Conservation of Arctic Marine Mammals Faced with Climate Change Author(s): Timothy J. Ragen, Henry P. Huntington and Grete K. Hovelsrud Source: Ecological Applications, Vol. 18, No. 2, Supplement: Arctic Marine Mammals and Climate Change (Mar., 2008), pp. S166-S174 Published by: Wiley on behalf of the Ecological Society of America Stable URL: http://www.jstor.org/stable/40062164 Accessed: 04-04-2017 17:09 UTC

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This content downloaded from 199.8.170.13 on Tue, 04 Apr 2017 17:09:29 UTC All use subject to http://about.jstor.org/terms Ecological Applications, 18(2) Supplement, 2008, pp. S166-S174 © 2008 by the Ecological Society of America

CONSERVATION OF ARCTIC MARINE MAMMALS FACED WITH CLIMATE CHANGE

Timothy J. Ragen,1'4 Henry P. Huntington,2 and Grete K. Hovelsrud3

]U.S. Marine Mammal Commission, 4340 East- West Highway, Room 905, Bethesda, Maryland 20814 USA 2Huntington Consulting, 23834 The Clearing Drive, Eagle River, Alaska 99577 USA 3 Cent re for International Climate and Environmental Research - Oslo (CICERO), P.O. Box 1129, Blindern N-0318 Oslo, Norway

Abstract. On a daily basis, societies are making decisions that will influence the effects of climate change for decades or even centuries to come. To promote informed management of the associated risks, we review available conservation measures for Arctic marine mammals, a group that includes some of the most charismatic species on earth. The majority of available conservation measures (e.g., restrictions on hunting, protection of essential habitat areas from development, reduction of incidental take) are intended to address the effects of increasing human activity in the Arctic that are likely to follow decreasing sea ice and rising temperatures. As important as those measures will be in the effort to conserve Arctic marine mammals and ecosystems, they will not address the primary physicalmanifestations of climate change, such as loss of sea ice. Short of actions to prevent climate change, there are no known conservation measures that can be used to ensure the long-term persistence of these species and ecosystems as we know them today. Key words: Arctic; climate change; conservation; marine mammals; risk analysis.

Introduction The papers in this Special Issue examine the ongoing Anthropogenic climate change, perhaps more and than potential physical effects of climate change in the any other consequence of human civilization, hascoming the century and their likely impacts on Arctic potential to change Arctic ecosystems profoundly. marine mammals. In this paper, we consider a range Temperatures and sea levels are rising and will of lead conservation to measures to address those impacts. By "conservation measures" we mean actions that can be coastal and insular inundation (McCarthy et al. 2001). Important Arctic habitat, most notably sea ice (Parkin- taken to prevent, minimize, or mitigate human impacts son et al. 1999), will be altered or destroyed, oncausing Arctic ecosystem components and processes, thereby extensive redistribution of mobile species, the perpetuating disap- the natural ecology and evolution of these pearance of nonmobile species throughout portions ecosystems. of The term "prevention" may not be strictly their range, and possible species extinction (Thomas accurate, et inasmuch as climate change is underway and al. 2004). Climate change will involve alteration ofcan water no longer be prevented fully. Although "minimiza- and nutrient cycles and energy pathways in the tion"world's might be a more accurate term, we use "preven- oceans (Macdonald et al. 2005). It may alter oceanic tion" andbecause it connotes a stronger, more effective, and, atmospheric circulation patterns (Schmittner 2005), to thewith extent possible, more proactive management potentially severe biological and ecological consequenc- approach. es for many, if not all, ecosystems, marine Whether and mindful of it or not, societies already are terrestrial. Through physical, chemical, and biological conducting a de facto risk analysis on climate change linkages, these changes will cascade through ecosystems. and its potential consequences. In this paper we use a The unexpectedly rapid disintegration of the Larsenrisk analysis B framework (Maguire 1991, Harwood 2000) ice shelf in the Antarctic (Shepherd et al. 2003), to consider the potential conservation measures to address surprisingly rapid pace of glacial decline on Greenland those risks. By taking this approach, we hope to make (Rignot and Kanagaratnam 2006), and other recent, the analysis clearer and more useful for managing the unanticipated observations suggest we are in for human a great activities that contribute to climate change or many surprises with respect to the regional and exacerbate global climate change effects. effects of climate change. The end result may be beyond The first steps in such an analysis are identification of our ability to predict or imagine. the physical causes and manifestations of climate change and description of the hazards to which marine mammals may be exposed. Preceding papers in this Manuscript received 4 May 2006; accepted 19 June 2006; volume provide such information, and we review them final version received 19 September 2006. Corresponding Editor: P. K. Dayton. For reprints of this Special Issue, see only briefly here. A range of natural factors contribute footnote 1, p. SI. to climate change, including variations in energy output 4 E-mail: tragen(a) mmc.gov from the sun, variations in the geometric relationship

