Dogfish

With 119 species, dogfish sharks are the second-largest shark order. Dogfish sharks get their name from fishermen who have seen them hunting after smaller fish in dog-like gangs. During the day, schools of hundreds of dogfish sharks move close together, seeking herring, mackerel, and capelin, as well as squid and jellyfish in some circumstances. Despite its spiky spines, this dogfish eats its prey by biting it down with sharp teeth and a powerful jaw. Scientists believe that during the winter months when they swim to extreme depths of up to 2,900 feet below the surface, spiny dogfish eat less. The sharks will return to the surface in the spring, looking slimmer, but will swiftly migrate to warmer coastal waters for summer feeding.

The piked dogfish, rock salmon, and spiky dog are all names for the spiny dogfish, but only one fully depicts this shark's unique defence method. To defend itself, the spiny dogfish uses the two spines at the base of each dorsal fin to inject venom into predators. The term "dogfish" comes from the fact that fishermen have seen this species pursuing smaller fish in dog-like gangs. The spiny dogfish was formerly one of the most prolific shark species in the ocean, but while populations are still plentiful, many have plummeted. Despite the fact that they are forage-feeding sharks, they are small and harmless to humans.

The most prolific and frequently seen shark in Narragansett Bay is the spiny dogfish. The smooth dogfish Mustelis canis, a similar shark species, can be found in Rhode Island waters. The spiny dogfish swims in schools of individuals of comparable size when migrating to locate food. The fish is ravenous, scattering and destroying groups of mackerel and other fish on a regular basis. The spiny dogfish is a prominent predator of American lobster and large crabs, in addition to consuming worms, shrimp, crabs, and comb jellies. Unlike the small skate, which lays eggs or encases eggs in a capsule, spiny dogfish bear lives young and can have up to six pups each litter. They reproduce slowly, and hence wild populations are vulnerable to overfishing.

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Life Cycle

Spiny dogfish are ovoviviparous, meaning their eggs mature inside the female's uterus and the offspring develop further until being born as fully developed pups. They have the longest gestation time of any vertebrate, much alone shark, at 22 to 24 months. The usual spiny dogfish litter contains five to six pups, however, the number of pups born in a litter is determined by the female's size. The larger the female, the larger the litter, with some litters having as many as 14 babies. Males and females reach sexual maturity at around 10 and 16 years old, respectively, however, this can be as late as 35 years old in some cases.

During the day, schools of hundreds of spiny dogfish move close together, chasing herring, mackerel, and capelin, as well as squid and jellyfish in some circumstances. They are opportunistic eaters, though, and may eat both larger and smaller prey, including as cod and haddock, as well as crabs and polychaete worms. Despite the fact that their dorsal fins have sharp spines, these dogfish feed by biting down on prey with sharp teeth and a powerful jaw. Spiny dogfish can hunt fish up to three times their own size as young pups. Larger sharks, seals, orcas, adult cod, and red hake are among the spiny dogfish's predators. To protect itself, the spiny dogfish uses two spines near the dorsal fins to inject venom into predators. Humans are at risk if all these sharks are handled incorrectly.

Description

A small shark with a narrow, flattened head, a blunt, tapering snout, and a small crescent-shaped mouth, the spiny dogfish. The spiny dogfish's teeth are tiny and have sharp tips that curve outward. The teeth are arranged in multiple rows and are used to grind rather than tear. The spiny dogfish's first dorsal fin is slightly larger than the second dorsal fin. In front of each dorsal fin are two massive, pointed, mildly venomous dorsal spines. The spiny dogfish defends itself by folding up its body and striking at an adversary with its spines. The skin of a spiny dogfish is rough, with a tooth-like scaled surface known as dermal denticles. When rubbing the skin with the grain of the denticles, it feels smooth, but when rubbing against the grain, it feels rough.

