| ||Squalus spinax Olivius, 1780, (not Linnaeus, 1758 = Etmopterus spinax).|
| ||Squalus fernandinus Molina, 1782|
| ||Acanthias antiguorum Leach, 1818|
| ||Acanthias vulgaris Risso, 1826|
| ||Acanthias americanus Storer, 1846|
| ||Spinax mediterraneus Gistel, 1848|
| ||Spinax (Acanthias) suckleyi Girard, 1854|
| ||Acanthias sucklii Girard, 1858, (error for suckleyi ?).|
| ||Acanthias linnei Malm, 1877|
| ||Acanthias lebruni Vaillant, 1888|
| ||Acanthias commun Navarette, 1898|
| ||Squalus mitsukurii Tanaka, 1917(not Jordan & Fowler, 1903).|
| ||Squalus wakiyae Tanaka, 1918|
| ||Squalus kirki Phillips, 1931|
| ||Squalus whitleyi Phillipps, 1931|
| ||Squalus barbouri Howell-Rivero, 1936|
|En - Picked dogfish, Fr - Aiguillat commun, Sp - Mielga.|
3Alpha Code: DGS Taxonomic Code: 1090100704|
|Scientific Name with Original Description|
|Squalus acanthias Linnaeus, 1758, Syst. Nat., ed. 10, 1: 233. Holotype: Unknown. Type Locality: "Oceano Europaeo."|
Body fairly slender. Snout subangular, pointed, narrow, and moderately long, diagonal distance from snout tip to excurrent aperture of nostril greater than that from excurrent aperture to upper labial furrow, preoral snout about 1.2-1.3 times mouth width, preorbital snout less than twice eye length. Eyes about equidistant between snout tip and first gill slits. Nostrils nearer snout tip than mouth; anterior nasal flap with posterior secondary lobe minute or absent. Lateral trunk denticles small, tricuspidate and with deeply scalloped posterior borders in adults.
Pectoral fins narrow and falcate, posterior margins slightly concave, rear tips narrowly rounded. Pelvic midbases closer to second dorsal base than to first. First dorsal spine short, much shorter than fin base and with tip falling far below apex of fin; second moderately long, about as high as fin, and less than 5% of total length; first dorsal fin more posteriorly situated, with origin over or behind pectoral free rear tips and spine origin behind tips; first dorsal low, height less than half length from origin to rear tip; second dorsal markedly smaller than first, with height less than 5% of total length; pectoral fins narrow and falcate, posterior margins slightly concave, rear tips narrowly rounded; pelvic midbases closer to second dorsal base than to first; caudal fin narrow-lobed and moderately long, with a long ventral lobe and strongly notched postventral margin. Upper precaudal pit well developed on caudal peduncle.
Colour gray above, white below, usually with conspicuous white spots present on sides of body, dorsal and fins without white edges but dusky-tipped in young and plain in adults. Size moderate to large, up to 1.5 m but mostly smaller.
|fieldmarks: Two dorsal fins with ungrooved large spines, first dorsal spine origin behind pectoral rear tips, white spots on gray sides, oblique-cusped cutting teeth in both jaws, no subterminal notch on caudal fin, no anal fin, and upper precaudal pit and lateral keels on caudal peduncle.|
|AntetropicalWestern Atlantic: Greenland and Labrador (Canada) to Florida (USA), Cuba; Uruguay and Argentina. Eastern Atlantic: Iceland and Murman Coast (Russia) to Morocco, West Sahara, Canary Islands, Mediterranean and Black Sea; Cape coast of South Africa. Western Pacific: Bering Sea to Japan, Sea of Okhots, Republic of Korea and northern China; southern Australia, New Zealand, ? Papua New Guinea. Eastern Pacific: Bering Sea to southern Baja California, possibly Gulf of California; Chile.|
|Habitat and Biology|
|An extremely abundant, boreal to warm-temperate,inshore and offshore dogfish of continental and insular shelf waters and the upper slopes, from the surface down to the bottom but usually near the bottom; found from the intertidal down to at least 900 m.This is possibly the most abundant living shark, despite its restricted range, and the only one that supports fisheries of a size rivalling those of the more commercially important bony fishes. Bigelow & Schroeder (1948) noted that in a time of peak abundance in 1904-05 an estimated 27,000,000 dogfish were taken off the Massachusetts coast each year. The piked dogfish is probably the best-known of living sharks, particularly from a morphological, experimental and fisheries-biological viewpoint, though its ecological relationships and ethology is far less well known than some other sharks, particularly certain tropical carcharhinids and sphyrnids. Knowledge of its biology clearly reflects the concerns of fisheries and the interests of fisheries biologists, as well as its great abundance, but even with the massive corpus of information available great gaps remain in our knowledge of its biology. The literature on this shark is so enormous that only a small amount of the available information can be presented here. [more...]|
