Shortfin Mako Shark: Hunting, Sensory, Migration, Reproduction

The shortfin mako (Isurus oxyrinchus) is widely regarded as the fastest shark in the ocean, capable of bursts that may exceed 70 km/h, and its biology is tuned to match that reputation. From skin texture that reduces drag to eyes built for tracking fast-moving prey in open water, almost every feature of this animal reflects a life spent chasing and being chased across enormous stretches of ocean. Its hunting behavior, sensory toolkit, migratory routes, and reproductive strategy each reveal how a large pelagic predator manages to survive in one of the most demanding environments on Earth.

Skin Built for Speed

One reason the shortfin mako swims so efficiently is the structure of its skin. Like other sharks, makos are covered in tiny tooth-like scales called dermal denticles, but mako denticles are especially refined for reducing drag. The denticles create a riblet-like surface texture that interacts with turbulent water flow in two ways: the ridges lift small vortices away from the skin so less surface area is exposed to high shear stress, and they also restrict sideways flow fluctuations that would otherwise transfer momentum and slow the shark down. Research on bioinspired riblet structures suggests that the ideal spacing for drag reduction is roughly one-third to one-half the diameter of the streamwise vortices in the boundary layer, and mako denticles sit close to that range across much of the body.¹

Denticle shape and size vary across different regions of the mako’s body. Computational fluid dynamics work on mako skin has shown that as denticle height increases, flow velocity and lift effects decrease while drag increases, meaning there is a sweet spot in denticle geometry that differs depending on where on the body the denticle sits.² The snout and leading edges of the fins tend to have shorter, more tightly packed denticles, while the flanks and trailing body have slightly taller ones. This mosaic of denticle sizes is not random; it reflects the different flow conditions each body region encounters at high speed.

Speed alone does not explain the mako’s performance, though. Shortfin makos belong to the family Lamnidae, a group of sharks that includes great whites and salmon sharks. All lamnids are regional endotherms, meaning they retain metabolic heat in certain tissues through a system of counter-current heat exchangers in their blood vessels. In practice, this means a mako can keep its swimming muscles, brain, and eyes warmer than the surrounding water. Warmer muscles contract faster and more powerfully, which is a direct advantage when chasing agile prey or making explosive vertical lunges.

Sensory Equipment for Open-Water Hunting

Shortfin makos hunt in the open ocean, often far from the seafloor and in water that can range from brilliantly lit surface layers to near-total darkness several hundred meters down. Their eyes are large relative to body size, and research comparing retinal anatomy across shark species has found that active pelagic sharks feeding on fast-moving prey tend to have higher spatial resolving power than bottom-dwelling species. Spatial resolving power across the sharks studied ranged from about 2 to over 10 cycles per degree, with the pelagic species at the high end of that range.³ For a mako, keen eyesight helps it spot and track schooling fish or squid from a distance in clear, blue oceanic water where other cues are scarce.

Vision is not the whole story. Like all sharks, makos possess electroreceptors called ampullae of Lorenzini, clustered around the snout. These gel-filled pores detect the weak electric fields generated by the muscle contractions of nearby animals. The system works best at close range, within roughly a meter or so, and is thought to play a role in the final moments of a strike, helping the shark orient its bite even when prey is just out of visual range or when the shark is moving too fast for precise visual tracking. Makos also have a lateral line system that detects pressure waves and vibrations in the water, useful for sensing the movements of prey at intermediate distances. Combined with an acute sense of smell that allows them to follow chemical gradients over longer distances, these senses give the mako overlapping detection capabilities that cover everything from kilometers away down to the last few centimeters before a bite.

Diet and Feeding Behavior

Shortfin makos are generalist predators with a broad palate, though certain prey species dominate depending on which ocean the shark lives in. In the California Current off the western United States, stomach content analyses of 330 makos found 42 different prey species, with jumbo squid and Pacific saury showing up as the most common items. Compared to blue sharks and common thresher sharks sampled from the same waters, makos had the most diverse diet by a comfortable margin.⁴ They ate a mix of bony fish and cephalopods, which reflects an animal that hunts across multiple depth zones and does not specialize on a single prey type.

On the other side of the continent, the picture shifts. In the northwest Atlantic, bluefish dominated the mako diet, making up about 78% of stomach contents by volume, and fish remains of some kind appeared in roughly two-thirds of all stomachs examined. Squid, by contrast, were consumed mainly offshore and accounted for a much smaller fraction of the diet.⁵ The difference between Pacific and Atlantic diets is mostly about what is available: bluefish are abundant inshore along the U.S. East Coast, while jumbo squid swarm through the eastern Pacific. Makos adapt accordingly, and their dietary flexibility is part of what makes them effective predators across such a wide geographic range.

Satellite tagging has revealed that makos do not just patrol the surface. Sharks tracked off Taiwan exhibited pronounced day-night vertical migrations, diving to maximum depths of nearly 1,000 meters. Larger sharks tended to dive deeper and spent more time in the 200-to-300-meter depth range. The deepest dives were correlated with sea surface temperature, mixed layer depth, and the presence of anticyclonic ocean eddies, suggesting the sharks were following prey concentrations that accumulate along these oceanographic features.⁶ In other words, makos do not simply swim around waiting to bump into food. They actively read the ocean’s structure and position themselves where prey is most likely to be concentrated.

