Salmon Shark Tracks Amaze Scientists
The salmon shark is a unique animal. This shark has a very broad geographic and vertical distribution, ranging across the North Pacific from the cold subarctic waters of the Bering Sea to warm, tropical waters as far south as Hawaii (22ºN), and diving to depths in excess of 1000 m. Across all of these diverse environments and habitats, salmon sharks are highly active and successful predators. It is well known to be a highly active shark capable of swimming at great speeds. Indeed it is frequently observed breaching from the water when in pursuit of salmon in
How do they do this? How are they able to use such a diverse array of habitats, especially the cold waters of the subarctic North Pacific? As anybody who’s been swimming in cold water knows, it takes a lot of energy to maintain your body temperature and still remain active. The same general issues basically apply to salmon sharks. Salmon sharks, however, have some unique adaptations that allow them to deal with these thermal issues. All sharks in the family Lamnidae (e.g. salmon, porbeagle, mako, white sharks) have some degree of anatomical and physiological specialization associated with a capacity for heat conservation and endothermy. Salmon sharks possess counter-current heat exchangers (retia mirabilia) that allow them to retain the metabolic heat generated by highly aerobic tissues in the muscles, viscera, kidney, and brain. This enables the sharks to maintain body temperatures that are elevated as much as 21.2ºC (about 70ºF) above ambient water temperature. In addition, salmon shark cardiac physiology is also specialized for utilizing cold habitats, which allows their hearts to provide their active, warm tissues with enough oxygen to effectively forage in cold environments. So in essence, through these adaptations, these sharks are able to generate and conserve body heat, allowing them to be more active and effective across a wide range of temperatures. These unique characteristics allow the salmon shark to be highly active predators across their broad geographic and vertical range, and likely underlie their ability to use the highly productive boreal and polar waters of the north Pacific.
This last summer, as part of ongoing research we tagged several salmon sharks with SPOT tags in
Another shark (1710014) is in the deep oceanic waters of the North Pacific approximately 1200 miles west of