Perils of deep-sea fisheries – A rethink urgently needed

Sustainability of deep-sea fisheries

Elliott A. Norse, Sandra Brooke,William W.L. Cheung, Malcolm R. Clark, Ivar Ekeland, Rainer Froese, Kristina M. Gjerde, Richard L. Haedrich, Selina S. Heppell, Telmo Morato, Lance E. Morgan, Daniel Pauly, Rashid Sumaila, Reg Watson

Marine Policy
Volume 36, Issue 2,

In the paper referred to above marine scientists from around the world is recommending an end to most commercial fishing in the deep sea. They recommend fishing in more productive waters nearer to consumers and underline the fact that with rare exceptions, deep-sea fisheries are unsustainable.  

The deep sea may the largest but it is the least productive part of the oceans. Most deep-sea fishes have far less population resilience and productivity than shallow-water fishes. Life processes happen at a slower pace than near the sea surface. The researchers say like old-growth trees and great whales, their biomass makes them tempting targets while their low productivity creates strong economic incentive to liquidate their populations rather than exploiting them sustainably (Clark's Law).

Deep sea fishes have long life history. Some of them live more than a century. Some deep-sea corals can live more than 4,000 years.  Deep sea fishing makes it difficult for them to repopulate. They can only sustain a very low rate of fishing. Populations’ sharks and orange roughy have taken a nose dive in recent years. Orange roughy take 30 years to reach sexual maturity and can live 125 years. Deep-sea fisheries can be sustainable only where the fish population grows quickly 

The researchers signs off with the following words “Instead of mining fish from the least-suitable places on Earth, an ecologically and economically preferable strategy would be rebuilding and sustainably fishing resilient populations in the most suitable places, namely shallower and more productive marine ecosystems that are closer to markets.”