Introduction to Marine Mammals

MARINE MAMMAL CLASSIFICATION The Southern California Bight (Point Conception to San Diego) has one of the most diverse and largest populations of marine mammals in the world. Over 34 species of marine mammals have been documented here, and over 150,000 animals representing up to 30 species can be found in the Bight at one time. At least 28 species of whales and dolphins have been sighted in the sanctuary and about 18 species are seen regularly and are considered "residents." Little is known about the areas of concentration, life history or behavior of the resident populations. The sanctuary lies on the migratory pathway of the California gray whale and other large baleen and toothed whales. Gray whales with calves have been observed in the nearshore kelp beds of the sanctuary. The gigantic blue whales have also been sighted in sanctuary waters in recent summers (since 1980's).

All marine mammals share the following characteristics:

• • • • •

Hair/ fur/ vibrissae Warm-blooded Nurse young Give birth to live young Air breathing (have lungs)

Marine Mammal Adaptations

Marine mammals have adapted to the life at sea much like fishes, in some cases people confuse marine mammals with fishes due to their similar shape and form. These shared similarities/ adaptations are called convergent evolution.

• • •

Streamlined bodies (no outer ear flaps or limbs) Few hairs Blubber

Classification: Kingdom Phylum Class

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Order

Family

Genus

Species

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Introduction to Marine Mammals

Class Mammalia

Order Carnivora (bears, cats, dogs, otters, skunks…) Family Mustelidae • weasels, skunks, otters, badgers local species: Sea Otter Family Ursidae • polar bear Order Pinnipedia (“feather-footed”) Family Phocidae • true seals (harbor seals, elephant seals) local species: harbor seal, elephant seal Family Otariidae • eared seals (sea lion, fur seals) local species: California sea lion, Northern fur seal, Guadalupe & Stellar sea lions Family Odobenidae • walrus Order Cetacea (from the Latin “cetus” whale or sea monster) Suborder Mysticeti (baleen “mustached whales”) Family Balaenidae • bowhead and right whale Family Eschrichtiidae • gray whale Family Balaenopteridae • blue, fin, humpback, & minke whales Family Neobalaenidae • pygmy right whale Suborder Odontocete (toothed whales) Family Physeteridae • Sperm whales Family Monodontidae • Narwhale and beluga whales Family Ziphiidae • beaked whales Family Delphinidae • dolphins, orcas Family Phocoenidae • porpoises Family Platanistidae • river dolphins Order Sirenia - Sea Cows, manatees

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MARINE MAMMALS: BASIC FACTS Charles J. Rennie, III, M.D. Research Associate, Marine Mammalogy Santa Barbara Museum of Natural History Why marine mammals? / Why the Santa Barbara Channel? • Marine mammals have fascinated humans for millennia; the earliest known depiction of them dates to the Neolithic period. • Greek and Roman art provided frequent depictions of marine mammals. Both Aristotle (384322 B.C.E.) and Pliny the Elder (24-79 C.E.) wrote extensively about them. • The North American whale fishery dates to at least the end of the fifteenth century, and possibly to the mid-fourteenth century. • Systematic observations of marine mammals began in the sixteenth century, although marine mammal science as a discipline has existed only for the last 30-40 years. • The Santa Barbara Channel is a semi-enclosed basin, bounded by the central California coast on the north, Point Conception on the west, the Channel Islands on the South, and Point Dume on the east. It averages 500 m in depth, and is adjacent to a major group of submarine canyons. This area has a unique admixture of colder, northern water and warmer, southern water and represents a boundary area for many marine species. Local upwellings are common. This combines to create a rich area for marine mammals; some 39 species occur or have occurred in the recent past here. The Santa Barbara Channel is one of the richest areas in the world for marine mammals; it is also the only area in the continental United States where one can reliably find both Balaenoptera musculus (Blue whales) and Megaptera noveangliae (Humpback whales) in significant quantities. What is a marine mammal? • Marine mammals are mammals in perfectly good standing. They have hair (albeit rudimentary follicles), four-chambered hearts, a diaphragm separating the thorax from the abdominal cavity, bear live young, and nurse their young. • There are seven broadly defined groups of marine mammals. The order Carnivora includes five of those groups: Family Otariidae (sea lions and fur seals) Family Odobenidae (walruses) Family Phocidae (seals) Family Mustelidae (Enhydra lutris, the sea otter) Family Ursidae (Ursus maritimus, the polar bear) The order Cetacea includes whales, dolphins, and porpoises. The order Sirenia includes the manatees and dugongs.

