Marine sources such as fish and krill do not produce the omega-3 fatty acids, but rather accumulate it in their fatty tissue from the algae they consume. Fatty tissue also accumulates industrial and environmental contaminants; thus oils derived from these tissues contain high concentrations of toxins.
Since fish are the most economical way to extract essential fatty acids, the demand for fish oil supplements is affecting the world’s fish population. Over 70% of fish species are either fully exploited or depleted. Studies have predicted that if overfishing continues, there will be a complete collapse of the ocean’s ecosystem by 2048.