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Isurus
Temporal range: Early Oligocene - recent
Shortfin mako shark (I. oxyrinchus)
Longfin mako shark (I. paucus)
Scientific classification Edit this classification
Kingdom: Animalia
Phylum: Chordata
Class: Chondrichthyes
Subclass: Elasmobranchii
Division: Selachii
Order: Lamniformes
Family: Lamnidae
Genus: Isurus
Rafinesque, 1810
Type species
Isurus oxyrinchus
Rafinesque, 1810
Synonyms[1]
  • Isuropsis Gill, 1862
  • Lamiostoma Glückman, 1964
  • Oxirhyna Costa, 1866
  • Oxyrhina Agassiz, 1838
  • Oxyrhine

Isurus (meaning "equal tail")[2] is a genus of mackerel sharks in the family Lamnidae, commonly known as the mako sharks. They are largely pelagic,[3] and are fast, predatory fish capable of swimming at speeds of up to 50 km/h (31 mph).[4][5]

Fossil history and evolution

[edit]

Although fossil teeth of Isurus have been reported from as early as the Late Cretaceous,[6][7] they are likely to be of a shark with a similar dentition, Cretoxyrhina; since at one point they were considered to be the same (now defunct) genus Oxyrhina,[8] and modern referrals to Isurus in the Cretaceous are scant. The earliest appearance of Isurus proper seems to be during the Oligocene with Isurus desori.[9][10]

There has been much debate and speculation about the evolutionary origin and relationships between Isurus and its closest relatives, including the extant great white shark (Carcharodon carcharias). Molecular clock analyses place the last common ancestor of Isurus and Carcharodon between 43–60 million years ago during the Late Paleocene-Early Eocene.[11] This insight should guide efforts to better resolve the fossil ancestry of both lineages, by providing a window of time in which to search for ancestor candidates.

Many fossil species of Lamnids have historically been placed under Isurus, which are now largely considered separate genera. These include species of Carcharodon (Cosmopolitodus) like C. hastalis, C. planus,[12] species of Macrorhizodus,[13][14] Isurolamna,[15][16] and others.

Description

[edit]

The two living species are the shortfin mako shark (I. oxyrinchus) and the longfin mako shark (I. paucus). They range in length from 2.5 to 4.5 m (8.2 to 14.8 ft),[17] and have an approximate maximum weight of 680 kg (1,500 lb).[citation needed] They both have a distinctive blue-gray color scheme common among mackerel sharks.

Species

[edit]

The genus contains these species:[18]

See also

[edit]

References

[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

Isurus

View on Grokipedia
from Grokipedia
Isurus is a of mackerel sharks in the family , known commonly as mako sharks, comprising two extant species: the shortfin mako (Isurus oxyrinchus) and the longfin mako (Isurus paucus). These epipelagic predators are distinguished by their streamlined, spindle-shaped bodies, pointed snouts, large eyes, and lunate caudal fins, adaptations that enable exceptional speeds of up to 70 km/h in bursts. Both species exhibit regional endothermy, allowing them to maintain elevated body temperatures for enhanced metabolic efficiency in cold waters. Mako sharks of the genus Isurus are highly migratory, inhabiting the upper layers of temperate and tropical oceans globally, with the shortfin mako showing a and the longfin mako more restricted to subtropical regions like the western Atlantic and . They typically dwell in offshore waters from the surface to depths of around 500 m, though they occasionally dive deeper. As apex predators, their diet consists primarily of bony fishes such as tunas, billfishes, and cephalopods, hunted using ambush tactics and powerful bursts of speed. is ovoviviparous with in both species; the shortfin mako produces litters of 4–30 pups after a period of 15–18 months, while the longfin mako has litters of 2–8 pups with period unknown. The shortfin mako can grow to a maximum length of 4.45 m and weight over 500 kg, while the longfin mako reaches up to 4.3 m, though it is less commonly encountered and poorly studied. Both feature smooth-edged, triangular teeth suited for grasping prey and a single lateral on the caudal peduncle for stability during high-speed pursuits. Coloration is typically metallic blue-gray dorsally fading to white ventrally, providing in open water. Isurus species face significant conservation challenges due to overfishing in commercial longline fisheries targeting swordfish and tunas, leading to both being listed as Endangered by the IUCN since 2019. Their late maturity (around 7–8 years) and low fecundity contribute to slow population recovery, prompting international management measures like quotas under organizations such as ICCAT. Despite their commercial value for meat and fins, efforts are underway to mitigate bycatch and promote sustainable practices.