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Whales, Dolphins, and Porpoises The order Cetacea is subdivided into the Mysticetes (from the Greek word for moustache), or baleen whales, and the Odontocetes, or toothed whales, dolphins, and porpoises. The words whale, dolphin, and porpoise are rather arbitrary. One (European) system of grouping these animals by common names is to consider all of the mysticetes, the sperm whale, and the pygmy sperm whale to be whales. All other odontocetes (except porpoises), even those with whale in their common name, are actually dolphins. The porpoises are members of the family Phocoenidae and are characterized by cusped teeth, blunt snouts, and triangular fins (whereas dolphins have pegged teeth and frequently have “bottle-noses” and falcate (“fastback”) fins. All cetaceans are aquatic, have nostrils that have migrated to the top of the skull, and have telescoped (elongated) facial bones. Origins The fossil record (and DNA evidence) suggests that Cetaceans are most closely related to Artiodactyls (even-toed ungulates), with hippopotamuses as their closest living relative. The Mesonychidae, small furry quadrupeds, are a possible ancestral group. The transition to water probably entailed amphibious forms, perhaps like otters. These evolved into the Archaeocetes, an extinct suborder of Cetacea that flourished from 49-34 million years ago. Both Odontocetes and Mysticetes diverged approximately 34 million years ago. The three families of Mysticetes are the Balaenidae (right whales), the Balaenopteridae (humpback whales, blue whales, and similar species), and the Eschrichtidae (gray whales); they appear in the fossil record approximately 20 million, 15 million, and 100,000 years ago respectively. Among the Odontocetes, the ancestral record for Physiteridae (sperm whales) extends back 23 million years, while those of Ziphiidae (beaked whales) and Delphinidae (dolphins) extend back 10 and 25 million years respectively. Anatomy/Physiology General: Mysticetes have baleen (see below); Odontocetes have teeth. In Mysticetes, the skull is symmetrical with paired nasal openings; in Odontocetes, the skull is asymmetrical with a solitary nasal opening. Mysticetes have fewer ribs that articulate with the vertebrae and (unlike Odontocetes) only one pair of ribs articulate with the sternum. The Balaenidae are stocky, with long baleen and no dorsal fin (their thick blubber, high oil yield, high-quality baleen, slow speed, and habit of floating when dead gave them the common name of “right” whales; they were the right whale to hunt.). The Eschrichtidae are fairly stout and have no dorsal fin. The Balaenopteridae are more streamlined, have small dorsal fins, and have numerous throat grooves (hence their grouping as “rorquals,” after the Norwegian word for furrow). Toothed whales tend to be much more diverse in form; however, most are fairly streamlined and have prominent dorsal fins (although some have no dorsal fin at all). Hearing: Sound in water travels approximately four times as fast as it does on land and sound reception poses unique problems. Cetacean hearing is complex. Neither Mysticetes nor Odontocetes have an external ear. In Mysticetes, the ear canal is filled with a wax plug, which may transmit sound; this plug is absent in Odontocetes. Whether either group transmits sounds

