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Shortfin mako fishing: the shark that is warmer than the sea around it

Almost every fish has the temperature of the water it swims in. The shortfin mako does not: a heat exchanger of densely interwoven arteries and veins — the rete mirabile, the “wonderful net” — keeps the heat its muscles produce inside the body. According to the English Wikipedia, this makes it 4 to 5.5 °C warmer than the surrounding water; the Russian Wikipedia writes that it keeps muscles, brain, internal organs and eyes warmer. According to the Japanese Wikipedia it keeps the shark agile even in cold water, and according to the English Wikipedia it partly explains its pace: FishBase calls it probably the fastest of all sharks. This article is about the shortfin mako, *Isurus oxyrinchus* — in German Kurzflossen-Mako, in Spanish marrajo, in Italian mako pinna corta, in French requin mako or requin-taupe bleu, in Portuguese tubarão-anequim, in Dutch kortvinmakreelhaai, in Danish makrelhaj, in Swedish makohaj, in Norwegian makrellhai, in Finnish makrillihai, in Russian акула-мако, in Turkish sivriburun camgöz, in Greek ρυγχοκαρχαρίας, in Croatian dugonosa psina, in Japanese アオザメ (aozame). And because the IUCN lists it worldwide as Endangered, this is about recognising it and releasing it — not about taking it home.

A relative of the great white

The shortfin mako belongs to the mackerel sharks (Lamnidae) — according to the English Wikipedia a family of only five living species, together with the great white shark, the porbeagle, the salmon shark and its closest relative, the longfin mako (*Isurus paucus*). It was described by the naturalist Constantine Rafinesque — in 1810 according to FishBase, GBIF and the Russian and Swedish Wikipedias, in 1809 according to the English Wikipedia. The word mako comes from the language of the Māori and, according to the English and Russian Wikipedias, means both shark and shark tooth; it was first written down in 1820 in a New Zealand vocabulary, simply as “a certain fish”.

According to FishBase it is an oceanic fish that sometimes comes close inshore; it lives worldwide in temperate and tropical seas between 65° North and 54° South, in water from about 16 °C. According to the English Wikipedia, swordfish are a good indicator of makos: they are their prey and prefer the same conditions. An isotope analysis showed, according to FishBase, that off eastern Australia the shortfin mako is the highest-level fish predator of the open ocean.

Its prey: according to FishBase bony fishes, other sharks and cephalopods; large individuals also take billfish and small cetaceans. According to the English Wikipedia, bluefish — to which this series devotes a group of its own — made up 77.5 % of the stomach contents (by volume) between Cape Hatteras and the Grand Banks. In the stomachs of two makos of 300 and 360 kg, researchers found whole swordfish of 54 and 67 kg, according to the Russian Wikipedia. But the swordfish fights back: at Ganzirri and Lipari in Sicily, makos have been found with broken-off bills lodged in their heads or gills (English, Russian, Greek Wikipedias). According to the English Wikipedia it attacks from below, tearing chunks from flanks and fins — and, at roughly 13,000 newtons, holds the record for the strongest bite ever measured in a shark, recorded in 2020 off Mayor Island in New Zealand.

How to recognise it

According to FishBase a large, spindle-shaped shark with large black eyes, a sharp snout and large, narrow, hooked teeth with smooth edges. The tail fin is crescent-shaped, its lower lobe strongly developed; the second dorsal fin and the anal fin are tiny. The back is a brilliant metallic blue, the belly white, the line between them sharp (FishBase, English Wikipedia); seen from the side, the Japanese Wikipedia describes three tones: dark blue, light blue, white. The underside of the snout and the area around the mouth are white too. According to the Russian and Swedish Wikipedias, the front teeth of the lower jaw are visible even with the mouth closed. Juveniles, according to the English Wikipedia, have a blackish stain on the tip of the snout.

The name comes from the pectoral fin: according to the Russian Wikipedia its leading edge is shorter than the head. The longfin mako, according to the English Wikipedia, has considerably larger pectoral fins, darker colouring around the mouth and larger eyes. Two things separate it from the porbeagle (genus *Lamna*), according to the English Wikipedia: it has only one keel on each side of the tail base, and its teeth lack the small lateral cusps.

