Dogfish Shark
Squalus acanthias
The dogfish are a diminutive and largely docile species of shark. They are known for their curious nature and pack-like hunting techniques. They can school in packs of thousands of individuals, with even newborns hunting prey many times their size. Dogfish have venomous spines in front of each dorsal fin to protect them from predators like larger sharks and seals. Dogfish are also highly migratory with one documented to have travelled 5,000 miles across the Pacific Ocean!
SPECIES IN DETAIL
Dogfish Shark
Squalus acanthias
CONSERVATION STATUS: Vulnerable-Protected
CLIMATE CHANGE: Vulnerable
Geographic Distribution
The dogfish are found in the Atlantic, Pacific, and Eastern Indian Oceans, Mediterranean Sea, Black Sea, and from Alaska to Baja California. They can be found in temperate and subarctic waters worldwide!
Habitat
They spend the winter in deep water up to 2,900 feet below the surface, returning to shallow coastal waters to feed during the summer.
Physical Characteristics
Dogfish sharks exhibit countershading, with a dark grey topside and white underbelly, as a means to confuse potential predators. Simultaneously, it acts as camouflage against both the ocean surface and seafloor to help in ambushing unsuspecting prey. Dogfish feature distinctive white spots on the side of their bodies. Venomous spines anterior to each dorsal fin provide an extra measure of protection against larger sharks, cod, and seals which are known to hunt dogfish. Like most squaliform sharks, the dogfish lacks an anal fin and has a compact, hydrodynamic body that provides crucial agility in predatory pursuit.
Size
Male dogfish can reach 99 centimeters (39 inches), but females can grow up to 124 centimeters (49 inches). They both can weigh up to 22 pounds.
Diet
Dogfish prey on small fish such as capelin, herring, and mackerel as well as crustaceans and cephalopods. Notorious for their aggressive schooling behavior, dogfish employ pack-hunting strategies in numbers up to the thousands of individuals.
Reproduction
Dogfish reproduce by aplacental viviparity. The male dogfish internally fertilizes a female with his claspers. The female dogfish carries her young in specialized membranes within her uterus for twenty-two to twenty-four months. When her young fully develop within the uterus, dogfish give live birth to a litter that can number from two to eleven.
Behavior
In spite of their small size, dogfish have been observed to be highly aggressive toward prospective prey, especially when schooling with other members of their species. When massed in large numbers, dogfish relentlessly pursue their prey with even newborn dogfish being capable of hunting prey items multiple times their size. Dogfish are a migratory species with a particular tagged individual documented to have travelled 8,047 kilometers (5,000 miles) on an oceanic voyage from the Pacific coast of Washington state to the island of Japan.
Adaptation
Dogfish have many adaptations that it shares amongst its shark relatives. The dogfish breathes using ram ventilation where it opens its mouth during swimming to force oxygen-rich water over its gills. However, it still retains vestigial spiracles which enables the dogfish to conserve energy while lying in wait for prey on the seafloor. The skin of the dogfish is composed of an overlaying network of dermal denticles that form a protective layer. The dogfish also has venomous spines near the front of each dorsal fin.
Longevity
Pacific spiny dogfish live up to 80 years whereas the Atlantic species has an average lifespan of thirty-five to forty years.
Conservation
Not regarded as a commercially significant species in the United States, dogfish stocks are generally quite healthy around North America. However, dogfish is commonly marketed under more appealing names such as rock salmon in European countries. As a result, the increased consumer demand for dogfish in Europe has already eclipsed the reproduction rate of the species, and the Atlantic stock is put under tremendous pressure. In 2014, the Atlantic States Marine Fishing Commission passed legislation that outlawed the finning of dogfish sharks. After the European subset of the dogfish population was listed as critically endangered by the IUCN (International Union for Conservation of Nature), the European Union prohibited the fishing of dogfish in its waters.