Life History and Behavior

The spiny dogfish (Squalus acanthias) is a tiny shark that lives predominantly in temperate and subarctic locations on both sides of the North Atlantic and North Pacific Oceans. The stock can be found from Labrador to Florida in the Northwest Atlantic and is most numerous between Nova Scotia to Cape Hatteras. In the spring and summer, spiny dogfish move north, and in the fall and winter, they travel south. They concentrate predominantly in Mid-Atlantic waters in the winter and spring, although they also expand onto the shelf break of southern Georges Bank. They migrate inshore into bays and estuaries in the summer, moving further north in Canadian seas. Dogfish have travelled north in large numbers by autumn, with high concentrations in Southern New England, Georges Bank, and the Gulf of Maine. They stay in northern waters until the water temperatures cool in the fall, then return to the Mid-Atlantic.

Spiny dogfish juveniles school by size until sexual maturity, at which point they aggregate by both size and sex. Female dogfish attain sexual maturity at the age of 12 years (29.5 inches), while male dogfish reach sexual maturity at the age of six years (23.6 inches). Mating takes place throughout the winter months, and the pups are delivered to the wintering grounds offshore. Females have litters ranging from two to fifteen puppies every two years. The female will begin producing eggs for the fertilisation of her next litter while carrying one litter. Puppies are born at an average size of 14 inches after an 18 to 24 month gestation period.

These sharks are one of a small number of sociable shark species. Dogfish will cluster and even hunt in packs alongside lemon sharks, blue sharks, and hammerhead sharks. Their appetite is ravenous, and they will consume just about anything they can get their hands on. The groups will disperse and sweep a large area, chasing any prey into the open.

Commercial Use

Humans eat spiny dogfish in Europe, the United States, Canada, New Zealand, Venezuela, and Chile. England, France, Italy, the Benelux countries, and Germany are the main consumers of meat.

Dogfish Locations

This species can be found at the shores of any temperate or subarctic ocean on the planet. They can be found almost anywhere except the equator and the poles. They live along with South America's, Africa's, and Australia's southern shores. Their range also includes the entire eastern North American coast, as well as southern Greenland. They can also be found along Europe's shores.

Habitat

These sharks enjoy shallow, coastal waters for the most part. Researchers have discovered them at depths of up to 3,000 feet below the surface. Rather than swimming in the open ocean, they prefer to hunt for food on the seafloor. These sharks, unlike many other shark species, will travel into subarctic seas. They can be found in temperate and subarctic environments all around the world.

Dogfish and Human Interaction

These sharks are used in commercial and recreational fishing all around the world. As a result, the global population of this species is declining. Because females cannot spawn until they are roughly 20 years old, overfishing is particularly harmful to this species.

This suggests that the number of animals reaching adulthood is insufficient to replenish the population. As a result, the IUCN has classified this species as Vulnerable. In an attempt to decrease population decline, a number of programmes have been launched to regulate dogfish harvest.

Dogfish Care

These sharks are more successful in aquariums than their larger cousins since they are smaller, bottom-dwelling species. You can keep them in tanks with other sharks of comparable size, but any smaller fish or crustaceans you keep with them will likely be eaten.

Because these sharks are social, anyone can keep a group of them in the same aquarium. Scientists can study the behaviour and reproductive techniques of these sharks in aquariums to learn more about their wild counterparts.

Diet of the Dogfish

These sharks, like the dogs from whom they got their name, aren't very picky eaters. They'll pack their belongings and eat just about anything they can get their hands on. They're known for being ruthless and vicious predators. Even newborns have been observed pursuing prey that is several times their own size. Fish, squid, crabs, various crustaceans, and invertebrates are among their favourite foods.

Predator and Prey

The name "dogfish" derives from the fact that this shark hunts for prey and feeds in groups. Thousands of people can be found in a single pack. Jellyfish, squid, crab, worms, octopus, and schools of fish are all common food sources. Crustaceans are the primary food of smaller spiny dogfish.

They have a huge appetite. Fishermen have reported seeing packs of dogfish consuming big amounts of mackerel and herring, as well as chewing through their nets to release the fish. These sea creature's spines have the potential to destroy commercial fishing nets.

