Sharks of the Deep Sea

Nearly all shark species are experiencing severe population declines -some are at population levels less than 1% of their numbers just 35 years ago.  Sharks are generally slow-growing and long-lived and breed late in life, making them extremely vulnerable to exploitation and slow to recover from decline.  While all shark populations are experiencing declines, deep-sea sharks are the most vulnerable to overexploitation and take the longest time to recover, if they recover at all. Yet, these shark species are being pulled from the depths of the oceans and killed for their liver oil.
  
There are more than 100 species of sharks that occupy the deepest depths of the ocean. Since deep-sea sharks are hard to find, information is lacking about these less common shark species.  Examples of deep-sea sharks targeted for their liver oil include: the gulper shark (Centrophorus granulosus), the Portuguese dogfish (Centroscymnus coelolepis), the spiny dogfish (Squalus acanthias), and the leafscale gulper shark (Centrophorus squamosus).  These deep sea sharks are truly fascinating creatures. 

• The Portuguese dogfish occupies depths of 270-3,700 m, the deepest diver amongst any of its fellow sharks.
• Deep-sea sharks, such as the Spiny dogfish, mature late in life since they live so long, up to 100 years.
• The gulper shark is believed to have the lowest reproductive potential of all sharks and rays, only 1 pup every 2 years, making them extremely vulnerable to fishing pressure.
• According to the International Council for the Exploration of the Seas (ICES), stocks of Portuguese dogfish and leafscale gulper shark are considered to be depleted.  Given this very poor state, ICES recommends a zero catch of deepwater sharks.