Called “dogfish” by fishermen who saw these sharks chasing smaller fish in large dog-like packs, they are also commonly referred to as “blue dog,” “common spinyfish,” “darwen salmon” and many more nicknames.
These sharks are found in the western Atlantic Ocean, from the tip of South America, along the eastern seaboard of the United States and the tip of Greenland/Iceland. They are also found in South Africa, in European waters, the southeastern tip of Australia and all of New Zealand, and the western coast of the United States (including Baja California) and around Japan/China.
As mentioned before, they swim in large packs of individuals who are around the same size. They continue to stay in this pack; immature packs tend to stay offshore while mature females are often seen inshore.
It should be no surprise that these animals are very migratory, migrating seasonally.
They have a slender, elongated body with a flat head and pretty large eyes. Both dorsal fins have spines in front of them. They are a gray/brown with white spots scattered along their body in lateral lines. These dots are brighter in immature individuals, and tend to fade as they continue to grow; they might disappear altogether from some adults. Their underbelly is sometimes a light gray to white.
So what do they spend 25-30 years doing? Harrassing fishermen.
In fact, dogfish are “pests” as they drive off and eat large quantities of their favorite fish, such as mackerel, menhaden, capelin, sand lace and herring. They bite through nets to get at fish, and can release many while doing this. However, their diets also include squid, jellies, shrimps, crabs, octopus and sea cucumbers (ew, who would want that in their diet I have no idea).
During the winter, it is hypothesized that these animals do not eat as much, as they are in deeper waters. Nobody has confirmed this (at least to my knowledge).
Mating is usually offshore, and litter sizes range from 1-15 with the average being 6-7. They are ovoviviparous, and gestation is thought to be up to 24 months, the longest gestation period of any vertebrate.
Again, to all pregnant readers, be glad you are not a shark. And if you are not pregnant, thank your mother for not being a shark.
Click HERE for "A Firsthand Observation Of A Spiny Dogfish Giving Birth In The Wild."
If you’ve heard of the recent Massachusetts ban, it doesn’t include spiny dogfish in it. Landing of spiny dogfish in 1974 was 27,400 metric tons (mt); they are usually caught in trawls or gill nets. It declined in the 80’s to 5,900 mt, and in the 1990s rose over 28,000 mt.
Ever had fish and chips? Your “fish” might actually be spiny dogfish! They are also used for their oil and used as fish meal. If you’ve had a biology class where you dissect a shark, it’s probably a spiny dogfish, too.
In 2001, the Atlantic States Marine Fisheries Commission (ASMFC) extended action to close state waters to fishing for these animals. Federal and state recovery plans are currently in place but continually challenged. In mid 2003, the ASMFC voted to lower the spiny dogfish quota to a level supported by scientific data (hooray politics using science). However, this it failed to achieve the 2/3 majority rule.
The National Marine Fisheries Service is in charge of regulating shark fisheries in federal waters. The spiny dogfish is considered as "Vulnerable" by the IUCN.