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between the sun and the earth, terms volcanic and come eruptions, to grips with and the discipline and continental drift. Human activities contribute to climate constraints they require. Thus, they can easily become change primarily through their influence on the earth's more a facade than a true standard against which we atmosphere. Emissions of carbon dioxide, methane, and measure our impacts. Before considering the potential other greenhouse gases appear to be the most important risks from climate change and deciding how best to anthropogenic drivers of climate change, and much ofrespond to them, it is important to determine both the the discussion regarding prevention measures has tolerance of Arctic ecosystems for climate change effects focused on controlling such emissions. (i.e., inherent ability to withstand perturbation), as well The major physical manifestations of climate change as our (society's) tolerance for Arctic degradation (i.e., in the Arctic marine environment (ACIA 2004, Walsh subjective human sensitivity to environmental loss). 2008) include changes in temperature, sea ice, terrestrial Although science can estimate the risk and resilience ice (including permafrost), precipitation, freshwater of species and ecosystem processes to changes in climatic flow, sea level, sea surface and water column tempera- conditions, society's perception of the risks and its tures, and oceanic and atmospheric circulation. willingness to accept a given level of environmental The biological and ecological consequences of climate disturbance are more difficult to quantify. Determining change will vary depending on the species involved. Asthose limits is vital because they will shape the standards in other papers in this volume, we focus our discussion and measures used to guide and influence Arctic of "Arctic" marine mammals (i.e., those occurring in the conservation in the face of climate change. Arctic year-round) on polar bear (Ursus maritimus), Determining "safe" thresholds for human activities walrus (Odobenus rosmarus), ringed seal (Phoca hispida), and impacts in the Arctic and elsewhere is made difficult bearded seal (Erignathus barbatus), beluga whale (De- by the considerable uncertainty about what constitutes a phinapterus leucas), narwhal (Monodon monoceros), and healthy ecosystem and how much disturbance different bowhead whale {Balaena mysticetus) species. Other ecosystems can withstand before basic functions are lost species that inhabit the Arctic at least seasonally include or unacceptably diminished. The uncertainty stems in ribbon seals {Histrio phoca fasciata), spotted seals part from the complexity of ecosystems and the (Phoca larghd), harp seals (Phoca groenlandica), hooded difficulty in understanding their physical, chemical, seals (Cystophora cristata), gray whales (Eschrichtius and biological elements and natural dynamics. The robustus), killer whales (Orcinus orca), minke whales uncertainty is further confounded by the addition of (Balaenoptera acutorostrata), fin whales (Balaenoptera human activities that may alter ecosystem composition physalus), and humpback whales (Megaptera novaean- and dynamics before sufficient baseline information has gliae). been collected to provide a basis for distinguishing The physical manifestations of climate change will natural dynamics from anthropogenic disturbance. For affect Arctic marine mammals both directly and the purpose of conserving relatively natural ecosystems, indirectly by changing their habitat and encouraging the undesirable consequence of such uncertainty is that increased human presence and activities in Arctic we may mistakenly attribute changes we see to natural regions. The possible effects of these changes are causes, effectively rationalizing perpetual ecosystem discussed in detail in other papers in this volume (Bluhm decline from a healthy condition (e.g., the shifting and Gradinger 2008, Burek et al. 2008, Laidre et al. baseline syndrome; Pauly 1995). Furthermore, uncer- 2008) and in other scientific publications (Stirling and tainty increases the subjectivity of threat assessment, Derocher 1993, Tynan and DeMaster 1997, Lowry 2000, allowing proponents of potentially damaging actions to Stirling 2002, ACIA 2004, Derocher et al. 2004). The justify their positions by claiming uncertainty as to cumulative impact of independent (additive) and inter- whether damage will occur and with what severity. acting (synergistic) risk factors will determine the overall The U.S. Marine Mammal Protection Act (MMPA) significance of climate change for marine mammals and provides a national example of an effort to set tolerable that impact is considered in detail in Moore and limits for ecosystem disturbance. The MMPA has as its Huntington (2008). primary objective the maintenance of marine ecosystem The remaining steps in a risk analysis focus on health and stability. In support of that objective, the Act determination of the tolerable level of climate change establishes a specific tolerance for change in the status of effects, evaluation of the probability that those effects marine mammal populations. Marine mammal popula- will be realized, and identification and evaluation of tions that fall below their "optimum sustainable existing and potential conservation measures. population," which ranges from their maximum net productivity level (lower limit) to their environmental The Tolerable Effects of Climate Change carrying capacity (upper limit), are deemed to be We, the human species, are changing the face ofdepleted, the unable to fulfill their natural ecological role earth in profound ways. How much change is tolerable within marine ecosystems, and in need of special is a question yet to be answered. We often cast management our protection (Gehringer 1976). aspirations in terms such as "sustainable" and "healthy The implementation of the MMPA illustrates the ecosystems," but we have not effectively defined difficultiesthose inherent in setting and abiding by such limits

