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WHAT IS ELASMODIVER? 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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SHORTNOSE SPURDOG |
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Shortnose spurdog, piked dogfish, shortnose dogfish. Valid Scientific Name: Squalus megalops Synonyms: Squalus tasmaniensis Family: Squalidae Identification: The shortnose spurdog has a short snout with a obtusely pointed tip. Dorsal fin apices maybe black or dusky edged. First dorsal fin spine is opposite or slightly posterior to free rear tip of pectoral fins. Pectoral and caudal fins have white posterior margins. Pelvic fin positioned midway between dorsal fins. Eyes large. Mildly venomous spines on first and second dorsal fins. Anal fin absent. Ventral coloration white. Size: Maximum length 77cm. size at birth 20-25cm. Mature males 34-51. Mature females 37-62. Habitat: Temperate and tropical continental shelf from surface to 732m. Abundance and distribution: A common to abundant species in the Eastern Atlantic from Spain to North Africa and West Africa to South Africa around the Cape of Africa to Madagascar. Also eastern Indo-Pacific in Australia, China and possibly elsewhere. Current research suggests that the shortnose spurdog is actually a complex of multiple closely related but geographically isolated species.
Conservation Status: The shortnose spurdog is listed as Data Deficient by the IUCN. However, it is taken in significant quantities in bottom trawls and also caught with lines and mesh nets. Squalus megalops is one of the most abundant chondrichthyan species on the outer continental shelf and upper slope of southern Australia. Its distribution includes some heavily fished areas, for example, off southeast Australia, although significant declines have not been documented to date. It is a minor component of the demersal gillnet fisheries through Bass Strait, off South Australia and Western Australia. However, S. megalops is too small to be readily captured by gillnets, particularly the 6 to 6½-inch mesh of shark nets, and there has been no detectable changes in catch rates of this species by commercial shark gillnets in Bass Strait since the 1970s. There are large regions around southern Australia where S. megalops is not greatly impacted by fishing, including a large area off the northern west coast which is closed to shark fishing. Consequently, the species is assessed as Least Concern in Australia, but the situation should be monitored because there are recent indications that fishing pressure may be affecting the local abundance of the species in some areas e.g., off Ulladulla, New South Wales. It should be noted that although currently considered a wide-ranging single species, S. megalops, as assessed here, may in fact be an Australian endemic pending further taxonomic studies. Due to taxonomic uncertainty, the global assessment is Data Deficient, pending further study. Citation: Cavanagh, R.D. & Lisney, T.J. (SSG Australia & Oceania Regional Workshop, March 2003) 2003. Squalus megalops. The IUCN Red List of Threatened Species. Version 2014.3. <www.iucnredlist.org> Behavior: Often found in large schools but may also be solitary. Reproduction: Ovoviviparous. Litter size from 1- 6. Photographs/video: East London, South Africa. Similar species: Spiny Dogfish Squalus acanthias. The wide ranging spiny dogfish has a longer nose and usually displays scattered white spots. The longnose spurdog Squalus blainville (present in the Mediterranean and along the west coast of Africa) has a much longer laterally pointed nose, white margined fins and a thicker more robust first dorsal spine. Reaction to divers: Usually found too deep to come in contact with divers. No known encounters. Diving logistics: None. The video of two shortnose spurdogs on this page was accomplished by dropping a baited remote camera to approximately 100m.
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