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Home , Caribbean monk seal, Lutra, Mediterranean monk seal, Steller sea lion

90 A

LEAH GERBER

The U.S. Endangered Act establishes categories for endangered and threatened species but provides no crite- ria for deciding when a species should be listed, delisted, or downlisted. As a result, listing and recovery actions for marine are widely inconsistent. In most cases, Act listing and recovery actions have been done without the benefit of high-quality population assessments and have been based on arbitrary, nonquantitative criteria. A new approach to determining classification criteria for marine mammals is presented, with the North Pacific humpback whale as a test case. The key idea underlying this approach is an attempt to incorporate biological uncertainty explicitly in the definition of threatened and endangered. I sketch the essential ingredients of this new approach and its motivation and use this discussion to illuminate the challenges we face in pursuing conser- vation in an uncertain and data-poor world.

KEY WORDS: Endangered Species Act listing criteria, marine mammals

Marine mammals have captured unique, but to the public there is no deny- it was not until the onset of European the public's imagination as symbols of ing that some species possess a special technology that species and popula- conservation-often appearing on the charisma, and marine mammals seem to tions of marine mammals were actually front pages of newspapers or even on epitomize this quality. extirpated in the Northern Hemisphere: national television broadcasts. Since When scientific controversy and sen- Ironically, although we have been har- thousands of speciesfrom the lousewart timentality meet, conservation biologists vesting marine mammals for the last 350 to the grizzly are threatened with typically face their greatest challenge. In years,we are still surprisingly ignorant the risk of , it is interesting to this paper I consider Endangered Species about their distribution and abundance consider why the 17endangered marine Act (ESA)listing decisions regarding ma- prior to the onset of exploitation. mammalselicit so much passionand emo- rine mammals as a prism with which to We do know that to date, four ma- tion. One reason may be that the causes view a central conundrum of conserva- rine populations have disap- of their endangerment often include over- tion-what types of data are needed and peared forever: the Steller's sea cow,the harvesting, pollution, kills incidental to how those data should be used to decide Atlantic gray whale,the monk commercial fisheries, and entanglement when a species warrants listing as endan- seal, and the Japanese sea . The in marine debris,all of which seemunnec- gered. Before delving into this question, it Steller's sea cow, a member of the order essaryand tragic.Certainly another appeal is useful to review the history of marine Sirenia (manatees and dugongs), was exterminated by Russiansealers in 1767, of marine mammals is simply how unique mammal and their current only 27 years after its discovery} Unlike they are. To a biologist, all species are . other sirenians, sea cows occupied a cold environment, subsisted on kelp, EXTINCTION HISTORY OF and reached a length of 25 feet, nearly Leah Gerber is a graduate student at MARINE MAMMALS AND twice that of their tropical counterparts. the University of Washington working CURRENT STATUS These subarctic sea cows had thick, on the development of predictive barklike skin and were completely models for Endangered Species Act The exploitation of marine mammals toothless, with only horny pads at the classification for several marine mam- dates from the earliest occupancy of front of their jaws to mash kelp (Fig. 1). mal populations. Her field researchfo- North America. Marine mammals pro- Among the marine vertebrates,sea cows cuseson the behavioral and population vided a source of food and oil to early were unique in having no phalanges on ecology of humpback whales. Since immigrants. Thousands of whales, dol- their short flippers and in seldom sub- 1996, Leah has served on the Board of phins, porpoises, sirenians, seals, sea , merging themselves but habituallyfloat- Governors for the Society for Marine and sea have been killed annually ing with their backsout of the water.Sadly, Mammalogy. since aboriginal people learned to hunt there are only four speciesremaining from large vertebrates successfully. However, this order,which historically included as ARTICLES NTEGRAT V E B OLOGY 91

