Scomber scomber Linnaeus, 1758
The Atlantic mackerel (Scomber scombrus), also known as Boston mackerel, Norwegian mackerel, Scottish mackerel or just mackerel, is a pelagic schooling species of mackerel found in the Mediterranean Sea, the Black Sea, and the north Atlantic Ocean. The fish's dorsum is steel-blue and marked with wavy black lines, while the belly is silvery-white. One distinguishing feature is the wide spacing between the dorsal fins. An Atlantic mackerel can reach sizes of up to 60 cm (2.0 ft) and 3.4 kg (7.5 lb). During the summer, which it spends close to shore, it is extremely common in huge shoals near the ocean surface. When fall arrives, the mackerel begin moving out into deeper and more southern waters, reappearing along the coast in spring. Atlantic mackerel reach sexual maturity at around 2 years old and can live to be 17. Reproduction is oviparous and occurs during the summer months, during which a female can produce as many as 450,000 eggs. Despite its highly commercial status, the Atlantic mackerel is listed as Least Concern by the International Union for the Conservation of Nature (IUCN) and global catch has remained sustainable.
Taxonomy and phylogeny
|Phylogenetic tree of Scomber.|
The Atlantic mackerel was first described in 1758 by Swedish zoologist Carl Linnaeus in his 10th edition of Systema Naturae. Linnaeus gave it the scientific name Scomber scomber from the Greek word skombros meaning "tunny" or "mackerel." Because of its wide distribution, the Atlantic mackerel was independently described 6 more times by 5 different scientists between 1814 and 1863. Its specific name was later changed to scombrus by B. B. Collette and C. E. Nauen in 1983. It is differentiated from its congeners in a number of ways, the first being the absence of a swim bladder. Its palatine bone is also wider than other members of its genus and its otolith is oval-shaped where its congeners' are rectangular.
In the eastern Atlantic Ocean there are three three stocks differentiated by location and time at which spawning occurs, but studies have not found any distinct genetic differences between these populations. Genetic differences only start to appear at the transatlantic scale, a fact supported by a lack of migration between western and eastern Atlantic populations, whereas eastern Atlantic stocks are known to converge in certain locations like the Norwegian Sea and North Sea.
The Atlantic mackerel has an elongate, fusiform body with a long, pointed snout. The eyes are large and covered by an adipose eyelid, while the teeth are small, sharp, and conical. Scales are also small, with the exceptions of those immediately posterior to the head and around the pectoral fins. These small scales give the Atlantic mackerel a velvet-like feel. The two dorsal fins are large and spaced far apart. The second dorsal fin is typically followed by 5 dorsal finlets, though it can have 4 or 6. The anal fin, which originates slightly behind the second dorsal fin, is similar to it in size and shape and is also succeeded 5 by finlets. The fish's body tapers to a slim caudal peduncle, the end of the fish to which the short but broad tail fin is attached. Its body is steel-blue dorsally with wavy black lines running perpendicular to the fish's length. The rest of its body is silvery-white to yellow and may have darker splotches. It can reach sizes of up to 60 cm (24 in) and has a common length of 30 cm (12 in). Its maximum published weight is 3.4 kg (7.5 lb).
Distribution and habitat
The Atlantic mackerel's native range in the western Atlantic extends from Labrador, Canada to Cape Lookout, North Carolina. In the eastern Atlantic, it can be found from Iceland to as far south as Mauritania. It is also found in the Mediterranean, Black, and Baltic Seas. Its latitudinal range is 70°N-25°N and its longitudinal range is 77°W-42°E. Its preferred water temperature is above 8 °C (46 °F), but Atlantic mackerel are common in waters as cold as 7 °C (45 °F) and have been found, albeit rarely, in 4.5 °C (40.1 °F) waters. The Atlantic mackerel's common depth range extends from the surface to 200 m (660 ft), but individuals can be found as deep as 1,000 m (3,300 ft).