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through the ear canal remains controversial. In Odontocetes some sounds are received through the lower jaw and transmitted directly to the inner ear. In both groups, the auditory bone complex is isolated from the rest of the skull, which prevents sound conduction through bone (bone conduction would hinder the animal’s ability to determine direction of sound source). Echolocation/Sound Production: Echolocation has been demonstrated only in Odontocetes. Unique fatty deposits in their heads (melon) and lower jaws facilitate both echolocation and sound reception by focusing and transmitting sound beams. Sound production in Odontocetes occurs by moving air through a complex system of nasal sacs, which branch off from the nasal passages just below the blowhole. Low frequency clicks are used for general scanning, broad frequency clicks for general information about objects, and progressively higher frequency clicks for more detailed information about objects. Most species studied can echolocate to distances of at least 800 m. Although some Mysticetes have been observed to emit relatively narrow-band clicks, no unequivocal echolocation has been demonstrated. Mysticetes lack the specialized fatty deposits of Odontocetes; any echolocation system they have would be primitive at best. Among the Mysticetes, the humpback whales are noted for producing “songs” of repetitive phrases. Within any population of humpback whales, the songs are identical. In all populations, the songs change somewhat each year. Many of the larger Mysticetes produce loud, low frequency (non-echolocating) sounds that are audible for thousands of miles. Navigation: Although individual animals in some species may undertake annual migrations of thousands of miles, little is known about navigation. “Spy-hopping” behavior has been proposed as one method of orientation, but it is of no utility out of site of land, and the quality of Cetacean eyesight in air is equivocal. There is some speculation that a sophisticated sense of taste aids coastal migration by allowing animals to sample water flowing off land masses. Recently, enthusiasm for a hypothesis involving a geomagnetic sense has increased sharply. Geomagnetic senses have been demonstrated in other species, and magnetic crystals have been demonstrated in tissues surrounding the brain in a number of Cetacean species. Miscellaneous senses: Sense of smell is essentially absent (neuroanatomical evidence). The sense of touch is highly developed; it is likely that the sense of taste is also. Feeding: The two suborders differ widely. Odontocetes capture prey through echolocation. Their teeth are “pegged” (no roots), except for Phocoenidae, and are used only to grasp prey. There is no mastication. Mysticetes take large quantities of water into their mouths and strain it through their baleen. The baleen is composed of parallel rows of keratin plates (analogous to fingernails) with fringes that act to filter the water passed through them. Each species has baleen of somewhat different length. Each of the three families feeds somewhat differently, although there is a great deal of overlap. The Balaenidae tend to feed by skimming through the water. The Balaenopteridae are “gulpers,” and the Eschrichtidae suction feed on the bottom. Humpback whales have evolved a unique strategy called “bubblenet feeding.” The whale, while at depth, blows a circle of bubbles around a school of fish. As the bubbles rise in the water column, they are acoustically opaque; the fish will not swim through them. The whales then rise within the circle, mouth open, and feed on the fish. Odontocetes have evolved a diversity of feeding strategies, from the cooperative hunting of killer whales to the intentional beaching of killer whales and some species of dolphins in a search for food. Cetacean stomachs

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are multi-chambered, as they are in many ruminants, and the intestines are not differentiated into a “small” intestine and a “large” intestine as they are in humans. Large intestines are effective in water conservation; cetaceans accomplish this through other means (see “Renal Functions” below). Respiration: Here the divergence between the two suborders is not as great as that between the shallow divers and the deep divers. Sperm whales have been seen to dive to depths of 3000 m on sonar; even at far lesser depths, there is enormous potential toxicity from air in the lungs. Nitrogen at high pressures (great depth = great pressure) is toxic to mammals, and oxygen in blood that is rapidly depressurized (e.g., ascent to the surface) forms bubbles much the way champagne does when a bottle is rapidly opened. Cetaceans have solved this problem by not using air when they are at depth. Deep divers have proportionately smaller lungs than other mammals. All cetaceans have an extremely flexible thorax; at depth it collapses, forcing air out of the lungs into the bronchi where no gas is exchanged. This air is then kept out of the lungs by a series of functional valves created by smooth muscle sphincters extending from the mouth of each alveolus up into the bronchial tree. Cetaceans have evolved a number of elegant mechanisms for surviving dives without oxygen in their lungs. First, they store more oxygen in their muscle than other mammals, and they have more oxygen-carrying red blood cells than other mammals. Also, most of their organs function anaerobically during diving; that is, blood flow to these organs ceases and they do without oxygen. Only the brain, the heart, the adrenals, and a select group of muscles used in diving get blood. These mechanisms tend to be better developed in deeper divers. Because diving represents a major metabolic stress, most cetaceans do not make repeated dives to depth without lengthy surface intervals. During dives, cetaceans become extremely bradycardic (slow heart rate). In shallow-diving species, the mechanisms described above are often less well developed. Additionally, since shallow-diving species have less to worry about from the toxic effect of oxygen and nitrogen at pressure, lung volumes are often proportionately larger than in other mammals. All marine mammals exchange approximately 98% of the air in their lungs with each breath; humans exchange only 15%. Sperm whales may dive for 2 hours and attain depths of 3000 m, rorquals for 40 minutes to a few hundred meters, gray whales for 15-20 minutes at shallow depths, and dolphins for 2-15 minutes at depths of 50100 m. Circulation/Heat Conservation: Cetaceans have large hearts, although their globular configuration is less efficient than a cylindrical configuration. The circulatory system is marked by a number of retia mirabilia (“wonderful nets” composed of arterioles and venules) in the abdomen and thorax. These are poorly understood but may play a pressure-damping role or may function to help prevent the bends. Better understood is a counter-current exchange system, in which arteries traveling to the surface are surrounded by veins returning from the surface. The arterial blood gives its heat to the venous blood returning to the central circulation, thus conserving heat. The primary insulation of Cetaceans is through blubber. Although blubber is commonly thought of as fat, a major component of it is a fibrous stroma of connective tissue. Reproduction: Cetaceans have a bicornate (two-horn) uterus. Gestation is generally approximately 12 months, and pregnancies are usually every two years or longer. More work has been done on Mysticetes, which tend to migrate to tropical or subtropical breeding grounds, than on Odontocetes. Genitalia are recessed in all species. Some species engage in “sperm