Taxonomy

Etymology

The genus name Isurus derives from the Greek words isos (ἴσος), meaning "equal," and oura (οὐρά), meaning "tail," alluding to the nearly symmetrical lobes of the caudal fin that distinguish mako sharks within the mackerel shark family. Isurus was established as a genus by the naturalist in 1810, in his work Caratteri di alcuni nuovi generi e nuove specie di animali e piante della Sicilia, with Isurus oxyrinchus designated as the by monotypy. This naming reflected early observations of the shark's distinctive tail morphology, which Rafinesque used to differentiate it from other lamniform sharks. Over the subsequent decades, several synonyms were proposed for Isurus, often based on incomplete specimens or regional variations, but these were later consolidated under the original name due to taxonomic priority and morphological overlap. Oxyrhina, introduced by in 1838 with Lamna oxyrhina (now synonymous with I. oxyrinchus) as the type, became obsolete as a junior following the application of Linnaean priority rules. Similarly, Oxyrrhina Bonaparte, 1846, and Plectrostoma Gistel, 1848, both referencing the same core species, were rejected for lacking substantive diagnostic differences from Isurus. Another synonym, Isuropsis Gill, 1862, was erected to accommodate species like Oxyrhina glauca but was reclassified into Isurus after detailed anatomical studies revealed no reliable morphological distinctions, such as in fin structure or , to justify separation. These reclassifications underscore the evolving understanding of shark in the 19th and 20th centuries, prioritizing Rafinesque's original description.

Classification

The genus Isurus is classified within the kingdom Animalia, phylum Chordata, class , order , family , and genus Isurus. This placement situates Isurus among the mackerel sharks of the Lamnidae family, characterized by their streamlined bodies, regional endothermy, and predatory adaptations in pelagic environments. The genus comprises two extant species: the shortfin mako (Isurus oxyrinchus) and the longfin mako (Isurus paucus), both recognized for their high-speed swimming and in tropical and temperate oceans. These species are distinguished from other lamnids by specific morphological traits, including lunate caudal fins with nearly equal lobes and a pointed . Historically, the of Isurus has undergone revisions to separate it from related genera such as , primarily based on dental and skeletal morphology. Early classifications often synonymized fossil and extant forms under broader categories, but analyses of tooth structure—such as the narrow, smooth-edged, triangular cusps in Isurus lacking serrations—distinguished it from the broader, serrated teeth of . Skeletal differences, including variations in vertebral and rostral shape, further supported this separation, as detailed in systematic reviews by Compagno (1984) and Cappetta (1987). These revisions refined the boundaries, excluding forms like Isurus hastalis, now often reassigned to extinct lineages closer to .

