Salmon sharks (Lamna ditropis) are fascinating marine creatures that inhabit the northern Pacific ocean. As their name suggests, these large sharks primarily feed on salmon but they also eat other fish squid, seabirds, and even marine mammals. In this article, we’ll take a closer look at where these powerful predators live and their habitat range across the Pacific.
An Overview of Salmon Shark Habitat
Salmon sharks live in cold, temperate waters of the North Pacific, from Baja California in Mexico up to the Bering Sea and Sea of Okhotsk near Russia. They are found both in the coastal waters along continental shelves as well as farther offshore in the open ocean.
Some key facts about salmon shark habitat include:
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Depth range: Salmon sharks are most abundant from the surface down to about 500 feet deep, but they have been recorded as deep as 2,200 feet.
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Water temperatures: These sharks prefer water temps between 45-61°F (7-16°C). Their range is limited by temperature.
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Migrations: Salmon sharks make extensive north-south migrations every year, following prey like salmon.
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Coastal and offshore: They occupy both nearshore coastal habitats and offshore oceanic environments.
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Western and eastern Pacific: Separate populations live on each side of the Pacific, exhibiting some genetic differences.
Regional Habitats Across the Pacific
Salmon sharks live throughout the Pacific, but their habitat use and density varies in different regions based on factors like food availability and water temperature.
Western Pacific
In the western Pacific, salmon sharks are found from northern Japan up to the Kamchatka Peninsula and Sea of Okhotsk in Russia. Some key habitat areas include:
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Sea of Japan – Salmon sharks breed off the coast of Japan in late summer/early fall.
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Sea of Okhotsk – An important summer feeding ground off Russia with salmon runs.
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Northern Japan – Coastal waters that provide overwintering sites and access to prey.
Eastern Pacific
On the eastern side of the Pacific Ocean, salmon sharks occupy a large geographic range from Mexico to Alaska:
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Gulf of Alaska – An important feeding ground, especially Prince William Sound during salmon runs.
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Oregon and California – Salmon sharks migrate here in winter to give birth to pups offshore.
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Baja California, Mexico – The southern end of their range based on water temperature.
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Bering Sea – Northern feeding grounds in Alaska with access to seasonal prey.
Coastal vs. Offshore Habitat Use
An interesting aspect of salmon shark habitat is their use of both nearshore coastal environments and offshore oceanic habitats:
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Coastal – Salmon sharks come close to shore to hunt salmon near river mouths and take advantage of upwelling zones full of prey.
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Offshore – They spend large parts of the year in open ocean habitats far from land foraging on pelagic fish and squid.
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Sea mounts – Underwater structures like seamounts and islands are attractive habitats due to localized abundance of food.
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Migrations – Seasonal migrations take them from offshore feeding areas to more coastal wintering sites.
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** juveniles** – Young salmon sharks tend to remain in shallow, nearshore nursery habitats until reaching larger sizes.
Diving Depth and Water Temperature
Two key environmental factors that influence salmon shark habitat are diving depth and water temperature:
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Surface to 500 feet – Although capable of diving much deeper, salmon sharks spend most of their time in epipelagic waters down to around 500 feet where food is abundant.
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45-61°F preferred range – They favor cold temperate waters and seem limited by both lower and upper temperature thresholds.
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Subarctic to subtropical – Their broad latitude range spans subarctic Alaska down to subtropical Baja, California.
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Seasonal migrations – Salmon sharks move great distances to remain in their preferred temperature zone as seasons change.
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Thermoregulation – Special circulatory adaptations allow them to maintain body temperature and exploit colder habitats.
Habitat Connections to Prey
Salmon sharks are strongly tied to key prey species, especially salmon. Access to abundant seasonal food supplies directly shapes their habitat use and migrations:
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Salmon – Migrations allow salmon sharks to follow salmon runs on both sides of the Pacific.
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Herring – Spawning events draw sharks to coastal habitats like bays and inlets.
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Seabirds – Breeding colonies provide seasonal concentrations of prey for opportunistic sharks.
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Squid spawning – Reproductive events of market squid influence sharks aggregating offshore.