This content downloaded from 199.8.170.13 on Tue, 04 Apr 2017 17:09:29 UTC All use subject to http://about.jstor.org/terms S168 TIMOTHY J.RAGENETAL. E-'°^1 JjgSS and assessing progress in adhering to them. These The conflict between socioeconomic expansion and difficulties can be placed in three categories: obtaining ecosystem conservation is perhaps nowhere more data on species, determining ecosystem parameters, evident and than in the question of how we, as individuals, turning societal aspiration into action. With regard communities, to nations, and a world community, will data, the maximum net productivity level and respond the to human-driven climate change. The Kyoto environmental carrying capacity have not been assessed Protocol (available online)5 characterizes the interna- for the majority of marine mammal stocks, including tional response and has as its objective most of those in the U.S. Arctic (e.g., ringed seal, the stabilization of atmospheric concentrations of bearded seal, walrus, polar bear, beluga whale). Even greenhouse gases at a level that would prevent reasonably precise estimates of abundance (e.g., with dangerous anthropogenic interference with the climate coefficients of variation < 0.3) are available only for four of the 10 stocks of Arctic marine mammals in U.S. system. Such a level should be achieved within a time- frame sufficient to allow ecosystems to adapt naturally waters. The lack of information occurs in part because to climate change, to ensure that food production is not of the scientific and logistical difficulties in assessing threatened and to enable economic development to these stocks and in part because funding support (i.e., social commitment) needed to conduct such assessments proceed in a sustainable manner. has so far been lacking. Although general, this statement reflects important Ecosystem parameters are even more complex. The progress inasmuch as it recognizes human influence on maximum net productivity level and environmental the earth's climate system and acknowledges the carrying capacity are themselves subject to human potentially dangerous effects of climate change on the influence, that is, they can be altered by the very human earth's ecosystems. It also recognizes the relationship activities they are supposed to constrain. If they are not between climate change and economic development. assessed for a population when it is in a relatively Importantly, the Kyoto Protocol establishes a specific natural state, these levels may be underestimated, target for global greenhouse gas emissions at 5% below allowing more change than intended by the MMPA. 1990 levels, to be achieved by 2012. Although a 5% In the Arctic, for example, if the environmental carrying reduction in emissions below 1990 levels may not be capacity for ringed seals is determined by the amount sufficientof to contain climate change within tolerable land-fast ice available for reproduction and the amount limits, this standard provides an initial, measurable of land-fast ice available during the reproductive season reference point and constitutes a partial basis for has already declined due to climate change, then evaluation of efforts to combat the anthropogenic estimates of the environmental carrying capacity based component of climate change. The question that remains on current conditions would be biased low relative to the is whether we, collectively, are willing to modify our natural conditions they were intended to reflect. socioeconomicIn behavior to meet such standards and effect, standards lose their utility if they decline along conserve the Arctic and other ecosystems as we know with ecosystem health. them. Finally, even well-intentioned standards for prevent- ing environmental degradation have little meaning or The Probability of Climate Change Effects utility if they are not acted upon. The complexity Although the long-term risks cannot be reliably inherent in Arctic conservation is illustrated by the fact quantified at present, the direction of probable effects that the United States, which has some of the most is evident for the majority of Arctic marine mammals. progressive conservation laws in the world (e.g., the The long-term impacts may range from positive or MMPA, the Endangered Species Act, etc.) is also a large mixed for a few species (e.g., the gray whale) to negative contributor to climate change and has declined to ratify but minor for species with plastic or variable natural the Kyoto Protocol of the United Nations Framework history patterns and limited dependence on specific Convention on Climate Change because doing so may habitats. For others, those with relatively fixed or affect its economy. The inconsistency reflects the inflexible life history patterns and strongly dependent fundamental conflict between socioeconomic systems on specific habitat types at risk, the effects may be based on resource consumption and human population seriously negative (Tynan and DeMaster 1997, Lowry growth on the one hand and environmental conserva- 2000, Derocher et al. 2004, Laidre et al. 2008). Severe tion on the other. Although laudable conservation goals have been established on both national and internation- impacts could range from population reduction to extirpation throughout much of a species' natural range al levels, those goals have little meaning if we do not set corresponding limits on our activities and take the and eventual extinction. With respect to the latter point, the Center for Biological Diversity recently petitioned actions necessary to ensure that we are abiding by them. Whether we will do so, now or in the future, is a matter the U.S. Fish and Wildlife Service to list polar bears as of choice, and that choice will influence whether the endangered under the U.S. Endangered Species Act, adverse ecological effects that have been projected will, in fact, be realized. 5 (http://www.un.org/millennium/law/xxvii-23.htm)

