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Small Cetaceans: Small Whales, Dolphins and Porpoisesby Kieran Mulvaney and Bruce McKay An edited version of this paper appeared in the three volume series Seas at The Millennium (edited by C. Sheppard), published by Elsevier Science Ltd., 2000. --- INTRODUCTION When does a cetacean qualify as a "small" cetacean? The answer depends on who you ask. The term is as much political as biological, and has generally been used to describe those species which do not have their names appended to the International Convention for the Regulation of Whaling (ICRW). This 'Annex of Nomenclature' was drawn up at the 1946 meeting at which the ICRW was completed, and from which the International Whaling Commission (IWC) was born. Those unlisted species came to be referred to as "small cetaceans", and many of the IWC's Member States (primarily, but not exclusively, countries which exploit these species) argue that their non-listing means they are beyond the Commission's purview. Threats to the small cetaceans come from various human activities, including directed hunting and fisheries, pollution, vessel traffic, and coastal development. This chapter briefly summarises the taxonomic groups of small cetaceans, and then describes in more detail the impacts affecting these mammals and assesses their current status. CLASSIFICATION OF SMALL CETACEANS The mammalian order of Cetacea is divided into two sub-orders: the mysticeti, or baleen whales, and odontoceti, or toothed whales. The baleen whales include the blue whale, (Balaenoptera musculus), the largest animal to have ever lived on Earth. The toothed whales include all species of dolphins and porpoises, including the smallest - and possibly rarest - cetacean, the vaquita or Gulf of California porpoise (Phocoena sinus). Not coincidentally, all the species commonly referred to as "small cetaceans" are odontoceti. Not that all mysticeti are large and all odontoceti are small: the Baird's beaked whale is larger than the minke whale (Balaenoptera acutorostrata); the sperm whale (Physeter macrocephalus), the largest odontocete, dwarfs the smallest mysticete, the pygmy right whale (Caperea marginata). Nonetheless, with the exception of the sperm whale and its smaller relatives, the dwarf sperm whale and pygmy sperm whale, we will include all odontocetes in this chapter, and exclude the mysticetes. This serves the purpose of including all the dolphins and porpoises, which - notwithstanding the large size of the largest delphinid, the orca or killer whale (Orcinus orca) - legitimately qualify as small cetaceans. The only borderline species are the beaked and bottlenosed whales, which are included because some at least qualify under any criteria; and the aforementioned dwarf and pygmy sperm whales (Kogia simus and K. breviceps) and pygmy right whale, which are not. As with any species, there is always an element of uncertainty concerning the classification of cetaceans. For now, however, the following is a broadly accepted breakdown of the species included in this chapter (after Castello, 1996; Jefferson et al., 1993): Order: Cetacea Sub-Order: Odontoceti Family Platanistidae
Family Pontoporiidae
The river dolphins are mostly freshwater species. The exception is the franciscana, or La Plata river dolphin, which is primarily a marine and estuarine species, found in the coastal waters of South America from Sao Paulo, Brazil, south to Peninsula Valdes, Argentina, and including the estuary of the La Plata River (Evans, 1987). Although variations occur from one species to the next, the basic body shape is distinctive. The bodies are small (approx. 2-2.5 m in most species; 1.5-1.7 m for the franciscana), and the beaks are long and narrow. None are considered particularly common, but the status of the Indus river dolphin and, especially, the baiji give particular cause for concern. The baiji, having formerly occurred along nearly 2,000 km of the Yangtze river, is now restricted to small groups in limited stretches of the lower and middle parts of the river (Chen and Hua, 1989). Its continued survival is considered by several authors to be unlikely in the long-term (Perrin, 1999). Threats to river dolphin populations include habitat loss from dam and barrage construction and flood control measures; environmental pollution; disturbance; conflicts with fisheries, notably gear entanglement; and directed hunts (Smith, 1996). Family Monodontidae
Restricted to Arctic and sub-arctic waters, both species are highly distinctive. Narwhals measure approximately 4-5 m in length, and have a mottled grayish body. Males, which are larger, and females have just one pair of teeth in the upper jaw; in the male, the left tooth erupts as a long (1.5 - 3 m) spiraling tusk. With the exception of this tusk in males, none of the narwhal's teeth erupt, and so the species can be considered functionally toothless. Adult belugas are white all over, and measure about 3-5 m. The Scientific Committee of the IWC recently recognized 29 stocks of belugas throughout the Arctic and sub-arctic. Of these, eight were strongly or tentatively considered to be stable - i.e. neither decreasing nor increasing, although three of those were already considered depleted. An additional eleven were considered depleted; of those, one - in Cook Inlet, Alaska - is continuing to decline; a second, in West Greenland, has been reduced by approximately 60% between 1981 and 1994; and a third, in Ungava Bay in the Canadian Arctic, is close to extirpation (IWC, 1999). Although estimates do exist for the abundance of narwhal populations, the IWC has been "unable to make a meaningful assessment of any stocks" (IWC, 1999). Family Phocoenidae
The "true" porpoises, easily distinguishable from other cetaceans by their rounded bodies and snub noses, are relatively small. Harbor porpoises, for example, may measure between approximately 1.5 and 2 m in length, depending on geographic location (Read 1998); based on relatively few recorded samples, the vaquita, the smallest of all cetaceans, has a length range of 90.3 - 143.5 cm (Brownell et al., 1987; Vidal et al., 1998). With the exception of the Dall's porpoise, most major populations of which are oceanic (Houck and Jefferson, 1998), most species are primarily coastal in nature. As a result, porpoise populations frequently come into conflict with human activities. Harbor porpoises and Dall's porpoises are generally considered abundant through much of their respective ranges, although there are concerns for the status of some stocks as a result of direct and indirect catches (IWC, 1991). There is little information on abundance or status of the finless, spectacled and Burmeister's porpoises (IWC, 1991). The vaquita is apparently restricted in range to the upper Gulf of California and is considered critically endangered. The population size in 1997 was estimated at approximately 570 animals (Jaramillo-Legorreta et al., 1999). Family Delphinidae