moved. This is well illustrated by the northern ,which was har- vested so severely in the 1800s that by 1890 the species was estimated to in- clude fewer than 100 and may have dropped as low as only 20 animals.6 Once the species was protected from harvesting in 1922,it began to reoccupy its original range, so that by 1991 there were an estimated 127,000animals! Of course dramatic recoveriesfrom popula- tion bottlenecks carry with them (at least in theory) their own hazards.In particular, Figure 1. The Steller sea cow was harvested to extinction in 1767,just 27 the thousands of elephant sealsalive to- years after its discovery (Illustration by E.Soulanille). day are all direct descendants of a small group of animals that managed to survive the period of extreme overexploitation. This suggeststhe possibility of major ge- many as seven species2.All four extant long been hunted for meat and oil and netic effects; in fact, research on both speciesare currently threatened with ex- was harvested to the point of extremely nuclear and mitochondrial DNA has re- tinction (the Amazon manatee,the West low numbers by the early 1900s.The spe- vealed unusually low heterozygosity in Indian manatee,the West African mana- cieswas consideredto be virtually extinct Northern elephant seals! tee,and the dugong).The extinction of an until one was sighted in 19525 Several cetacean populations have entire order would be dire,and conserva- Although the species is categorized as also declined to critically low numbers. tion efforts have beenvigorously directed extinct,it ispossible that someliving speci- Both North Pacific and North Atlantic at conserving manateesand dugongs. mens existon remote islandsin the Seaof right whales were hunted to virtual ex- The now extinct Atlantic gray whale Japanor off the coast of Russia. tinction; by 1900 populations were was a mysticete,the family of cetaceans In addition to the above extinctions, thought to include less than 100 and that includes the largest animals ever to severalpinniped specieshave come per- 300 animals,respectively.Additionally,as inhabit the earth. The mystecetes,or ba- ilously close to extermination. Six spe- a result of incidental take and direct har- leen whales,are distantly related to the cies of otariids (fur seals and sea lions), vest, both the Gulf of California harbor hoofed mammals, and have adapted porpoise and the Chinese river dolphin over the last tens of millions of years to It is not clear exactly now number less than a few hundred feeding on small and zooplankton, animals. Finally, the California sea and have evolved plates of baleen in what circumstances population was hunted to less than 50 place of teeth to filter minute organisms animals during the 19thcentury (but for- of the sea.Little is known about Atlantic should trigger a tunately recovered to approximately gray whales,but whaling recordsand sub- 2,400 animals by 19948). fossil specimensindicate that the species species to be listed Overall, 20 species was present up to the 17'hcentury.3 Evi- are currently listed under the Endan- dently this population was exterminated gered Species Act's List of Endangered by long-term and intensive hunting.! under the ESA. and Threatened Wildlife (the List)(Table The final victims in this tale of marine 1). Due to concern about overutilization mammal extinction are the , including the Guadalupe, Juan Fernan- and inadequate protective regulations, some of which have been exterminated dez, Antarctic, Subantarctic, New Zea- 8 of the 11 species of large cetaceans- by fishing activities and by direct har- vest. The Caribbean was land, and South African fur seals,were blue, fin, sei, humpback, right, bowhead, nearly extinct in the 17thcentury but driven to populations in the low hun- gray,and sperm whales-were listed as managed to persist for another two cen- dreds during the 1800sand early 1900s threatened with extinction under the turies.lronically, this species was finally as a result of over-harvesting. Among Endangered Species Conservation Act driven to extinction during the 1950sby the phocids (true seals),the Mediterra- (ESCA)of 1%9 and subsequently as en- fishermen who viewed the last handful nean monk seal is currently on the brink dangered under the ESAin 1973 (which of animals as competitors.4 This notion of extinction as a result of mortality due replacedthe ESCA).The remaining 12 spe- of pinnipeds as competitors to ourselves to commercial fisheries, poaching, and cies inTable 1 were listed on an individual persists today,and many speciesare still pollution. Fortunately, pinnipeds have basisin responseto either declining or low routinely killed for this reason.The ap- shown the potential to rebound from abundance,or to specific risks of extinc- parently extinct Japanese sea lion (a low populations if the pressures that tion.Population sizefor marine mammals subsoeciesof the ) had drove them toward extinction are re- listed as endanaered ranaes from 43.000 ART C L E S

TABLE 1. Summary of marine mammal species on the List of Endangered and Threatened Wildlife and primary threats

Species Status Primary cause

Amazonian manatee Endangered Poaching (Trichechus inunguis) West African manatee Threatened Poaching (Trichechus senegalensis) West Indian manatee" Endangered Poaching,watercraft interactions (Trichechus manatus) Dugong Endangered Poaching (Dugong dugon) Endangered Poaching,pollution, habitat loss ( felina) Southern " Threatened Directed harvest and mortality due to fisheries (En hydra lutris nereis) Gulf of California harbor porpoise Endangered Mortality due to fisheries (Phocoena sinus) Chinese river dolphin Endangered Mortality due to fisheries (Lipotes vexillifer) Eastern stock, " Threatened Unknown (Eumetopias jubatus) Western stock, Steller sea lion" Endangered Unknown (Eumetopias jubatus) Endangered Directed harvest (Monachus tropicalis) " Endangered Human-related disturbance (Monachus shauinslandi) Endangered Mortality due to fisheries, poaching, pollution (Monachus monachus) Guadalupe Threatened Directed harvest ( townsendi) Blue whale Endangered Directed harvest (Balaenoptera musculus) Bowhead whale Endangered Directed harvest (Balaena mysticetus) Finback whale Endangered Directed harvest (Balaenoptera physalus) Humpback whale" Endangered Directed harvest (Megaptera novaeang/iae) Northern Right whale" Endangered Directed harvest (Ba/aena glacialis) Sei whale Endangered Directed harvest (Ba/aenoptera borealis) Sperm whale Endangered Directed harvest (Physeter catodon)

