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Porbeagle: the shark that plays with driftwood

According to the English Wikipedia, there are reports of porbeagles rolling in kelp fronds and chasing or nudging objects — driftwood and even anglers’ balloon floats. Wikipedia cautiously calls this apparent play. This article is about the porbeagle, *Lamna nasus* — Heringshai in German, marrajo sardinero in Spanish, smeriglio in Italian, requin-taupe commun in French (also maraîche), tubarão-sardo in Portuguese, haringhaai in Dutch, sildehaj in Danish, håbrand or sillhaj in Swedish, håbrann in Norwegian, sillihai in Finnish, атлантическая сельдевая акула in Russian, dik burun köpekbalığı in Turkish (GBIF), Λάμνα in Greek (also Λάμια, according to the Catalogue of Life), atlantska psina in Croatian, atlantski morski pes in Slovenian (GBIF), tonil in Albanian (GBIF), ニシネズミザメ in Japanese and بربيجل in Arabic (Wikidata). It is a predator of cold seas, now all but vanished from the Mediterranean — and according to the English Wikipedia, fishing for it in EU waters has been banned since 2011. Here is how to recognise it, and why, if one does bite, it belongs back in the water.

A name full of riddles

It was described by the French naturalist Pierre Joseph Bonnaterre in 1788 as *Squalus nasus* — based on an account by Thomas Pennant from 1769 (English Wikipedia). *Nasus* is Latin for nose; according to FishBase, because of its moderately long, conical snout. According to FishBase, *Lamna* comes from the Greek lamia, a large, voracious shark. Nobody knows for sure where the English porbeagle comes from: the English Wikipedia mentions a blend of porpoise and beagle, as well as a derivation from Cornish — porth for harbour and bugel for shepherd; the Oxford English Dictionary finds no evidence for the porpoise reading. The German name, Heringshai (“herring shark”), is easier to explain: according to the German Wikipedia, it eats schooling fish such as mackerel, herring and cod — and in Danish, Swedish and Finnish, too, it is named after the herring.

How to recognise it

According to the German Wikipedia, its body is spindle-shaped, with a conical snout, five long gill slits and a crescent-shaped tail fin. The most reliable feature sits on the first dorsal fin: its free rear tip is white or light grey (English Wikipedia). At the base of the tail it carries two pairs of keels — a main keel and a shorter second one below it —, and its teeth have three cusps: a central one with two small lateral cusplets beside it. It is exactly these two features that set it apart from the shortfin mako, which according to the English Wikipedia has only one keel on each side and whose teeth lack the cusplets. The porbeagle is grey to slate grey above and white below; adults in the Southern Hemisphere are often dark under the head (English Wikipedia).

  • Size: typically around 2.5 m (English Wikipedia), 244 cm according to FishBase. In the North Atlantic, males up to 2.5 m and females up to 3.0 m are confirmed; according to FishBase, the females grow larger.
  • Weight: mostly up to 135 kg; the heaviest known specimen weighed 230 kg and, according to the English Wikipedia, was caught off Caithness in Scotland in 1993.
  • A slow life: in the North Atlantic, according to the English Wikipedia, males reach sexual maturity at 6 to 11 years, females only at 12 to 18. FishBase rates its resilience as very low: a population needs more than 14 years to double.

A warm shark in cold water

The porbeagle keeps its body core 8 to 10 °C warmer than the water around it — among sharks, according to the English Wikipedia, only the salmon shark beats it at this. A network of blood vessels behind the eyes raises the temperature of the brain and eyes by a further 3 to 6 °C. This lets a predator hunt where others turn sluggish: FishBase calls it a fish of cold latitudes and gives –1 to 23 °C; according to the English Wikipedia, it is mostly found at 8 to 20 °C, and in the Northwest Atlantic, according to the German Wikipedia, mostly at 5 to 10 °C.

Where it lives

According to FishBase, it lives in the open sea, migrates widely and occurs from the surface down to 1,360 m, but mostly in the top 300 m. It is at home around the globe in the temperate latitudes of both hemispheres and is absent from equatorial seas. According to the German Wikipedia, its core range is the North Atlantic, from Macaronesia and Bermuda to Greenland and northern Norway, including the North Sea and, rarely, the western Baltic; in the Southern Hemisphere it lives off southern Australia, New Zealand and South Africa, among other places. It occurs in the Mediterranean, but not in the Black Sea. In summer, according to the German Wikipedia, it moves shallow and close to the coast, in winter offshore and deeper; FishBase describes a Northwest Atlantic population that shuttles between Newfoundland and Massachusetts. It is absent from the North Pacific — there, according to the English Wikipedia, the salmon shark fills its role.

What it eats

According to FishBase, it eats small and medium-sized schooling fish of open water, other sharks, squid and bottom fish such as cod, hake, haddock and cusk. The English Wikipedia calls it an opportunistic hunter that mainly takes bony fish and cephalopods, especially squid; according to the German Wikipedia, it hunts both in open water and on the bottom. FishBase places it at trophic level 4.6 — high up the food chain.