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arguing that the species faces ecological a real consequences possibility of climate changeof or to changes extinction in the foreseeable future in human (information activities secondary avail- to climate change (e.g., able online).6 The Fish and Wildlife shipping, tourism, Service, development). in turn, Such measures may be found that the evidence in the petitionessential in the was short sufficientterm to prevent lossesto from factors warrant full review. A precedent other than has climate already change and been also as interim measures established, albeit in another typeto retain of species ecosystem, or distributions for until longer-term listing species as threatened undermeasures take the effect. Endangered Species Act due to the risks posed In Table by 1 we climate list and consider change the potential utility of (see NOAA [2006] for listing determinations various conservation measures for to elkhornaddress the threats to [Acropora palmata] and staghorn marine [A. mammalscervicornis] and ecosystems corals). as discussed in this Arctic marine mammals may Special experience Issue. A review multipleof potential effects of climate negative impacts, the majority change of andwhich corresponding involve conservation pro- measures for found changes in habitat. Habitat Arctic marine loss mammals has been and marine "the ecosystems indi- primary factor responsible for catesthe the rapid following: rate of species extinctions and the global decline 1 )in The biodiversitypersistence of marine in mammals the in the Arctic past one hundred years" (Dayton will be determined et al. by 2002:24).the cumulative influence of natural Habitat degradation resulting fromphenomena climate and anthropogenic change factors, has including cli- the potential to exceed that mate caused change and by the rateany at whichother marine mammals and anthropogenic factor (Thomas ecosystems et al. adapt2004). to accumulating The full risks. extent of climate-related habitat 2) degradation Conservation measures is, howev-cannot change the basic er, difficult to predict because natural relationships history traits of betweenaffected marine mammal climate and habitat features are populations not well in the understood, wild (e.g., foraging patterns, distribu- anthropogenic contributions to tionclimate and movement change patterns, have or reproductive yet strategy) or to be brought under control, enhance and thea varietyrate at which theyof adaptother to climate change. factors contribute to habitat degradation. 3) The most significant Thus, direct effect the of climate change relative effect of climate change will be maydegradation be anddifficult loss of habitat, to which can only distinguish from the effects beof addressed other by prevention. ongoing risk factors. Current climate models 4) predictPrevention (includingprogression the potential of for reversal) the physical manifestations of appears climate to be key inchange the long term (ACIA as virtually all other 2004), yet it is difficult to determine conservation how measures far-reaching identified to date thedo not address direct and indirect biological and directly ecological the expected consequenc- consequences of climate change es of these changes might be. andNonetheless, are limited to avoiding, evidence minimizing, of or mitigating effects is mounting (Stirling and the Smithconfounding 2004, effects Stirling of increasing et human presence al. 2004), and new and intensified and activities human in the Arctic. activities are being planned based on anticipated 5) Other conservationchanges measures that may will be useful in the render the Arctic increasingly shorteraccessible term to thein extent the that coming they delay irreversible decades. Experience from areas changes outside such as the extirpation Arctic and extinction. (e.g., Reducing Northridge and Hofman 1999, the rate Laist of loss, however,et al. is 2001,not a substitute for true Reynolds et al. 2005, Bejder et conservation, al. 2006) as lowersuggests populations that in smaller or these activities will pose new risks degraded to habitats marine are at mammals.higher risk. In other words, conservation measures that are limited to addressing Conservation Efforts to Address Climate Change consequences rather than the underlying causes of Hypothetically, conservation measures could climate be change must be part of a larger strategy to have aimed at the causes of climate change, the physical long-term utility. manifestations of that change, or their biological 6)and Specific, objective indicators are needed to establish ecological consequences. With regard to the causes thresholds of in population or habitat loss akin to climate change, virtually all effort is currently focused "depletion" under the MMPA. Such indicators also on controlling emissions of greenhouse gases to prevent can be used to assess trends and measure conservation or minimize the extent of change, and we know effectiveness.of no Recognizing that data for Arctic marine other method for addressing those causes. We also mammalsknow are often difficult and expensive to obtain, of no measures that society can use to modify some or basic indicators could still be identified, such as sea alleviate the physical manifestations of climate change ice extent, population trends in well-studied species such (e.g., melting sea ice, melting permafrost, increasing as the bowhead or beluga whale, or health and rainfall). Thus, beyond prevention, all known conserva- reproductive trends in often-captured species such as tion measures are limited either to the biological the and polar bear. 7) Monitoring of marine mammal populations and 6 (http://www.biologicaldiversity.org/swcbd/species/ stocks will be essential to provide an empirical measure polarbear/index.html) of their response to the cumulative impact of all risk