In terms of species, the largest of all marine mammal families (Ridgway and Harrison, 1998), the delphinidae contains probably the most familiar of small cetaceans. The bottlenose dolphin is well-known as the most common species in dolphin shows, and as the star of the TV series "Flipper"; the orca or killer whale, similarly also frequently seen performing in captivity, is unmistakable, its black-and-white markings and considerable size - up to 7.7 m in females, 9 m in males (Dahlheim and Heyning, 1998) - causing it to stand out. Appearances vary greatly among members of this family. The bottlenose, common and, to some extent, rough-toothed dolphins, and the Lagenorhynchus and Stenella species, perhaps most conform to the commonly-held stereotype of a "typical" dolphin: streamlined, with dorsal fins and prominent beaks. The pilot whales, in contrast, have a much more robust body shape, with a large bulbous melon and sickle-shaped pectoral fins. They are also among the larger delphinids, males reaching 7.2 m in the western North Pacific and 6.17 m in the western North Atlantic (Bernard and Reilly, 1998). The smallest of the delphinidae are the tucuxi, with a maximum length of about 1.9 m., and the Cephalorhynchus species, which range from approximately 1.4 m to 1.7 m in length (Leatherwood and Reeves, 1983). Several of these species have wide ranges; indeed, the orca is the most widely distributed mammal in the world (Dahlheim and Heyning, 1998). The bottlenose dolphin, common dolphin, Risso's dolphin, false killer whale and both species of pilot whales are found in all the world's temperate and tropical oceans (Bernard and Reilly, 1998; Evans, 1987; Kruse et al., 1998; Leatherwood and Reeves, 1983; May, 1990; Odell and McClune, 1998; Wells and Scott, 1998). Some others are more localized in distribution. The Cephalorhynchus species, for example, are all restricted to coastal waters of the southern hemisphere: the Commerson's dolphin is found in the western South Atlantic, near the tip of South America and in the vicinity of Kerguelen Island in the Indian Ocean; the black dolphin is restricted to coastal waters of Chile, the Hector's dolphin to the waters of New Zealand, and the Heaviside's dolphin to the coastal waters of southwestern Africa (Leatherwood and Reeves, 1983). Similarly, the Irrawaddy dolphin is found only in the tropical Indo-Pacific, primarily near shore and in some large rivers, while the tucuxi is limited to rivers and nearshore marine waters of northeastern South America and eastern Central America (Leatherwood and Reeves, 1983). Several populations of delphinidae species have been impacted by human activities. Two of them - the northern offshore form of the spotted dolphin, and the eastern form of spinner dolphin, accounted for 80% of the total mortality in the Eastern Tropical Pacific purse-seine fishery for yellowfin tuna. It is likely that these stocks were significantly reduced in the early years of the fishery, although more recent analysis suggests that, while probably depleted, the populations are now apparently stable (IWC, 1992; Perrin, 1999). The northern stock of common dolphins, also targeted by the fishery, has, however, shown signs of significant recent decline (IWC, 1993). The IWC Scientific Committee has on several occasions expressed concern over the status of the striped dolphin in Japanese waters as a result of directed hunts there (IWC 1982, 1993; Perrin, 1999). Dusky dolphin numbers may be being heavily impacted by directed takes off Peru; recent evidence suggests that duskys now constitute an ever-smaller proportion of the catch, and the average body size of those being caught is also decreasing - both signs of a possible decline in numbers (IWC, 1997). Peale's dolphins had become extremely rare in certain parts of the Magellan region by the late 1980s, presumably due to hunting for use as crab bait in Chile; however, indications now are that they are returning to the region (IWC, 1997). Species with limited range may be especially vulnerable to human impacts: Hector's dolphins, for example, are frequently caught in fishing nets in New Zealand waters, apparently causing at least two of three populations to decline (Martien et al., 1999). Some populations of several species, including the northern right whale dolphin, striped dolphin, common dolphin, and Pacific white-sided dolphin, may have been significantly depleted by high levels of incidental mortality in high seas drift net fisheries (IWC, 1992). The Irrawaddy dolphin may be in decline in parts of its range, possibly as a result of a wide combination of factors, including incidental mortality in fishing gear, shooting by soldiers and villagers, the use of explosives to catch fish, and general habitat deterioration as a result of the Vietnam War (IWC, 1994). Family Ziphiidae
The majority of the beaked and bottlenosed whales are little known and relatively rarely seen. Some species are known only from isolated sightings, stranded animals or skulls. Not all species have even been fully described. The mesopolodonts range in size from roughly 4.5 m to about 6.5 m in length. The northern and southern bottlenose whales reach lengths of approximately 9.8 m, while the Baird's and Arnoux's beaked whales may reach almost 13 m. (Leatherwood and Reeves, 1983). Abundance and distribution are not well known for many species in this family. Few are commonly seen; however, the fact that some species, such as the relatively widespread Cuvier's beaked whale, strand with some frequency suggests that at least some species may be more common than the relative paucity of sightings indicates. Baird's beaked whales are hunted by a coastal operation off Japan; 54 whales are taken annually. The northern bottlenose whale was hunted intensively by Norwegian and, to a lesser extent, Scottish and Canadian whalers earlier this century; as a result, it is possible that some stocks may be depleted (Leatherwood and Reeves, 1983). HUMAN IMPACTS 1. Directed and Indirect Catches There have been numerous reviews of small cetacean exploitation, including directed kills and conflicts with fisheries (e.g. Beddington et al., 1985; Currey et al., 1990; Holliday et al., 1996; IWC, 1991; Mitchell, 1975; Mulvaney, 1996; Northridge, 1984; Northridge and Pilleri, 1986; Northridge and Hofman, 1999; Perrin, 1999; Read, 1996). Many of these have included recent historical catches; however, as the purpose of this volume is to assess the status of, and threats to, small cetaceans at the turn of the millennium, we have focused here only on those principal hunts, and major cases of incidental catches as a result of fishing operations, known to be occurring in the final few years of the twentieth century. Beluga and Narwhal in the Arctic Hunts for beluga, or white whale, and narwhal have long been conducted by native peoples in the Arctic and sub-arctic, providing blubber oil for lighting and cooking and food in the form of muktuk - the name given to the whales' skin and adhering blubber - and meat, which is also fed to sled dogs (Mitchell, 1975). In addition, male narwhals are considered commercially valuable for their long tusks (Holliday et al., 1996). Although there is considerable variance from year to year, annual takes of belugas in recent years in Alaska have averaged approximately 400, from five recognized populations (IWC, 1999). In Greenland, it is estimated that approximately 600 whales are taken annually. Although catch figures are not widely available for the number of belugas caught in Canadian waters (IWC, 1999), efforts are ongoing to compile accurate catch statistics (R. Reeves, pers. comm.) In a review of small cetacean exploitation worldwide, the IWC noted a recorded total of 703 narwhals killed in Greenland in 1987 - an increase from 278 in 1975. Catch figures in Canada over the same period showed no particular sign of increase or decrease, with highs of 406, 404 and 350 in 1981, 1982 and 1980 respectively, and lows of 152, 181 and 255 in 1974, 1987 and 1977 (IWC 1992). The same review, noted, however, increasing difficulties in gathering accurate and complete data; by 1999, the Commission was reduced to noting that "directed takes are known to be continuing in Canada and Greenland, presumably at a similar scale to what they have been for at least the past decade." (IWC, 1999). Pilot whales in the Faeroe Islands In the Faeroe Islands, a group of islands in the North Atlantic situated roughly halfway between Iceland and Scotland, pilot whales have