(for Steller sea lions) to less than 600 (for " seem to have received spe- contrast,the average percentage of pro- Northern right whales) (Fig. 2). cial preference over other species. For tection at the subspecific or population Despite the real threats to marine example, 70% of the mammals that are level for all other taxa is lessthan 15%.9 mammals, in the broad scheme of species listed under the ESA are afforded pro- Plants are probably the least protected conservation. these and other "charismatic tection as subspecies or populations; in of all species,as evidenced by the fact 92 NTEGRATIVE BIOLOGY ARTICLES

TABLE 1. Summary of marine mammal species on the List of Endangered and Threatened Wildlife and primary threats

Species Status Primary cause

Amazonian manatee Endangered Poaching (Trichechus inunguis) West African manatee Threatened Poaching (Trichechus senegalensis) West Indian manatee" Endangered Poaching,watercraft interactions (Trichechus manatus) Dugong Endangered Poaching (Dugong dugon) Marine otter Endangered Poaching, pollution, habitat loss (Lutra felina) Southern sea otter" Threatened Directed harvest and mortality due to fisheries (Enhydra lutris nereis) Gulf of California harbor porpoise Endangered Mortality due to fisheries (Phocoena sinus) Chinese river dolphin Endangered Mortality due to fisheries (Lipotes vexillifer) Eastern stock, Steller sea lion" Threatened Unknown (Eumetopias jubatus) Western stock, Steller sea lion" Endangered Unknown (Eumetopias jubatus) Caribbean monk seal Endangered Directed harvest (Monachus tropicalis) Hawaiian monk seal" Endangered Human-related disturbance (Monachus shauinslandi) Mediterranean monk seal Endangered Mortality due to fisheries, poaching, pollution (Monachus monachus) Threatened Directed harvest (Arctocephalus townsendi) Blue whale Endangered Directed harvest (Balaenoptera musculus) Bowhead whale Endangered Directed harvest (Balaena mysticetus) Finback whale Endangered Directed harvest (Balaenoptera physalus) Humpback whale" Endangered Directed harvest (Megaptera novaeangliae) Northern Right whale" Endangered Directed harvest (Balaena glacialis) Sei whale Endangered Directed harvest (Balaenoptera borealis) Sperm whale Endangered Directed harvest (Physeter catodon)

'Species for which a Recovery Plan has been finalized.

(for Steller sea lions) to less than 600 (for megafauna" seem to have received spe- contrast,the average percentage of pro- Northern right whales) (Fig. 2). cial preference over other species. For tection at the subspecific or population Despite the real threats to marine example, 70% of the mammals that are level for all other taxa is less than 15%.9 mammals, in the broad scheme of species listed under the ESA are afforded pro- Plants are probably the least protected conservation, these and other "charismatic tection as subspecies or populations; in of all species, as evidenced by the fact ARTICLES

have gone so far as to propose that cer- tain populations be considered for re- moval from the List.One such population, the eastern North Pacific population of gray whales,was removed from the List in June 1994. Ironically, this means that the only marine mammal species to be delisted is a species for which no recov- ery plan was ever written; in contrast,the six species for which recovery plans ex- ist remain unrecovered! We discuss be- low the role of recovery plans in ESA conservation and implementation.