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Table 1 . Conservation measures and their potential utility in addressing hazards to Arctic marine mammals from climate change.

Potential utility (effect of the proposed Nature of hazards Protection measures protection measure)

Reduced foraging conditions and prey availability (Bluhm and Gradinger 2008) Changes in physical and chemical Protection of marine Fishery measures would reduce or remove a environmental conditions will lead to mammals from direct and source of impacts, one that may increase reduction and degradation of ice-related indirect interactions with in the Arctic with reduction of sea ice. habitat and feeding grounds, and fisheries through fishery Specific measures would target direct or changing distribution of marine prohibitions on certain operational effects (e.g., marine mammal mammal prey. prey, restrictions on certain bycatch) and indirect or ecological effects gear types, and time/area (e.g., competition for prey or disturbance closures. of habitat). Fishery measures and ecosystem monitoring also will be essential to detect and minimize or avoid changes in biodiversity caused by fishing (e.g., as might occur from fishing Arctic cod, a keystone species). Declining health and condition (Burek et al. 2008) Marine mammals stressed by changes in Captive care of animals Captive care would allow for veterinary their physical and biological with slow growth or poor medical treatment of individuals and environment may experience slower condition. provision of adequate nutrition. Captive growth (juveniles) and/or poor care is feasible only for pinnipeds and small physiological condition. They may be cetaceans. It is largely impractical in the more susceptible to disease and Arctic but may be an action of last resort contaminants. Exposure to disease will for stocks or populations approaching increase as the range of pathogens extinction. shifts or expands northward. Climate Cleanup of existing Reduction of pollutants is necessary to avoid change impacts may be exacerbated contaminants and confounding the effects of climate change, by increasing levels and types of prevention of further Within the Arctic, the cleanup of existing contaminants from added regional contamination. contaminated sites and prevention of human activities as well as global further contamination will require action at sources of pollution. local, regional, national, and international levels. Vaccination to minimize Vaccination may reduce susceptibility directly susceptibility to disease. and exposure indirectly if it helps prevent spread of disease. However, vaccination likely will be of limited utility because administration of vaccine would be costly and logistically difficult. In addition, vaccines are not available for many marine mammal diseases. Protect multiple stocks/ Protection of multiple stocks, populations, populations of each and habitats will reduce the consequences of species to ensure recovery a disease outbreak or other single event, potential. Conservation of multiple stocks is essential to retain intra-species diversity and distribution.