  • Size: FishBase gives 445 cm total length as the maximum, 270 cm as the common length and 505.8 kg as the heaviest published weight. According to the English Wikipedia, the heaviest mako taken on hook and line weighed 600 kg (California, 3 June 2013); the longest verified one measured 4.45 m and was caught in September 1973 off the French Mediterranean coast.
  • A slow life: Until 2006 it was believed to lay down two growth bands a year in its vertebrae. A study of 258 animals showed: it is one. Since then, according to the English and Russian Wikipedias: females only mature at about 18 years, males at about 8; the oldest female was 32, the oldest male 29. FishBase has explicitly removed the old values.
  • Young: According to FishBase it is live-bearing; the embryos feed in the womb on unfertilised eggs. Gestation lasts 15 to 18 months, and a female only gives birth about every three years, to pups measuring 60 to 70 cm. FishBase therefore rates its resilience as low: a population needs 4.5 to 14 years to double.

Where it lives — the Mediterranean included

FishBase: in the western Atlantic from the Gulf of Maine to Argentina, in the eastern Atlantic from Norway to South Africa — including the Mediterranean —, in the Indo-Pacific from East Africa to Hawaii, in the eastern Pacific from California to Chile. It travels far: a female tagged off California was recaptured 2,776 km away in the central Pacific, and another mako swam 2,128 km in 37 days (English, Russian Wikipedias). Of 2,459 makos tagged off the US east coast, one crossed the Atlantic, according to the Russian Wikipedia, and was caught off Spain after 4,000 km.

In the Mediterranean, according to the Russian Wikipedia, it is widespread in the west and rarer in the east — the Aegean, the Sea of Marmara; it is absent from the Black Sea. The western Mediterranean and the Strait of Gibraltar are considered nurseries there: of 321 makos reported in 2005 as bycatch of tuna and swordfish fishing, 268 came from the Alboran Sea and 42 from the Balearics, and most were not yet mature. In the Ligurian Sea, catches have fallen so sharply since 1950 that it has almost disappeared there. And the Adriatic? According to the Russian Wikipedia, there has been no record from the eastern Adriatic since 1972; the Croatian Wikipedia, by contrast, writes that it is found there along the coast and in the open sea.

Endangered — and what that means on the line

According to the English Wikipedia the shortfin mako is a sought-after game fish, famous for leaping high out of the water when hooked; in some cases it has jumped into the boat. The Japanese Wikipedia reports a case from 2004: off Susami (Wakayama), a mako of 3.5 m and 350 kg jumped into a fishing boat at night, and an angler was seriously injured. FishBase lists it as potentially dangerous. The figures contradict each other: according to the English Wikipedia, the International Shark Attack File records 10 attacks on humans between 1980 and 2024; according to the Russian Wikipedia, 42 between 1980 and 2010 — both name 3 fatal ones and 20 attacks on boats, and both say many were provoked, often during capture.

The other way round matters more. According to FishBase, the IUCN lists it worldwide as Endangered (assessed on 5 November 2018); it is on Appendix II of CITES. For the Mediterranean, the IUCN had already classified it — together with the porbeagle — as Critically Endangered in its press release of 16 November 2007. For the North Atlantic, the tuna commission ICCAT, in its Recommendation 21-09, prohibited retaining on board or landing makos caught in ICCAT fisheries in 2022 and 2023; according to the same text, the spawning stock will keep shrinking until 2035 whatever the catch limit. In Croatia, according to the Croatian Wikipedia, it is strictly protected. Which rules apply on your water today is something you check yourself before you head out — with the harbour office, the fisheries authority, your guide. If you hook a mako, release it as gently as possible, in the water.

