Spiny Dogfish

The Spiny Dogfish is a smaller shark that is found in both the Atlantic and Pacific Oceans. They prefer a saltwater habitat but may enter brackish water. Spiny Dogfish are unique in that they have two spines. If they are attacked, they will use these two spines to arch their backs and inject venom into their attacker.

Some other key characteristics of a Dogfish include the white spots on its side, large eyes, and the brownish/grayish coloring on its top that fades to a white belly.

Classification and Scientific Name

The scientific name for these sharks is Squalus acanthias. Squalus comes from the Latin word for shark, and acanthias is derived from the Greek word akanthias, which refers to the spines of a Spiny Dogfish.

The Spiny Dogfish is also known by many other names, including piked dogfish, spiky dog, and rock salmon. It belongs to the Squalidae family and is in the Chondrichthyes class. There are 40 different species in the Squalidae family.

Recently, scientists determined that the Spiny Dogfish that live in the northern Pacific Ocean were a separate species. This species is called the Pacific Spiny Dogfish. Its scientific name is Squalus suckleyi.

Appearance

The Spiny Dogfish, or Dogfish Shark, is smaller than many other species of sharks. A male’s body has a maximum length of 39 inches, and a female’s body has a maximum length of 49 inches. Most of them weigh around 8 pounds.

These sharks have a very slender body with a pointy snout and large eyes. A Spiny Dogfish’s skin is darker on the top and fades to white or a pale color on the belly.

The skin is brown or gray along the top of the body. Another one of the key characteristics is the small white spots that go along the sides of their body. As a Spiny Dogfish ages, these spots will begin to fade.

Spiny Dogfish have two spines that they use for self-defense. If they get captured, they will arch their back and use the spines near their dorsal fin to pierce the predator and secrete venom into it.

Distribution, Population, and Habitat

These sharks are found in the Atlantic and Pacific Oceans. Recently, the Spiny Dogfish in the Pacific Ocean was determined to be a separate species and was given the name Pacific Spiny Dogfish.

In the Atlantic Ocean, they are found between Greenland and Argentina on the western side of the ocean. They can also be found in the eastern Atlantic Ocean between Iceland/the Murmansk Coast down to South Africa. These sharks are also found in the Black Sea and the Mediterranean Sea. The Pacific Spiny Dogfish can be found in the Pacific Ocean between the Bering Sea and Baja California.

These sharks may swim both inshore and offshore over the continental shelf. They prefer to swim in saltwater, but they may enter brackish water at times. They cannot be found in freshwater, however. Most of the time, Spiny Dogfish prefer to swim at depths between 160 and 490 feet beneath the surface. However, they may venture as deep as 2,300 feet beneath the surface at times.

This shark population has seen a big decrease over the years. At one time, they were the most abundant species of sharks, but now the International Union for Conservation of Nature has given them a classification as vulnerable globally and critically endangered in the northeast section of the Atlantic Ocean.

In 2010, it was estimated that these sharks had a total biomass of 106.8 thousand metric tons in the Atlantic Ocean and that there were about 44,660,000 fish in the Pacific Ocean.

Predators and Prey

What Threatens the Spiny Dogfish?

There are a few natural predators that threaten these sharks. These include Killer Whales, seals, large sharks, tuna, and American anglerfish. When attacked, the Dogfish will try to protect itself by arching its back and using its dorsal spines to inject venom into its attacker.

Humans also pose a threat to the Dogfish. Overfishing by humans has led to a significant decrease in the population of Spiny Dogfish. One of the reasons they are so impacted by fishing is that this species has a longer gestation period than many other species of fish and has smaller litters of young.

It also takes females longer to reach sexual maturity, which makes it harder for the population to grow quickly. The sharp decrease in their numbers in the past years has led to them being classified as vulnerable by the International Union for Conservation of Nature.

What do Spiny Dogfish Eat?

These sharks often hunt for food in a larger pack of up to 1,000 Dogfish. They eat octopuses, crabs, squid, smaller sharks, jellyfish, shrimp, and sea cucumbers. They use their very strong jaws and sharp teeth to bite their prey. It is believed that they consume less food during winter when they spend more time in deeper water. During the spring and summer months, they swim towards the coasts where it is warmer, and they can find more food.

Reproduction and Lifespan

Males reach the age of sexual maturity around the age of 11 years, and females reach the age of sexual maturity by the time they are 12 or 14 years old. Mating normally takes place in offshore waters with internal fertilization.

After fertilization, a hard shell forms around the embryos to keep them protected. This shell will shed off after four to six months, but the young fish will continue to gestate for 18 to 20 more months. This means that the total gestation period for the Spiny Dogfish is about 2 years, the longest of any vertebrate.

On average, six pups are born in each litter. There could be as few as two pups or as many as 11 pups in each litter, though. The pups are between 20 and 33 centimeters long when they are born. Nearly right away, Spiny Dogfish will begin hunting for food. They may even start hunting food that is more than twice their size.

The lifespan of these sharks is typically between 20 and 24 years, but there have been some that lived to be 50 years old.

Fishing and Cooking

These sharks are fished both commercially and recreationally. Their meat is particularly popular in France, Italy, Germany, England, and other European countries. They are also eaten in the United States, Chile, Canada, New Zealand, and other places around the globe.

In Chinese cuisine, they are used to make fin-needles as an alternative to shark fin soup. The fins and tails of these sharks are used to make the fin needles. Spiny Dogfish are sold as “huss” in England, “small salmon” in France, and “sea eel” in Germany and Belgium.