Special Notes
The dogfish has a variety of names that includes spring dogfish, spur dog, and grayfish. Dogfish are closely related to sleeper sharks, kitefin sharks, and gulper sharks. They can live for more than eighty years and have a very long gestation period of twenty-two to twenty-four months. Names for their tendency to school together, they pursue prey items as a pack.
SPECIES IN DETAIL | Print full entry
Dogfish Shark
Squalus acanthias
CONSERVATION STATUS: Vulnerable-Protected
CLIMATE CHANGE: Vulnerable
The dogfish are found in the Atlantic, Pacific, and Eastern Indian Oceans, Mediterranean Sea, Black Sea, and from Alaska to Baja California. They can be found in temperate and subarctic waters worldwide!
They spend the winter in deep water up to 2,900 feet below the surface, returning to shallow coastal waters to feed during the summer.
Dogfish sharks exhibit countershading, with a dark grey topside and white underbelly, as a means to confuse potential predators. Simultaneously, it acts as camouflage against both the ocean surface and seafloor to help in ambushing unsuspecting prey. Dogfish feature distinctive white spots on the side of their bodies. Venomous spines anterior to each dorsal fin provide an extra measure of protection against larger sharks, cod, and seals which are known to hunt dogfish. Like most squaliform sharks, the dogfish lacks an anal fin and has a compact, hydrodynamic body that provides crucial agility in predatory pursuit.
Male dogfish can reach 99 centimeters (39 inches), but females can grow up to 124 centimeters (49 inches). They both can weigh up to 22 pounds.
Dogfish prey on small fish such as capelin, herring, and mackerel as well as crustaceans and cephalopods. Notorious for their aggressive schooling behavior, dogfish employ pack-hunting strategies in numbers up to the thousands of individuals.
Dogfish reproduce by aplacental viviparity. The male dogfish internally fertilizes a female with his claspers. The female dogfish carries her young in specialized membranes within her uterus for twenty-two to twenty-four months. When her young fully develop within the uterus, dogfish give live birth to a litter that can number from two to eleven.
In spite of their small size, dogfish have been observed to be highly aggressive toward prospective prey, especially when schooling with other members of their species. When massed in large numbers, dogfish relentlessly pursue their prey with even newborn dogfish being capable of hunting prey items multiple times their size. Dogfish are a migratory species with a particular tagged individual documented to have travelled 8,047 kilometers (5,000 miles) on an oceanic voyage from the Pacific coast of Washington state to the island of Japan.
Dogfish have many adaptations that it shares amongst its shark relatives. The dogfish breathes using ram ventilation where it opens its mouth during swimming to force oxygen-rich water over its gills. However, it still retains vestigial spiracles which enables the dogfish to conserve energy while lying in wait for prey on the seafloor. The skin of the dogfish is composed of an overlaying network of dermal denticles that form a protective layer. The dogfish also has venomous spines near the front of each dorsal fin.
Pacific spiny dogfish live up to 80 years whereas the Atlantic species has an average lifespan of thirty-five to forty years.
Not regarded as a commercially significant species in the United States, dogfish stocks are generally quite healthy around North America. However, dogfish is commonly marketed under more appealing names such as rock salmon in European countries. As a result, the increased consumer demand for dogfish in Europe has already eclipsed the reproduction rate of the species, and the Atlantic stock is put under tremendous pressure. In 2014, the Atlantic States Marine Fishing Commission passed legislation that outlawed the finning of dogfish sharks. After the European subset of the dogfish population was listed as critically endangered by the IUCN (International Union for Conservation of Nature), the European Union prohibited the fishing of dogfish in its waters.
The dogfish has a variety of names that includes spring dogfish, spur dog, and grayfish. Dogfish are closely related to sleeper sharks, kitefin sharks, and gulper sharks. They can live for more than eighty years and have a very long gestation period of twenty-two to twenty-four months. Names for their tendency to school together, they pursue prey items as a pack.