THE NATURAL HISTORY OF ENDANGERED SPECIES REGULATION AND STANDARD CONSERVATION TOOLS FOR MAKING Figure 2. Despite its "charisma,"the Western population of Steller sea li- LISTING DECISIONS ons has declined by 65% since the 1960s and is currently listed as endan- gered under the ESA. According to Webster's dictionary,"dan- ger" is a generic term implying "exposure or liability to injury, loss, pain or other that whereas they represent 50% of the rine mammals have a legislative advan- evil."'3 The danger of human activities listed species they have received only tage over those less charismatic species threatening extinction of plant and 8% of the recovery funds.lO Setting con- that must decline to extremely low sizes populations was the impetus for the en- servation priorities based on the public to be afforded protection. In fact, the asp actment of the ESA of 1973. The primary definition of which species are most lov- criterion means that marine mammals can goal of the ESAwas to prevent extinction able is clearly not ideal, and the job of be protected under the MMPA with popu- of plant and animal populations.Ofcourse, scientists should be to push more ratio- lation sizes as large as 1,000,000 (e.g., long before Homo sapiens appeared on nal approaches to the forefront. We cer- Northern fur seals), whereas the median the planet, species were naturally going tainly should not invoke conservation population size of species when listed extinct-a biological reality that draws actions more vigorously and with less under the ESA is about 1,000 for verte- attention to the fact that what the ESA re- data just because the species of concern brates and 100 for plants.'2 ally aims to accomplish is the elimination is particularly photogenic. An additional piece of legislation, of human-induced extinctions. In light of Perhaps as a result of their popular- the International Convention on the the obvious impossibility of preventing ity, marine mammals have been afforded Regulation of Whaling, has dramatically extinction of all species over indefinite a tier of protection in addition to that pro- changed management practices of ma- time periods, it is not clear exactly what vided by the ESA.The Marine Mammal rine mammals since large whales were circumstances should trigger a species to Protection Act of 1972 as amended listed under the ESA in 1969.ln 1985 and be listed under the ESA.The ESA defines (MMPA) provides an overarching frame- 1986 the International Whaling Commis- "endangered" as any species that is in work for protecting all marine mammals, sion (IWC) imposed a moratorium on danger of extinction throughout all or a while the ESAapplies only to those spe- commercial harvesting of large whales. significant portion of its range and"threat- cies that are designated as threatened Since the early 1970s, many large whale ened" as any species that is likely to be- or endangered. The central objective of populations have increased in abun- come an endangered species within the the MMPA is to maintain populations at dance. However, while several large foreseeable future throughout all or a sig- their optimum sustainable population whale populations have apparently nificant portion of its range. The question level (OSP). This level is defined as the started to recover, several dolphin, por- remains: What time frame and what level number of animals that will result in the poise, and populations have of risk implies that a species is in danger maximum productivity of the popula- declined. This suggests that large whales of extinction? tion, consistent with the optimum car- may be receiving undue protection or at- With no clear definition for ESA - rying capacity of the habitat and the tention in comparison with small ceta- egories of threat, it is up to recovery health of the ecosystem.11 Clearly, OSP ceans and pinnipeds. Indeed, several teams to define criteria for each species constitutes a population level signifi- prominent whale biologists have recog- in recovery plans. However, for the 1, 13S cantly larger than a population defined nized that some large whale populations species currently listed under the ESA, as being at risk of extinction. Thus ma- may no longer need such "coddling" and fewer than one-third of the listed spe- 94 NTEGRA V E BIOLOG ART C L E S cies have recovery plans, and wi~hin the first time in the law's 25-year history marine mammal recovery planning and those that do, listing and recovery crite- that such a large number of species listing decisions creates a demand for ria for species are widely inconsistent.At would be earmarked for removal from sharper science. Clearly, science alone first glance, the fact that only a small the list. Over a two year period, some of cannot solve conflicts among economic fraction of listed species have recovery the species would be down listed to and political interests and the well-be- plans may seem reprehensible. However, threatened and others for removal from ing of certain species. However, science because these documents have no leg- the law's protection altogether, al- can help to define when species should islative"teeth" (i.e., no mandate to imple- though states could still regulate them. be listed as endangered