Reduced reproduction Reproduction may decline if growth and Protection of key Protecting key reproductive habitat would condition are compromised, reproductive reproductive habitat. reduce or remove a major threat to species habitat is degraded or lost, or conservation and retain the potential for reproductive capacity is compromised by species recovery over time. Several species contaminants or disease. appear to have strict habitat requirements for reproduction (ringed seal, bearded seal, polar bear). Short of prevention, nothing can be done to conserve ice-based reproductive habitat. If seal species and walruses attempt to reproduce on land, then measures to protect them from human activities and other predators (bears, wolves) may be possible and essential, although they also may be controversial depending on the status of bear and wolf populations. Cleanup of contaminated See Declining health and condition. sites and prevention of further contamination. Vaccinations for disease. See Declining health and condition.

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Table 1. Continued.

Potential utility (effect of the proposed Nature of hazards Protection measures protection measure)

Reduced survival Survival may decrease due to poor Clean-up of contaminated See Declining health and condition. condition of animals unable to sites and prevention of forage effectively; increased susceptibility further contamination. and exposure to contaminants and Vaccination for disease. See Declining health and condition. disease; increase in commercial, sport, Hunting bans or limits. Reduction of hunting pressure would reduce and subsistence hunting; increased or remove one source of mortality. Bans or vulnerability to predators (e.g., killer limits of commercial, sport, and subsistence whales); ship strikes from increased hunting may be essential for declining vessel traffic; and interactions with species with no tolerance for additional fisheries. sources of mortality. Although marine mammal hunting is an integral part of many Arctic cultures, the long-term survival of some species and thus their availability to future generations of hunters may require hunting restrictions. Loss of species will benefit no one. Predator removal. Removal of predators (e.g., killer whales) may help conserve species or populations that are on the brink of disappearance. Such removal is likely to be highly controversial and of uncertain utility. Control or removal of bears and wolves near haul-out sites also may be highly controversial. Vessel corridors, speed limits, Ship strikes are a major concern for some and observer programs. endangered marine mammals outside the Arctic (e.g., North Atlantic right whales and Florida manatees), and removal or reduction of this threat to Arctic marine mammals may be important for species or stocks on the brink of extinction. If sea ice extent decreases, shipping will almost certainly increase in Arctic waters. Techniques that have been used elsewhere (e.g., vessel corridors, speed limits, observer programs) may be effective in reducing ship strikes. Fishery regulations to See above, this section, avoid direct and indirect interactions. Regulations on oil, gas, Reducing or removing risks associated with and mineral extraction; increased human activities, particularly tourism; military activities; industrial development, would provide coastal development. species with an additional margin of safety. Mortality is more likely to be secondary to loss of habitat from these activities; direct mortality is likely to be limited unless marine mammals (e.g., polar bears) become concentrated in areas of human activity. Most development is already subject to environmental regulation, although cumulative impacts and incremental losses of habitat are seldom adequately addressed. Loss of habitat (Laidre et al. 2008) Habitat will be lost and degraded by the Marine protected areas to Protected areas would reduce or remove physical changes in the Arctic (e.g., loss avoid or minimize the human activities in specific locations, of sea ice) as well as human activities secondary effects of reducing risks and perhaps helping to that occur secondary to climate change. human activities. protect vital life history stages or events such as reproduction. Such areas may require extensive zoning, including buffers, as well as dynamic management to preclude human alteration of important or potentially important marine mammal habitats. Marine protected areas are controversial in some regions and enforcement can be problematic. Under climate or other environmental change, key habitat characteristics may move, requiring that protected areas be adjusted as well if they are to remain effective.