been the targets of a regular hunt for several hundred years (Bourne, 1965; Mitchell, 1975). In a process known to the islanders as the grindadrap, pods of pilot whales are herded toward shore by small boats, then killed in shallows or on the shore with spears and knives. The meat is distributed free of charge to local inhabitants. Hunting statistics extend back to 1584, and largely unbroken records exist from 1709 to the present (Bloch et al., 1990). Between 1709 and 1996, 239,413 whales were recorded as being killed (IWC, 1992, 1998, 1999). Use of Small Cetaceans as Fish Bait in Chile Small cetaceans have been taken deliberately since the mid-1970s in the Magellan region of Chile for use as bait in traps set for southern king crab or centolla (Lithodes santolla) and false king crab or centollon (Paralomis granulosa). Despite prohibition on the catch, transportation and commercialization, possession or processing of small cetaceans since 1977, Peale's dolphins, black dolphins and Commerson's dolphins continue to be taken (IWC, 1995). Marine mammal meat has been preferred to fish because it can stay in the water for three days before deteriorating and it is free; fish deteriorates within 24 hours and costs money. One dead dolphin can bait 350 traps (Stone et al., 1987). In recent years, the catch seems to have declined as a result of a decrease in fishing effort, lessening the demand for bait; the fact that, by 1992, wastes from slaughterhouses and industrial fisheries were providing most of the bait needs; and an apparent decline in abundance of the dolphins in fishing areas. In 1994, the IWC estimated that "the take of small cetaceans [did] not exceed 10% (45T) of the total demand of bait, or an equivalent of 600 dolphins per year" (IWC, 1995). Directed and Indirect Catches in Peru Catches of small cetaceans in Peruvian waters, both deliberate and incidental, had been relatively low until the mid-1970s, when they suddenly increased, possibly as a consequence of the decline in the region's anchoveta fishery (Read et al., 1988; Van Waerebeek and Reyes, 1990). Cetaceans are caught directly and indirectly in drift and set gill-nets, are harpooned or are caught by purse-seiners (and often landed alive) operating in the fishmeal industry. The cetaceans are used primarily for human consumption. Principal species include dusky dolphins, long-beaked common dolphins, Burmeister's porpoises, and bottlenose dolphins (IWC, 1995). In 1988, Read et al. estimated the total annual catch of small cetaceans in Peruvian waters at about 10,000 animals. In November 1990, the Peruvian government passed a national ban on cetacean use and exploitation. The effect on the hunt seems to have been minimal at best. Studies by researcher Koen van Waerebeek tentatively suggest that, even since the ban, the annual catch is now roughly 17,600 (IWC, 1995). Directed and Indirect Catches in Sri Lanka Large numbers of small cetaceans are caught in gill-nets, incidentally and deliberately, in Sri Lanka as a direct result of a fisheries modernization program initiated by the Food and Agriculture Organization of the United Nations (FAO). Small cetaceans had long been caught occasionally by coastal gill-net fisheries in Sri Lanka, but the nets were made of natural fibers such as jute or cotton, and most dolphins could either detect them with their sonar or break free if they did become entangled. However, under the FAO program, nets were supplied that were made of stronger materials, which the dolphins can neither detect nor break. Initially, incidentally caught dolphins were probably discarded by most fishermen, but as uses for the dolphins were identified and the market grew, gillnets came to be set intentionally to catch dolphins for food and bait (Leatherwood and Reeves, 1989). Estimates of the number of small cetaceans killed annually in this way vary from 8,042-11,821 to 12,950 (IWC, 1992; Leatherwood, 1995). At least seventeen species of small cetaceans are involved; catches also include a few large cetaceans (Leatherwood and Reeves, 1989). Directed Hunts of Small Cetaceans in Japan Of the 21 or so species of small cetaceans occurring in Japanese waters, 16 are, or have recently been, subject to significant directed hunts (Miyazaki, 1983). The Baird's beaked whale - which, as already noted, on the grounds of size alone barely qualifies for consideration as a "small" cetacean - is the target of a coastal whaling operation which uses small vessels equipped with harpoon guns armed with explosive harpoons. The hunt is not regulated by the IWC; Japan presently assigns itself an annual quota of 54 whales (Balcomb and Goebel, 1977; IWC, 1992, 1999; Kasuya and Ohsumi, 1984; Mitchell, 1975). A similar operation also conducts hunts for short-finned pilot whales and Risso's dolphins out of Taiji on the Kii Peninsula, with quotas of up to 50 and 30 respectively (IWC, 1993). The majority of species taken in Japanese waters are killed in so-called drive fisheries. When a herd of dolphins is spotted out to sea, a number of small boats drive the dolphins toward shore and into a bay or inlet. The dolphins may be corralled by means of a net drawn across the mouth of the bay; they may then be left there overnight and killed the next morning (May, 1990). These drive fisheries have operated in western Japan since the late 17th century. Historically, there were drive fisheries in at least four villages on the Sea of Japan, nine villages on the Izu coast, one in Iwate on the Pacific coast of northern Japan and islands off northern Kyushu and one in the Ryukyus. Today, there are two groups still operating - at Futo on the Izu coast, and at Taiji (IWC, 1993). Eleven species are taken, of which the most frequently caught are striped dolphins, short-finned pilot whales, bottlenose dolphins, false killer whales, Risso's dolphins and spotted dolphins (IWC, 1993). Some hunting in some locations is conducted with hand harpoons or cross bows rather than via drive fisheries (IWC, 1993). By far the largest number of catches has been of striped dolphins, although takes of the species at both Izu and Taiji have declined in recent years. Prior to 1963, annual catches were as high as 10,000-20,000, although catch records are incomplete. After 1963, the catch dropped to a mean average of 7,350, until 1980 when, following a peak catch year of 16,237, the mean over the following decade dropped to 2,390. 449 were reported killed in 1998 (IWC, 1993, 1999). Two species, the Pacific white-sided dolphin and Dall's porpoise, are killed with hand-harpoons, the former because it is difficult to herd and the latter because it does not form in large enough groups to be caught in a drive fishery (May, 1990). Dall's porpoises have been hunted in Japanese waters since at least the 1940s, and the species has generally been the most heavily exploited by fishermen (Miyazaki, 1983). Prior to 1988, the annual take was approximately 10,000 (IWC, 1999); however, in 1988, the recorded take soared to 40,367, before declining again to 29,048 in 1989 and 21,804 in 1990 (IWC, 1990, 1991, 1992). Following criticism of the increased hunt by environmental organizations and by the IWC Scientific Committee, the Government of Japan established an annual quota of 17,700. The actual reported take in 1998 was 11,385 (IWC, 1999). Mortality Associated With Yellowfin Tuna Purse-seine Fisheries in the Eastern Tropical Pacific For reasons which still are not entirely clear, groups of certain dolphin species in the Eastern Tropical Pacific (ETP) swim in association with schools of large yellowfin tuna. Since at least the 1920s, fishermen who have known of this association have taken advantage of it to catch fish. Initially, however, this was done without harming