Atlantic mackerel are migratory fish, spending the spring and summer closer to shore about 32–161 km (20–100 mi) out, with juveniles moving closer in to shore than adults. Occasionally, fish will even enter harbors, and those that do are usually juveniles. In the fall and winter they move farther out and farther south to the warmer waters on the edge of the continental shelf. They first come in to land in North America in April at the southern end of their range, but are found along the coast through their entire range by July. They start moving back out to sea again in September and are completely gone from the coast by December. Food availability increases greatly during the summer, and fish reach a peak for fat tissue in August, a mere four months after their lowest point in April.
Biology and ecology
The Atlantic mackerel is an active, fast-moving fish that must keep in constant motion to bring in enough oxygen to survive. It swims using short movements of the rear of its body and the caudal fin. Unlike other mackerels, Atlantic mackerel don't leap out of the water unless attempting to escape a predator. They form large schools, consisting of individuals of the same relative size, near the ocean surface during all seasons but winter. Because larger fish have a greater ratio of muscle mass to surface area, schools of larger fish are able to swim more quickly than schools made up of smaller individuals.
When feeding on larger prey, schools tend to break down into shoals and individuals find food on their own. When consuming plankton, however, mackerels form tight aggregations, open their mouths as wide as possible, and extend their operculums, swimming in a tightly-packed school that acts like a series of miniature tow nets. Spaced only about the diameter of a single fish's mouth apart, this formation greatly reduces the ability of plankton to evade capture, as a plankton darting out of the way of one fish is likely to end up in the jaws of another. Copepods make up the majority of the Atlantic mackerel's diet and of the copepods it eats, Calanus finmarchicus makes up the greatest portion.
Like other mackerels, reproduction in the Atlantic mackerel is oviparous. Spawning occurs day or night in the spring and summer months, primarily within 48 km (30 mi) of shore, though it can occur as far out as 130 km (81 mi). A single female can spawn as many as 450,000 eggs in a spawning season. Eggs mature in batches over the course of a week and are pelagic once released, remaining within 15–25 m (49–82 ft) of the surface. Time to hatching is dependent on the water temperature, and ranges from 2 days at 21 °C (70 °F) to 8.5 days at 10 °C (50 °F). Most eggs are spawned in waters 9–12 °C (48–54 °F) in temperaure, and as such the majority of eggs hatch in about a week. Eggs are anywhere from 1.0–1.3 mm (0.039–0.051 in) in size, trending towards smaller as the spawning season goes on. Larvae undergo three developmental stages: the yolk sac stage, the larval stage, and the post-larval stage. Larvae are 3 mm (0.12 in) when they hatch and feed on the yolk sac for about 5 days. During the larval stage, which lasts about a month, larvae grow to 10 mm (0.39 in) in length. They are largely incapable of swimming, instead floating with the current. During the post-larval stage, which occurs over the next 40 days and during which the fish reaches 50 mm (2.0 in) in length, it swims to the surface at night and down to deeper waters during the day. At the end of the post-larval stage, juveniles resemble an adult mackerel in all but size. Schooling behavior occurs around this time.
Sexual maturity is reached at around 2 years of age, though some fish may reproduce a season earlier or a season later. Though some fish are sexually mature at 25 cm (9.8 in) in length, even by 34 cm (13 in) only about half of females will be ready to reproduce. At 37 cm (15 in), 90% of fish are capable of reproduction. An atlantic mackerel can live for up to 17 years and attain a length of 60 cm (24 in) and a weight of 3.4 kg (7.5 lb).
|Nutritional value per 100 g (3.5 oz)|
|Energy||858 kJ (205 kcal)|
|Vitamin A equiv.||
|Percentages are roughly approximated using US recommendations for adults.
Source: USDA Nutrient Database
The Atlantic mackerel is of commercial importance to many Atlantic fisheries, which catch it with purse seines, trawls, gill and trammel nets, and trolling lines. Catch data goes as far back as the 1950s, and has, for the most part, remained under 1 million tonnes. In 2014, however, a nearly 50% increase put worldwide catch at nearly 1.5 million tonnes. The countries that fish the most Atlantic mackerel are the United Kingdom and Norway, with catch coming in at over 166,000 tonnes and 160,000 tonnes respectively. There are three eastern Atlantic stocks: southern, western, and North Sea, which are found in the waters off of Spain and Portugal, near Ireland and the United Kingdom, and in the North Sea respectively. There are two populations in the Mediterranean, eastern and western, which are genetically distinct. In the western Atlantic there are two stocks, northern and southern, for which assessments are, according to the IUCN, "highly uncertain."
