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Whales Are Vital for Marine Ecosystem Health

FACTSHEET IWC 66 2016

Humpback Whale © Jürgen Freund / WWF Whales are Vital for Marine

There has been an ongoing debate at the IWC focused on the role that large whales play in the ecosystem and whether they should be viewed as competitors for resources, a marine resource to be harvested, or essential elements of healthy marine . Historical and cultural values will greatly influence perspectives on this, but modern science overwhelmingly supports the view that whales play an important regulatory function in marine ecosystems. While it is tempting for some to believe that whales eat , and therefore fewer whales will leave more fish for human consumption, several studies and multiple scientific meetings throughout the years have concluded that there is “no clear and direct relationship between marine mammals’ predation and the potential catch by fisheries” 1,2. In fact, the IWC Scientific committee in 2003 concluded that for ‘no system at present are we in the position, in terms of data HUMANS ARE SOLELY availability and model development, to provide quantitative management advice RESPONSIBLE FOR on the impact of cetaceans on fisheries…” Humans are solely responsible for the increasing scarcity of fisheries and THE INCREASING other food resources. Whales have been shown to play an important role in the maintenance of healthy marine ecosystems. In addition to the various SCARCITY OF FISHERIES biological, bio-physical and bio-chemical contributions whales make, they have an inherent cultural and , and can render ecosystem services AND OTHER FOOD and strengthen economic security for coastal communities through their RESOURCES. ecotourism potential 3. THE SCIENCE

Recent evidence suggests that we are entering a new geological era, the , marked by mass of a range of terrestrial and aquatic species. Unlike previous mass extinctions that were driven by climate change and/or catastrophe (volcanic eruptions, asteroid impact), today’s extinctions are human-driven. In the Iron e and nitrogen are both limited in marine Whales promote vertical mixing of nutrients in the water ecosystems but essential for plant and animal life at all column through their diving and surfacing as well as by marine realm extinctions are disproportionately levels of the food web. These elements need to be available at “ploughing the seabed and suspending nutrients during affecting large-bodied marine animals, including 66% - 90% the surface of the where they can stimulate primary bottom feeding . marine mammals and large predatory fish. While WHALES REMOVED FROM GLOBAL through photosynthesis. any whales feed at climate change and habitat loss play an increasing depth but defecate and urinate at the surface thus playing role, human direct takes have been the dominant a crucial role in transporting these limiting nutrients. This cause of species loss to date 22. ECOSYSTEMS SINCE 1000 AD contribution exceeds their calculated consumption thus enhancing rather than limiting ocean productivity and It is estimated that large predatory fish rom the time that asue began around yields . This process also helps to combat climate today is only about 10% of pre-industrial levels it is estimated that of all whales have been removed change and global warming as carbon is absorbed and 23. World per capita fish consumption increased from global ecosystems . While some of seuestered during photosynthesis. from an average of 9.9kg in the 1960s to 19.7kg in whales are increasing in number total numbers of great 2013. The United Nation’s Food and whales and their combined biomass is still estimated to be only of what it was prior to whaling . lue whales urthermore due to their large body mass baleen whales Organization’s (FAO) analysis of assessed fish are thought to amount to only of their prewhaling store a great deal of carbon both when living and when stocks indicates that the proportion of fish numbers . their carcasses sin after death . It is estimated that large stocks within biologically sustainable levels has baleen whales now store less carbon than they did in the declined from 90 percent in 1974 to 68.6 percent prewhaling era. in 2013, meaning that nearly a third of the world’s fish stocks are being fished at a biologically unsustainable levels 24. These statistics make it clear that humans and not REMOVING A TOP PREDATOR COULD whales are responsible for the increasing scarcity of fisheries resources 25. The Convention for the POTENTIALLY DISRUPT THE FOOD WEB NITROGEN (N) Conservation of Antarctic Marine Living Resources (CCAMLR), the of the European Union (EU), FAO Technical Guidelines It is tempting for some to believe that these dramatic arine ecosystems are infinitely complex and the pathways Whales also transport nutrients horiontally from highly for Responsible Fisheries, and the United Nations decreases in whale numbers and biomass would yield a that lin whales and commercially harvested fish involve productive temperate and polar feeding grounds to nutrient surplus of marine resources for human harvesting. However myriads of other species and marine processes . ome poor tropical breeding grounds where they excrete nitrogen Convention on the Law of the Sea (UNCLOS), all this argument has never held up under scientific scrutiny . researchers have found that rather than yielding a fisheries in their urine and contribute other nutrients through their require that the possible effects of a fishery on its ven in the very few cases where the prey of large whales surplus the largescale removal of whales from ecosystems placentas and carcasses . ecosystem should be taken into account. has been associated with ecosystem disruption and overlaps with commercially targeted marine resources there Fisheries remains the leading cause of are many reasons why reducing whale numbers will not “trophic cascades that impact multiple species and in result in increased fisheries yields. some cases lead to ecosystem collapse . In the orth human-induced cetacean mortality, responsible acific for example the scarcity of baleen whales after While live whales transport important nutrients upward for the death of an estimated minimum of whaling led iller whales that previously fed on large through the whale carcasses sin and 300,000 cetaceans per year 26. It is clear that whales to switch prey to smaller marine mammals such as transport carbon and other organic matter to the fisheries present a greater threat to cetaceans seals sea lions and sea otters. ea otters control urchin seabed . ecomposing whale carcasses create their own than vice versa. Any collaboration of the IWC populations which if left uncheced can destroy elp beds. miniecosystems more than species can inhabit a single elp forests act as important nurseries for several fish seleton contributing to marine biodiversity and ecosystem with the FAO or other intergovernmental ECOSYSTEMS ENGINEERS species and their loss can have significant cascading complexity . organisations in relation to cetaceans impacts on commercial fish stocs . imilar should focus on mitigating bycatch n increasing number of studies show that whales play preyswitching and trophic cascades are also thought to as a means of sustaining biodiversity have occurred in the outhern Hemisphere . an important role as ecosystem engineers supporting and maintaining ecosystem health and healthy ecosystems in ways that extend well beyond simple predatorprey relationships . therefore food security. WHALES ARE VITAL FOR HEALTH MARINE-FLAGSHIPS.PANDA.ORG (eds J.A.(eds Estes Ch. 16, et al.) 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vironmen y with nature on Marine Mammal Science, Estes 262-278 Ch. ( 20, et al.) 508-509 (2003). rm production in the Southern abundances the at global scale. natural en humans Enhance Primary Productivity in in ha ’s the Environment 12, 377-385 h ve ion of the plan at h humans li the degrad ture in whic fu ild a future in whic y we are here g.uk stop

