Desforges, J-P

Dietz, R

Eulaers, I

Jepson, PD

Letcher, RJ

Sonne, C

English

UCL Discovery

Contents lists available at ScienceDirectEnvironment Internationaljournal homepage: www.elsevier.com/locate/envintCorrespondenceKiller whales call for further protectionA R T I C L E I N F OHandling Editor: Adrian CovaciIt is widely accepted that persistent environmental contaminants arepresent at levels to cause concern in top predators (see, for example, R.J. Letcher et al. Sci. Tot. Environ. 408: 2995–3043; 2010). The longbanned industrial chemical polychlorinated biphenyls (PCBs) remains amajor threat to marine top predators such as killer whales because of itspersistence and empirically demonstrated adverse effects on almost allphysiological systems in the mammalian body, including importantlyreproduction and immunity (J.-P. Desforges et al. Environ. Internat.86:126–139; 2016).Now, our recent modelling study published in Science has suggestedthat the long-term viability of over half of the worlds studied killerwhale (Orcinus orca) populations is at risk because of PCBs (J.-P.Desforges et al. Science, 361, 6409: 1373–1376; 2018). These newfindings support previous suggestions of population-level effects inkiller whales as well as reproductive effects on striped dolphin (Stenellacoeruleoalba) and bottlenose dolphin (Tursiops truncatus) (P. D. Jepsonet al. Scient. Rep. 6:18573; 2016). Our modelling study also provides animportant framework to model future cumulative effects of anthro-pogenic stressors at the population-level. While our work was intendedto highlight the potential risk of only one important chemical stressor, itis imperative for future studies to consider the complex mixture ofstressors facing killer whales in the real world. PCBs is but one stressor,and we know that human disturbance and underwater noise from boattraffic as well as food limitations are two other critical factors influ-encing different populations of killer whales (J. K. Ford et al. Biol. Lett.,6(1): 139–142; 2009; DFO, Canada, https://www.canada.ca/en/environment-climate-change/services/species-risk-public-registry/related-information/southern-resident-killer-whale-imminent-threat-assessment.html; 2018). Individual population dynamic studies require a case-by-case assessment of the cumulative impacts from the various factorsinfluencing those populations.Among the killer whale populations highly exposed and threatenedby PCBs, are those foraging on marine mammals along the coast of EastGreenland (J.-P. Desforges et al. Science, 361, 6409: 1373–1376; 2018).Due to their recent appearance in the area, no hunting regulations existfor the local subsistence hunt, and more than 43 killer whales have beenlegally landed since 2009, creating an additional stressor to this po-pulation (Piniarneq, Ministry of Fisheries & Hunting, Government ofGreenland; 2017). Unknown hunting losses (animals shot and sinkingbefore being secured for transport to shore) are also likely to contributeto greater mortality rates than reported. To preserve this population,regulations or a provisional hunting ban would be appropriate untilbasic information on population structure and numbers is available.While efforts to reduce PCB contamination in killer whales may takesome time, action on hunting in Greenland will have immediate effectsto protect this population.The Greenland Health Authorities (The Greenland Nutrition andExercise Council, Veterinary and Food Authorities of Greenland),promptly (within a week) responded to the Desforges et al. (2018)paper. The Authorities recommended that the hunters and general po-pulation stop consuming killer whales due to high concentrations ofPCBs (Government of Greenland, https://naalakkersuisut.gl/da/Naalakkersuisut/Nyheder/2018/10/0510_spaekhuggere; 2018). Suchfast action and recommendations, if followed by the hunters, shouldreduce the hunters as well as the sled dog (likewise being fed killerwhale tissue) exposure to PCBs, with the added benefit of reducing thehunting stress on the killer whale population bordering SoutheastGreenland.The IUCN Red List currently lists killer whales as ‘data deficient’,rather than a more protective “endangered” listing (IUCN Red list,2018). While population numbers and genetics are missing for manypopulations of killer whales, we argue that known population stressfrom underwater noise and food limitations, combined with the recentfindings on hunting and our modeled predictions of PCB affects at thepopulation-level, warrants further efforts to update the status of thisvulnerable species. However, from the reviews of this correspondence itis evident that other stressors like food limitation, underwater noise andeven inbreeding loads, potentially all could impact fitness and fe-cundity, and for some populations be even more severe than the pre-dicted PCB effects.One piece of recent information that adds to the contaminationissue for killer whales and other toothed whales is linked with reducedenzymatic CYP-450 activity that reduces the ability to metabolize or-ganochlorine (S. Kim et al. Gen. Biol. 17:211.; 2016; M. A. McKinneyet al., Environ. Toxicol. Chem. 30:1506–1514; 2011; C. Sonne et al.Science 361, 6498: 1208; 2018).This story reveals that PCBs, despite been regulated since the 1970s,still appear to be a problem for long-lived top predators such as killerwhales (J.-P. Desforges et al. Science, 361, 6409: 1373–1376; 2018) andpresumably other toothed whales at the population-level. In caseswhere humans consume toothed whales, this elevated exposure maynegatively affect the health of these hunters and their families. Hence,continued research into physiological and fitness consequences of PCBexposure in marine mammals and improvements of modelling techni-ques to predict population effects are needed. This combined with ad-ditional regulatory efforts at the national and international level forrapid and permanent elimination of major PCB contamination (S. J.Stuart-Smith and P. D. Jepson, P.D., 2017.Mar. Policy 84, 69–75; 2017)https://doi.org/10.1016/j.envint.2019.02.060Received 5 December 2018; Received in revised form 25 February 2019; Accepted 25 February 2019Environment International 126 (2019) 443–444Available online 03 March 20190160-4120/ © 2019 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/BY-NC-ND/4.0/).Tas well as outreach and participation across academic, governmental,non-governmental (stakeholders), and industrial partners is needed toimprove environmental quality for human and wildlife health.Rune Dietza,⁎, Christian Sonnea, Jean-Pierre Desforgesa, Igor Eulaersa,Robert J. Letcherb, Paul D. JepsoncaAarhus University, Roskilde, Denmarkb Carleton University, Ottawa, Canadac Institute of Zoology, London, UKE-mail address: rdi@bios.au.dk (R. Dietz).⁎ Corresponding author.Correspondence Environment International 126 (2019) 443–444444

Killer whales call for further protection

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Killer whales call for further protection

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