the cetaceans: the surface disturbances created by the dolphins were used to locate the schools of tuna, at which point fishermen would throw live bait overboard, sending the tuna into a feeding frenzy; the tuna would then bite at everything, including the hooks lowered to catch them. The dolphins could avoid the hooks with their sonar and were "rewarded" by taking some of the bait (Allen, 1985) However, beginning in the 1950s, the nature of the fishery changed from small-scale to highly commercial with the development of the "power block," a hydraulic pulley which allowed the rapid retrieval of huge lengths of purse-seine net. Instead of hauling tuna aboard one fish at a time, it became possible to deploy a net around an entire herd of dolphins and draw, or "purse" it closed at the bottom, trapping both tuna and dolphins (Gosliner, 1999). Many dolphins were drowned or were crushed in the nets; others were crushed after they passed through the winch. Annual mortality was estimated at between 200,000 and 500,000 for the period 1959-1972; altogether, over seven million dolphins are believed to have been killed this way over the course of around four decades (Allen, 1985; Gosliner, 1999; May, 1990; Scheele and Wilkinson, 1988). Following intense and prolonged campaigning by environmental organizations, an international agreement, negotiated in 1992 by the Inter-American Tropical Tuna Commission (IATTC), set annual quotas of dolphin by-catch for IATTC member states and cooperating nations. Having already declined to just over 15,000 in 1992, reported catches continued to decrease markedly over subsequent years, to 3,274 in 1995, 2,547 in 1996, and 3,005 in 1997 (IWC, 1999). Incidental Catch of Vaquita in the Gulf of California In comparison with some of the other directed and indirect catches noted in this chapter, the absolute number of vaquitas killed as a result of human activities is low. Between March 1985 and January 1994, 76 vaquitas were recorded as being caught in gill nets set for the endangered totoaba fish (Totoaba macdonaldi) in the upper Gulf of California (Vidal, 1995). However, this is certainly an underestimate of the total number caught; in addition, vaquitas have also been reported entangled in nets set for other fisheries in the region (Vidal et al., 1998). Given that, as already observed, the vaquita population is almost certainly at a critically low level, it is considered essential that even these levels of by-catch are ended if the species is to have a chance of recovery (IWC 1995, 1999; Rojas-Bracho and Taylor, 1999). By-Catch of Harbor Porpoises in the North Atlantic Largely as a result of their habitat in productive coastal waters, harbor porpoises are captured incidentally in commercial fisheries throughout their range (Gaskin, 1984; Read, 1998). Although several different gear types are involved, the majority of fisheries interactions are as a result of bottom-set gill nets (Read, 1998). The most notable by-catches occur in the waters of the Bay of Fundy and Gulf of Maine, Newfoundland and Labrador, Britain and Ireland, Denmark, the Baltic, western Greenland, Iceland, and Sweden and Norway (Hutchinson, 1996; Read, 1998). Read (1998) compiled annual by-catch estimates in several locations from different sources: 1,200-2,900 in the Gulf of Maine; 101-424 in the Bay of Fundy; 134-1531 for West Greenland; 17 for the Skaggerak; 4,629 for the (Danish) North Sea; and 2,049 for the Celtic shelf. Fisheries closures have resulted in declines in incidental catches in some areas, but by-catch levels have remained high elsewhere. Other Directed and Indirect Takes If the above represent the major directed and indirect takes of small cetaceans worldwide, they are by no means the only ones. Among some of the other instances over which concern has been expressed at various times are: possible continued illegal hunting of dolphins in the Black Sea; incidental catches of Indus and Ganges river dolphins and the baiji, or Yangtze river dolphin; gillnet fisheries off the coast of California; entanglement in shark nets off South Africa and Australia; incidental mortality of Hector's dolphins off New Zealand; high levels of incidental mortality of franciscana in Uruguay and Brazil - and, indeed, of delphinid species throughout the Americas. Concerns persist, also, over occasional continued illegal use of drift nets on the high seas. But nor is the above list comprehensive. Those examples which are cited are relatively well-known simply because of the intensive efforts to investigate by-catches and direct kills in, for example, American and European waters. It is safe to say that, wherever coastal gillnets are in operation, there are likely to be very high by-catches of small cetacean species (R. Reeves, pers. comm.). Many of these catches are in less developed countries, as a result of which documentation and analysis are relatively limited. In addition, circumstances in coastal communities in these countries are often such that priority is on meeting day-to-day nutritional and economic needs, making them resistant to outside appeals to reduce what may be seen as largely irrelevant, if unfortunate, cetacean mortality (see, for example, Mulvaney, 1996). In addition, as has been the case in, for example, Peru and Sri Lanka, these situations can lead easily from indirect to directed catches and the establishment of a market for small cetaceans. Keeping tabs on such situations, which are likely to remain for some time by far the largest source of mortality for small cetaceans, will be a major challenge for researchers and environmentalists entering the 21st century (for reviews see, for example, Holliday et al., 1996, IWC, 1995). 2. Pollution Cetaceans may be affected by a number of environmental pollutants. Perhaps surprisingly, there is little evidence of the extent to which such pollutants may or may not affect individual cetaceans, let alone impact populations. Nonetheless, concern has been expressed, to varying levels, about the possible consequences of contamination from, among others, heavy metals, organochlorines, oil, and radionuclides. Heavy Metals Concern over the possible effects of metals such as mercury, selenium, lead and zinc results at least partly from their observed impacts on other species, including humans. For example, human symptoms following ingestion of methylmercury include loss of coordination, loss of vision and hearing and mental deterioration (Law, 1995). However, marine mammals have some physiological adaptations enabling them to neutralize some heavy metals. For example, in dolphin bodies mercury can sometimes be found as granules in the liver, where it arrives as a result of a process which effectively takes it out of general circulation, and away from tissues that might do damage (Simmonds et al., 1999). Nonetheless, there is evidence that there is a limit to the level of mercury contamination which cetaceans can safely accumulate. One study found an apparent correlation between liver disease and mercury concentrations in dolphins; disease symptoms appeared to be initiated at liver concentrations between 50 and 61 parts per million (ppm). This is significantly greater than levels that have generally been recorded in stranded dolphins, although higher levels have been found by some researchers (Gaskin et al., 1974; Honda et al., 1983; Simmonds et al., 1999a). Furthermore, Bennet et al. (1999) showed that the mean liver concentrations of mercury, selenium and zinc in porpoises that died of infectious diseases were higher than those which died of physical trauma. It is also interesting to note that, despite criticisms from environmentalists about the possible impacts on pilot whale populations in the North Atlantic of