shark evolution, biology, and conservation. There is a large library of reviewed shark books, a constantly updated shark taxonomy page, a monster list of shark links, and deeper in the site there are numerous articles and stories about shark encounters. Elasmodiver is now so difficult to check for updates, that new information and pictures are listed on an Elasmodiver Updates Page that can be accessed here:

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Shark picture - green sawfish

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HALAVI GUITARFISH

View all available Halavi Guitarfish Pictures

Common English Names: Halavi guitarfish, halavi ray.

 

Latin Name: Glaucostegus halavi

Family: Rhinobatidae

Identification: Dorsum uniformly tan to greyish brown. Ventrum pale. A single row of enlarged tubercles (dermal denticles) run along centre line from back from eyes to tail. Two very short lines of enlarged denticles positioned midway between spiracles and trailing edge of pectoral fins. Snout bluntly pointed.  Anterior margin of pectoral fins and snout straight. Posterior margin of pectoral fins convex. Two large equally sized dorsal fins with pointed apices positioned along posterior half of tail. Rostral cartilage thin and somewhat translucent. Eyes tan colored (matching dorsal coloration). Spiracles roughly twice as large as eyes. Spiracle have two visible posterior skin folds (scalloping).

Size: Maximum length 120cm.

Habitat: Sandy bottoms, reefs and sea grass beds from 0-40m

Abundance and distribution: Red Sea to Gulf of Oman. Possibly Gulf of Aden and northwestern Arabian Sea. Sightings from further east (as far as Southeast Asia) require confirmation. In 2007 an albino Halavi Guitarfish was reported off the coast of Tunisia confirming the presence of this species in the Mediterranean. This was likely after migrating through the Suez Canal.

Behavior: Lays on sea grass or sand or partially buries in sand when not foraging for food.

Diet: Feeds on small mollusks and bony fishes.

Reproduction: Guitarfishes are ovoviviparous (yolk sac viviparity). After absorbing all of the yolk, embryos suckle from tiny club shaped villi (projections) that provide nutrients for the young as they develop.

Conservation Status: The IUCN lists the Halavi guitarfish as Data Deficient due to its unclear range. However, it is a targeted and utilized bycatch in fisheries, but the amount of catch relative to stock size is not known (Bonfil and Abdallah 2004). Aggregation behavior during spawning may make this species particularly vulnerable to exploitation.
Off Saudi Arabia, in the Red Sea, artisanal fisheries production is almost entirely from handline and gillnet methods, while the industrial fleet utilizes fish and shrimp trawl nets and purse seine nets (FAO 2007). The industrial vessels operating in the Red Sea utilize trawl nets to target both demersal fish stocks and shrimp, with the majority of these vessels belong to Saudi Fisheries Company and operate out of Jizan on the southern Red Sea coast (FAO 2007).
Oman has a long established traditional shark fishery, which has experienced increased demand in recent years due to the shark fin trade (Henderson et al. 2007). In Omani waters, elasmobranchs are mainly captured by artisanal fishermen using wooden dhows and fiberglass skiffs with bottom-set longlines, bottom-set gillnets and driftnets (Henderson et al. 2007). The majority of fishing takes place in water shallower than 100 m and is therefore confined to inshore areas (Henderson et al. 2007). The presence of this species in shallow inshore areas would seem to put them at risk of capture in fisheries, but fishermen in Oman prefer to focus their fishing efforts in deeper waters where they catch grouper and other more valuable species (A. Henderson pers. obs. 2007). The fishermen operating in shallow coastal waters tend to surface-gillnet around reefs, or cast net for sardines and similar species, so the this species doesn't appear to be under much pressure in Oman (A. Henderson pers. obs. 2007). It is taken as incidental bycatch in Oman, and these catches appear to be limited to the Gulf of Oman (from Musandam in the north, to Muscat) (A. Henderson pers. obs. 2007). Landings of this species reported in (Henderson et al. 2007) all came from a single haul, thus artificially elevating the species' importance in the landings for that region.

Photographs: Dubai, UAE.

Similar species: The halavi guitarfish shares its range with the sharpnose guitarfish Glaucostegus granulatus which has a longer, more acutely pointed snout.

Reaction to divers: Skittish but possible to approach with careful slow movements. May slowly move away or bolt upon close examination.

Diving logistics: The halavi guitarfish is frequently seen by divers in Egypt. It is also a common sight around Musandam in Northern Oman. Dive shops in those areas should be able to put you in the water with this species.

 

Citations and References:

Barnett, L.A.K., Ebert, D.A. & Henderson, A. 2009. Glaucostegus halavi. The IUCN Red List of Threatened Species. Version 2015.2. <www.iucnredlist.org>.

 

Ben Souissi, J., Golani, D., Mejri, H., Ben Salem, M. and Capape, C. 2007. First confirmed record of the Halave's Guitarfish, Rhinobatos halavi (Forsskal, 1775) (Chondrichthyes: Rhinobatidae) in the Mediterranean Sea with a description of a case of albinism in elasmobranchs. Cahiers de Biologie Marine 48(1): 67-75.

 

 

 

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