Evolutionary History

Fossil Record

The fossil record of the genus Isurus commences in the epoch, with the earliest recognized being Isurus desori (Agassiz, 1843), known from deposits approximately 33–23 million years old. This is characterized by narrow, pointed teeth typical of early mako-like lamniforms and represents the initial appearance of the in the paleontological record. Subsequent species, such as Isurus praecursor (Leriche, 1905), appear in the late Eocene to early , though many specimens formerly assigned to Isurus have been reclassified into separate genera like Macrorhizodus based on distinct tooth morphologies, including broader crowns and structures. Similarly, numerous and fossils previously under Isurus, such as Isurus hastalis (Agassiz, 1843) and Isurus planus (Brock, 1982), have been transferred to Cosmopolitodus due to serrated edges and triangular forms linking them more closely to the white shark lineage. These reclassifications reflect ongoing taxonomic revisions emphasizing dental evidence over historical nomenclature. Fossils attributed to Isurus and its reassigned relatives occur globally in marine sediments, with notable occurrences in (e.g., formations in ), (e.g., deposits in ), and (e.g., Eocene to sites in ). No verified Isurus remains exist from the period; such pre- lamniform fossils, including those once labeled Isurus denticulatus (Glückman, 1957), are now assigned to the distinct genus Cretoxyrhina following detailed skeletal and dental analyses. Approximately 10–15 extinct species have been described within Isurus historically, including I. desori, I. retroflexus (Agassiz, 1843), and I. subserratus (Agassiz, 1843), though the majority are now deemed junior synonyms, invalid, or reclassified, leaving only a few as potentially valid fossils alongside the two extant species.

Phylogenetic Relationships

The genus Isurus occupies a basal position within the family Lamnidae, closely related to other genera such as Lamna (porbeagle sharks) and Carcharodon (great white sharks), as supported by analyses of mitochondrial cytochrome b gene sequences. DNA studies indicate that Isurus forms a monophyletic clade sister to Carcharodon, with Lamna representing the most ancestral lineage in the family based on nucleotide parsimony. These molecular data highlight Isurus as a foundational branch in lamnid evolution, diverging early from shared ancestors adapted to pelagic lifestyles. Molecular clock estimates place the last common ancestor of Isurus and Carcharodon between 43 and 60 million years ago, corresponding to the Late Paleocene to Early Eocene epochs. This divergence aligns with paleoenvironmental shifts following the Cretaceous-Paleogene extinction, enabling the radiation of modern into open-ocean niches. Phylogenetic relationships within Lamnidae are further corroborated by morphological synapomorphies shared among Isurus and its relatives, including a highly hydrodynamic body form optimized for sustained cruising speeds and a nearly equal-lobed (lunate) caudal fin that enhances propulsive efficiency. Additionally, the elevated density of across the head and body supports precise electrolocation in low-visibility pelagic environments, a trait distinguishing from more benthic families. Recent genetic analyses in the 2020s, including complete mitogenome sequencing, have reaffirmed the of Isurus, with high sequence identity (98.4%) across global populations of I. oxyrinchus and consistent clustering within . These studies also indicate that the modern Isurus lineage diverged from fossil ancestors near the Eocene-Oligocene boundary, around 34 million years ago, coinciding with cooling ocean currents and expanded open-water habitats.

Physical Characteristics

Morphology

The genus Isurus comprises characterized by a streamlined, optimized for high-speed swimming in pelagic environments. This body shape features a pointed, conical that reduces hydrodynamic drag, large eyes positioned laterally for enhanced , and five prominent slits that facilitate efficient oxygen extraction during rapid movement. The caudal fin in Isurus species is lunate with nearly equal upper and lower lobes, exhibiting a heterocercal structure that is functionally symmetrical to support powerful propulsion and maneuverability. A strong lateral on the caudal peduncle provides stability and prevents lateral oscillation during bursts of speed. in Isurus consists of large, triangular teeth with single, finely pointed cusps and smooth, razor-sharp edges lacking serrations or lateral denticles, enabling effective grasping and retention of fast-moving prey such as teleosts and cephalopods. These teeth are arranged in multiple rows, typically 12–13 per side in the upper jaw and 11–13 per side in the lower jaw, allowing for continuous replacement to maintain functionality. Internally, Isurus sharks possess adaptations for regional endothermy, including a vascular counter-current exchange system in the red muscle that elevates tissue temperatures above ambient water levels, supporting sustained swimming speeds and endurance. Additionally, the orbital rete mirabile warms blood supply to the and , enhancing in low-light oceanic conditions by maintaining ocular temperatures approximately 5°C above ambient.

