Research is the gathering of knowledge, then we can think of marine mammal research to have gone on as long as humans have gazed at whales spouting offshore and seals pupping on beaches. But early observations of nature were largely tied up with myths about animals and legends of their capabilities. A common theme appears to have been the changing of humans to dolphins and whales, and the reverse. This theme is recognized in remaining legends of Australian aborigine “dream time,” baiji (Lipotes vexillifer) and boto (Inia geof-frensis) river dolphin folklore (Zhou and Zhang, 1991; Sangama de Beaver and Beaver, 1989, respectively), tales of the god-like killer whales (Orcinus orca) of Pacific Northwest indigenous tribes (Mclntyre, 1974), and many more.
Nevertheless, some early writings show remarkable insights in marine mammal biology. Well over 2000 years ago, scholars of China’s Han Dynasty described baiji as related to marine dolphins, implying that those were known to intellectuals of the time. These descriptions, in the annotated dictionary “Er-Ya,” survive to this day. Even earlier, the Greek philosopher/scientist Aristotle (384-322 b.c.) differentiated between baleen and toothed whales, and described both types in some detail. It is unfortunate but totally understandable in hindsight that he classified cetaceans as fishes, a practice still present in Britain’s “Royal Fishes” as all whales and dolphins belonging by law to the Crown.
Not much scientific inquiry or thought was conducted between Roman times and the western Renaissance, and knowledge, at least written knowledge, of marine mammals languished as well. The modern progression of marine mammal research can perhaps best be described as occurring in four general (and not mutually exclusive) phases: (1) morphological description from beach-cast specimens and fossils, (2) descriptions of behavior and anatomy as gathered during hunting and whaling activities, (3) studies of physiology and behavior in captivity, and (4) studies of ecology, behavior, and physiology in nature. These phases follow a rough chronology, with morphology and systematics the main topics pre-1900s, hunting-related morphological and behavioral research mainly from the 1850s to the 1970s, scientific captive animal descriptions beginning around 1950, and more ecologically oriented descriptions in nature beginning around the 1970s. All phases are ongoing, with electronic devices promising to elevate in-field research on marine mammal lives to a new level of sophistication. A very readable recent account of the history of marine mammal studies is found in Berta and Sumich (1999). This volume lists some of the major deceased marine mammal researchers of the past, with their annotated classic works in the field.
Pierre Belon was probably the first “modern” marine mammal author since Pliny’s time. He published accurate descriptions and woodcuts of whales, dolphins, and seals (Belloni, 1553), and these (and also, unfortunately, the less accurate ones) were much-copied by others in the next two centuries.
The real burst of marine mammal knowledge did not come until later, however. And then it came suddenly, in tune with 18th centuiy awakening of scientific thought in the western world. While many authors could be mentioned, three early contemporaries did much to advance cetacean descriptions, taxonomy, and systematics. These were the French zoologist La Cepede (1804) and the Cuvier brothers. Georges Cuvier, who arguably founded modern evolutionary theory, wrote on many topics, including cetaceans; whereas his less-famed brother Frederic published two important works on cetaceans (F. Cuvier, 1829, 1836). These three were followed by the Belgian zoologist Van Beneden in the latter half of the 19th century, with work mainly consisting of compilations of information on fossil whales, and by a host of fine morphologists, taxonomists, systematists, and evolutionary historians in the 20th century (summaries are provided by Rice, 1998; Pabst et al., 1999; Reynolds et al, 1999;). While much of the earlier work centered on cetaceans, the British zoologist John Gray described both seals and whales in the British Museum (Gray, 1866), and the American zoologist Joel Allen wrote excellent monographs on whales, pinnipeds, and sirenians (Allen, 1880).
Yamase (1760) began the science of marine mammalogy in Japan at about the same time as serious studies began in the west. He presented accurate figures and descriptions of the external morphology of six toothed and seven baleen whale species and distinguished them iroin fishes. His work was brought to the west in a marine mammal section of “Fauna Japonica” by Siebold (1844). Otsuki began to describe the internal anatomy of cetaceans of Japan in 1808, but his manuscript remains unpublished.
