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Sharks of Onslow County
Atlantic Spiny Dogfish

Taxonomy & Biology

Taxonomy

Common Name(s): Atlantic spiny dogfish, spurdog, piked dogfish

Scientific Name: Squalus acanthias

Classification:

  • Kingdom: Animalia
  • Subkingdom: Bilateria
  • Infrakingdom: Deuterostomia
  • Phylum: Chordata
  • Subphylum: Vertebrata
  • Infraphylum: Gnathostomata
  • Class: Chondrichthyes
  • Subclass: Elasmobranchii
  • Superorder: Euselachii
  • Order: Squaliformes
  • Family: Squalidae
  • Genus: Squalus
  • Species: acanthias

Biology

Population

They school together as juveniles by size until they reach sexual maturity, then they aggregate by sex and size (ASFMC, 2021).

Body Size

Females grow to about 29.5 inches; males to about 23.6 inches. Babies are born at about 14 inches (NOAA, 2021).

Feeding & Diet

They are opportunistic feeders. It has recently been found that they follow much of their prey through the water column. Their most activity, discovered by PSAT tagging, found that they preferred morning and early afternoon. While they eat crustaceans, they target the following fish through the water column (Sagarese et al., 2016):

  • Butterfish, Peprilus triacanthus
  • Atlantic Herring, Clupea harengus
  • Shortfin squid, Illex spp.
  • Longfin squid, Doryteuthis spp.
  • Atlantic mackerel, Scomber scombrus 

Position in the Food Web

Atlantic spiny dogfish are considered mesopredators. A mesopredator is a mid-ranking predator in the trophic level that preys on smaller organisms. Mesopredators are determined based on the role that they play in the food web rather than on individual characteristics. In the absence of apex predators, mesopredators may alter their foraging behavior and increase in abundance and can become the top predators in their ecosystems (Tambling et al., 2018).

Reproduction

Females reach sexual maturity at age 12, while males reach sexual maturity at age 6 (NOAA, 2021). They breed just off the continental shelf in pelagic waters in the winter (ASFMC, 2021). Females are oviviparous. When the female begins her litter, she will begin to carry and develop fertilized eggs for her next litter over the next 2 years. Their gestation period for each litter is 18-24 months (about 2 years), some of the longest gestation periods for sharks (Street, 2002; Oceana, 2021). Females breed every two years with 2 to 15 pups in each litter. They will deliver their pups offshore in the winter (ASFMC, 2021).

Natural Mortality

Predators include humans, larger sharks, other spiny dogfish, orca, seals, cod, and red hake (Street, 2002). They live to 35-40 years old (NOAA, 2021).

Biodiversity

The spiny dogfish inhabits temperate waters and subarctic latitudes of the North Atlantic and North Pacific oceans. Some species have been found in the Mediterranean and Black Seas. In the Northwest Atlantic, they are found from Labrador to Florida and from Nova Scotia to North Carolina where they are in most abundance (NOAA, 2021).

Demographics

They live in aggregate schools. As juveniles, they school by size, and as adults, they school by sex. Females are larger than males and live to be about 35-40 years old (NOAA, 2021). They have the longest gestation period for sharks – about 2 years (Street, 2002). Females are the target catch because they have the largest biomass, especially when they are pregnant because of their belly flaps. Its belly flaps are exported to England for fish and chips and in Germany for a beer garden snack called “shillerlocken” (ASFMC, 2021). In Maine, they utilize the squalamine and the liver for medical anti-cancer production (ASFMC, 2021).

Migratory Pattern

They do a north-south migration in the northwestern United States; to temperate waters in the winter and spring; and subarctic waters in the summer and fall. They stay in nearshore waters unless they are breeding, then they will seek more open water. One study in North Carolina in 2012 found Atlantic spiny dogfish in the estuary waters in higher temperatures later in the season than expected which was atypical behavior for the species. This coincided with a quick rebound of the species, a four-fold increase, after a rapid rate of decline (Bangley & Rulifson, 2014; Carlson et al., 2014)). It is suggested that their movement patterns may be making a change and thus creating the marked change in population dynamics (Carlson et al., 2014).

Atlantic spiny dogfish gather in schools. The Carson et al., 2014 study revealed that there are two different schooling groups: one in the north and one in the south. Each migrates at contrasting times, and it was previously thought that they may share ocean waters at the same time with each other at various times of the year. Their study found, through PSAT tracking, that the northern group migrated nearer to their territory than the southern group who was more widespread (Carson et al., 2014). They also determined that much of their migration patterns could also be dependent upon search and seek for water temperature variability with seasonal changes, prey availability and changing position in the water column (Carson et al., 2014). These dogfish are more likely to be caught in morning and peak in the afternoon based on diel movements of their prey (Sagarese et al., 2016).