the Faeroese grindadrap, high levels of contaminants, including mercury, in pilot whale blubber could ultimately spell the end to the hunt as the meat is increasingly considered safe to eat only in the smallest quantities (Simmonds et al., 1994). Organic Chemicals Every living marine mammal is exposed to a suite of chemical pollutants via its food. Many of these are persistent and readily accumulate in body tissue, and are transferred by the female to their offspring during gestation and via their milk - the most sensitive periods of development. The number of chemicals entering the environment is growing, perhaps by more than 1000 per year (Caroli et al., 1996; National Research Council, 1984). Currently, as many as 70,000 may have relatively common application. Adequate information to assess overall toxicity risk is available for approximately 2 per cent; even less is known of the effects of complex mixtures, the typical environmental scenario (McCarthy and Shugart, 1990). There are large knowledge gaps concerning future trends in chemical production, on the biological and ecological effects of "new generation" pesticides, and on the potential interactive effects between environmental pollution and other components of global change. It is expected, as well, that hitherto unrealized impacts will continue to be uncovered as scientific knowledge increases. Notwithstanding these uncertainties, great concern has been expressed about the possible impact on the environment and wildlife, including marine ecosystems and cetaceans, of a number of these chemicals. Of particular concern to the health of marine mammal populations are the halogenated hydrocarbons (HHCs) such as the PCBs, DDT, chlordane, dioxins and furans, and the chlorinated and brominated diphenyl ethers. Other chemical groups of concern include organometals such as tributyltin, and polycyclic aromatic hydrocarbons (PAHs) (O'Shea 1999). While it is well-documented that exposure to even low levels of various environmental pollutants can have severe effects on laboratory animals and on wildlife populations, ethical and logistical considerations have made it difficult accurately to determine impacts on marine mammals. Overall, however, there is general scientific agreement that a number of health-related aspects are likely being compromised in at least some marine mammal populations and that, ultimately, their survival and reproduction are being affected. The few experimental studies which have attempted to discern the possible impacts of contaminants on marine mammals have generally focussed on pinnipeds. Harbor seals fed fish from contaminated European waters showed a range of immune system impacts (De Swart, 1994; Ross, 1995) as well as reproductive failure (Reijnders, 1986). Elevated DDT and PCB concentrations have been implicated in premature pupping and still births in California sea lions (DeLong et al., 1973), although a cause-and-effect relationship was not established. Similarly, gray and ringed seals in the Baltic Sea have shown impaired reproductive ability and a variety of lesions in kidneys, intestines, arteries, adrenal glands and skull bones that have been associated with environmental contaminants (see, e.g.: Bergman et al., 1992; Bergman and Olsson, 1985; Helle, 1980). In terms of small cetaceans, contaminant-induced immunosuppression has been suggested as the reason for the high incidence and severity of bacteria-related lesions found in dead beluga whales from the St. Lawrence River and estuary in eastern Canada (DeGuise et al., 1995). Subsequent research in which beluga whale immune cells were exposed to environmentally-relevant doses of mercury, cadmium, DDT and various PCBs, showed immune system-related impacts, such as reduced proliferation of lymphocytes (De Guise et al., 1996, 1998). Lahvis et al., (1995) noticed reduced immune system response in bottlenose dolphins from the U.S. Gulf of Mexico that was associated with increased blood concentrations of PCBs and DDT. It is noteworthy that the small and geographically-isolated population of St. Lawrence belugas has also been discovered with a high incidence of other ailments and abnormalities, including cancer, gastric ulcers, and hermaphroditism (De Guise et al., 1994, 1994a, 1994b; De Guise et al., 1995; Lair, 1997) as well as having abnormally low levels of recruitment relative to arctic populations (Beland et al., 1993). Ross et al. (in press) have found high levels of PCBs in three populations of orcas in the Puget Sound region, on the western U.S./Canada border. Mean levels in male transient orcas were 251 parts per million (ppm), and in males from the southern resident population were 151 ppm. Ross et al. consider the orcas to be "among the most contaminated marine mammals in the world," noting that mean PCB concentrations in the transient males are four to five times higher than those for the St. Lawrence belugas. The southern resident population has declined from 96 to 82 whales over a four-year timespan, although Ross et al. note that this is still an increase since the end of a live-capture fishery in the region. The Canadian government has declared the orcas as threatened, citing diminished food supply and increased boat traffic, as well as contaminants, as possible threats. High levels of, notably, organochlorines were recorded in dolphins involved in mass die-offs in U.S. waters and from the Mediterranean Sea (Aguillar and Borrell, 1994; Kuehl et al., 1991, 1994). Organotins were also found in bottlenose dolphins from the 1987/88 U.S. east coast mass mortality event (Kannan et al., 1997). The extent of the role of contaminants in these die-offs, if any, is uncertain, although much speculation has focussed on the possibility that they may have played a role in compromising the animals' immune systems, thus rendering them more vulnerable to an infectious agent. Oil There are very few studies of the effect of either chronic or acute oil pollution on dolphins and porpoises. There are indications that, except in situations where oil on the water surface is so thick that it forms mousse, small cetaceans do not generally avoid it (Geraci, 1990; Harvey and Dahlheim, 1994; Simmonds and Hutchinson, 1992). This apparent lack of avoidance has led to concerns about cetaceans inhaling volatile hydrocarbons, or oil adhering to their skin or eyes or contaminating their prey (Harvey and Dahlheim, 1994). Based on observations of other species, among the possible impacts of such contact are inflammation of lung membranes, lung congestion and pneumonia (Simmonds and Hutchinson, 1992). The Exxon Valdez oil spill, in which approximately 11 million gallons of crude oil were spilled into Alaska's Prince William Sound on March 24, 1989, apparently resulted in the deaths and/or disappearance of 14 killer whales from one pod, although the exact causes of this could not be ascertained (Dahlheim and Matkin, 1994). This pod has still not recovered, although overall numbers of orcas in the Prince William Sound area remain roughly the same or perhaps slightly higher than before the spill (Matkin et al., 1994; Oil Spill Trustee Council, 1999). Radionuclides Ionizing radiation can result in a wide range of effects in mammals, including changes in behavior, growth and development, and effects such as mutations and carcinomas (Eisler, 1994; O'Shea, 1999). Anthropogenic radionuclides that contaminate today's ecosystems derive primarily from fallout from atmospheric nuclear weapons testing, the 1986 Chernobyl accident, nuclear reactor operations, nuclear fuel processing and disposal, and applications in medicine, industry, agriculture, and research (O'Shea 1999). There have been only a few studies of radionuclide contamination in marine mammals, and none has identified any associated effects. Calmet et al. (1992) found negligible concentrations in muscle and liver tissues from spotted, spinner and common dolphins from the eastern Pacific. A study of milk and tissues of gray seals collected from the North Sea and North Atlantic in 1987 revealed low levels of cesium-137, about 70% of which was ascribed to the nuclear reprocessing industry in England, and the rest to Chernobyl (Anderson et al., 1990). Analysis of liver and muscle tissue from harbor seals, gray seals and harbor porpoises found stranded along the UK coast revealed that radionuclide contamination decreased with distance from the reprocessing plant at Sellafield. The maximum radiation dose to the marine mammals from radiocaesium was higher than doses previously assessed for critical groups of humans living near Sellafield, while the maximum dose from plutonium was comparable to the doses for humans (Watson et al., 1999). 