Larger sea creatures may hunt them down. They will be eaten by larger sharks, seals, orcas, some larger fish, and even other spiny dogfish. Their spines serve as a deterrent to would-be predators. Dogfish may curl into a bow shape and strike out at enemies, injuring them.

Conservation Status

The Spiny Dogfish, Squalus acanthias, is a migratory shark that lives in temperate waters all over the world. It has a thin, elongated body with a slate-coloured head that is fairly flattened. The popular name "dogfish" stems from the species' hunting behaviours, which include chasing prey in big dog-like gangs. The term "spiny" alludes to two sharp spines near its dorsal fins that it utilises to defend itself by imparting a minor poison. Many Spiny Dogfish populations have been severely decimated by fisheries around the world, despite their natural abundance. Spiny dogfish meat is in high demand, especially in Europe, which drives international trade and targeted fisheries all over the world. Spiny Dogfish is used in the popular British dish "fish and chips," and its fins are utilised in less expensive versions of shark fin soup in Chinese cuisine. It's also used as a fertiliser, as well as a source of liver oil and pet food.

The International Plan of Action for the Conservation and Management of Sharks (IPOA-sharks) was adopted by the Food and Agriculture Organization (FAO) Committee on Fisheries (COFI) in 1999, recognising the need for better shark fisheries management. However, only around 20% of COFI member states have drafted national Action Plans to implement the Action Plan.

Interesting Facts about the Dogfish

Dogfish are less terrifying than some of their larger cousins, yet they are fascinating creatures. Find out more about these little sharks below:

• Long-lived - Scientists estimate this species could live for up to 100 years or more! Female dogfish do not attain sexual maturity until they are roughly 20 years old, implying that they live a long time.

• There are not many dogfish hybrids discovered to date. 

• “Spiny” - The first half of the name of the spiny dogfish is self-explanatory. Because it has sharp spines in front of each dorsal fin, it is called "spiny." If it is grabbed by a predator, it will arch its back and shove the spines into the predator's skin or mouth.

• “Dogfish” - The name “dogfish” comes from the way this species behaves. These little sharks gather in large groups to hunt, and they can be rather aggressive in their pursuit of prey. They receive their name from the fact that they feed in groups and have dog-like tenacity.

• Fish and Chips - If you order "fish and chips" in Europe, you're almost certainly getting dogfish and chips. Their meat is in high demand all around the world. Their numbers have plummeted as a result of the increased fishing pressure. 

• “Dogfish Clothing”- Designer apparel, footwear, and accessories are sold in this men's casualwear store. It’s interesting to see Dogfish Clothing brand without connection to these fishes. 

Conclusion

In two aspects, this shark species is unique. For starters, it's one of only two species with a venomous spine just in front of the dorsal fins (the other species with this unusual defence mechanism is the Horn Shark, which is not native to Oregon). In addition, unlike most sharks, the Spiny Dogfish lacks an anal fin. It has white patches on its back and a grey or brown coloured body. Dogfish Locations can be found all throughout the Pacific Ocean, often hunting in schools of tens of thousands of individuals. They are opportunistic, like other sharks, but because of their small size, they prefer to eat smaller fish, krill, squid, and octopus. Spiny Dogfish can be found in both sunlit shallows and dark ocean canyons, living from the intertidal zone to at least 3,000 feet (915 metres). They can be found as far south as Chile, but are most numerous off the coasts of British Columbia and Washington. Anglers fishing for other species is more likely to catch Spiny Dogfish, which are often loathed by fisherman. Squid strips or sliced pieces of fish can be used to catch them. Many populations of Spiny Dogfish have been severely depleted, and the species has been characterised by recurrent depletion around the world. In the late 1980s, as fisheries off the coast of Europe were depleted, fisheries in the United States and Argentina grew to replace the void in the European market. Following the drop in US capture, fisheries off the coasts of Canada and New Zealand grew. With the establishment of a fishery off the coast of Morocco, this trend appears to be continuing.