The Pacific Spiny dogfish (Squalus suckleyi) is a common species of dogfish of the family Squalidae. They are one of the most common and plentiful sharks in the world. Only modern research and scientific techniques were able to successfully re-classify this species as an individual, instead of classifying it the same species as the Piked dogfish or sometimes called the Spiny dogfish. These techniques used were meristic, morphological and molecular data collection.
Family: SquAlidae – Dogfish Sharks
Genus: Squalus
Species: suckleyi
Phylum– Chordata
Class– Chondrichthyles
Subclass– Elasmobranchii
Common Name– Dogfish Sharks
Family– Squalidae
Common Name– Dogfish Sharks
Genus– Squalus
Species– suckleyi
Status: IUCN Red List LEAST CONCERN
Average Size and Length: The maximum length of a Pacific Spiny dogfish can be up to 4.3 feet, though typically measure around 3.3 feet.
Average Weight: Female Pacific Spiny dogfish reach a weight of 15 to 20 pounds by maturity, while the males are smaller.
Teeth and Jaw: The mouth is small and crescent-shaped. The teeth of the Pacific Spiny dogfish are flat with sharp edges, better for grinding than tearing. The teeth are organized into several rows.
Head: The Pacific Spiny Dogfish has a flattened head, blunt, tapered snout, and large eyes closer to the snout than the first gill slit. There are spiracles present behind the eyes.
Tail: They have a larger caudal fin.
Demographic, Distribution, Habitat, Environment and Range: The Pacific Spiny dogfish can be found in the northern Pacific Ocean and they prefer to be in temperatures ranging from 45 to 59 degrees Fahrenheit. They range from Korea, Japan, and Russia. They are also found in the Gulf of Alaska down to Baja, California. They can be found inshore and offshore and in bays, on the bottom of the continental shelves. They have been found at depths anywhere between 49-4,055 feet.
Analyses of tagged Pacific Spiny dogfish have shown a seasonal north-south migration along the west coast of the United States and Canada as well as a seasonal pattern of Pacific Spiny dogfish tagged in the inside waters of the Puget Sound repeatedly leaving that area for outside coastal waters in the summer. The Canadian (BC) group were mostly recaptured in the same area, however 10 were recaptured near Japan. There are some suggestions that they undergo trans-Pacific migrations (McFarlane, G. A., & King, J. R. (2003). “Migration patterns of spiny dogfish (Squalus acanthias) in the North Pacific Ocean“. Fishery Bulletin. 101 (2): 358–367).
Diet: They are known to eat mollusks, octopus, squid, crustaceans and small bony fish. Pacific Spiny dogfish are able to eat more carbohydrates compared to other elasmobranchs. The rectal gland is activated when they consume food. This gland helps the Pacific Spiny dogfish become glucose dependent. This means that they have the ability to break down a small amount of glucose (Yang, M-S (November 2017). “Diets of Spotted Spiny Dogfish, Squalus suckleyi, in Marmot Bay, Gulf of Alaska, Between 2006 and 2014“).
Predators include larger sharks, whales like Orca, seals and even larger bony fish.
Aesthetic Identification: The Pacific Spiny dogfish has a cylindrical shaped body. The dermal side is gray color with scattered white spots while the ventral side is lighter white/light gray in color. The first dorsal fin of the Pacific Spiny dogfish is somewhat larger than the second dorsal fin. Both dorsal fins have spines preceding them. The annuli on the enamel that makes up the spines can be used scientifically for age estimation. Some suggest that the spines are venomous. No anal fin.
Biology and Reproduction: The Pacific Spiny dogfish has a slow growth rate and they can live up to 100 years. On average maturation is 25 years, but anywhere from 10-30 years.
Pacific Spiny dogfish are ovoviviparous. Fertilization usually occurs from the beginning of October to the beginning of February. Their gestation period is between 18-24 months. Pacific Spiny dogfish that live in cooler water may have an increased duration of pregnancy. Females are also known to migrate from deep to shallow water as the pregnancy continues. This migration pattern is known to influence embryonic growth.
The size of the litter ranges anywhere from 1 to 20 pups. The length of a newborn Pacific Spiny dogfish is around 8.7-9.1 inches. Females seem to be significantly larger than male dogfish. At sexual maturity the male dogfish is 1.9-2.3 feet while the female is about 2.3-3.3 feet.
Behavioral Traits, Sensing and Intelligence: Some believe that when threatened, the Pacific Spiny dogfish will curl into a ball exposing their spines in defense, however this is not confirmed.
There is age and sex segregation. Females are typically seen inshore and pups and juveniles are seen offshore.
Speed: The first dorsal fin helps the Pacific Spiny dogfish maintain a stable body position while swimming, while the second dorsal fin supports generating thrust. The caudal fin is larger than normal, which helps them maneuver through the water quickly without wasting energy. They can remain motionless on the bottom of the ocean floor.
Pacific Spiny Dogfish Future and Conservation: Although Pacific Spiny dogfish have extremely slow reproductive and growth rates, they are not vulnerable to overfishing currently. In the past they were targeted for their oil, meat and fins, but this was a long time ago. No current conservation efforts are in place because currently they are of least concern.
Pacific Spiny Dogfish Recorded Attacks on Humans: Not a threat to humans.