Topic: Porbeagle

The porbeagle can be up to 3 m long and weigh up to 150-200 kg, roughly half the size of the white shark, but an impressive sight nonetheless. It is the most common species in the Family Lamnidae (sometimes referred to as mackerel sharks) in our waters and has a wide distribution across the North Atlantic, the Mediterranean, and along the Norwegian coast north to the Barents Sea. Porbeagles usually stay some distance offshore where they tend to hunt at or near the surface. In winter they tend to remain in deeper waters between 200-1000 m deep.

Characteristic features

Like most active swimmers, the porbeagle has a conical snout, a torpedo-shaped body, and a large, powerful crescent-shaped tail. It has a bluish-grey dorsal and creamy-white ventral coloration, a countershading strategy used by many active swimmers to camouflage them from above and below. Like other mackerel sharks, the porbeagle has an impressive set of teeth arranged in multiple rows, which function like a conveyor belt whereby the back rows continually replace any teeth lost in the heat of battle. The teeth are smooth and sharp with two small lateral cusps. These features make the porbeagle an efficient top predator, feeding primarily on schooling fish such as herring, mackerel, horse mackerel, as well as squid and other fishes.

Biology

Males generally mature at 4-5 years of age, and females 1-2 years later, at which point they are around 1.5 m long. Like many other sharks, porbeagles are ovoviviparous, a reproductive mode in which embryos hatch from egg-cases within the mother’s uterus and are born as fully developed pups that are immediately ready to swim and hunt. Mothers usually give birth in May-June, after a gestation period of around 8 months, to up to four pups each approximately 60 cm in size. Porbeagles are thought to reach around 30 years of age. These characteristics mean that porbeagles have a much slower recruitment than many other species.

Fishery

Porbeagle meat is considered a delicacy and has been compared to veal. The consumption of porbeagle meat is not a tradition in Norway, and Norwegian landings have generally been exported to other parts of Europe where there was a higher demand for its meat. Its liver was sometimes used to produce liver oil (tran) and its skin used to produce leather. The Norwegian longline porbeagle fishery dates back to the 1920s, largely in the North Sea-Skagerrak area, around the Shetland-Orkney islands and along the coast of Vestlandet. Annual landings in the 1960s were around 1000 to 2000 tonnes, but peaked at close to 4000 tonnes for a short period in the 1930s. From 1970 onwards, landings dropped significantly and this fishery was considered a thing of the past. A strong fishing pressure has likely contributed to population declines, and today the porbeagle is included on multiple international lists of endangered and protected species.

The population has shown signs of recovery in recent years, and ICES has issued non-zero catch advice since 2023. However, the porbeagle remains a protected species in Norway and the EU, and live porbeagles caught as bycatch must be released.