Fishing for Squalene
despite moral implications, It comes As no surprise that sharks are highly sought after for their liver oil.
Shark-derived squalene not only yields the most oil, compared to plant-derived alternatives, but it is also assumed to be the cheapest and simplest means of extraction. To be more specific, deep-sea sharks are targeted for the squalene market because they have some of the highest concentrations of squalene in their livers, some taking up to 20% of their body weight! Why do they have such massive livers? Most fish have a pocket of gas called a “swim bladder” to control buoyancy. Deep-sea sharks, however, have a large liver instead because it helps them stay buoyant under the immense pressure of the deep ocean.
These deepwater sharks are also some of the most vulnerable to exploitation because of their extremely low reproductive potential. In other words, their populations are more likely to be easily decimated if sexually mature sharks with the largest livers are the ones being fished. This is why the liver oil trade has been detrimental to several shark species and caused the downfall of the Gulper shark fishery in the Maldives, only 20 years after it began (Adam et al. 1998). The Portuguese shark is also heavily targeted for the squalene, resulting in a decline of overall abundance (OSPAR 2010).
So where are all of these sharks fished from? The French and Spanish used to lead the race in deep-sea shark fishing for squalene in the North East Atlantic, but in 2006 the European Union banned targeted deep-sea fisheries because of the steep decline in shark populations. Consequently, this act pushed industrial fleets out of EU waters. Squalene fisheries primarily are in the Indian, southeastern Atlantic and western Pacific oceans today.
It is estimated that 1 ton of shark liver oil is produced from 2,500 to 3,000 sharks. As we stated in the previous blog, that amounts to about 2.7 million sharks harvested every year for their livers.
When fishermen set out to sea, usually they have to come back to port fairly quickly after their catch to keep the seafood fresh. With shark fins, assuming that the shark is finned at sea, fishermen can keep the fins drying in the sun for as long as they like. Shark fins also take up far less room than a whole animal on a boat. The same is true with shark liver. Shark liver can be stored at room temperature, making it easy for the fishermen to stay at sea longer and catch more instead of using a costly refrigerator. It has also been known that fishermen will catch a shark, take out its liver and throw it back (not surviving). But this frees up room for more catches on the boat.
top shark species that are targeted for their livers:
Top shark species that are targeted for their livers, by the FAO.