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Birth sites – Pupping grounds are chosen to provide newborns ample food.
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Residence times – Salmon sharks seem to remain longer in habitats with more prey availability.
Conservation Status and Threats
Currently salmon sharks are listed as Least Concern on the IUCN Red List. However, potential threats include:
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Bycatch – Incidental capture in commercial fisheries is a source of mortality.
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Sport fishing – Recreational landings also contribute to fishing pressure on populations.
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Climate change – Warming ocean conditions may constrict their preferred cold-water habitat.
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Prey declines – Drops in salmon abundance could negatively impact shark numbers.
Sustainable management will be key for protecting the future of these fascinating apex predators and the habitats they depend on. Careful monitoring of populations, fisheries bycatch, and habitat conditions will ensure salmon sharks continue thriving across their vast Pacific ranges.
Lamna ditropisSalmon shark
Salmon sharks are widely distributed throughout coastal and pelagic environments within the subarctic and temperate North Pacific Ocean, between 10°N and 70°N latitude. Their range includes the Bering Sea, the Sea of Okhotsk, and the Sea of Japan, and also extends from the Gulf of Alaska to southern Baja California. Salmon sharks generally range from 35°N to 65°N latitude in the western Pacific ocean and from 30°N to 65°N in the eastern Pacific, with highest densities found between 50°N and 60°N. (Goldman and Musick, 2008)
Salmon sharks are primarily pelagic, but are also found in coastal waters of the North Pacific. They generally swim in the surface layer of subarctic water, but also occur in deeper waters of warmer southern regions to at least 150m. This species appears to prefer water temperatures from 2°C to 24°C. (Ganong and Shillinger, 2009; Goldman and Musick, 2008; Roman, 2010)
Populations of salmon sharks show seasonal density fluctuations in the Coastal Alaska Downwelling Region, which is characterized by turbulent mixing and strong seasonality of light and temperature. The summer-autumn usage of this ecoregion by salmon sharks coincides with the return of Pacific salmon (a preferred prey item) to their spawning rivers. (Ganong and Shillinger, 2009)
- Aquatic Biomes
- pelagic
- coastal
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- Range depth
- 1 to 255 m
- 3.28 to 836.61 ft
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- Average depth
- 150 m
- 492.13 ft
Adult salmon sharks can weigh at least 220 kg (485 lbs). There are unofficial reports of salmon sharks weighing 450 kg (992 lbs), but it is likely that this specimen was a misidentified white shark (Carcharodon carcharias). Sharks in the eastern North Pacific have a greater weight to length ratio than their counterparts in the western North Pacific. (Goldman and Musick, 2008; Roman, 2010; Taylor, 1993)
When reporting shark lengths, precaudal length (PCL) is often used, even though it excludes the tail fin. This allows discussion of a standardized length measure, as different possible orientations of the tail can give different measurements of total length. The PCL is determined by calculating the straight-line-distance between two vertical lines, one projected from the tip of the snout, and the other from the precaudal point. Adult salmon sharks typically range in size from 180 to 210 cm PCL. (Goldman and Musick, 2008)
Most fishes are ectotherms, meaning their body temperature remains identical to the surrounding water. Salmon sharks, however, are endothermic, meaning they maintain a core body temperature higher than the surrounding water (up to 16°C). This is accomplished through retention of heat produced by cell metabolism. However, no information on the basal metabolic rate of Lamna ditropis was found. (Roman, 2010)
