Most sharks are often thought off as slow-moving creature of cold water, but salmon shark is something else entirely. It runs hot on the inside and relies on special heat-exchange mechanisms to keep its body temperature above the freezing waters of North Pacific. At the heart of this warm-blooded beast are an ability to move very fast. Much faster then any cold-blooded predator can hope to achieve. Sprinting power is what makes difference between full belly and an empty one when chasing down a jumping Chinook salmon at speeds up to 35 miles per hour.
Young pups start out pretty small (just a couple of feet long)… But they don’t reach sexual maturity until they are about seven to ten years old. That happens after about seven to ten years, when the pup reaches a size of about six to seven feet. After that point, the shark simply keeps increasing its weight and size for the next decade or so. At this point, it’s well over six hundred pounds and can reach lengths of up to ten feet without any problem. It is not as large as its celebrity cousins, but it is still quite big by all accounts.
The Fast Salmon Shark
The chart puts them among other mackerel sharks, including porbeagle and the shortfin mako. All these are big fish found in nearshore waters. Salmon sharks cap out at ten feet, while great whites goes into the twenties. And there lies part of the story: They’re not giant open-ocean cruisers; they’re medium-sized speedsters. That’s right for their hunting niche, because it gives them plenty of power to hang on to struggling prey but also keeps them nimble enough to turn quickly.
To spot a salmon shark out in nature, it’s not so much about bulk as it is the details. Turns out they resemble another shark species, the Atlantic Ocean porbeagle, so they can be easy to confuse. To differentiate, check out belly markings and the shape of its snout. Salmon sharks is typically marked with blotches on their white underside and have a short, blunt conical snout. Porbeagles has relatively longer snouts and whiter bellies (not as dirty) without the unique spots. Salmon sharks also have an extra ridge at base of their tail where their two ridges join, something porbeagles do not have. It is a small physical difference, but it makes all the differnce for proper identification.
How and what they eat They’re tightly tied to time and place. Follow the salmon run in the summer, and you’ll find ’em. They travel aggressively to seek out food. This brings us to July and September, a couple of hot spots when thousands upon thousands of fish returns to spawn in places like Gulf of Alaska and Prince William Sound. It’s in this window that anglers specifically target them because the sharks feed aggressively near the surface.
And the breakdown of their diet reveals their dependence on certain prey species: well over half of their intake come from Pacific salmon. Herring and squid makes up the balance. That dependence on particular prey species not only gives the sharks an opportunity but also make them vulnerable to changes in their populations. The conservation outlook is not good for these apex predators. According to global conservation groups, they are now classified as Near Threatened.
The main threats is directed fisheries and bycatch in commercial driftnets operating out of certain Asian countries. These sharks has a slow reproductive rate (a few puppies a couple times a year) so heavy fishing pressure cannot be offset easily. Another wrinkle involves climate change which is also affecting their salmon prey’s migration pattern. When the fish dissapears or relocate, it directly impacts the shark population.
But it’s also important to understand what they are from a broader perspective (not only their aggression and teeth). For starters, they are very specialized cold-water predators designed for efficient and fast movement. And because they are warm blooded, they has an advantage over other slower-moving predator in cold water. If you’ve ever witnessed one break the surface as it pursues a baitfish, then you know you’re watching millions of years of evolution in action.
And all that explosive energy is keeping the coastal ecosystems up and down the North Pacific in balance. Saving the habitat and the prey base saves the whole food web supported by those frenzied summertime trips. You should of seen them hunt.