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Table 1. Continued.

Potential utility (effect of the proposed Nature of hazards Protection measures protection measure)

Reduced evolutionary potential Populations, stocks, and species may Identify and seek to Understanding the extant intraspecific be extirpated throughout portions of conserve genetic diversity diversity of Arctic marine mammals is their range or driven extinct, causing a within each species. necessary to identify specific conservation loss of genetic diversity. units and targets. Research on genetic diversity is needed for many species. Identify and seek to conserve Maintaining multiple populations in different populations and stocks of habitats will facilitate species adaptation to species in different habitats rapidly changing selective forces, thereby and subject to different promoting long-term conservation, selective forces. Persistence over evolutionary time is, in part, a function of the variability in selective forces to which each species is exposed (cf. metapopulation theory; Hanski and Gilpin 1991). Climate change constitutes a major change in selective forces, one that is acting over much shorter time frames than most. Prevent fragmentation and Retaining intact, connected habitats will isolation of habitats. promote genetic exchange among populations and reduce the risk of a catastrophic event. Reproductive habitat in particular should be protected. Fragmentation and isolation may' be less of an issue with mobile mammal populations in a marine environment, but may occur as populations decline, reproductive habitat is degraded, potentially disruptive human activities expand (e.g., shipping), or coastal areas are developed. Increasing human activities (Hovelsrud et al. 2008) May contribute to or exacerbate all of Will require a broad range of Evident in all sections of this table, the above hazards. measures as indicated above for various human activities.

Cumulative effects (Moore and Huntington 2008) Cumulative impact will be determined by Prevention Prevention would remove climate change as a the sum of the independent (additive) threat to Arctic marine mammals. It is and synergistic (interacting) effects of all indeed the only measure that can do so the above hazards. completely. It requires, however, a substantial societal commitment. All measures above. The measures described above will address specific secondary threats, particularly human activity. They are therefore necessary, but not necessarily sufficient for addressing the full effects of climate change. Monitoring of population Monitoring of marine mammal population status. status and trends will be essential for tailoring the available conservation measures to secondary effects, thereby maximizing their utility and efficacy in conserving marine mammals faced with the consequences of climate change.

Notes: In all cases, prevention is the only way to completely remove the threats posed by climate change but would require substantial societal commitment. To avoid repetition, we have not listed prevention in each section of the table, but only under cumulative effects.

factors, natural and anthropogenic. To date, studies of informed decision making about the status of Arctic marine mammal stocks in the Arctic generally have been marine mammals now and, if not remedied, will insufficient to determine stock structure, status, trends, undermine informed decision making in the future. or the influence of individual risk factors on status and 8) In view of the time lag between climate change trends. The current level of research support limits cause and consequence, the uncertainty regarding full

