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Not just Shark Pictures: Elasmodiver contains photos of sharks, skates, rays, and chimaera's from around the world. It began as a simple web based field guide to help divers find the best places to encounter different species of sharks and rays but it has slowly evolved into a much larger project containing information on all aspects of shark diving and photography. There are now more than a thousand shark pictures  and sections on shark evolution, biology, and conservation. There is a large library of reviewed shark books, a constantly outdated shark taxonomy page, a monster list of shark links, and deeper in the site there are numerous articles and stories about shark encounters.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:

WHAT'S NEW?

Shark picture - green sawfish

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ELASMODIVER EXPANDED

If you're looking for a broader range of marine life pictures the following links represent a new area that contains pictures on other marine organisms and on marine habitats. This expansion of Elasmodiver is in its first stages but will eventually include pages on everything from sea stars to nudibranchs. Creating this portal will take time and for now it consists of a token offering of fish pictures. Please return regularly to enjoy the progress.

 

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SPINY DOGFISH

 

View all available Spiny Dogfish Pictures

Common Names: Spiny dogfish, Common spiny dogfish, Piked dogfish, Mud shark.

Latin Name: Squalus acanthias

Family: Squalidae

Identification: Long, flattened, pointed snout. Grey to brown above usually with small white spots. White spots may follow lateral line.  Eyes large. Mildly venomous spines on first and second dorsal fins. Anal fin absent. Belly white.

Size: Maximum length 1.6 meters. size at birth 22-33 cm. Maximum recorded age 66 years.

Habitat: Often cruise over sand and mud bottoms. Also frequently encountered over rocky reefs. From 0 to 900 meters.  Inhabits estuarine, coastal and offshore waters sometimes migrating over great distances - 30 tagged individuals traveled from British Columbia to Japan, 7000km! Newfoundland tagged individuals have been captured years later in Iceland. Normal migration patterns are usually more localized; both Atlantic and Pacific groups migrate between Canada and the US in order to stay within a seasonal temperate range.

Abundance and distribution: Worldwide in temperate seas. Known on the Atlantic coast from Labrador to the Gulf of Mexico and on the Pacific Coast from the Aleutians to Central Baja. Once thought to be the most abundant shark in the world the Spiny dogfish is now facing commercial extinction and a grass roots movement around the world is attempting to lobby for a reduction in quotas. In the UK and Europe Spiny dogfish are the principal fish utilized in "fish and chips". It is also ground up to be used in fertilizers.

Behavior: Cruises over soft bottoms either alone or in small groups. Occasionally schools (often segregated by sex) in response to food supply such as squid or salmon runs. May also form schools with other species such as leopard sharks and smoothhounds. Diet consists mainly of bony fishes. Other foods include octopus, squid and crustaceans. 

Reproduction: Ovoviviparous. Litter size from 1- 20. Spiny dogfish have a slow maturity rate (around 12 years) which makes them very vulnerable to over fishing. They also have the longest gestation period of any known vertibrate 18-24 months. 

Observations: 

Photographs: Saanich inlet, Vancouver Island. 

Similar species: Smooth Dogfish mustelus canis which has a sympatric range from the Bay of Fundy to the Gulf of Florida and from Southern Brazil to Argentina.

Reaction to divers: These are curious and harmless sharks that will often closely approach divers and on occasion accompany them on their dives. If divers are buzzed by a dogfish they can often be recalled by tapping two stones together. The dogfish seem to find this irresistible and will repeatedly return to satisfy their curiosity. If engaging in dogfish feeds it is possible to play tug of war with these little sharks. Care should be taken to avoid their mildly venomous spines. 

Diving logistics: On Vancouver Island dogfish are present during the summer months most often from July to September. It is possible to see them occasionally whilst shore diving in Saanich Inlet during this period. Reputedly they are relatively common to the north around Campbell River. For an overview of the dive sites of Saanich Inlet visit the Victoria Scuba Club Website listed on the elasmo-links page. 

On Quadra Island it is possible to go on a freestyle dogfish feed. This is one of the most entertaining shark interactions that you could have.

Spiny dogfish at Quadra Island trip report

Other diving locations submitted by readers:

Read about the spiny dogfish debate

References: 

Migration Patterns of Spiny Dogfish (Squalus acanthias) in the North Pacific ocean - G.A. McFarlane and J.R. King. - Fisheries and Oceans Canada.

Maximum Ages of Ground Fishes in Waters off Alaska and British Columbia and Considerations of Age Determination. - Kristen M. Munk - Alaska Fisheries Research Bulletin Vol. 8 No.1 Summer 2001.

Reef Sharks and Rays of the World - Scott W. Michael.

Coastal Fish Identification, California to Alaska. - Paul Humann - New World Publications.

Sharks - Andrea and Antonella Ferrari - Firefly

Marine life of the North Atlantic - Andrew J Martinez - Down East Publications. 

 

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