Salmon sharks have a heavy, spindle-shaped body with a short, conical snout. These sharks have relatively long gill slits. The mouth is broadly rounded, with the upper jaw containing 28 to 30 teeth and the lower jaw containing 26 to 27 moderately large, blade-like teeth with cusplets (small bumps or “mini-teeth”) on either side of each tooth. Unpaired fins consist of a large first and much smaller second dorsal fin, a small anal fins and a crescent-shaped caudal fin. The caudal fin is homocercal, meaning the dorsal and ventral lobes are nearly equal in size. Paired fins include large pectoral fins and much smaller pelvic fins, which are modified to form reproductive structures in males. A distinctive keel is present on the caudal peduncle and a short secondary keel is present on the caudal base. Dorsal and lateral areas are dark bluish-gray to black. The belly is white, and often includes various dark paatches in adults. The ventral surface of the snout is also dark-colored. (Goldman and Musick, 2008; Roman, 2010; Taylor, 1993)
Salmon sharks can be distinguished from great white sharks (Carcarodon carcharias) by the presence of a secondary keel on the caudal base, dark coloration on the ventral surface of the snout, and dusky patches on the belly, all of which are lacking in great whites. Salmon sharks are also similar in appearance to porbeagle sharks (Lamna nasus), but can easily be distinguished by their distributions (porbeagles are absent from the North Pacific range of salmon sharks). (Francis, et al., 2008; Roman, 2010)
- Other Physical Features
- ectothermic
- heterothermic
- bilateral symmetry
- Sexual Dimorphism
- female larger
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- Range mass
- 220 (high) kg
- 484.58 (high) lb
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- Range length
- 140 to 215 cm
- 55.12 to 84.65 in
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- Average length
- 180-210 cm
- in
Like other species in the family Lamnidae, only the right ovary of salmon sharks is functional. Fertilization is internal, and development proceeds within the uterus. Salmon sharks are ovoviviparous, but developing embryos maintain no direct connection to the mother to obtain nutrition. Oophagy has been observed in this species, and likely represents the primary source of nutrition for developing embryos. The pregnant female ovulates and the unfertilized eggs are sent to the nidamental gland, where they are filled with yolk. The eggs are then moved to the uterus, where the embryos can feed on them. Litters tend to contain 4 to 5 young, which are approximately 60 to 65 cm PCL at birth. (Roman, 2010)
Little is known about how salmon sharks find and select mates, although seasonal migrations and aggregations of individuals likely facilitates this process. Males hold on to females by biting their pectoral fin during copulation, which consists of the insertion of one of the males claspers (modified pelvic fins) into the females cloaca. Couples have no further contact following copulation. (Roman, 2010)
- Mating System
- polygynandrous (promiscuous)
Salmon sharks mate in northern waters during autumn and give birth after a 9 month gestation period, during their southern migration in late spring through early summer. Individuals that populate the central and western North Pacific are thought to breed off the coast of Honshu, Japan. Those that populate the eastern North Pacific breed off the coasts of Oregon and California. Pups are born in nursery grounds in the central North Pacific transition zone or along the coast of United States and Canada. Female salmon sharks in the western North Pacific reproduce annually, and are estimated to bear 70 offspring in their lifetime, while evidence suggests that females in the eastern North Pacific reproduce every two years. (Ganong and Shillinger, 2009; Roman, 2010; Tribuzio, 2004)
Sexual maturity of males in the western North Pacific is estimated to occur at approximately 140 cm PCL (corresponding to an age of 5 years), and between 170 and 180 cm (ages 8 to 10 years) for females. For salmon sharks in the eastern North Pacific, sexual maturity is reached between 125 and 145 cm PCL (ages 3 to 5 years) for males and 160 to 180 cm (ages 6 to 9) for females. Salmon sharks in both regions reach maximum lengths of approximately 215 cm PCL for females and about 190cm PCL for males. (Roman, 2010)
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- Breeding interval
- Females in the eastern North Pacific breed every two years, while those in the western North Pacific breed annually.
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- Breeding season
- Breeding occurs in autumn and winter in the northern hemisphere.