Atlantic mackerel are sought after for food either cooked or as sashimi and consist mostly of red meat with a strong taste desirable to some consumers. The fish is extremely high in vitamin B12 as well as omega 3 (a class of fatty acids) and contains nearly twice as much of the latter per unit weight as salmon. Unlike the King and Spanish species, Northern Atlantic mackerel are very low in mercury, and can be eaten at least twice a week according to United States Environmental Protection Agency guidelines. Mainly in Scandinavia and the United Kingdom, canned mackerel in tomato sauce, brine, or vegetable oil is sometimes eaten with salad or in sandwiches. Mackerel is an excellent source of phosphatidylserine, as it contains about 480 mg / 100 grams by weight.
Despite its commercial status, the Atlantic mackerel was assessed to be of Least Concern by the IUCN in 2011. Its abundance and extensive range combined with a cyclical increase/decrease in catch mean that it is not currently in danger of going extinct. The IUCN did recommend careful monitoring, however, especially as the effects of climate change may impact population size and distribution. In the northeastern Atlantic, several countries impose minimum landing sizes. In the European Union this size is 18 cm (7.1 in), Ukraine 15 cm (5.9 in), Turkey 20 cm (7.9 in), and Romania 23 cm (9.1 in)
- Collette, B.; A. Boustany; K. E. Carpenter; A. Di Natale; W. Fox; J. Graves; M. Juan Jorda; O. Kada; R. Nelson; H. Oxenford (2011). "Scomber scombrus". IUCN Red List of Threatened Species. Version 2010.1. International Union for Conservation of Nature. Retrieved 19 February 2017.
- Abdussamad, E. M.; Sandhya Sukumaran; Arun K. O. Ratheesh; K. Mohamed Koya; K. P. S. Koya; Prathibha Rohit; Sally Reader; K. V. Akhilesh; A. Gopalakrishnan (2016). "Scomber indicus, a new species of mackerel (Scombridae: Scombrini) from the Eastern Arabian Sea" (PDF). Indian Journal of Fisheries. 63 (3): 1–10. doi:10.21077/ijf.2016.63.3.59184-01.
- Froese, Rainer and Pauly, Daniel, eds. (2017). "Scomber scombrus" in FishBase. February 2017 version.
- Nesbo, Camilla L.; Eli K. Rueness; Svein A. Iversen; Dankert W. Skagen; Kjetill S. Jakobsen (2000). "Phylogeography and population history of Atlantic mackerel (Scomber scombrus L.): a genealogical approach reveals genetic structuring among the eastern Atlantic stocks". Proceedings of the Royal Society B. 267: 281–292. doi:10.1098/rspb.2000.0998.
- "Mackerel (Scomber scombrus)". gma.org. Gulf of Maine Research Institute.
- "Scomber scombrus". FAO.org. Food and Agriculture Organization of the United Nations. Retrieved 19 February 2017.
- Sette, Oscar Elton (1952). "Biology of the Atlantic mackerel (Scomber scombrus) of North America: Part II-Migrations and Habits" (PDF). Fishery Bulletin of the Fish and Wildlife Service. 51: 251–358.
- Sette, Oscar Elton (1943). "Biology of the Atlantic Mackerel (Scomber scombrus) of North America: Part I:Early life history, including the growth, drift, and mortality of the egg and larval populations" (pdf). Fishery Bulletin of the Fish and Wildlife Service. 50: 149–237.
- Media related to Scomber scombrus at Wikimedia Commons
- Data related to Scomber scombrus at Wikispecies
- EDF Report on Mackerel – Atlantic Mackerel conservation and contamination report
|External identifiers for Scomber scombrus|
|Encyclopedia of Life||46324676|
|Also found in: Wikispecies, FishBase|