PIKED DOGFISH OR SPINY DOGFISH
A shark with spikes that primarily feeds seasonally and travels long distances
The Piked Dogfish (Squalus acanthias), also known as the Spiny Dogfish, the Mud Shark and the Spurdog is a species belonging to the Squalidae, or common name Dogfish shark family, which is part of the Squaliformes order. The Piked Dogfish is distinguished by having two spines, one anterior to each dorsal fin. They are found worldwide, and travel through the water column seasonally and are highly migratory.
Family: Squalidae – Dogfish Sharks
Common Name– Dogfish Sharks
Common Name– Dogfish Sharks
Status: IUCN Red List VULNERABLE
Average Size and Length: Piked dogfish are born between 7-12.9 inches. Mature males are between1.7-3.3 feet, and females are between 2.2-3.9 feet. The maximum recorded length is between 5.2-6.6 feet.
Average Weight: Mature female Spiny dogfish reach weights of 7.1-9.9 pounds, with a maximum recorded weight of 21.6 pounds.
Teeth and Jaw: The upper and lower teeth of the Piked dogfish are small and similar in shape with oblique points bent toward the outer corners of the mouth. The cusps are deeply notched outward with a single sharp point. These form a nearly continuous cutting edge from one corner of the mouth to the other. There are 28 upper teeth and 22-24 lower teeth in the jaws.
Head: The head of a Piked dogfish is narrow with a long, pointed snout, and large eyes.
Denticles: Dermal denticles of the Piked dogfish or the Spiny dogfish are small and low with three cusps. The central ridge is prominent and the lateral extensions are wing-like.
Tail: The caudal fin has asymmetrical lobes, forming a heterocercal tail. There are low lateral keels located on the caudal peduncle. There is no notch on the upper caudal lobe and the lower caudal lobe is not well-developed.
Demographic, Distribution, Habitat, Environment and Range: Piked Dogfish are found worldwide, except for the tropics and near the poles. The Northern and Southern hemisphere populations seldom have any mixing between them. They prefer boreal to warm temperate continental and insular shelves, and occasionally slopes. This is between 0-1,969 feet, with reports as deep as 4,744 feet, demersal. They also are found to be epipelagic from 0- 656 feet when the water is cold. They prefer soft bottoms and sediments. They travel through the water column and change seasonally. They are highly migratory, spending winters in deeper water eating very little, and summers in coastal waters eating a lot. Nursery grounds are usually in open bays and estuaries, although in some populations they have been deep in the open ocean.
Diet: In winter, they don’t eat much, in summer they eat a variety of bony fishes, small sharks, and other organisms. Schooling pelagic fishes tend to draw in large schools and aggregations of hungry Piked dogfish.
Spiny dogfish have been found in the stomachs of larger fish, other Spiny dogfish, Orcas, Seals and other larger sharks.
Aesthetic Identification: The Piked Dogfish is slender, being greyish-brown with white spots along its back dorsally, and counter-shaded lighter ventrally, sometimes having white spots on the sides. The spots disappear as the shark ages. It has no anal fin. The dorsal fins, tips and edges are dusky or plain in adults. The Piked Dogfish is distinguished by having two spines, one anterior to each dorsal fin. Research suggests that these spines are used defensively, and maybe even produce a mild venom, however this isn’t confirmed yet. They do wear down in older sharks. The first dorsal fin is low, and the spine is slender. The first dorsal fin is larger than the second dorsal fin. The first dorsal fin is located about halfway between the pectoral and pelvic fin origins and behind the rear tips of the pectoral fins. The second dorsal fin is about two-thirds the size of the first and is located behind the pelvic fins. The pectoral fins have shallow, concave posterior margins and narrowly rounded rear tips.
Biology and Reproduction: Reproduction in Piked dogfish is ovoviviparous or aplacental viviparous. Mating takes place in the winter months with gestation lasting 18–24 months. Litters range between 2 and 11 but average 6 or 7 pups. Males mature sexually at around 11 years of age, growing to 2.6–3.3 feet in length; females mature in 18–21 years and are slightly larger than males, reaching 3.2–5.2 feet. Life span of Piked Dogfish is estimated to be between 70 and 100 years.
Behavioral Traits, Sensing and Intelligence: Piked dogfish can occur solitary or schooling with other small sharks, forming large feeding aggregations, especially because feeding is seasonally. Juveniles segregate by sex and size in packs and schools.
Speed: Piked dogfish are slow swimmers, but can undertake long journeys. Recorded distances range from 994-4,039 miles.
Piked Dogfish or Spiny Dogfish Future and Conservation: Piked dogfish or Spiny dogfish are consumed as human food in Europe, the United States, Canada, New Zealand and Chile. The meat is primarily consumed in England, France, the Benelux countries and Germany. The fins and tails are processed into fin needles and are used in less expensive versions of shark fin soup in Chinese cuisine. In England they are sold in fish and chip shops as “huss”, and it was historically sold as “rock salmon” until this term was outlawed by consumer legislation. In France it is sold as “small salmon” and in Belgium and Germany it is sold as “sea eel” It is also used as fertilizer, liver oil, and pet food, and, because of its availability, cartilaginous skull, and manageable size, as a popular vertebrate dissection specimen, in both high schools and universities, in which, this was the first shark that I dissected myself. Reported catches in 2000–2009 varied between 13,800 (2008) and 31,700 (2000) tonnes. Total landings of spiny dogfish peaked in 1974 at 27,400 metric tonnes, followed by a sharp decline, stabilizing at 5,900 mt during the 1980s.
The Cape Cod Commercial Fishermen’s Alliance has sponsored an initiative which promotes local, sustainably caught use of the dogfish in restaurants and fish markets in the Cape Cod area of Massachusetts. The effort is funded by the National Oceanographic and Atmospheric Administration and attempts to get the public to consume under-utilized fish.
Bottom trawlers and sink gillnets are the primary used. In Mid-Atlantic and Southern New England fisheries, they are often caught when harvesting larger groundfish, classified as bycatch, and discarded.
Recreational fishing accounts for an insignificant portion of the Piked dogfish.
Piked Dogfish or Spiny Dogfish Recorded Attacks on Humans: Not a threat to humans.