A second major phase of information gathering, often linked intricately with that just described, involved descriptions of animals as related to hunting and whaling. Morphological information was at the core of these descriptions, but behavior and the basic society structure of whales and pinnipeds—of course much of the time affected by the hunting activities themselves—were recorded as well. One of the earliest accurate accounts consisted of German-born and Russian-naturalized Georg Steller’s descriptions of pinnipeds and the soon-after extinct Steller’s sea cow (Hydrodamalis gigas), the largest and only cold-water sirenian known (originally published in Latin in 1751, but republished in English as Steller, 1899). In the 20th century, one of the most famous works largely relying on whaling-accumulated data consists of Ever-hard Sliper’s “Whales and Dolphins” (published in English in 1976). A very readable account of whaling and the literature derived from whaling can be found in “Men and Whales” by Richard Ellis (1991).
While whaling, sealing, and other forms of direct hunting are much abated today as compared to in the 1960s, there are still powerful low-level, oft-indigenous hunts, especially in protein-poor areas of the world. As a result, data are being accumulated and analyzed on morphology, genetics, taxonomy and systematics, life history, prey patterns, and so on. Excellent recent information has become available from results of hunting on (for example) pilot whales (Globicephala spp.), oceanic dolphins (especially of the genus Stenella), bow-head whales (Balaena mysticetus), sperm whales (Phi/seter rnacrocephalus), and several seal, fur seal, and sea lion species (summaries in Berta and Sumich, 1999; Reynolds and Rommel, 1999; and Twiss and Reeves, 1999).
A third major research avenue has come about as a result of keeping marine mammals in captivity. Attempts to do so in the early part of the last century usually resulted in the animals’ untimely deaths—due to poor water, incorrect or tainted food, disease, and intraanimal aggression in confined spaces. Facilities that housed marine mammals simply replaced dead ones by more captures from nature. However, especially since the 1970s, amazing strides in husbandry have been made for all marine mammals (except large whales), and the better aquaria now keep—and breed—animals very well. Unfortunately, there are still many “primitive” facilities, especially in less-developed parts of the world. At present, there are representatives of all major taxonomic groups in captivity, as show animals and for research: toothed whales and dolphins (only two baleen whales, each time young gray whales, Eschrichtiits robustus, have been kept); pinnipeds of all types, but especially California sea lions (Zalophus californianus)■ sirenians (mainly the Caribbean manatee, Trichechus manatus, and the dugong, Dugong dugon,)-, and polar bears (Ursus inaritimus) and sea otters (Enhydra lutris).
Only through holding animals in controlled situations have researchers learned that dolphins echolocate (Au, 1993); that all marine mammals exhibit reduced heart and general metabolic rates during dives (Ridgway, 1972; Pabst et al, 1999); and that both dolphins and sea lions have remarkably advanced cognitive capabilities (Tyack, 1999). Furthermore, it is now fully appreciated that while pinnipeds and cetaceans are finely tuned underwater swimmers and divers with superbly evolved methods of breath holding, avoiding or reducing lactic acid depth during long submergences, and navigating in dark and cold waters, there is no secret “magic” to their energetic capabilities (Costa and Williams, 1999).
One major misstep from studies in captivity took place: the American John Lilly avowed in the 1960s that his research on bottlenose dolphins (Tursiops truncatus) proved that these popular show animals have an intelligence superior even to that of the brightest dogs and chimpanzees, and likely equal to that of humans (Lilly, 1967). Careful studies by others have shown that dolphins are undeniably “smart” (intelligence is very difficult to define and compare, but has something to do with well-developed flexibilities of behavior and of innovative learning), but that there is no reason to believe that dolphins fare better in this “intelligence/cognition” sphere than many other highly social mammals (Herman, 1980, 1986; Tyack, 1999; Wells et al, 1999).
While the study of marine mammals as derived dead from nature and live from captivity continues and grows, a relatively new approach has become the major research avenue since the 1970s. This consists of researchers going out into nature to observe the animals in their own milieu; as the animals associate with conspecifics; eat and are being eaten; and mate, give birth, and raise their young. We are learning more about the lives of these generally social creatures as they face storms, heavy years of sea ice, seasons of poor food resources (e.g., caused by “El Nino” southern oscillation climatic events), giant parasite infestations, adoring but noisy boatloads of whale-watching tourists, crowded shipping lanes, and habitat degradation near shore and in mighty rivers. This information on ecology of marine mammals is vital if we are to help protect them and their natural ecosystems from the depredations of overfishing, habitat pollution by chemicals, heavy metals, and noise; and the very real possibility of global climate change and whole-scale habitat destruction due to the effects of ozone depletion and global warming (Tynan and DeMaster, 1997).