Size and Coloration

Species in the genus Isurus attain average adult lengths ranging from 2.5 to 4 meters, with maximum recorded lengths approaching 4.5 meters across both I. oxyrinchus and I. paucus. Adult weights typically reach up to 570 kilograms, reflecting their robust, streamlined build adapted for pelagic life. Sexual dimorphism is pronounced, with females growing 10–20% larger than males, often exceeding males in both length and mass at maturity to support greater reproductive output. The coloration of Isurus species features a metallic blue-gray dorsal surface that fades to brilliant white on the ventral side, providing effective camouflage against the open ocean backdrop to reduce visibility to prey from above and below. Juveniles may exhibit additional markings, such as a dark tip on the , which fades with age. This pigmentation enhances their in epipelagic environments by blending with the . Growth in Isurus is rapid during juvenile stages, with rates up to 30 cm per year in the first few years, as determined by tag-recapture studies and vertebral analysis. This pace slows considerably in adults, contributing to an overall lifespan of 20–30 years, estimated through annual band counts in vertebrae that serve as reliable age indicators.

Species

Shortfin Mako Shark

The shortfin mako shark (Isurus oxyrinchus) is characterized by its slender, spindle-shaped body and short pectoral fins, which are notably shorter than the length of its head, distinguishing it from the longfin mako. This streamlined morphology supports its high-speed lifestyle in open ocean environments. The species reaches a maximum total length of up to 4.45 meters (females generally larger than males); maximum recorded weight is around 570 kg. The shortfin mako has a in tropical and temperate oceanic waters worldwide (see Distribution and ). It prefers waters warmer than 16°C but can tolerate cooler temperatures during migrations. Unique to the shortfin mako among sharks is its exceptional swimming speed, with sustained rates up to 50 km/h and burst speeds reaching 74 km/h, enabled by specialized red muscle and hydrodynamic denticles. It is renowned for acrobatic leaps of up to 6 meters out of the water, often during hunting or when hooked, showcasing its agility. The diet primarily consists of fast-swimming pelagic fishes such as , , mackerels, and , supplemented by cephalopods and occasionally other elasmobranchs (see and Behavior). Reproduction in the shortfin mako is ovoviviparous, with females giving birth to litters of 4–25 pups after a period of 15–18 months, followed by a three-year reproductive cycle (see Ecology and Behavior). Pups are born live at 60–74 cm in length and grow rapidly in their early years. is attained at lengths of 2.2–2.9 meters, corresponding to ages of 7–9 years for males and 18–21 years for females. The shortfin mako is classified as Endangered on the based on the 2019 assessment (updated from 2020 regional evaluations), with a global population decline of over 46% inferred over three generations due to (see ).