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- Average number of offspring
- 4-5
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- Average gestation period
- 9 months
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- Range age at sexual or reproductive maturity (female)
- 6 to 10 years
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- Range age at sexual or reproductive maturity (male)
- 3 to 5 years
Females provide nutrition to their embryos through unfertilized eggs, which are consumed by the developing young. Protection is provided to embryos through residence within the mothers uterus until they have fully developed and are able to fend for themselves. (Tribuzio, 2004)
- Parental Investment
- female parental care
- pre-hatching/birth
- provisioning
- female
- protecting
- female
- provisioning
The maximum age of salmon sharks has been estimated through vertebral analysis. In both western and eastern North Pacific populations longevity estimates are similar, between 20 and 30 years. Salmon sharks are not currently held in captivity in large oceanaria and there is no published information regarding their lifespan under captive conditions. (Goldman and Musick, 2008)
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- Range lifespanStatus: wild
- 17 to 25 years
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- Typical lifespanStatus: wild
- 20 to 30 years
Like many shark species, salmon sharks segregate by size and sex. In this species, an interesting sex ratio difference has been observed across the North Pacific basin. The western population is dominated by males whereas the eastern population is dominated by females. A north/south segregation has also been noted, with larger sharks ranging farther north than smaller ones. Salmon sharks are known to hunt both alone and in feeding aggregations of several individuals (up to 30 to 40 sharks have been observed in these schools). They are seasonal migrants, and are strongly suspected to follow the movements of preferred prey items. In the case of eastern North Pacific populations, the prey item followed appears to be Pacific salmon species, while distribution of western North Pacific populations appears to be linked to the distribution of herring and sardines. The distributional and migratory patterns of both subpopulations also appears to be influenced by the sex, size, and age of individuals. (Goldman and Musick, 2008; Roman, 2010)
- Key Behaviors
- natatorial
- motile
- migratory
- solitary
Salmon sharks are migratory predators that have no permanent territories or home ranges. (Goldman and Musick, 2008; Roman, 2010)
While information on intraspecific communication in salmon sharks is lacking, this species, like other cartilaginous fishes, perceives its environment using visual, olfactory, chemo- and electroreceptive, mechanical, and auditory sensory systems. (Karleskint, et al., 2010)
- Perception Channels
- visual
- tactile
- acoustic
- vibrations
- chemical
- electric
- Primary Diet
- carnivore
- piscivore
- Animal Foods
- fish
- carrion
Small salmon sharks from 70 to 110 cm PCL are at risk of being preyed upon by larger sharks, including other salmon sharks, blue sharks (Prionace glauca), and great white sharks (Carcharodon carcharias). Once maturity is reached, salmon sharks occupy the highest trophic level in the food web of subarctic waters, alongside marine mammals and seabirds. The only known predators of mature salmon sharks are humans. (Roman, 2010)
Small salmon sharks are found in abundance in waters north of the subarctic boundary, which are thought to be their nursery ground. There they can avoid predation by larger sharks, which inhabit areas that are further north or south. Juveniles also display obliterate countershading, and lack the dark blotches found on the ventral areas of adults. (Roman, 2010)
- Anti-predator Adaptations
- cryptic
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- Known Predators
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- salmon sharks (Lamna ditropis)
- blue sharks (Prionace glauca)
- great white sharks (Carcharodon carcharias)
- humans (Homo sapiens)
Salmon sharks are apex predators in subarctic waters, helping to regulate populations of their prey species within the ecosystem. (Nagasawa, 1998; Roman, 2010)
- flatworms (Nybelinia surmenicola)
- nematodes (Anisakis simplex)
- copepods (Anthosoma crassum)
- copepods (Echthrogleus coleopteratus)
- copepods (Dinemoura latifolia)
- copepods (Dinemoura affinis)
Economic Importance for Humans: Positive
Shark meat and shark fins have high economic value and salmon sharks are often caught by commercial fisheries, although this is often as bycatch in pursuit of other species. In Japan, their hearts are used for sashimi. They are also caught by sports fishermen for recreation. (Roman, 2010; “Tagging of Pacific Predators, Salmon Shark.”, 2010)
- Positive Impacts
- food
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FAQ
Where can you find salmon sharks?
They range across the North Pacific from the Bering Sea and the Sea of Okhotsk to the Sea of Japan in the western Pacific, and from the Gulf of Alaska to southern Baja California, Mexico, in the eastern Pacific.
Can a salmon shark live in freshwater?
With the exception of the bull shark, sharks can not swim in freshwater. A salmon shark, which typically doesn’t grow more than 10-feet, have been occasionally seen off Washington state’s coast and, believe it or not, have been mistaken for a small great white.
Is the salmon shark edible?
Do salmon sharks live in Alaska?
Yes, salmon sharks do live in Alaskan waters, particularly in the Gulf of Alaska and surrounding areas. They are a common predator in the region, known to feed on salmon and other fish.