Studies in nature often rely on visual or photographic recognition of individual whales, dolphins, and pinnipeds, often with the help of tags or color marks but also by natural markings (Hammond et al, 1990). Researchers have described movement patterns by tracking animals with surveyor’s transits from shore, and from shore and vessels by small radio tags placed on their bodies (Wiirsig et al, 1991). Since the early 1990s, satellite tags that relay position information to earth-orbiting satellites have become smaller, less expensive, and ever more popular. As a result, we know that northern elephant seals (Mirounga angustirostris) swim and dive into deep oceanic waters for months at a time, humpback whales (Megaptera no-vaeartgliae) take rapid zigzag courses between their mating and feeding grounds, North Atlantic right whales (Eubataena glacialis) undergo previously unsuspected jaunts between Greenland and New England during the feeding summer, and much more (Wells et al, 1999). Tags are being fitted not only with depth-of-dive measuring and telemetering devices, but also with ways to ascertain swimming velocity, angles of dives, water and skin temperature, individual sound production, heart rate, and, in the future, other physiological measures. Recent advances in small and low-light capable video camera/record systems are even giving data on swimming, socializing, and feeding behavior directly from the animals underwater (Davis et al, 1999).
Physiological research, previously entirely within the realm of captivity, is more and more possible with innovative or sophisticated techniques in nature. Samples of stool, urine, blood, and even mother’s milk are being collected from pinnipeds resting on land or ice. Trained dolphins have been released at sea, commanded to dive, and then told to exhale into a funnel to ascertain oxygen consumption values and to station themselves so that blood can be drawn. This interaction between animals in captivity and nature is especially fruitful for physiological research. Small darts have been developed that are fired from a cross bow or pneumatic pistol and that obtain skin and blubber samples for analyses of genetics (Dizon et al, 1997), toxin loads, and blubber energy content for relative measurements of health within and between populations. Skin samples of breaching whales have been successfully (and in a totally benign fashion) collected from the water and genetically sampled for gender, social grouping, and population data. A technique has been developed to harmlessly “skin-swab” bow-riding dolphins, also for genetic analysis (Harlin et al, 1999).
In response to an apparent increase in marine mammal strandings and the emergence of new marine mammal diseases in recent years, studies of wild marine mammal disease and ocean chemical contaminants are on the increase. While studies in nature have yielded data on the presence of deadly viruses and contaminant levels in tissues of beached and dying marine mammals (Aguilar and Borrell, 1997), they have provided little insight into immune defense against disease or the biochemical consequences of contaminants. For example, species-specific biomarkers have been developed to assess the dolphin immune system (Romano et al, 1999). Because they are readily available for long-term studies requiring serial sampling of tissues and health and reproductive histories, captive marine mammals afford unique opportunities to provide basic insight into the relationships among contaminants, the immune system, and animal health. Once they are developed and tested on animals in captivity, bioinarkers can be used with wild marine mammal populations to assess contaminant exposures and their possible effects on immune systems and neurologic responses (Ridgway and Au, 1999). as well as on reproductive success (Ridgway and Reddy, 1995), growth, and development.
The sensitive hearing of marine mammals has led to concerns that intense sound or noise pollution generated by humans could impede communication, cause stress, or damage hearing. Marine mammal hearing studies currently underway should help to define mitigation criteria for the effects of human-generated sound in the ocean (Schluiidt et ah. 2000), and ultimately allow us to find a balance between the ecological needs of marine mammals and the role the ocean plays in commerce. exploration, travel, and defense.
Ever-more sophisticated electronic and biochemical techniques are being developed to study the lives of marine mammals. However, the “tried and true” methods of looking at fossil bones, dissecting and describing pathologies of a net-entangled animal or one cast on shore after a storm, safely and carefully experimenting with animals in captivity, and the dogged gathering of behavioral information by binoculars and notebook are by no means passe. We are, in this new 21st century, in a vibrant phase of marine mammal research, and we see a very bright future for ever-more knowledge being gathered within our field.