Longfin Mako Shark

The (Isurus paucus) is distinguished by its more robust, spindle-shaped body and elongated pectoral fins, which extend longer than the head length and feature broad tips, contrasting with the shorter fins of its congener. The is less pointed, the eyes are large, and the overall coloration is dark blue to bluish-black dorsally, fading to white ventrally with dusky markings on the snout and mouth underside in adults. These adaptations suggest a oriented toward deeper, less pelagic environments compared to the shortfin mako. This species attains a maximum total length of approximately 4.3 , with females growing larger than males; common lengths are around 2.2 , and newborns measure 97–120 cm at birth. Weights for typical s reach about 70 kg, though larger individuals may exceed this, with rarer captures documenting specimens up to 4.3 . Maturity is reached at lengths of 2.0–2.5 for females and around 2.0 for males. Isurus paucus inhabits tropical and warm temperate oceanic waters across the Atlantic, Pacific, and s, with confirmed records from the western Atlantic (e.g., off , , and ), eastern Atlantic (e.g., off and ), western (e.g., near ), and central Pacific (e.g., north of and near ) (see Distribution and ). It often occurs in epipelagic to mesopelagic zones, with depth records ranging from surface waters to 1,752 m, though it favors 110–220 m overall. Swimming speeds are presumed slower than those of the shortfin mako. Its diet consists primarily of pelagic schooling fishes and cephalopods such as , reflecting its deeper-water foraging habits (see Ecology and Behavior). Reproduction is ovoviviparous, with where embryos consume unfertilized eggs for nourishment; lasts approximately 15–18 months, and litters typically comprise 2–8 pups (see Ecology and Behavior). Females give birth in nearshore waters, and the species exhibits a low reproductive rate with maturity delayed until several years of age, contributing to slower recovery. estimates are lower and more uncertain than for the shortfin mako due to its rarity and data deficiencies. The longfin mako is classified as Endangered by the IUCN Red List since 2019, primarily due to bycatch in pelagic longline fisheries, targeted fishing for fins and meat, and its low intrinsic rate of population increase; as of 2025, limited data indicate populations remain data-poor but stable in some regions with no significant recovery noted (see Conservation Status). It is listed under CITES Appendix II for monitored international trade.

Distribution and Habitat

Geographic Range

The genus Isurus, comprising the shortfin mako (I. oxyrinchus) and longfin mako (I. paucus), exhibits a broadly across the world's oceans, though with distinct patterns between the species. The shortfin mako is panoceanic, occurring in the Atlantic, Pacific, and Indian Oceans within temperate and tropical waters, spanning latitudes from approximately 60°N to 50°S. In contrast, the longfin mako has a more restricted range, primarily in tropical and warm-temperate waters of the Indian, Pacific, northwestern Atlantic, and eastern Atlantic Oceans, generally between 35°N and 35°S. The Atlantic Ocean holds the majority of records for both species, with abundant sightings in the North and South Atlantic, including the Mediterranean Sea where shortfin makos are frequently encountered. The Indo-Pacific region also features significant populations, particularly off the coasts of South Africa, India, Sri Lanka, and in the western Pacific. Migration patterns for Isurus species involve seasonal north-south movements linked to prey availability, enabling transoceanic travels across vast distances. Tagging studies reveal highly migratory behavior, with shortfin makos capable of covering up to 12,000 miles annually in the Pacific and demonstrating site fidelity during migrations. In the Mediterranean, a 2024 satellite tagging of a juvenile shortfin mako documented travel exceeding 1,200 km over 54 days, highlighting connectivity within regional waters. These patterns underscore the species' pelagic lifestyle and exposure to international fisheries across oceanic basins.

Habitat Preferences

Isurus species, comprising the shortfin mako (I. oxyrinchus) and longfin mako (I. paucus), exhibit a distinctly , inhabiting open environments rather than nearshore or coastal areas. The shortfin mako primarily occupies the epipelagic zone, spending most of its time between 0 and 200 meters depth, with mean depths around 68.5 meters and frequent utilization above 90 meters. In contrast, the longfin mako shows a preference for deeper waters, allocating 42–54% of its time below 200 meters and extending into the up to 1,000 meters or more, with recorded depths reaching 1,767 meters. Both species avoid coastal shallows, favoring offshore pelagic habitats that provide expansive, unobstructed ranges for their highly mobile nature. Temperature plays a critical role in habitat selection for Isurus, with both species favoring waters between 12 and 28°C, though their regional endothermy—enabled by vascular retia mirabilia that retain metabolic heat—allows tolerance of cooler conditions outside this range. Shortfin makos most commonly experience temperatures of 18–22°C (mean 19.4°C), but can endure from 7.4°C to 29.9°C, using thermoregulatory capabilities to maintain elevated body temperatures during dives into colder layers. Longfin makos similarly span 4.0–28.8°C, leveraging endothermy for prolonged stays in cold mesopelagic waters. This physiological adaptation broadens their vertical niche, distinguishing them from strictly ectothermic elasmobranchs. Isurus sharks are frequently associated with dynamic oceanic features such as fronts and upwellings, where nutrient-rich waters enhance productivity and concentrate resources. These environments, including shelf-edge fronts and convergence zones, attract shortfin makos to areas like the Subtropical Convergence Zone and upwelling system. Longfin makos also exploit similar features during their deeper excursions, though data on their associations remain sparser. Recent 2025 research in the highlights potential breeding grounds for shortfin makos in shelf-slope habitats at 100–300 meters depth, particularly in the northwestern region west of the , where pregnant females exhibit residency and bite marks suggestive of gestation areas.