or threatened, ment recovery actions outlined in the This proposal is remarkable in light of and when species should be heralded plan), the absence of plans may be irrel- the inconsistency or absence ofdelisting as recovered. Towards this end, modern evant to actual recovery. Moreover, re- criteria for each of these 29 species. As conservation biology has yielded new covery plans are not legally required in all environmentalists scrutinize the merits tools for evaluating species viability,de- cases;instead the U.S. Fish andWildlife Ser- of each species that is delisted, it will be termining appropriate strategies for vice (FWS)(for all terrestrial species and a interesting to see how the scientific ra- protecting threatened species, design- few marine species) or the National Ma- tionale underlying these decisions will ing nature reserves, and initiating cap- rine Fisheries Service (NMFS) (for most stand up under fire, and to ask whether tive breeding programs. These practical marine species) are required to develop alternative approaches might produce approaches may help fulfill the ESA re- a recovery plan only if these agencies a less vituperative debate. Certainly, quirement that recovery plans include determine that a plan will promote the this landmark announcement by Bab- "objective, measurable criteria which, recovery of a listed species. bitt highlights the fact that the devel- when met, would result in a determina- Although recovery plans lack the le- opment of delisting criteria will be tion ...that the species be removed gal clout to implement their recommen- increasingly in the limelight of conser- from the List."16 Here I explore the pos- dations, they do have one important vation biology. sibility of applying conservation biology regulatory attribute-only in recovery theory to practice-the pragmatic ques- plans is it specified what criteria would Marine mammal tion I seek to answer is how we establish suffice to remove a species from the List. listing and recovery priorities for marine Thus, for those listed species lacking re- recovery planning mammals. To do this I examine the listing covery plans, there is no formal docu- criteria for a particular species-the North ment in which delisting criteria may be and listing decisions Pacific humpback whale-and suggest an defined. For those species that do have approach to developing quantitative, bio- recovery plans, there is still no guaran- create a demand for logically based criteria that are applicable tee that criteria for delisting are rational. to species with similar life histories. In fact, previous analyses of existing re- sharper science. covery plans have led some biologists A CASE STUDY EXAMINING to conclude that most plans do not in- BIOLOGICAL UNCERTAINTY clude biologically defensible guidelines In addition to these regulatory IN DECIDING WHETHER A in terms of population size and trends.14 subtleties involving recovery plans, the SPECIES IS ENDANGERED: Ironically, 28% of threatened and endan- issue of recovery takes on a special chal- NORTH PACIFIC HUMPBACK gered species for which population size lenge with regard to marine mammals. WHALES data were available had recovery goals For many terrestrial species, habitat de- set at or below the existing population struction is the primary source of endan- The IUCN, or World Conservation Union, size.9While there may be good reasons germent, and recovery can often be has been one of the first major public for this, it raises some suspicion about directly linked to habitat protection and institutions to embrace some of the whether biology or political pragmatism restoration.15 In contrast, for marine modern theoretical ideas from conser- determines recovery goals. mammals, there is generally no straight- vation biology. In particular, in an effort Since the late 1970s, only six spe- forward solution that can be identified to increase the scientific rigor of listing cies have recovered enough to be re- as the key to recovery. For example, bi- decisions, the IUCN has recommended moved from the List. An additional 14 ologists may know that northern right new quantitative criteria for classifica- species were removed after they either whales have failed to recover due to a tion of species on the Red List of Threat- became extinct or new information was low population growth rate, yet even if ened and Endangered Wildlife!7. These uncovered indicating they never should there were political will and unlimited criteria, which emphasize factors such as have been put on the list in the first resources, it would not be possible to extent of occurrence or degree of frag- place. Recently, a proposal to delist 29 adopt any single action that would im- mentation,are primarily oriented toward plant and animal species was an- mediately increase the growth rate of terrestrial species and are difficult to ap- nounced by the Department of Interior. the northern right whale. Taken to- ply to wide-ranging marine species. For This proposal, unveiled by Interior Sec- gether, the conflagration of regulatory large whales, the IUCN criteria are not eas- retary Bruce Babbitt in May 1998, marks and biological ambiguities surrounding ily applied because habitat fragmentation 95