Play — or curiosity?

According to the English Wikipedia, it lives alone or in groups, and it shows a behaviour rarely described in fish: it rolls in kelp, chases driftwood and nudges floats. It poses little danger to people. FishBase considers it potentially dangerous because of its size, but writes that it has rarely if ever been involved in attacks on people or boats; according to the English Wikipedia, the International Shark Attack File had counted three bites up to 2009, one of them provoked, none fatal, two of them on boats.

Cannibals before birth

The porbeagle gives birth to live young, without a placenta. Once the yolk sac is used up, according to FishBase, the embryos eat their mother’s unfertilised eggs; according to the German Wikipedia, their teeth are functional for this early on. According to FishBase, a litter numbers 1 to 5 pups, usually four, each 60 to 80 cm long; gestation lasts 8 to 9 months. Mating takes place in late summer, and FishBase describes it as pair formation with an embrace. According to the English Wikipedia, the pups are born mainly in April and May in the North Atlantic and in June and July in the Southern Hemisphere — usually every year.

Why it belongs back in the water

Globally, the IUCN lists it as Vulnerable (assessed on 6 November 2018, according to FishBase). Regionally, things look worse: in the Northwest Atlantic it is considered Endangered, in the Northeast Atlantic and the Mediterranean Critically Endangered (German and English Wikipedia). For the Mediterranean, the English Wikipedia gives a decline of more than 99.99% since the middle of the 20th century. Since March 2013 it has been listed in Appendix II of the CITES convention, in force since 14 September 2014 (German Wikipedia); FishBase also lists it in Appendix II of the Bonn Convention (CMS). In the EU, according to the English Wikipedia, fishing for it has been banned since 2011, with the catch quota set at zero; Norway has protected it since 2012. In Ireland, Britain and the US, anglers prize it as a sport fish. Which rules apply on your water today is something you check yourself before heading out — with the harbour office, the fisheries authority, your guide or skipper. If a porbeagle is hooked, release it as gently as possible in the water.

Five contradictions, left standing

  • How long does it get? FishBase: at most 350 cm. The English Wikipedia: an unconfirmed figure of 3.7 m, possibly a mix-up with other mackerel sharks; 3.0 m is confirmed. The German Wikipedia: over 3 m.
  • How deep does it go? FishBase and the English Wikipedia: down to 1,360 m. The German Wikipedia: over 700 m.
  • How old does it get? FishBase: up to 65 years (an estimate from the Southern Hemisphere), at least 26 in the North Atlantic. The English Wikipedia: 30 to 40 years in the Atlantic, perhaps 65 in the South Pacific; the oldest recorded specimen was 26. The German Wikipedia: over 30 years.
  • How cold can it be? FishBase: –1 to 23 °C. The English Wikipedia: 1 to 23 °C, mostly 8 to 20 °C. The German Wikipedia: mostly 5 to 10 °C in the Northwest Atlantic.
  • When is it adult? The English Wikipedia counts years: males 6 to 11, females 12 to 18. The German one measures length: in the Northwest Atlantic, females at 200 to 250 cm, males at 150 to 200 cm. FishBase gives a mean of 186.5 cm (170 to 219 cm).

Three names that lead to the wrong fish

  • “Heringshai”, “sildehaj”, “haringhaai”, “smeriglio”. These names belong to the porbeagle — but GBIF also lists sildehaj and haringhaai for the shortfin mako, and according to the Italian Wikipedia the mako is sold in the trade as smeriglio, even though the name actually belongs to the porbeagle. Anyone identifying a shark by these names should look at the keels and teeth.
  • “Blue shark”, “blue dog”, “tintorera”. GBIF also lists these names for the porbeagle — but otherwise they mean the blue shark, *Prionace glauca*, to which this series devotes a group of its own. In Spain, tintorera is the name of the blue shark.
  • “Salmon shark”. This name, too, appears in GBIF for the porbeagle, but the salmon shark is a species of its own, *Lamna ditropis*: its closest relative, which according to the English Wikipedia lives in the North Pacific — exactly where the porbeagle is absent.

That leaves the question every article in this series starts with: when. Habitat, prey and habits are set out above, and they are fixed. What changes every day is everything else — light, wind, current, water temperature — and that is exactly where it is decided whether a day at sea is worth it. That is what StrikeAhead works out: it takes the conditions on your water and tells you when the trip is worth it. And because you cannot know an unfamiliar area, its edges and its rules from day one, StrikeAhead Pathfinder tells you who to go out with: curated guides and skippers, personally vetted before listing — licence and insurance —, with verified catches instead of promo photos, no paid ranking and, for you as an angler, no booking fee. The app tells you when, Pathfinder who.