Ecology and Behavior

Diet and Predation

Species of the genus Isurus, including the shortfin mako (Isurus oxyrinchus) and longfin mako (Isurus paucus), are apex predators in pelagic marine ecosystems, occupying high trophic positions with diets dominated by fast-swimming prey. Stomach content analyses from fishery reveal that fishes constitute the majority of their diet, typically around 70-80%, including species such as tunas ( spp.), mackerels (Scomber spp.), and sauries (Scomberesox saurus). Cephalopods, particularly squids like the jumbo flying squid (Dosidicus gigas), account for approximately 15-20%, while elasmobranchs and other prey groups make up the remaining 10%, with occasional records of cetaceans or sea turtles. The longfin mako exhibits a similar composition, though data are sparser and suggest a preference for smaller schooling fishes and pelagic squids. These sharks employ specialized hunting strategies adapted to their high-speed lifestyle, relying on ambush bursts to close distances on evasive prey, with recorded speeds up to 74 km/h facilitating rapid pursuits. Their protrusible jaws enhance bite efficiency by extending forward during strikes, allowing precise capture of slippery or armored prey, a mechanism observed in lamniform sharks through biomechanical studies. Diet studies, often derived from stomach contents of incidentally caught individuals in longline fisheries, indicate opportunistic feeding with ontogenetic shifts: juveniles consume smaller cephalopods and fishes, while adults target larger teleosts. This predatory role positions Isurus at a mean of approximately 4.5, reflecting their position as tertiary carnivores in oceanic food webs. As high-level predators, Isurus species experience of contaminants like mercury in their tissues, with concentrations increasing with body size and correlating to their trophic position, often exceeding safe consumption thresholds for humans. Interspecific predation is limited, with adults rarely targeted due to their size and agility; however, juveniles are vulnerable to attacks from larger elasmobranchs such as great white sharks (Carcharodon carcharias) or marine mammals like orcas (Orcinus orca). This vulnerability underscores the ' role in complex trophic interactions, where they both exert top-down control on prey populations and face risks during early life stages.

Reproduction and Life Cycle

Species of the genus Isurus exhibit ovoviviparous reproduction, in which eggs are fertilized internally and develop within the without a placental connection to the mother. Embryos initially rely on nourishment, transitioning to where they consume unfertilized eggs produced by the mother. This strategy supports the development of relatively large pups, enhancing their survival post-birth. periods typically last 15–18 months, contributing to a prolonged reproductive timeline. Sexual maturity in Isurus species is reached at varying ages depending on sex and geographic population, with data primarily available for the shortfin mako; the longfin mako is less studied. For the shortfin mako, maturity occurs generally between 7 and 21 years, with males attaining maturity earlier, around 7–10 years at lengths of 180–200 cm total length (TL), while females mature later, at approximately 19–21 years and 250–280 cm TL. remains low across the genus, with litters ranging from 2 to 25 pups (averaging 10–16 for shortfin mako, smaller for longfin mako at 2–8) produced every 2–3 years due to the extended and a resting period for females. This infrequent reproduction underscores the vulnerability of Isurus populations to exploitation, as recovery from losses is slow. The life cycle of Isurus begins with neonates measuring 60–80 cm at birth, born live in litters during warmer months in nursery areas. Juveniles experience rapid growth, gaining about 39 cm in fork length during the first year, followed by slower but steady increases until maturity; males and females grow at similar rates post-maturity. Lifespan extends to 29–32 years, with typically occurring after 20 years, marked by reduced growth and reproductive output in older individuals. Breeding migrations in Isurus involve females moving to warmer equatorial or tropical waters to facilitate and parturition, often exhibiting to specific regions. Recent genetic analyses from 2025 reveal low connectivity between northern and populations, driven by female and limited trans-equatorial dispersal, supporting the need for hemisphere-specific management. This structure implies discrete breeding units despite the species' pelagic nature.

