The salmon shark (Lamna ditropis) is a powerful predator of the North Pacific, renowned for its resemblance to the great white shark (Carcharodon carcharias) and its remarkable ability to regulate its body temperature.
Unlike most fish, this shark can regulate its body temperature 14 to 20 degrees Fahrenheit above the ambient water temperature, enhancing its agility and hunting prowess. While often focused on salmon, its diet encompasses a diverse range of marine life. Known by various names in Japanese waters, including Sakezame, Radukazame, and Mokazame, the salmon shark plays a vital role in the aquatic ecosystem.
Read on to explore more about the fascinating world of this unique shark.
Appearance
The salmon shark is a gray-colored shark that, like most large marine animals, has a paler underside. It has white markings and darker blotches on its underside as well. The shark also has a wide tail with a short ridge running along the upper part of the lower lobe.
Juveniles are smaller in appearance but are generally identical. Both have shorter snouts and a similar appearance to a great white shark, although significantly smaller. Similarly to great whites, and other oceanic sharks, the salmon shark has blade-like teeth which is used to efficiently kill its prey.
These sharks grow between 6.5 and 8.5 ft, or 198 – 260 cm, and can weigh up to 485 lbs, or 220 kg. Male sharks reach a slightly smaller size than their female counterparts, a familiar trait in sharks. The largest-ever confirmed sighting was 10 feet, with the highest estimated weight at 992 pounds. It’s believed these sharks can live to around twenty-five years old.
Large, muscular pectoral fins provide lift and control, enabling swift turns and bursts of speed. The large first dorsal fin acts as a stabilizer, while the crescent-shaped caudal fin (tail fin) generates the thrust needed for its predatory lifestyle.
Did you know…
Its ability to thermoregulate is a unique adaptation that sets the salmon shark apart. Specialized blood vessel networks in the muscles called “retia mirabilia” allow the shark to retain metabolic heat, keeping its core body temperature and stomach temperatures higher than the surrounding water. This elevated temperature enhances muscle performance, reaction times, and overall hunting efficiency.
Habitat
Salmon sharks live primarily in offshore waters and oceanic environments but it’s not uncommon to see them inshore, just off the beach line. They range from the sub-Arctic to subtropical waters. It can be found throughout the North Pacific Ocean as well, with a range as far south as the Sea of Japan and as far north as Alaska.
There is a difference in range depending on sex and age. Eastern populations of these sharks are primarily female, while the Western populations are mostly male. It’s not known exactly what causes this separation.
Many sea creatures rely heavily on the water temperatures around them. However, the populations are different in this respect. The retia mirabilia, or counter-current heat exchangers allows the salmon shark to thrive in cool temperate waters.
Some of these colder waters include the Sea of Okhotsk and the Bering Sea in the Northeast Pacific from the Gulf of Alaska to Southern Baja California near Mexico, in the eastern Pacific.
They have an interesting migration pattern that tends to be segregated sexually until summer or fall when males and females gather in the Gulf of Alaska or Japanese waters to mate.
Diet
These opportunistic predators eat whatever is abundant. Their large blade-like teeth have lateral cusplets, small bumps on either side of each tooth. The first upper lateral teeth have oblique (diagonally-oriented) cusps.
It’s common for them to feed on different fish, walleye pollock, pacific herring, squid, salmon, birds, sea otters, and more. Some of these fish include halibut, pollock, sablefish, tunas, codfish, sardines, and more.
Reproduction
Like other sharks, they are ovoviviparous. This means that they develop eggs inside the womb of the female’s body. The eggs remain there until the mother is ready to give birth. The embryos feed on the ova produced by the mother. A typical salmon shark litter size is between two to six pups.
It’s believed that females reach maturity at around 8-10 years of age, with males maturing by five. The gestation period is around nine months. In pups, it is said that there are around 2.2 males born for every female.
Threats
Salmon sharks are not a particular threat from fisheries and commercial fishing. There do not appear to be any commercial fisheries that target these sharks. But, like almost every marine creature, they are sometimes captured as bycatch but are usually discarded.
They are also liable to consume parts of the intended catch. Due to the frequency of these sharks being captured as bycatch, their conservation status is considered to be vulnerable to extinction. This is heightened by the development along seashores and around coastal waters where nurseries are located.
Salmon sharks live in relatively high levels of abundance. A good sign of their population health is that they are currently marked as animals of least concern on the IUCN Red List of Threatened Species. Their population within the Western Pacific, Eastern North Pacific, and Northwest Pacific, to name some, are prime examples of this.
When these sharks are caught, sometimes their fins are cut off and sold. Their flesh is uncommonly sold in the United States, but it does happen. More often, products like leather and oil are created by the captured salmon sharks.
They are also not considered a threat to human beings. They are likely capable of injuring humans, but few, if any, attacks have ever been reported. Salmon sharks are sometimes hunted by other larger sharks, their biggest natural apex predator.
6 More Quick Facts about Salmon Sharks
- Salmon sharks typically roam the open ocean alone or in small, loose groups, unlike some shark species that form larger aggregations.
- With excellent eyesight and a sensitive olfactory system, salmon sharks can detect prey from considerable distances, even in murky water.
- Like many sharks, salmon sharks possess specialized electroreceptors called ampullae of Lorenzini, allowing them to sense the faint electrical fields emitted by living organisms.
- Salmon sharks can venture to depths of over 500 feet in search of prey.
- Dark blotches on the underside are also used to distinguish the salmon shark from the white shark.
- Their preferred temperature range is 2.5 to 24 degrees Celsius.
FAQs
Are salmon sharks dangerous?
The salmon shark is a “potential” danger to human beings. This means that it has the ability to harm human beings but there are few, if any, reported injuries or attacks by salmon sharks.
How long is a salmon shark?
Salmon sharks can grow between 8-10 feet long. There have been reports of some significantly longer. But, like most outliers, these sights often go unconfirmed.
Are salmon sharks good to eat?
Some people like to eat salmon sharks. For example, in Japan, the heart is considered a delicacy. Some fishermen in Alaska and other parts of the world also choose to fish for these sharks.
Are salmon sharks related to mako sharks?
Yes. The salmon shark belongs to the Lamnidae family. This family includes the shortfin and longfin mako shark, the porbeagle, also known as a mackerel shark, and the great white.
Can you own a salmon shark?
While it is legal to own a salmon shark, as it is with most sharks, it’s unlikely that the salmon shark would make a good pet. They are large animals, although not as large as their relatives, the great white, and would require specialized care.