The dogfish forms immense feeding aggregations or packs in rich foraging grounds and may be present in thousands.Longline sets of 700 to 1500 hooks with nearly every hook bearing a dogfish have been reported from the Western North Atlantic. Dogfish often occur in schools segregated by size and sex, including those of small juveniles of both sexes in equal numbers, mature males, larger immature females, and large mature females. Mixed schools of adults have also been reported, but at best these are probably less common than segregated schools. These schools are dense and localized in a given area, and move erratically over short periods of time, possibly reflecting pursuit of schooling prey fishes. In general, males occur in shallower water than females, with the exception of large pregnant females. Pregnant females may congregate in enclosed shallow bays like San Francisco Bay in California, and drop their young there. Dogfish are also found as solitary individuals and may also associate with schools or aggregations of other temperate sharks such as the leopard shark (Triakis semifasciata ) and the brown smoothhound (Mustelus henlei ) in the Eastern North Pacific. Although the piked dogfish is often found in enclosed bays and estuaries, and can tolerate brackish water, it apparently cannot survive fresh water for more than a few hours and does not occur there. During the rainy winter and spring of California dogfish may leave San Francisco Bay and other shallow bays and estuaries as the salinity drops, but return in late spring and summer. Much has been written of the seasonal, bathymetric, and localized movements of this shark.An important correlate of dogfish movements seems to be water temperature; the sharks favour a temperature range with a minimum of 7-8°C and maximum of 12-15°C, and apparently make latitudinal and depth migrations to stay within their optimum range.
Thus in the Western North Atlantic dogfish move inshore from their wintering grounds in deep water off the US Middle Atlantic and Southern States as the water warms in spring, pressing northwards along the coasts of Newfoundland and Labrador and southwards along the US Atlantic coast occasionally to Cuba. [more...]
An ovoviviparous shark, with litters of 1 to 20 young. There is much regional variation in reported litter sizes that may be correlated with other factors than maternal size, but in general larger mother sharks have larger litters of fetuses that attain a larger size before birth than smaller ones. The gestation period is variously reported as 18 to 24 months, and may differ in areas. Mating of dogfish may occur in the winter. Birth in the dogfish may occur primarily during the cold months of the year, with considerable variation and with some young produced in spring and summer. The sex ratio at birth is 1:1. Young are delivered head first with a series of rhythmic contractions reminiscent of birth in mammals.
Age of piked dogfish is commonly determined by counting annual growth rings on the fin spines, though wear of the spines in large dogfish may limit the usefulness of this method. This is apparently a slow-growing and maturing species, that is very long-lived. Ages at maturity may vary regionally, and has been variously reported as 10-20 years for females and 11 or more years for males. Ketchen (1975), trying a variety of methods on British Columbian dogfish estimated an average of 14 years to maturation for males and 23 years for females. Maximum age is at least 25 to 30 years, with some estimates going much higher and approaching 100 years.This shark is a powerful, voracious predator that feeds primarily on bony fishes, and is capable of dismembering rather large prey with its strong jaws and clipper-like teeth. Its bony fish prey includes herring, sardines, menhaden and other clupeids, true smelt (Osmeridae) and their eggs, hake, cod, pollock, ling, haddock and other gadoids, midshipmen, blennies, sand lances, mackerel, porgies, croakers, flatfish and sculpins. [more...]
The main impact of this shark on people is economic, however: both negative, as it displaces or chases off other fishes, gets hooked or netted in gear intended for other species, damages fishing gear, and destroys hooked and netted fishes; and positive, as a fisheries species and an integral and important member of offshore and inshore marine communities. Suggestions have been made to 'control' the numbers of dogfish in the western North Atlantic, by a variety of sometimes bizarre methods, though the necessity of doing this is largely a result of prejudice against dogfish as human food and unreasoned hatred for these sharks. [more...]
Apart from human beings, this shark is preyed on by a number of larger sharks, some bony fishes, seals and killer whales.
|May exceptionally reach 160 cm in the eastern north Pacific, but most individuals there are smaller, and other populations apparently reach smaller maximum sizes. Size of males at maturity from 59 to 72 cm and maximum size of mature males from 83 to 100 cm; size of females at maturity from 70 to 100 cm and maximum size of mature females from 101 to 124 cm; size of young at birth 22 to 33 cm.|
|Interest to Fisheries|
|This is one of the most important sharks for fisheries because of its abundance in colder waters, utilization in various fisheries, and damage it does to gear and catches of other fishes. Catches of Squalus acanthias reached a peak in 1972 (73,500 t) then declined but in the last decade they have stabilized in a range between 36,000 and 51,000 t. Most of the catches reported to FAO have come firstly from area 27 (Northeast Atlantic) and then from area 21 (Northwest Atlantic) but in 1995 and 1996 catches taken in area 21 have exceeded those from area 27. Minor catches have been reported from Northeast Pacific (maximum 5,314 t in 1988) and Mediterranean and Black Sea (peaking at 1,789 t in 1988 but only 143 t in 1996).The total catch reported for this species to FAO for 1999 was 22 756 t. The countries with the largest catches were Canada (5 536 t) and Norway (1 461 t). It is captured primarily in bottom trawls and with longlines and handlines, but also commonly with gill nets seines, fish traps, and other gear; it is also readily taken by rod and reel .|
It is utilized fresh, fresh-frozen, smoked, boiled-marinated, dried-salted, and in the form of fish cakes for human consumption. It is also used for liver oil, fish meal, pet food, fertilizer and leather.