This content downloaded from 199.8.170.13 on Tue, 04 Apr 2017 17:09:29 UTC All use subject to http://about.jstor.org/terms March 2008 ARCTIC MARINE MAMMALS AND CLIMATE CHANGE SI 73 consequences and the potential severity of those increasing global strife. Unfortunately, if the value that consequences, climate change must be addressed with human societies place on conservation remains the same proactive, adaptive, and precautionary management in the future as is evident today, then conservation of aimed at prevention of adverse effects. Arctic regions is likely to remain a laudable, but secondary, objective in the face of growing socioeco- Looking Forward nomic pressures and political concerns. By delaying Climate change will have adverse and possibly action, we are foisting a burden on future generations irreversible repercussions. Loss of sea ice habitat and that we are unwilling to address ourselves. It will be the productive food web associated with it and under the weight of this burden that future generations increasing human presence and activities are likely the must address global climate change, and their task will most significant threats to Arctic marine mammals. be harder than ours, not easier (Stanley 1995). Cumulative effects of these and other factors may well Societies, communities, and individuals are confront- include extirpation of populations and even extinction ed with difficult choices that will determine the fate of of marine mammal species. Measures to minimize or Arctic marine mammals and ecosystems. Our lives are mitigate the effects of climate change on Arctic marine filled with similar circumstances (e.g., health care) where mammals are few and, at best, can address only the we take actions, form habits, or adopt whole lifestyles to secondary effects of climate change, including those avoid the possibility of adverse consequences years and resulting from additional human presence and activities even decades later. Such situations are ripe for in the Arctic. As part of a larger strategy, such measures precautionary decision making because waiting for may make the difference between persistence and absolute certainty often precludes effective response. extirpation or, in the worst case, extinction. Prevention Failure to act now to address climate change may through reductions in greenhouse gas emissions appears promote short-term gains, but may come with long-term to be the only approach that can ensure the long-term costs to ecosystems and the future generations that will conservation of Arctic marine mammals and Arctic depend on them. Conversely, aggressive measures taken ecosystems as we know them. today may impose short-term socioeconomic costs, but Until very recently, the reluctance to take strong are likely to avoid more costly long-term threats. Absent preventative action to address climate change stemmed such measures, society's ability to respond effectively in part from uncertainty about the probability of serious may be lost before the full implications of our inaction long-term consequences. Therein lies the dilemma become of apparent. climate change: its consequences are an outcome Alteringof our direction to reduce the factors that complex interactions among components of the contributeearth- to climate change will require reexamination ocean-atmospheric system, and the effects are subject of our to values. It will require a new perspective that considerable time lags (decades and perhaps centuries; places us squarely within ecosystems and willing to live Meehl et al. 2005). However, waiting for absolute within their natural limitations. It will require that we critically examine our personal and social choices and certainty and full knowledge about the consequences of climate change will preclude not only preventive aspirations with respect to family size, resource con- sumption, and lifestyles. If we are willing to accomplish measures, but perhaps any effective response. these tasks, then there may still be hope for Arctic We should have anticipated this dilemma. Many of regions and species as we know them. the concerns raised in the 1960s and 1970s and leading to important conservation legislation were based on Acknowledgments recognition of the fundamental clash between conserva- We thank Sue Moore for persistent encouragement to tion of the environment and increasing human abun- complete the manuscript and the authors of the accompanying dance and consumption-oriented economies. Postponing papers in this issue for discussions on potential conservation measures to address climate change or its consequences. We are decisions regarding climate change may only add to the grateful to Jennifer West at CICERO (Centre for International difficulty. The world's human population is expected to Climate and Environmental Research - Oslo), whose editing reach 9.2 billion by 2050, an increase of 2.8 billion or helped clarify an earlier draft, and to three anonymous 43% of estimates for 2005 (according to the U.S. Census reviewers, whose constructive comments helped us further improve the manuscript. Finally, we thank the Marine Bureau, available online)1 and will likely continue to Mammal Commission for its support of the project as a whole increase after that. The environmental effects of that and this paper in particular. growth in numbers may be further exacerbated by per Literature Cited capita changes in consumption patterns, both in developed and developing countries. Thus, future ACIA [Arctic Climate Impact Assessment]. 2004. Impacts of a warming Arctic: Arctic Climate Impact Assessment. Cam- decisions regarding Arctic conservation could well be bridge University Press, Cambridge, UK. made in an atmosphere of growing demand for goods Bejder, L., A. Samuels, H. Whitehead, N. Gales, J. Mann, R. and services, continuing environmental decline, and Connor, M. Heithaus, J. Watson-Capps, C. Flaherty, and M. Krutzen. 2006. Decline in relative abundance of bottlenose dolphins exposed to long-term disturbance. Conservation 7 (http://www.census.gov/ipc/www/worldpop.html) Biology 20:1791-1798.

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