Migration Patterns Across the Atlantic

Long-term satellite tracking has given researchers a detailed view of how shortfin makos use the western North Atlantic. A study that followed 26 sharks for periods ranging from about two and a half months to nearly a year and a half revealed strikingly region-specific movement patterns. Sharks tagged off the eastern United States ranged over a large area, moving between continental shelf waters and deep pelagic habitats. Their core distribution shifted with the seasons: they were found off South Carolina in winter and as far north as Nova Scotia by autumn, apparently tracking seasonal pulses of biological productivity while favoring warmer water masses.⁷

Sharks tagged off Mexico behaved quite differently. Their movements were much more restricted, largely confined to shelf habitats, with core activity centered year-round on the eastern Campeche Bank. There was surprisingly little overlap between the ranges of the U.S.-tagged and Mexico-tagged groups, hinting at population-level differences in habitat use that management plans need to account for. Seven of the U.S.-tagged sharks made long, highly directional excursions far to the south into nutrient-poor subtropical and tropical waters before returning north, and the purpose of these journeys is still debated. They might involve reproduction, thermal preference, or simply exploratory behavior.

One of the most sobering findings from that tracking study was that the sharks crossed the jurisdictional management boundaries of 17 different nations during their movements, and about 22% of the tracked animals were eventually harvested. That harvest rate was roughly double what conventional tagging studies had estimated, suggesting that fishery-dependent methods were underestimating how many makos are being caught.

Reproduction and Early Life

Shortfin mako reproduction is slow by any measure. Females in the western and central North Pacific give birth after a gestation period estimated at 9 to 13 months, with parturition occurring from winter to spring. Larger females tend to produce bigger litters, meaning fecundity increases as the mother grows.⁸ Typical litter sizes range from about 4 to 25 pups, though the most common numbers sit in the lower half of that range. Females likely do not reproduce every year; a resting period between pregnancies means the interval between litters may be two to three years.

The developing embryos sustain themselves through oophagy, a strategy in which the mother continues producing unfertilized eggs that the embryos consume inside the uterus. Examinations of embryos from multiple litters confirmed that when yolk was present in embryonic stomachs, it was present in all embryos from the same uterus, and always in large quantities. No partial feeding was observed: either all embryos in a uterus had full stomachs of yolk or none did, confirming oophagy as the primary source of embryonic nutrition rather than a supplemental one.⁹

Newborn makos are already sizeable, measuring roughly 60 to 70 cm in fork length at birth. Early growth is fast: young-of-the-year sharks gain about 50 cm in their first year, slowing to around 32 cm per year in their second.¹⁰ Despite that rapid early growth, reaching sexual maturity takes years. Estimates for age at first maturity vary depending on methodology, but males generally mature somewhere between 3 and 6 years of age while females take substantially longer, with estimates ranging from 7 to over 12 years. Longevity estimates place females at roughly 19 to 28 years and males at 16 to 23 years.¹¹

The combination of late female maturity, small litter sizes, and long intervals between pregnancies means the population’s capacity to recover from depletion is extremely limited. A female mako might produce only a handful of litters in her entire lifetime. This reproductive math is central to understanding why the species is in trouble.

Nursery Grounds and Juvenile Habitats

Young shortfin makos do not immediately take up the wide-ranging pelagic lifestyle of adults. The eastern North Pacific, for example, contains several coastal nursery areas where juveniles forage and grow before eventually venturing offshore into the open ocean, where seasonal migration and reproduction take place.¹² These nurseries appear to provide the warmer, more productive waters that fast-growing juveniles need, and identifying them is a priority for conservation. If a nursery area is degraded or heavily fished, the effects ripple through the entire population years later when those missing juveniles fail to recruit into the adult breeding pool.

Vertebral chemistry studies have been used to distinguish between nursery regions, because the chemical signatures deposited in a shark’s vertebrae during its first years of life act as a kind of geographic fingerprint. By reading those signatures in adult sharks, researchers can retroactively determine where an individual spent its youth, which helps map nursery boundaries even when direct juvenile tracking data are sparse.

Conservation and Fisheries Pressure

Shortfin makos were listed under Appendix II of CITES in 2019, a step triggered in part by stock assessments showing that the North Atlantic population was overfished and still experiencing overfishing. The International Commission for the Conservation of Atlantic Tunas, which manages the species in that region, has called for efforts to reduce mako bycatch, but progress has been uneven.¹³ Makos are caught both as targeted catch, especially in recreational fisheries where their speed and fight make them prized game fish, and as bycatch in commercial longline fisheries targeting tuna and swordfish. The satellite tracking data showing that 22% of tagged sharks were eventually harvested underlines the scale of the problem.

Because makos cross so many national boundaries during their migrations, effective management requires international coordination. A shark that spends winter off the Carolinas, summer in Canadian waters, and occasionally swings through the open Atlantic is not protected by any single country’s regulations alone. The mismatch between the species’ biology, which operates on ocean-basin scales, and human management, which is divided along political lines, remains one of the biggest obstacles to recovery.

Mercury Accumulation in Mako Tissue

As apex predators that feed on a wide variety of fish and squid, shortfin makos accumulate mercury in their muscle tissue through bioaccumulation. A study of 33 makos from waters off California, ranging in size from 75 to 330 cm fork length, found mercury levels in muscle tissue spanning 0.15 to 2.90 micrograms per gram. Mercury concentration increased with body size, and it did so significantly faster in makos than in common thresher sharks from the same region.¹⁴ The steeper accumulation curve in makos may reflect their more diverse diet and higher metabolic rate, both of which could increase the total mercury load ingested and retained over time.

For anyone who fishes for makos recreationally and keeps their catch, this has practical implications. Larger, older makos carry substantially more mercury than smaller individuals. Most health agencies advise limiting consumption of large predatory fish for this reason, and mako falls squarely into that category. The U.S. FDA’s general guidance for high-mercury fish applies, and pregnant women and young children are typically advised to avoid them altogether. Even for other adults, eating large mako frequently enough for it to be a regular part of your diet would push mercury intake into ranges most health authorities consider inadvisable.