or bu y we are here f. stop the degradation of the planet to Wh To Wh To ww to build a Morissette, L., Kaschner, K. & Gerber, L. ‘Whales eat Roman, & Palumbi, S. R. J. Whales before whaling in the Lavery, T. J. et al. J. Whales Lavery, T. sustain fisheries: Blue Morissette, Marine D. L., Christensen, & Pauly, V. Pershing, Christensen, A. J., L. Record, B., R., N. Roman, et al. J. Whales as marine ecosystem engineers. Branch, T. A. Branch, & Williams, T. in M. Whales, T. whaling and Roman, J., McCarthy, J. & Roopnarine, P. The McCarthy, Whale Roman, & Roopnarine, J., J. P. Thomas, P. O., Reeves, O., R. R. Thomas, & Brownell, P. R. L. Status

O’Connor, S., Campbell, S., O’Connor, R., Cortez, & Knowles, H.

Christensen, L. B. Marine mammal populations:

the ocean carbon cycle: why bigger was 5, better. one PloS e12444 (2010). Ocean. Marine Mammal Science 888-904, 30, doi:10.1111/ mms.12108 (2014). 11 B. Sherwood, & Stetson, D. G. P. a Coastal Basin. PLoS ONE 5, (2010). 47-123 10 whales stimulate primary (2014). 9 Pump: Marine Mammals Canada, 2012). 8 Frontiers in Ecology and doi:10.1111/mms.12281 (2015). doi:10.1111/mms.12281 7 Reconstructing historical (Fisheries165 Centre, University British of Columbia, North Atlantic. Science 301, 6 baleen whales. theof world’s ocean ecosystems J.A. (eds University Californiaof Press, 2006). 5 expenditures and expanding economic benefits. 1-295 (International Fund Animal for Welfare, Yarmouth MA, USA, 2009). 4 ecosystem. Fish and Fisheries 11, 388–404 (2010). 3 Whale Worldwide: Watching T. doi:10.1371/journal.pone.0043966 (2012). 2 fish’? Demystifying myth the in 1 Mammal Impacts in Exploited Ecosystems: Large Would Scale Culling Benefit Fisheries?PLoS7, e43966,ONE © 1986 Panda symbol WWF – World Wide Fund For Nature (Formerly World Wildlife Fund) ® “WWF” is a WWF Registered Trademark. WWF, Avenue du Mont-Blanc, Gland, 1196 Switzerland Fax 22 22 +41 +41 364 364 – Tel. 9111 0332. For contact details and further information, please visit www.panda.org at website our international References Humpback whale © Cat Holloway / WWF / Holloway Cat © whale Humpback

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