The salmon shark is a large predatory species that lives primarily in the cooler waters of the north Pacific. They have an average length of about 7 feet (2.1 meters) and a weight of about 1,000 pounds (454 kg). The salmon shark has large gills and a tall dorsal fin, with dark gray coloring on the back and white on the underside. In terms of general appearance, they look very similar to the great white shark, which is a close relative. Salmon sharks are known to be very fast swimmers, and they are commonly targeted by sport fishermen.
Bony fish are these sharks' primary source of food, and they have a particular liking for the Pacific salmon. Researchers think these sharks also eat squid, shrimp, and certain crabs, but the full extent of their diet is still somewhat mysterious. The sharks got their name because they are often spotted with the salmon who gather near river mouths before spawning. Sometimes salmon sharks are found alone, and sometimes they are found in large groups.
The salmon shark seems to be equally comfortable living in coastal regions or in the middle of the ocean. They have been spotted close to the surface, but they will also dive to depths as low as 500 feet (152 meters). There have been a tiny number of incidents where salmon sharks have been blamed in attacks on people, but the identification in those cases is disputed. Salmon sharks look so much like great white sharks that they could be mistaken for each other, and great whites are associated with many attacks. Despite the overall lack of incidents, the salmon shark is still considered dangerous because of its size and relation to other sharks that have shown aggressive behavior.
One aspect of the salmon shark that distinguishes it from many other species is the ability to maintain a warmer body temperature. This generally helps their muscles function more efficiently, and it allows them to live in very cold waters without that much difficulty. Overall, they have the warmest blood of any known shark species, and they achieve this using a specialized network of blood vessels that helps keep heat inside the body instead of letting it escape. They aren't the only sharks with this ability, but they generally do it with the most efficiency.
Salmon shark females give birth to live young. In a typical breeding season, their litter sizes are between three and seven pups, which are usually birthed in April or May. Once the sharks are born, they are completely independent, and they have to fend for themselves.