is not relevant and even the seemingly tion, and conservation biologists during known for North Pacific humpbacks; in simple idea of extent of occurrence is an .'expert opinion" workshop in January general, humpbacks are thought to be- quantifiable only with great difficulty in 1997.19Here I sketchthe essential ingre- come sexually mature between 4 and 9 the marine realm, particularly for highly dients of this new approach and its moti- years of age;S.26and the sex ratio is migratory species such as humpback vation as a means of offering insight into thought to be close to parity}7.28Annual whales. Furthermore, the IUCN criteria for the challenges we face in pursuing con- reproductive rates have been estimated the most part do not allow for incorpora- servation in a world of biological uncer- on breeding grounds at 0.58 calves per tion of uncertainty in available data. tainty and limited data. year and at 0.38 calves per year on feed- We need to develop classification The key idea is that endangerment ing grounds}9The survival rates are not criteria for listing species as endangered depends on two critical aspects of a well known for this population; with re- or threatened even when data on popu- population: population size and trends ported rates ranging from 0.85 to 1.00 lation size and trend are poor. The key is in population size due to intrinsic vari- for different feeding groups in :o that the criteria should be based on data ability in population growth rates.The Four basic types of data were iden- that either exist or are attainable in the way to combine these features is to at- tified as key to developing classification foreseeable future.! show how available tempt to identify a population size and criteria for whales during the January information for humpback whales can range of population growth rates above 1997 workshop: abundance, trends in be used under a new classification which there is a negligible probability abundance,changes in distribution,and scheme and how increasing the preci- that the population would fall below a regulatory status. The classification cri- sion of parameter estimates regarding level from which extinction is inevitable. teria described in Table 2 are intended demographic rates affects our ability to The method of implementing this to supplement the first four factors make classification decisions. approach will vary among species de- specified in the ESAto determine a spe- Humpback whales are one of the pending on the type and amount of cies' status (habitat loss,overutilization, two large whale species for which a re- data available. For humpback whales, diseaseor predation, regulatory mecha- covery plan exists. The Humpback Whale nisms 31)and serve as an objective crite- Recovery Plan of 1991 describes three The key idea is that rion for evaluating the fifth factor ("other types of recovery-related goals. The first influences"). Here I briefly discuss each is a biological goal of building and endangerment of the five ESAfactors in the context of maintaining populations large enough to humpback whale endangerment. endure changes in oceanographic condi- depends on popula- tions, epizootics, anthropogenic stress, 1. Present or Threatened environmental catastrophes, or inbreed- tion size and trends ing depression. The second is a numerical Destruction, Modification, or Curtailment of Habitat goal to establish desirable population in population size. sizes consonant with the biological goal Habitat modification or loss is a difficult and with continuing human use of the process to quantify for marine ecosys- oceans. Specifically, this goal aims to in- data on population size, trends, degree tems. Coastaldevelopment, competition crease humpback whale populations to of subdivision, and demographic rates with fisheries for prey species,the intro- at least 60% of either the number exist- are plagued with uncertainty. The North duction of pollutants and pathogens ing before commercial exploitation be- Pacific population of humpback whales from waste disposal,and disturbance or gan (i.e., historical carrying capacity) or alternates between high-latitude sum- pollution from oil, gas,or other mineral the current carrying capacity of the en- mer feeding areas in waters off Alaska, exploration and production may limit vironment. Because accurate estimates , and California and low- available habitat for humpback whales!2 of historical or current carrying capac- latitude winter breeding grounds off While the preciseimpacts of these factors ity are not available, an interim goal in Hawaii, Mexico, and Japan}O.21Popula- on humpback whale habitat are not well the Recovery Plan is to double existing tion structure of humpback whales is known,there is no evidence for a popula- population size within the next 20 years. thought to be linked to matrilineal fidel- tion-level effect of these influenceson the The third goal is to develop objective cri- ity to feeding areas and the tendency of humpback whale population. teria to classify stocks of humpback whales animals to return to traditional winter- as either endangered or threatened. Un- ing areas}2.23Although there is a strong 2. Overutilization for fortunately, the seemingly precise goal of suspicion that the population is increas- Commercial, Recreational, a doubled population within 20 years re- ing in abundance, no data on popula- Scientific, or Educational ally has no solid scientific basis.To redress tion trends currently exist. In 1997, the this problematic situation, I have devel- population was estimated to include Purposes oped with my colleague Doug DeMaster approximately 6,000 animals based on Although overutilization was a primary a new approach for consideration. ISThe mark recapture methods using individu- reason