A stout, spindle-shaped shark with large black eyes, a sharp, conical snout, long gill slits, and small, smooth-edged, narrow teeth with side cusps. Strong keels on the caudal peduncle, short secondary keels on the caudal base, and a crescentic caudal fin; the insertion of the small second dorsal fin is above the insertion of the anal fin. Dark grey dorsally, white ventrally, without blotches; rear tip of 1st dorsal abruptly white.

Biology

Length: It reaches a maximum size of 357 cm total length (TL), though maximum size is likely larger in the North Atlantic as individuals >230 cm TL are rare in the Southwest Pacific. Males mature at 140–165 cm TL in the Southern Hemisphere and 155–177 cm TL in the North Atlantic, females mature at about 170–195 cm TL in the Southern Hemisphere and 200–219 cm TL in the North Atlantic. Size at birth of 68–78 cm TL. 

Gestation Period: 8-9 months

Litter Size: 1-5

Life Expectancy: Female age at maturity is 13 and 16.5 years and maximum age is 26 and 60 years; generation length is therefore 19.5 and 38.3 years, respectively. 

Diet: Feeds on small and medium-sized pelagic schooling species, other sharks, squid and demersal fishes (cod, white hake, red hake, haddock and cusk.

Habitat and distribution

Habitat: Occurs inshore to offshore fishing banks and occasionally to open ocean areas. It is migratory, moves generally along the continental shelves (inshore to surface during simmer) and winters offshore in deeper water. Most abundant on continental offshore fishing banks but also found far from land in ocean basins and occasionally close inshore.

Distribution: The Porbeagle has an anti-tropical and disjunct distribution, occurring in the North Atlantic and Southern Hemisphere in temperate and cold-temperate waters (Ebert et al. 2013). Porbeagles do not occur in the North Pacific, where they are replaced by the congener, the Salmon Shark (Lamna ditropis).

Depth: 0-1809 m

Landing sites: 

Commercial Value

The Porbeagle is used for its fins, liver oil, and high-quality meat. Together with the Salmon Shark, the two species accounted for 0.2% of the fin imported in Hong Kong in 2014. In some counties, such as Spain, Porbeagle meat accounts for a significant proportion, at 15%, of all shark meat imported annually.

Threats

The Porbeagle is caught globally as target and bycatch in commercial and small-scale pelagic longline, purse seine, and gillnet fisheries. Most of the catch is taken as bycatch of large-scale pelagic fleets in offshore and high-seas waters. It may also be captured in coastal longlines, gillnets, trammel nets and sometimes trawls, as well as on rod on reel, particularly in areas with narrow continental shelves. The Northeast Atlantic stock has the longest history of commercial exploitation with the highest catches during the 1930s and 1950s.

Porbeagles are often retained for their meat and fins, although fishing and/or retention is prohibited in some areas. Under-reporting of catches in the pelagic and domestic fisheries is likely. The species is highly valued by recreational fishers, and although many practice catch and release, recreational fishing could be a threat due to post-release mortality. The post-release mortality on commercial longlines has been reported as 10–75%. 

References

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Campana, S.E., Gibson, A.J.F., Dorey, A. and Joyce, W. (2013) 
Population dynamics of Northwest Atlantic porbeagle (Lamna nasus), with an assessment of status and projections for recovery. Research Document 2012/096. Canadian Science Advisory Secretariat, Fisheries and Oceans Canada.

Campana, S.E., Joyce, W., Fowler, M. and Showell, M. (2016) 
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