3. Small Cetaceans and Environmental Change In addition to problems such as those listed above, cetaceans - as with all marine wildlife - face a range of consequences from broader environmental change. This includes, for example, such factors as habitat change and associated disturbance, cultural eutrophication and the spread of "harmful" algal blooms and toxins, depletion of fish stocks, reduction in the stratospheric ozone layer, and global climate change. Habitat Degradation and Change Numerous human activities degrade or alter the physical marine environment, primarily in coastal areas. In addition to those issues already addressed, these activities include coastal development, the introduction of exotic species and the damming of rivers (see, for example: IWCO, 1998; McKay et al., 1997; Thorne-Miller, 1999). However, although there have been numerous studies on the impacts of these activities, few have considered their effects on small cetaceans. It has been suggested that most oceanic cetacean species are likely relatively immune to direct changes in habitat as a result of human activity, and that such changes are most likely to affect species with largely inshore habitats or specific populations with restricted ranges that are close to human activity (Kemp, 1996). For example, the Chinese white dolphin, a subspecies (or, possibly, close relation) of the Indo-Pacific humpbacked dolphin, has apparently been adversely affected by habitat loss due to construction, and increased shipping traffic, among other factors; its numbers have reportedly dropped from around 200-400 in 1989 to 80 in 1995 (Kemp, 1996). There are widespread concerns that construction of the Three Gorges Dam on the Yangtze River will result in a number of fundamental changes to the riverine ecosystem that may seriously impact the already-depleted baiji, or Yangtze river dolphin (Chen and Hua, 1989a; Topping, 1995). Populations of the Ganges and Indus river dolphins have already been fragmented and diminished by dam construction and the alteration of habitat through irrigation and flood-control measures (Smith, 1996). Of rising importance are the noise and disturbances associated with a wide range of coastal and off-shore human-related activities including shipping, fishing, recreational boating and whale-watching, mariculture (i.e., acoustic harassment or warning devices), seismic exploration, geophysical surveys, dredging, minerals mining, oil and gas drilling, military activities (e.g., low-frequency active sonar) and even climate monitoring programs (such as the Acoustic Thermometry of Ocean Climate program (ATOC)). Ambient noise, mainly due to shipping, has likely increased by some 15 dB between 1950 and 2000 (Ross 1987) though, of course, levels will vary in different parts of the ocean depending on their proximity to human activities. Wells and Scott (1997) note, for example, that there are more than 700,000 registered boats in Florida and express concern over these vessels' impact on resident bottlenose dolphin populations. The effects of noise on the behavior, distribution and physiological condition of marine mammals are extremely difficult to quantify (Richardson and Wursig, 1997; Gisiner, 1998), though odontocetes are expected to sustain the least impacts because of their relatively poor sensitivity to low-frequency sound (Richardson et al., 1995). Still, responses may be biologically significant only over longer time periods as a result of the cumulative effects of chronic repetition. Differences in responses from species to species can be considerable: where various odontocetes actively approach ships, others such as beluga in the Canadian Arctic show noticeable avoidance behavior as much as 50 km from the sound source (Finley et al., 1990). Low-frequency active sonar was suggested (Frantzis, 1998) as the likely cause of the atypical and fatal strandings of 12 Cuvier's beaked whales off Greece, an event that closely coincided temporally and spatially with a NATO submarine detection testing program. The sensitivity of marine animals, including odontocetes, to intense sound is not known (Gisiner, 1998), although hearing damage could reduce or prevent an animal's ability to detect prey, avoid predation or boats, communicate, or care for young. Impacts of Fisheries In addition to direct impacts, such as entanglement in fishing gear, commercial fishing operations have the potential to affect small cetacean populations by reducing their prey or by scattering the required aggregations for effective feeding. Furthermore, community interactions may be altered in such a way that nutrient-deficient prey may come to proliferate. The possibility of such impacts is highlighted by the extent to which commercial fishing operations have affected fish stocks worldwide. According to the Food and Agriculture Organization of the United Nations (FAO), of the world's fish stocks for which assessment data are available, one in four is classified as over-exploited, depleted, or recovering from depletion. A further 44% are fully- or heavily-exploited (FAO, 1994). Although no links have been established between declines in small cetacean populations and fisheries-induced forage reduction, it is still reasonable to infer (Jennings and Kaiser, 1998) that reductions in marine mammal abundance will be the likely outcome of a decline in their prey. In addition, various observations do suggest a correlation between the behavior, abundance and distribution of other cetacean and marine mammal populations and the status of their food sources. Perhaps most notable was the drowning of over 80,000 starving harp seals (Pagophilus groenlandica) in fishing nets along the coast of Norway in the late 1980s, as they moved out of the Barents Sea in search of food following the collapse of the region's capelin fishery (Haug et al., 1991). Other examples include a shift in the distribution of humpback whales (Megaptera novaeangliae) in the NE Atlantic during the late 1980s after the collapse of the capelin stock (Christensen, 1990); and, during the late 1970s, the movement of humpbacks off the northeastern United States in apparent response to the overfishing of herring and mackerel (Payne et. al., 1990; Weinrich et. al., 1997). Thompson et. al. (1997) noted anemia in harbor seals in NE Scotland that correlated with switching from a clupeid-based diet (e.g. herring, sprat) to one that was gadoid-based (e.g. whiting, sandeel), although it was unclear if this was related to changes in the foraging behavior required for the alternate prey or due to the composition of the prey itself. The Norwegian "harp seal invasion" led to calls by many fishermen for a seal cull, apparently in the belief that the increased visibility of the seals was the result of an actual increase in the