There are and have been numerous fisheries for picked dogfish around the world. There have been several cases of overexploitation of this species, which is the most abundant shark in the world (Compagno 1984), but the enormous abundance of the stocks usually prevents a total collapse and the fisheries normally stop for economic reasons. A combination of overexploitation, shifting markets and economic constraints has caused almost all picked dogfish fisheries to undergo declines. In most of these fisheries, the larger females are primarily targeted and this usually leads to overexploitation of the female stock while the male stock might be still at a healthy level (Holden 1968, Bonfil in press b). In European waters (mainly the North and Irish Seas), picked dogfish has been fished since the beginning of this century mainly by British and Norwegian fishermen, but later also by the French and the Irish (Bonfil 1994). Total catches were on average of 3,000 t/y before the 1930s, rose to over 12,000 t/y by 1937 mainly due to increases in the Norwegian fishery and then varied between 20,000-42,000 t/y in the period 1951-70 (Holden 1977). Holden (1968) considered that the female part of the Scottish-Norwegian stock of picked dogfish was being overfished in the late 1960s, but no stock assessments are known for any of the European fisheries for picked dogfish. Holden (1977) and Myklevoll (1989d) illustrate many of the factors that have caused the variations in the catches of picked dogfish in the British and Norwegian fisheries. These include among others, differences in size and presentation of the product due to different capture methods, competitiveness of prices, limits on market demand, and the existence of alternative and more profitable fisheries. The British Columbia picked dogfish fishery, which dates at least from the mid-19th century, has undergone also several booms and busts due mostly to economic factors (Ketchen 1986, Bonfil in press b).
However, Ketchen (1986) reported a few signs of overexploitation for this stock during the heavy and uncontrolled vitamin A fishery, which might have brought about a large decline in the biomass of some local picked dogfish stocks. With that exception, the picked dogfish in the Northeastern Pacific has always remained at healthy levels. In Irish waters, a fishery for picked dogfish developed rapidly during the 1980s but decreasing catches in the NW fishing grounds shifted the effort towards the SW. This, together with the disappearance of larger females from the catches caused the concern of the Irish Department of the Marine (Rose 1996). In the western North Atlantic an increase in biomass of local picked dogfish stocks and a strong decline in more valuable groundfish stocks spurred an increase in dogfish exploitation mainly by US fishermen. Total dogfish catches rose from some 5,000 t/y in the mid-1980s to 22,500 t in 1993 (Rago et al . 1994). Most of this production of picked dogfish is exported to several markets in Europe for human consumption. The recreational catch of picked dogfish in this region is only about 8% of the commercial catch but large amounts of discards are suspected to happen in the size-discriminating commercial fishery and could add up to some 14,000 t/y (Rago et al. 1994). Fishable biomass of the NW Atlantic stock is estimated to have increased six-fold in the period 1968-89 to a peak of 300,000 t and then declined due to exploitation to less than 150,000 t (ICES 1998). A pronounced decrease in mean length of females has also been detected in this fishery where recently over 75% of the landed females were immature. The US Atlantic fishery is reported to have been recently declared as overexploited and a management plan is currently under preparation (ICES 1998).
Conservation Status : Smith et al. (1998) found that the picked dogfish has the lowest intrinsic rebound potential of the 26 shark species they analysed. This is due to the extreme biological characteristics of this species, which is very slow growing and attains sexual maturity after many years. The abundance of picked dogfish is certainly very high in general but the declines in several heavily exploited stocks signal the high likelihood of impacting individual stocks if not managed properly. This species seems to be a good candidate for Lower Risk/Least Concern at the world level and Lower Risk/Conservation Dependent in the NE and NW Atlantic where it is heavily fished and still unmanaged.
|Threat to humans: This is not a 'dangerous' species in the sense of attacking people in the water, but is a hazard to those who catch it because of its sharp teeth and toxic fin spines. The piked dogfish can curl itself and whip its tail about to inflict wounds with the long, sharp, second dorsal spine. The toxin is mildly irritating to most people, but some people can have a strong allergenic reaction to it and require hospital care.|
Bass, d'Aubrey & Kistnasamy, (1976)
Bigelow, & Schroeder, (1948, 1957)