Conservation Status

Population Threats

The primary threat to Isurus populations, encompassing both shortfin (Isurus oxyrinchus) and longfin (Isurus paucus) mako sharks, is through targeted capture and in pelagic longline fisheries targeting and . Shortfin mako sharks are particularly vulnerable, with post-release mortality rates estimated at 29.4% in pelagic longline operations, contributing substantially to overall fishing-induced mortality. in these fisheries represents a major source of mortality, as mako sharks are often hooked incidentally and suffer high at-vessel mortality rates ranging from 26% to 36% depending on gear and handling practices. Targeted fishing for their high-value fins and exacerbates the pressure, with under-reporting of catches further complicating . The 2025 ICCAT stock assessment for the South Atlantic shortfin mako stock indicates overfishing, with fishing mortality (F) exceeding maximum sustainable yield levels (F_MSY) since the 1990s and a median F_2023/F_MSY ratio of 1.052, signaling ongoing exploitation above sustainable thresholds. Population declines are evident across regions; the IUCN's 2019 global assessment estimates a median 46.6% reduction in shortfin mako abundance over three generations (approximately 72–75 years), with a 60% decline in the North Atlantic and probabilities of 50–79% decline in multiple ocean basins. Global biomass estimates for shortfin mako remain uncertain due to data limitations, but regional models suggest levels consistent with overexploitation, such as South Atlantic spawning stock fecundity at 94.9% of MSY in 2023. For longfin mako, population metrics are data-deficient globally, though similar fishing pressures imply comparable declines. Climate change intensifies these risks by altering ocean conditions, including warming surface waters that shift prey distributions such as those of tunas and cephalopods, potentially forcing mako sharks into higher-risk fishing zones and increasing encounter rates. Ocean warming also expands juvenile shortfin mako distributions to deeper, less optimal depths while contracting adult core habitats in the North Atlantic. Additional threats include ship strikes, which cause direct trauma in coastal and migratory pathways, though documentation remains limited. via ingestion affects Isurus species, with nearly 10% of examined shortfin mako stomachs containing debris, leading to potential internal injuries and reduced fitness. Habitat degradation from , driven by climate-induced expansion of oxygen minimum zones, further constrains pelagic habitats and exacerbates vulnerability to other stressors.

