About Pollachius virens (Linnaeus, 1758)
Pollachius virens can be distinguished from the closely related Pollachius pollachius through several physical traits. Unlike P. pollachius, which has a longer underslung lower jaw, P. virens has upper and lower jaws of approximately equal length, creating a distinctively different head profile. P. pollachius is typically brown or golden with a dark back, while P. virens is bright silver with a very dark green back. P. virens also generally has relatively smaller eyes than P. pollachius. The lateral line of P. pollachius has a noticeable kink over the pectoral fins, while the lateral line of P. virens is straighter. Additionally, the fresh uncooked flesh of P. virens is darkly coloured (a trait that gives it the common name coalfish), while the flesh of P. pollachius matches the typical pale colour of other cod family members. Adult P. virens usually live 16 to 20 years and grow to 100 to 120 centimetres (40 to 45 inches), though individuals as large as 130 cm (50 in) weighing up to 32 kg (71 lb) have been caught. The current IGFA All-Tackle World Record for the species is 22.7 kilograms (50 lb 1 oz), caught at Saltstraumen in Norway. This species is common in the northern regions of the North Atlantic Ocean, including the Bay of Biscay. Juvenile P. virens are typically found close to shore, especially in rocky areas, and move into deeper water as they mature. Saithe (another common name for P. virens) reach sexual maturity between 4 and 9 years old. They are iteroparous batch spawners with determinate fecundity. Depending on the female's size, they produce between 500 thousand and 9 million eggs, each with a diameter of 1.0 to 1.3 millimetres (5⁄128 to 7⁄128 in). Coalfish is edible and has commercial value, though it is considerably less valuable than premium whitefish such as cod and haddock. It can be salted and smoked to produce a salmon-like orange colour. In Germany, the fish is commonly sold as Seelachs, which translates literally to 'sea salmon', even though it is not closely related to any salmon species. While a large portion of the saithe consumed in Europe is caught in British waters, the species is not popular with consumers in Britain. Most of the British saithe catch is therefore exported to France, where it is widely eaten. The dark colour of coalfish's fresh uncooked flesh has led to the undeserved reputation that it is poor quality for eating. Saithe often congregate around fish farms and feed on uneaten salmon feed that passes through the net walls of the farm cages. Fishermen generally believe that saithe caught near fish farms is of poor quality. Quality testing shows only relatively minor differences in fillet quality between saithe caught close to fish farms and those caught farther away, but catches taken near fish farms do have a higher proportion of poor-quality individuals. There is a detectable difference in taste between saithe associated with fish farms and those that are not, but study results conflict on which group tastes better, so preference is likely a matter of consumer choice. Along with the more commonly used cod and Alaska pollock, saithe can be used to make fish fingers. Saithe is also used as food for domestic cats.