seal population, and that this was the cause of the fish stock collapse. This response is not atypical in instances of perceived conflicts between fisheries and marine mammals, including small cetaceans. Most famously, between 1976 and 1982, fishermen on Iki Island, Japan, killed a recorded total of 4,147 bottlenose dolphins, 466 Pacific white-sided dolphins, 953 false killer whales, and 525 Risso's dolphins, in the belief that the dolphins were responsible for declines in their catches of yellowtail (Kasuya, 1985). Although there are at present no such large-scale "culls" of small cetaceans, the argument is frequently made that cetaceans and other marine mammals need to be "controlled" to limit their impact on fish stocks. The rationale behind such culls is scientifically suspect. The complexity of marine ecosystems is such that it is, at best, difficult to draw a direct correlation between two individual elements of such systems. As several observers have pointed out, it is equally probable that reducing marine mammal populations could result in fewer fish for a commercial fishery, as cetaceans or pinnipeds frequently prey on fish which are themselves predators of the commercial fish species (D.M. Lavigne, pers. comm.). Harmful Algal Blooms and Toxins There are approximately 3,400-4,100 species of microalgae in the world's oceans (Sournia, 1995), including a number which undergo periods of intense and localized growth, known as "blooms". Although such blooms are natural phenomena, there is compelling evidence to suggest that an increase in bloom frequency, intensity and geographic extent has been occurring over recent years (Hallegraeff, 1993, Smayda, 1990). In addition, species hitherto undetected or previously characterized as benign have emerged as significant problems (see e.g., Burkholder et al., 1992; Todd, 1993). Cultural eutrophication, a condition plaguing increasingly large sections of coastline (Nixon 1995), is frequently invoked as an important factor (e.g. Paerl, 1999, Smayda, 1990), while dams or water diversions may play a role by altering nutrient ratios (Humborg et al., 1997). The geographic expansion of some toxic species has occurred through ballast water transport (McMinn et al., 1997), a phenomenon that can be expected to increase (Carlton and Geller, 1993). Of particular relevance to marine mammals are those microalgal species, primarily dinoflagellates, which produce potent toxins. These can be sequestered into their food where sub-lethal or lethal doses can be ingested (Geraci et al., 1989). Algal toxins have been implicated in a variety of marine mammal mortality events including humpback whales, manatees, monk seals, sea otters and sea lions (Anderson and White, 1989; Bossart et al., 1998; DeGange and Vacca, 1989; Hernandez et al., 1998; Ochoa et al., 1997; Scholin et al., 2000), although unambiguous evidence is frequently lacking. The toxic dinoflagellate Gymnodinium breve was considered the causative factor in the deaths of approximately 2,000 bottlenose dolphins along the east coast of the United States in 1987-88 (Geraci, 1989); however, this conclusion remains controversial in the face of the potential roles of, for example, environmental contaminants (Kannan et al. 1997; Kuehl et al., 1991,1994) and morbillivirus-related diseases (Schulman et al., 1997). Although no causal links were established, dead dolphins have been discovered in the same time and general area of G. breve blooms in the U.S. portion of the Gulf of Mexico (Gunter et al., 1948; Marine Mammal Commission, 1997). Atmospheric Impacts: Ozone Depletion and Global Climate Change Numerous studies have pointed to the potential impact of increased UV-B radiation as a result of depletion in the stratospheric ozone layer on marine ecosystems, particularly by causing increased mortality in fish eggs and larvae and phytoplankton (see, e.g. Cullen and Neale, 1994; Hunter et al., 1979; Karentz et al., 1994; Smith and Cullen, 1995; Vincent and Roy, 1993). The most likely impact on cetacean populations is as a result of reduced productivity and ecosystem disruption - an impact likely to be felt most acutely by the baleen whales of the Southern Ocean. However, the development of an "ozone hole" in Arctic regions has also led to some concerns that small cetacean species such as belugas and narwhals may be susceptible to the prolonged effects of reduced productivity (IWC, 1997; Perry and Trent, undated). Nonetheless, tremendous uncertainties on the effects of ozone depletion and increased UV-B fluxes mean that effects on wildlife and on ecosystems can conceivably range from minimal to catastrophic (e.g., Roberts, 1989; Voytek, 1990). Even under the most optimistic scenarios of reduction in ozone-destroying chemicals, planetary exposure to increased levels of UV-B radiation will continue for at least an additional 50 years. The tremendous scientific uncertainties remaining about the current and future impacts of the continuing ozone hole, however, make it evident that we are still in the beginning stages of documenting the effects of an uncontrolled global experiment. Similar statements can be made with respect to the possible impacts of human-induced climate change. According to the Intergovernmental Panel on Climate Change (IPCC), among the potential impacts of global warming on the oceans are: increases in sea surface temperature, leading to increases in coral bleaching and subsequent decreases in coral production; increased pollution in coastal and marine waters as a result of increased precipitation and run-off; the possibility of decreases in average primary productivity; and possible changes in ocean upwellings and currents (Ittekkot, 1996). Additionally, changes such as sea-level rise could also adversely affect coastal ecosystems such as mangroves, which provide important nursery areas for many marine species (Bijlsma, 1996). Drawing linkages from these often tentative predictions to the potential impacts on cetaceans is difficult. However, MacGarvin and Simmonds (1996) note that matters other than overall reduction in productivity and possible distribution of their prey need to be considered. They point out that: the apparent rate of climate change is likely to be well outside the evolutionary experience of existing cetacean species; many cetacean species have complicated life cycles and thus appear to be dependent on finding particular resources in particular regions; many cetacean populations are at extremely low population levels; species and populations are already being impacted by a range of other factors. Depending on local and regional conditions there will be a range of cumulative impacts, cascading responses, feedbacks, and combinations of biological effects; these, too, will play an important role in determining the final ecological and evolutionary impact of both ozone layer depletion and global climate change. The impacts, if any, on cetaceans and other higher-level predators may already be occurring or, if measurable, remain to be seen. CONCLUSION At the dawn of the twenty-first century, it seems safe to say that the great majority of small cetacean populations are in a healthier state than those of their larger brethren, of which a number of populations remain highly endangered as a result of decades of commercial whaling (Clapham et al., 1999). Nonetheless, concerns remain. A number of small cetacean populations - including dusky dolphins off Peru, Dall's porpoises and striped dolphins off Japan, some stocks of belugas in the Arctic and sub-arctic, Hector's dolphin off New Zealand, the white dolphin off Hong Kong, several river dolphin populations, and some delphinid populations in the Eastern Tropical Pacific - have been, or are being, reduced