Earth Protect Blog

The deep sea, the planet's biggest ecosystem, is in trouble, an international research team says, underling the need to stop commercial fishing in such waters and focus on productive waters instead. Presented in the journal Marine Policy, a comprehensive analysis reveals the unsustainability of deep-sea fisheries. 

The 'Sustainability of deep-sea fisheries' study was released prior to the United Nations decision on whether deep-sea fishing will be permitted to continue in international waters, what the UN calls 'high seas'. Researchers say the sea's cold depths are not a good niche for marine creatures. Sunlight that triggers photosynthesis is not applicable in such depths, and adding to the problem is the fact that food is scarce and life processes occur at a laggard pace compared with what happens at the water's surface. They say that while some fish at those depths can live for over 100 years and some corals can live for 4,000 years, creatures that have adapted to living in those waters fail to repopulate on human time scales. Exacerbating the problem even further are the powerful fishing technologies that are overwhelming them. 'The deep sea is the world's worst place to catch fish,' explains lead author Dr Elliott Norse, head of the Marine Conservation Institute in Bellevue, Washington in the United States. 'Deep-sea fishes are especially vulnerable because they can't repopulate quickly after being overfished.' The team, made up of marine ecologists, fisheries biologists, economists, international policy experts and mathematicians, says less than 1% of the seafood on our planet comes from the deep sea. Despite this number, bottom trawling continues, triggering significant damage to fish and life on the seabed. For nearly 40 years, commercial fishing fleets have been moving deeper and deeper into the seas because of overexploited coastal fisheries. 'Because these fish grow slowly and live a long time, they can only sustain a very low rate of fishing,' says Dr Selina Heppell, a marine fisheries ecologist at Oregon State University in the United States, and one of the authors of the study. 'On the high seas, it is impossible to control or even monitor the amount of fishing that is occurring. The effects on local populations can be devastating.' Some of the fish that are being impacted by deep-sea fishing are sharks, orange roughy, grenadiers and blue ling. Orange roughy, for example, needs around 30 years to reach sexual maturity and can live 125 years. 'Fifty years ago no one ate orange roughy,' Dr Daniel Pauly, a fisheries biologist with the University of British Columbia (UBC), Canada, points out. 'In fact, it used to be called slimehead, indicating no one ever thought we would eat it. But as we've overfished our coastal species, that changed and so did the name.' Says Dr Malcolm Clark of the National Institute of Water and Atmospheric Research in New Zealand: 'Fishing for orange roughy started in New Zealand and grew rapidly through the 1980s and 1990s. However, most of the fisheries were overexploited, and catch levels have either been dramatically reduced or the fisheries closed all together. The same pattern has been repeated in Australia, Namibia, the Southwest Indian Ocean, Chile and Ireland. It demonstrates how vulnerable deep-sea fish species can be to overfishing and potential stock collapse.' Dr Norse comments: 'Deep-sea fisheries can be sustainable only where the fish population grows quickly and fisheries are small-scale and use gear that don't destroy fish habitat. With slow-growing fish, there's economic incentive to kill them all and reinvest the money elsewhere to get a higher return-on-investment. Killing off life in the deep sea one place after another isn't good for our oceans or economies. Boom-and-bust fisheries are more like mining than fishing.' Also contributing to this study were experts from Canada, Germany, Portugal, Spain, Switzerland and the United Kingdom.

For more information, please visit: Marine Policy: http://www.elsevier.com/wps/find/journaldescription.cws_home/30453/description#description Marine Conservation Biology Institute: http://www.mcbi.org/

Related stories: 33769

Category: Miscellaneous
Data Source Provider: Marine Policy; Marine Conservation Biology Institute
Document Reference: Norse, E.A., et al. (2011) 'Sustainability of deep-sea fisheries', Marine Policy, published online 24 August. DOI: 10.1016/j.marpol.2011.06.008.
Subject Index: Policies; Earth Sciences; Biotechnology; Veterinary and animal sciences; Economic Aspects; Life Sciences; Scientific Research; Coordination, Cooperation; Sustainable development ; Resources of the Sea, Fisheries