Eight contradictions, left standing

  • How fast is it? The English Wikipedia: 50 km/h, in bursts 74 km/h. The French: 50 to 74 km/h, with cavitation preventing more. The Spanish: 70 km/h. The Turkish: 84 km/h. The Portuguese: 88 km/h. The Italian and the Japanese: 100 km/h. The Russian: in one experiment a juvenile accelerated to 110 km/h over 30 m in 2 seconds. The Swedish: 30 to 40 km/h over long distances. And the German considers figures of almost 80 km/h highly unreliable.
  • How warm is it? The English Wikipedia: 4 to 5.5 °C warmer than the water. The Russian: the muscles 1 to 10 °C warmer, more in cold water than in warm. The French: about 10 °C.
  • The giant from Turkey: According to FishBase, Kabasakal and de Maddalena reported in 2011 a historical catch off Turkey, estimated from photographs at about 585 cm. The English Wikipedia: 5.7 to 6.19 m, caught in the late 1950s off Marmaris. The Russian: 5.85 m. The Greek: two sharks of 5.77 and 6.19 m — in the Sea of Marmara, not off Marmaris on the Aegean. FishBase and the English Wikipedia stress that the lengths are estimated from photos.
  • How deep does it swim? FishBase: 0 to 888 m, usually 100 to 150 m — and elsewhere: usually in surface waters, down to about 150 m. The French and the Dutch Wikipedias: down to 740 m. The Croatian: 700 m. The Russian: 500 m. The Swedish: 400 m. And while the English says it lives normally far from land, the German calls it an inhabitant of inshore waters.
  • How high does it jump? The Italian Wikipedia: up to 7 m. The German: over 6 m. The Russian: up to 6 m. The French: 4 m or more. The Spanish: 3 to 4 m.
  • How many young? FishBase gives, on the same page, 4 to 16, up to 18 and 4 to 25 (usually 10 to 18). The English Wikipedia: 4 to 18. The French: 2 to 21. The Spanish: usually 4 to 8, at most 16. The Portuguese: 8 to 10. The Croatian: 4 to 26. The Russian: 4 to 30.
  • How old does it get — and when does it mature? FishBase: 32 years. The French Wikipedia: 25. The Croatian: 25 to 32. The Italian: 30 to 35. The Swedish still gives maturity at 2 (males) and 6 years (females) — such early values, according to the English Wikipedia, rested before 2006 on the disproved belief in two growth bands a year; today 8 and 18 years apply.
  • How threatened is it? FishBase: Endangered, assessed in 2018. The English and the Italian Wikipedias: uplisted in 2019, previously Vulnerable, and Near Threatened back in 2007. The Swedish: globally Vulnerable. New Zealand’s Department of Conservation classified it there as Not Threatened in 2018 (English Wikipedia). And while FishBase lists it on Appendix II of the Bonn Convention (CMS), the Russian Wikipedia writes that it was added to Appendix I in 2010.

Five names that lead to the wrong fish

  • “Makrelenhai” and “porbeagle”. According to the German Wikipedia, the shortfin mako is sold as food in Germany as “Makrelenhai” (“mackerel shark”) — but “mackerel sharks” is also the name of the whole family the great white belongs to. GBIF also lists it in Danish as sildehaj and in Dutch as haringhaai: both mean herring shark, the porbeagle, which is a different fish, *Lamna nasus*. The Italian Wikipedia warns that the trade name smeriglio properly belongs to the porbeagle.
  • “Blauhai”, “blue shark”, “aozame”. GBIF also lists the shortfin mako in German as Blauhai and in English as blue shark — but that is the name of a separate shark, *Prionace glauca*, Japanese ヨシキリザメ. And the mako’s own Japanese name, アオザメ (aozame), literally means “blue shark” according to the Japanese Wikipedia, after its colour.
  • “Mako” — which one? The English Wikipedia: “mako shark” is also used for the longfin mako. The Finnish Wikipedia: in today’s Finnish list of fish names, makohai explicitly means the longfin mako; the shortfin is called makrillihai there. Read “makohai” in Finnish and you are looking at the other mako.
  • “Isurus” — the equal tail that isn’t. According to FishBase the genus name means “equal tail”, after the supposedly equal lobes of the tail fin. FishBase adds drily: they are not; the upper one is clearly longer.
  • “Marrajo criollo”. GBIF lists marrajo criollo as a Portuguese name of the species. According to the English Wikipedia, though, it is the name of a distinct colour form with dusky mottling on the snout and around the mouth, thought to occur only around the Azores — not every mako is a marrajo criollo.

That leaves the question every article in this series starts with: when. Habitat, prey and habits are set out above, and they are fixed. Everything else changes every day — and that is exactly where it is decided whether a day on the water 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 read current edges, baitfish schools and the blue of the open sea from day one — and because a mako that is to be released needs experienced hands —, 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 tells you who with.

Fish the right moment →