Protection Measures

The shortfin mako shark (Isurus oxyrinchus) is classified as Endangered on the IUCN Red List (A2bd) following a 2019 assessment that documented substantial global population declines driven by fishing pressure. This status was informed by stock assessments from bodies like the International Commission for the Conservation of Atlantic Tunas (ICCAT) and the International Scientific Committee for Tuna and Tuna-like Species in the North Pacific Ocean. The longfin mako shark (Isurus paucus) is classified as Endangered (A2bd) under the same framework, highlighting its rarity, low fecundity, and vulnerability to incidental capture despite limited data on trends. Both species were added to CITES Appendix II in 2019 to monitor and regulate international trade in specimens, requiring non-detriment findings and permits to prevent unsustainable exploitation. Fisheries management efforts have focused on retention bans and quotas to curb directed and incidental catches. The ICCAT adopted Recommendation 21-09 in 2021, prohibiting the retention, , and landing of North Atlantic shortfin mako sharks caught in association with ICCAT fisheries, effective from 2022 to allow stock rebuilding. In alignment, the U.S. (NOAA) implemented a zero retention limit for shortfin mako in all Atlantic highly migratory fisheries starting July 2022, extending through at least 2025 pending further assessments. European Union regulations include -specific quotas for mako sharks in Atlantic waters, such as the 2023 South Atlantic shortfin mako management plan that sets catch limits to immediately address while supporting non-detriment findings under . Ongoing research initiatives emphasize tracking and to inform targeted protections. In 2025, tagging programs in the have identified potential nursery areas for shortfin mako, using satellite and acoustic tags to map juvenile habitats overlapping with fishing grounds. Complementary genetic studies, including a 2025 bi-organelle analysis, have delineated stock structure and connectivity for mako sharks across the Atlantic, revealing that supports transboundary management approaches. Notable conservation successes include bycatch mitigation through gear modifications, such as mandatory circle hooks in certain longline fleets, which have reduced at-vessel mortality for mako sharks by 20–30% in targeted trials by promoting rather than gut hooking. These measures, combined with retention bans, have shown early signs of stabilizing local abundances in managed areas like the North Atlantic.

References

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  2. https://www.floridamuseum.ufl.edu/discover-fish/species-profiles/shortfin-mako/
  3. https://repository.library.noaa.gov/view/noaa/30717/noaa_30717_DS1.pdf
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  5. https://www.bmis-bycatch.org/system/files/zotero_attachments/library_1/QPTPVJA6%2520-%2520Calle-Mor%25C3%25A1n%2520et%2520al.%2520-%25202023%2520-%2520Feeding%2520ecology%2520of%2520the%2520shortfin%2520mako%2520shark%252C%2520Isurus.pdf
  6. https://www.fishbase.se/summary/Isurus-paucus.html
  7. https://fishesofaustralia.net.au/home/genus/729
  8. https://www.fisheries.noaa.gov/species/pacific-shortfin-mako-shark
  9. https://www.iucnredlist.org/species/39341/2903170
  10. https://www.iucnredlist.org/species/60225/3095898
  11. https://uni.hi.is/scampana/files/2016/01/campana-et-al-2005-mako-for-fisheries-research.pdf
  12. https://www.iccat.int/Documents/CVSP/CV079_2022/n_4/CV079040183.pdf
  13. https://www.fishbase.se/summary/Isurus-oxyrinchus.html
  14. https://www.fao.org/4/x9293e/x9293e07.pdf
  15. https://www.fisheries.noaa.gov/species/shortfin-mako-shark
  16. https://www.sharktrust.org/shark-taxonomy
  17. https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/isurus
  18. https://openknowledge.fao.org/server/api/core/bitstreams/1b650fd0-3675-43cc-adcf-876cdc5a001f/content
  19. https://www.sciencedirect.com/science/article/pii/B9780124150317500057
  20. https://ufdcimages.uflib.ufl.edu/UF/E0/04/23/97/00001/ehret_d.pdf
  21. https://shark-references.com/species/view/Isurus-desori
  22. http://www.elasmo.com/genera/cenozoic/sharks/macrorhizodus.html
  23. https://www.researchgate.net/publication/387265039_Macrorhizodus_version_1
  24. https://shark-references.com/species/view/Isurus-oxyrinchus-f
  25. https://shark-references.com/species/listAllFossil/I
  26. https://www.researchgate.net/publication/364152578_Combining_morphological_and_molecular_information_to_infer_phylogenetic_relationships_of_lamniform_sharks_Combinando_informacion_morfologica_y_molecular_para_inferir_las_relaciones_filogeneticas_de_lo
  27. https://via.library.depaul.edu/cgi/viewcontent.cgi?article=1331&context=csh_etd
  28. https://www.tandfonline.com/doi/full/10.1080/23802359.2022.2060768
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