Ecological Relationships

These sharks are considered “sentinel species”. Sentinel species are species that can provide information about environmental components of ecosystems that we may not be able to observe easily with equipment (Hazen et al., 2019). In Australia, there is an abundant population of spiny dogfish that nearly resembles pelagic shark species of the environment, and utilizing telemetry, they have been able to determine that the atypical behavior of spiny dogfish make them an ideal sentinel species for these larger pelagic shark species (Moreno Iturria, 2018). Spiny dogfish remained in an estuary system instead of remaining along the coastline and emigrating offshore which is atypical behavior (Moreno Iturria, 2018). Stomach analysis of these opportunistic feeders showed high prevalence of empty stomachs demonstrating no viable prey (Moreno Iturra, 2018). Observations of females over the long gestation period revealed no or few pregnancies that demonstrated a compromised reproductive population (Moreno Iturria, 2018). Examining the anthropogenic effects within the estuary revealed impacts of mining, aquaculture, and waste pellets (Moreno Iturria, 2018).

Danger to Humans

These sharks are harmless, although any captured species of shark can, and will try, to bite an inattentive angler.

Danger to Humans

As of June 2025, in North Carolina, the Atlantic spiny dogfish has specific recreational and commercial fishing regulations. Commercial fishing allows a trip limit of 15,000 pounds. The fishery is open from November through April 30, or once the quota has been reached. They are exempt from harvest size restrictions in both fisheries (NOAA, 2021). This species is not to be confused with the smooth dogfish/smoothhound shark listed with NC Division of Marine Fisheries.

Please Note: The fishing regulations and information provided on this website are for general information purposes only. While we strive to ensure the accuracy and timeliness of the content, fishing laws and regulations can change frequently and vary by location. It is the responsibility of each angler to verify the current local, state, and federal fishing laws before fishing. Always consult the official website or contact the appropriate wildlife and fisheries agency for the most up-to-date rules and regulations.

We are not liable for any penalties, fines, or legal issues that may arise from the use or misuse of the information on this site.

References

Carlson, A. E., Hoffmayer, E. R., Tribuzio, C. A., & Sulikowski, J. A. (2014). The use of satellite tags to redefine movement patterns of spiny dogfish (Squalus acanthias) along the U.S. East Coast: Implications for fisheries management. PLoS ONE, 9(7), e103384. https://doi.org/10.1371/journal.pone.0103384

Harris, A. (2019). How a handful of fishing villages sparked a marine conservation revolution [Video]. TED: Ideas Worth Spreading. https://www.ted.com/talks/alasdair_harris_how_a_handful_of_fishing_villages_sparked_a_marine_conservation_revolution?language=en (Links to an external site.)

Hazen, E. L., Abrahms, B., Brodie, S., Carroll, G., Jacox, M. G., Savoca, M. S., Scales, K. L., Sydeman, W. J., & Bograd, S. J. (2019). Marine top predators as climate and ecosystem sentinels. Frontiers in Ecology and the Environment, 17(10), 565-574. https://doi.org/10.1002/fee.2125 (Links to an external site.)

Hilborn, R., & Hilborn, U. (2019). Ocean recovery: A sustainable future for global fisheries? Oxford University Press, USA.

Hutchings, J. A., Myers, R. A., García, V. B., Lucifora, L. O., & Kuparinen, A. (2012). Life-history correlates of extinction risk and recovery potential. Ecological Applications, 22(4), 1061-1067. https://doi.org/10.1890/11-1313.1

Moreno Iturria, D. (2018). An unusual habitat for a common shark: life history, ecology, and demographics of the spiny dogfish (Squalus acanthias) in Macquarie Harbour, Tasmania.

NOAA. (2021). Atlantic spiny dogfish. NOAA. Retrieved January 23, 2022, from https://www.fisheries.noaa.gov/species/atlantic-spiny-dogfish (Links to an external site.)

Pauly, D. (2019). Vanishing fish: Shifting baselines and the future of global fisheries. Greystone Books.

Pauly, D., Christensen, V., Dalsgaard, J., Froese, R., & Torres, F. (1998). Fishing down marine food webs. Science, 279(5352), 860-863. https://doi.org/10.1126/science.279.5352.860

Sagarese, S. R., Frisk, M. G., Cerrato, R. M., Sosebee, K. A., Musick, J. A., & Rago, P. J. (2016). Diel variations in survey catch rates and survey Catchability of spiny dogfish and their pelagic prey in the Northeast U.S. continental shelf large marine ecosystem. Marine and Coastal Fisheries, 8(1), 244-262. https://doi.org/10.1080/19425120.2015.1135219

Stone, R. B., Michael Bailey, C., McLaughlin, S. A., Mace, P. M., & Schulze, M. B. (1998). Federal management of US Atlantic shark fisheries. Fisheries Research, 39(2), 215-221. https://doi.org/10.1016/s0165-7836(98)00185-4

Street, R. (2002). Squalus acanthias. Animal Diversity Web. Retrieved November 9, 2021, from https://animaldiversity.org/accounts/squalus_acanthias/ Worm, B., Davis, B., Kettemer, L., Ward-Paige, C. A., Chapman, D., Heithaus, M. R., Kessel, S. T., & Gruber, S. H. (2013). Global catches, exploitation rates, and rebuilding options for sharks. Marine Policy, 40, 194-204. https://doi.org/10.1016/j.marpol.2012.12.034
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