for listing the humpback whale as approach is based on the recommenda- ally identified fluke photographs.24 Basic endangered, the species has been pro- tions of several prominent whale, popula- life history parameters are also not well tected from commercial whaling since species is at severe risk of extinction, and a high threshold above which a species has escaped serious risk. This can be for- Downlist from Endangered to Threatened malized by defining Nq as the quasiex- tinction threshold, or the population size 1. All designated wintering and feeding areas will maintain a population for which it is too late for management size such that, over the next 10 years, there is a high probability that to prevent extinction. Second, we define abundance will remain above a specified critical level (Nq). Nendas the population level above which 2. An international regime is in place and is effective in regulating human. there is a negligible chance of falling be- related disturbance and mortality. low Nq in 10 years. We can define an even higher "risk-escaping" threshold as the Downlist from Threatened to Delisted threshold for threatened status (Nth).This level is defined as the population level 1. All designated wintering and feedil 19 areas will maintain a population necessary to maintain a high probability size such that, over the next 25 yeairs,there is a high probability thathreshold of remaining above Nq for 35 years. The abundance will remain above the t2. level for endangered (N.nd).and criteria are intended to be applicable to a An international regime is in place is effective in regulating human- variety of types and levels of data quality related disturbance and mortality. and to incorporate a precautionary ap- proach. Using this classification frame- work, Nendand Nthare case specific and dependent on available abundance, population structure, and trend data. 1986 when the IWC established a zero is no evidence for marked population- An estimate of Nq for humpback catch limit. Nonetheless, it is possible that level effects of such infestations.3435 whales should represent the lower limit subsistence hunting, incidental entangle- for a population, below which a popula- tion would have a high probability of ex- ment in fishing gear, collision with ships, 4. Inadequacy of Existing tinction.Clearly this isa difficult parameter and disturbance or displacement caused Regulatory Mechanisms by boat or air traffic may inhibitrecovery!4 to estimate because empirical data are Data suggesting mortality due to en- Since 1985/1986 for pelagic seasons and limited and theoretical approaches are tanglement in fishing gear or due to ship 1986 for coastal seasons, the IWC has currently in dispute.As an initial approach, strikes are not currently adequate to in- imposed a moratorium on commercial I assumed an Nqvalue of 500 animals (Fig. fer effects on population status and re- whaling of large whales and has subse- 3). This number appears to be consistent covery. Much of the gillnet mortality of quently worked to develop a new regime with documented Allee effects in large large whales may go unobserved be- for managing levels of harvest by com- whale populations..I8That is,northern right cause whales swim away with a portion mercial whalers should the moratorium be whales were reduced to numbers less than of the net ordo not strand. Current regu- lifted. As described above, this regime is 500 each and have shown little or no sign latory mechanisms as defined by the considered effective in regulating distur- of recovery while many other large whale MMPA and IWC are intended to mini- bance and mortality of humpbackwhales. populations have increased in number mize overutilization. There is currently no over the past several decades. The sensi- information that indicates any popula- tivity to alternate assumptions about Nq 5. Other Natural or Human- tions of North Pacific humpback whales was also investigated (Fig. 3). Caused Factors Affecting are being overutilized. To implement our approach, our Continued Existence uncertainty about the demographic While the precise influence of each of rates that determine a population's dis- 3. Disease or Predation the factors described above on the con- annual rate of growth, A, is used to Natural mortality agents such as disease, tinued persistence of humpback whales establish frequency distributions of predation, parasitism, red-tide toxins, is unknown, the combination of these population fates and in turn S% chances and ice entrapment are the primary factors is ultimately reflected in the of extinction either in 10 and in 25 years. causes of humpback whale mortality!4 population growth rate and the popu- There are many different methods for To date, only one incident of natural lation size. The proposed classification obtaining variance profiles for popula- mass mortality of humpback whales has criteria, as described below, encompass tion fates. Given the lack of time series been documented. In 1987 and 1988, at these factors by incorporating the un- of abundance estimates for humpback least 14 humpback whales died in Cape certainty associated with our estimates whales, the solutions for Nendand Nth Cod Baydue to ingestion of mackerel in- population size and trend. were based on a population growth fected by a dinoflagellate saxitoxin.33 The down listing criteria summa- model that incorporates uncertainty in Humpback whales are known to be- rized in Table 2 make use of two thresh- demographic data and how the environ- come infested with parasites, but there olds: a low threshold below which a ment varies through time. A life table soning is explicit which is a vast improve- ment over simply requiring that the popu- lation needs to double within 20 years in order to be delisted.