by human activities, primarily direct hunting and mortality as a result of fishing operations. In addition, there remains uncertainty over the status of many populations in parts of the world where relatively little research has been conducted into levels of mortality as a result of directed and indirect catches, among other impacts. There is a genuine danger that at least two species - the baiji and the vaquita - will have, unless adequate conservation measures are taken, become extinct by the time a future author conducts a review similar to this paper one hundred years from now. Furthermore, cetaceans' position as apex predators potentially makes them especially vulnerable to the effects of harmful biotoxins and anthropogenic toxic substances, and to possible ecosystem changes as a result of, for example, increased UV-B radiation and global climate change. Most importantly, they are particularly susceptible to the cumulative impacts of these and other pressures. An example of the consequences of such cumulative and cascading impacts is provided by the changes underway in the Bering Sea region. These changes have been highlighted by dramatic declines in populations of Steller sea lion (Eumetopias jubatus) in the Bering Sea and Gulf of Alaska. This decline apparently began in the eastern Aleutian Islands in the early 1970s (National Research Council, 1996), and in most other areas by the early 1980s (Trites and Larkin, 1992). By 1989, the range-wide population estimate of 116,000 was only about 39 to 48 per cent of that estimated 30 years before (Loughlin et al., 1992). Populations of other wildlife species, such as harbor seals and sea ducks, are also experiencing similar declines (National Research Council, 1996). One apparent consequence of the declines in pinnipeds has been recent recorded decreases in sea otters (Enhydra lutris) in the Aleutian Islands. According to Estes et al. (1998), the most likely cause of these decreases is increased predation by orcas; they speculate that, given the lack of nutritional value in sea otters, and the absence of any records of previous consumption of sea otters by orcas in the region, the development is a direct result of declines in seals and sea lions, the cetaceans' usual marine mammal prey. The causes of the declines in Steller sea lions and harbor seals, and other associated changes in the Bering Sea ecosystem, are apparently complex. A 1996 review by the National Research Council of the National Academy of Sciences in the United States proposed a "cascade hypothesis," in which natural climatic fluctuations, combined with human exploitation of predators such as whales and fish, resulted in a change in the ecosystem from one dominated by clupeids to one dominated by gadoids - specifically, pollock. As a result, some forage fishes that have higher nutritional value than pollock may have become less available to some marine mammals and birds, leading to their decline. In addition, concentrated and intensive commercial fishing of pollock, particularly in the region of sea lion rookeries and haulouts and at times when young animals most need nutrition, may be limiting the amount of pollock available (NRC, 1996). There is also growing evidence that further climatic changes, in line with global warming projections made by the IPCC, are leading to continuing impacts on the coastal and marine ecosystems of the Bering and Chukchi Seas (Gibson and Schullinger, 1998; Weller and Anderson, 1998). Similar complexities surround issues concerning chemical pollutants. The toxicity of the vast majority of chemicals now released into the environment is poorly known, and even less so for the interactive effects of complex mixtures. Little is known about the cumulative effects of contaminants in conjunction with the variety of other stresses facing marine mammals, or on the indirect effects of contaminant-induced foodweb changes. Relatively speaking, it is easier to demonstrate the effects of directed hunts and bycatch on small cetacean populations - although here, too, claims of populations being depleted are frequently controversial, and evidence often not definitive. Many observers have argued the need for an international body to govern such catches, with the International Whaling Commission frequently cited as the ideal forum (see, for example, Currey et al., 1990). Although it has been argued that the International Whaling Commission does not have the authority to regulate small cetaceans, it is, as noted earlier, widely agreed that the only reason most small cetacean species were not listed on the "Annex of Nomenclature" at the signing of the ICRW is because it simply did not occur to those drawing up the list to include them (Holt, 1985). In addition, international law allows the IWC to, in the words of Commission Secretary Dr. Ray Gambell, decide for itself what it is and is not competent to regulate (Gambell, 1999; Mulvaney, 1987). Indeed, as is the case with, for example, the orca, the IWC has in the past chosen to express jurisdiction over species not explicitly covered in 1946 (Gambell, 1999; Mulvaney, 1996). The IWC has consistently demonstrated its unique and invaluable qualities with regard to the conservation of small cetaceans - for example, through the work of the IWC Scientific Committee, the organizing of such conferences as the 1990 Workshop on Cetacean Mortality in Passive Fishing Nets and Traps, and such resolutions as those passed on Japan's Dall's porpoise catches, which did much to bring about a reduction (albeit probably insufficient) in the size of that hunt. It is likely to remain the most widely used, and most suitable, vehicle for addressing small cetacean hunts for the foreseeable future. However, most of the countries where directed and indirect catches of small cetaceans take place are not represented in the IWC, and there is little incentive for them to be. Those countries which are members can not agree on the issue of competence, as evidenced by the ongoing debate over whether or not the Commission can or should regulate the Japanese Baird's beaked whale hunt. Most importantly, whereas the IWC was formed to regulate and manage a very specific industry, most catches of small cetaceans have relatively little in common, other than that they involve small cetaceans. Although commercial whaling, for example, is a clear-cut case of an industry dependent on the exploitation of cetaceans for its existence, directed kills of small cetaceans, in contrast, tend to result principally from broader economic and environmental difficulties, such as over-fishing, or fisheries-related issues. This is, clearly, even more the case when dealing with indirect catches. In order adequately to address the issues facing small cetaceans in the new millennium, it would be advisable for those concerned with the species' conservation not to look at such issues purely in terms of the species involved. In the same way that reducing contaminant burdens in cetaceans can only be achieved by addressing the sources of those contaminants so, in many cases, protection for small cetacean populations which are affected by directed hunts can best be attained by looking beyond the fact that small cetaceans are being killed, and addressing the social and environmental issues behind these kills. In this sense, the wide range of seemingly disparate and unrelated human impacts affecting small cetacean issues worldwide - from fisheries impacts to contaminants to direct hunts - can be seen to have one common thread. Small cetaceans are, in a sense, the canaries in the coalmine - harbingers of broader environmental change, or illustrations of wider economic or social pressures. 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