Sometimes omega-3 essential fatty acid supplements are advertised as being better because they are derived from deep sea fish. First of all, it helps to understand what a deep sea fish is.
A deep sea fish is a fish that lives in the colder, darker waters 100 to 1,500 meters (300 to 4,500 feet) beneath the surface of the sea. While deep sea fishing refers to the sport of taking a boat out over deep waters to catch fish, the fish are actually caught at the surface. Deep sea fish don't live at the surface. They live in the depths of the ocean.
And, actually, deep sea fish aren't the best source of omega-3 essential fatty acids, and harvesting of deep sea fish is environmentally destructive. Here are three things you need to know about deep sea fish oil.
- Most species of deep sea fish have been over-harvested.
- Most species of deep sea fish are not especially high in omega-3 essential fatty acids.
- Deep sea fish are much higher in heavy metals than surface fish.
Modern fishing methods have brought certain kinds of skate, hake, eel, and grenadier nearly to the point of extinction. When a deep-sea fish is hauled as much as a mile (1,600 meters) from the continental shelf to the surface, it literally explodes because of the change in pressure. There is no way to "throw back" the fish that the fishers don't want or don't need.
And when a deep sea fish dies, chances of replacement are slim. Certain kinds of sea creatures harvested for their omega-3 essential fatty acids, such as krill, only take a few days to reach sexual maturity. A deep water fish may take as long as twenty years to reach sexual maturity. This means that it can take decades to replenish a fish that has been harvested to extinction-even if that fish is actually just thrown away.
Smaller surface fish concentrate omega-3 essential fatty acids in their bodies by eating the algae that make them when they are exposed to sunlight. Larger surface fish concentrate omega-3 essential fatty acids in their bodies by eating smaller fish.
At the lower levels of the ocean, fish do not feed on algae. They don't have a chance to concentrate omega-3 essential fatty acids. They simply are not as nutritious as the much more abundant anchovies, salmon, tuna, mackerel, and herring that live near the surface.
A Chinese research vessel studying hagfish, which can go as deep as 10,000 feet (3,000 meters) below the surface, had 10 to 100 times the expected content of mercury in their muscles. This means that as a food fish, they are 10 to 100 times more dangerous than similar surface fish.
Heavy metals and other toxins can be removed from deep sea fish oil by distillation just as they can from surface fish-but why would these valuable fish be steamed for their oil alone? The obvious answer is that the deep sea fish that are turned into fish oil are the fish that stayed a little too long on the boat to be sold in the fish market, or they had some other defect that prevented them from being sold as much more expensive table fish.
Your best bet for fish oil is always surface fish. Deep sea fish just don't produce oil of the quality of Omega-3 DHA, Omega-3 Premium, or Omega-3 QH/Ultra.
- Chiu KH, Mok HK. Study on the Accumulation of Heavy Metals in Shallow-Water and Deep-Sea Hagfishes. Arch Environ Contam Toxicol. 2010 Jul 28. [Epub ahead of print]