INTEGRATING BIOLOGY AND REGULATION IN ENDANGERED SPECIES CONSERVATION Uncertainty is the norm in population data for most endangered and threat- ened species. Perhaps as a result, the vast majority of decisions regarding spe- r cies to be listed as threatened or endan- gered have lacked substantial biological information}9 Assuch,a key component of the proposed classification criteria is the identification of data indicating that ~~# # ,~ ,~ q~~ ~ ~ ~ ~ ~ ~~ b~~ ~ #, ~~~~ ~ # ~ ~~ ~ ' I ~' ~' ~~ ~~ ~'~~ ~~ ~~~~ ~ ~, I) ~~"'~ I)'~, I)' "'~ "'~ I)' I)' I)r I)' I)r species have recovered and are unlikely U- I to become extinct within the foresee- able future. In setting conservation pri- Figure 3. Relationship between the effect of A (the discrete annual rate of orities for marine mammals,we need to growth) on the estimated threshold population required to be exceeded if develop an approach that 1) incorpo- humpbacks are to be downlisted from endangered to threatened. As A in- rates biological uncertainty in a risk creases, the species may be down listed at a lower population size. The three averse manner, 2) allows for consistent, different curves are for different plausible minimum population thresholds yet species-specific listing decisions,and or Nqs,as defined in the text. For humpback whales we do not have a precise 3) identifies critical data needed to estimate of A;however, the above graph illustrates how listing criteria change evaluate a population's status. With this depending on what we might learn about A. Dotted line, Nq = 500; jagged emphasis, together with recognition line, Nq = 650; solid line, Nq = 1,000. that the scientific inputs to manage- ment decisions must be decoupled from cultural values, it should be possible to with uniform distributions for age-spe- mography to identify critical population overcome some of the subjectivity related cific survival and normal distributions thresholds. The final determination was to endangered speciesconservation. We for fecundity rates was used. Monte simple: the current best population es- cannot saywhether the proposed quan- Carlo simulations were conducted in timate of 6,000 was larger than the esti- titative criteria proposed for humpback which survivorship and fecundity rates mated threshold for endangered; whales are the"right answer." At least by were drawn randomly from these distri- however, the best estimate of current being explicit in our reasoning such butions of demographic rates. By per- abundance was less than the estimated quantitative approaches are subject to forming 1000 Monte Carlo simulations threshold for threatened. Thus, our scientific scrutiny and rejection-they fit for each level of environmental uncer- analysis would be consistent with a rec- the model of science much better than tainty and estimated sampling error,one ommendation to downlist humpback arbitrary numbers.lntegral in the future of obtains a distribution of expected an- whales in the North Pacific to a status of establishment of conservation priorities nual A'S.Each of these A'S is a stochastic threatened. for marine mammals is the development rate of population change, meaning that One of the useful features of this new of explicit approaches; we can identify it incorporates our uncertainty. The to- approach is that as uncertainty regarding mistakesand learn from suchapproaches. tal distribution of A'S generated in this population growth rate increases, the Thisarticle started by remarking on manner allows us to identify particular threshold level for threatened and endan- the unique "charisma" of marine mam- starting populations for which 95% of gered also increases (Fig.3). Therefore, with mals and the possibility that nonbiologi- the values will lead to an end popula- less precise information it becomes more cal factors might interfere with scientific tion that stays above the extinction difficult to delist or downlist a population reasoning when classifying species un- thresholds (i.e., less than 5% chance of classified as endangered. It will be inter- der the ESA.More general problems also extinction). esting to see the extent towhich these list- haunt the listing decisions of all species, This method thus gives us a simple ing recommendations change as more such as the absence of recovery plans way of using what we know and are un- elaborate simulations are explored. What- and the lack of regulatory teeth or of certain about regarding humpback de- ever the outcome, at least the train of rea- clear goals for existing plans. One solu- tion is the development of explicit quan- Status and prospects for success of the Endan- other North Pacific feeding grounds. Mar Mamm titative criteria for determining when a gered Species Act: A look at recovery plans. Sci- Sci 12:21S-226. ence 262: 976-977. species should be listed, delisted, or 25 Calambokidis J, Steiger GH, Straley JM, Quinn 10 Schemske DW, Husband BC, Ruckelshaus MH, TJ, Herman LM, Cerchio S, Salden DR, Yamaguchi downlisted. There will be a wide variety Goodwillie C,Parker 1M, Bishop JG (1994) Evaluat- M, Sato F, Urban J, Jacobson J, von Ziegesar 0, of such quantitative approaches, only ing approaches to the conservation of rare and Balcomb KC,Gabriele CM,Dalheim ME, Higashi N, one of which has been described in this endangered plants. Ecology 75:584-606. Uchida S, Ford JKB, Miyamura Y, Ladron de Guevara article. However, some sort of quantita- 11 The Marine Mammal Protection Act of 1972 as P, Mizroch SA, Schlender L, Rasmussen K (1997) tive approach is probably necessary, if amended (1995) Compiled and annotated by the Abundance and population structure of hump- Marine Mammal Commission, Washington D.C. only to ground the debate in numbers back whales in the North Pacific basin. Final Con- 12 Wilcove DS, McMillan M, Winston KC (1993) tract Report SOABNF100113 to SWFSC, P.O. Box that can be falsified and explicit algo- What exactly is an endangered species? An analy- 271, La Jolla, CA 92038. rithms that can be improved upon. Ulti- sis of the endangered species list, 1985-1991. 26 Clapham PJ (1992) The attainment of sexual ma- Conserv Bioi 7:87-93. mately, a great deal of natural history turityin humpbackwhales.CanJZooI70:1470-1472. needs to be learned about marine mam- 13 Websters New International Dictionary, 3d. ed., 27 Clapham PJ, Mayo CA (1987) The attainment of sexual maturity in two female humpback mals and all endangered species to s.v."danger: 14 Wilcove DS, McMillan M, Winston KC (1993) whales. Mar Mamm Sci 3:279-283. make rational conservation decisions. What exactly is an endangered species? An analy- 28 Straley JM, Gabriele CM, Baker CS (1994) An- Probably most biologists appreciate the sis of the endangered species list, 1985-1991. nual reproduction by individually identified need for more biological information. Conserv Bioi 7:87-93. humpback whales (Megaptera novaeangliae) in Less appreciated, perhaps, is the need to 15 Meffe G, Carroll CR (1994) Principles of Conser- Alaska waters. Mar Mamm Sci.10:87-92. vation Biology. Sunderland: Sinauer Associates. 29 Glockner DA (1983) Determining the sex of put that information into a quantitative 1616 U.S.C.§ 1533(f)(1)(B)(ii). humpback whales (Megaptera novaeangliae) in the framework that explicitly identifies thresh- 171UCN (1994)"/UCN Red ListCategories:Gland, natural environment. In Payne R (ed);"Communi- olds for downlisting. Quantification in this Switzerland: International Union for Conservation cation and Behavior of Whales, AAAS Selected case represents a synthesis and integra- of Nature and Natural Resources. Symposium 76..Boulder, Colorado:Westview Press, tion of what we know and do not know- 18 Gerber LR, DeMaster DP (1997) Endangered pp 447-464, Species Act Classification Criteria for North Pacific 30 Glockner-Ferarri DA, Ferrari MJ (1990) Repro- it is the "integrative biology. that is too humpback whales. In Hill PS, DeMaster DP (eds): duction in the humpback whale (Megaptera often missing from recovery plans and cri- "Marine Mammal Protection Act and Endangered novaeangliae) in Hawaiian waters, 1975-1988:The teria for listing species. Species Act Implementation Program 1996: life history, reproductive rates and behavior of Alaska Fisheries Science Center Processed Report known individuals identified through surface and 97-10. US DepartmentofCommerce,pp203-211. underwater photography. 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