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competition,” in which massive quantities of sperm are infused during copulation; the functional effect is to flush out the sperm of previous males. Right whales, which do exhibit sperm competition, have testes that weigh 500 kg each. Renal Function: Cetaceans have highly lobulated kidneys; this serves to increase filtration ability. Cetaceans probably do not drink seawater (despite one highly flawed old study that concluded otherwise), but instead derive their water from their prey and via metabolic pathways. Age: Techniques have been developed for determining age in Odontocetes (growth rings in teeth) and in Mysticetes (growth rings in baleen). Age at sexual maturity and life spans are data points that remain very tenuous for most species. Life spans range from 20-30 years to 7090 years. Intelligence: A great deal has been written on this topic, and a great deal of effort has been invested in developing indices for the comparative ranking of intelligence. Assessment of the intelligence of marine mammals remains very difficult; they have evolved to function in a world that is dramatically different from ours. There may be some correlation between microgyri and microsulci (the micro-folds and grooves) in the brain and intelligence. My personal experience in years of working with odontocetes is that they are about as intelligent as an intelligent canine; many workers in the field share this view (anecdotal though it is). Social Behavior: Wide differences exist among species here. Mysticetes tend to exhibit less social structure than Odontocetes and less complex behavior. Among the Odontocetes, the complex behavior and social structure of killer whales on the Northwest Coast of North America have been under investigation for decades. Sleep: Both observations in the wild and Russian experimental work indicate that Cetaceans do sleep. This appears to occur with only one side of the brain at a time; in fact, one eye is usually kept open. The awake side of the brain is then responsible for respiration (which in cetaceans, unlike humans, requires a high level of consciousness) and the movement of the tail flukes that keeps the animal near the surface. Stranding: Two types of stranding occur: solitary strandings and mass strandings. The latter may entail dozens or even hundreds of animals. In most solitary strandings the animals are dead before they hit the beach; the live strandings are usually heavily diseased. Overt disease and extremes of age account for virtually all solitary strandings. Mass strandings are another matter. Theories of causation abound, but all have drawbacks and none can be definitively proven. Middle ear or brain parasites held sway for a number of years, but incidental takes of dolphins in the pelagic tuna fishery have demonstrated equal numbers of parasites in healthy animals. Large herds of Odontocetes may be following a diseased leader onto the beach. This theory has some currency. Once even a healthy animal is on the beach, the blubber that insulates it so well in the water acts to trap a great deal of heat in a setting where there is already radiant heat gain. Studies of some strandings have shown that anatomical and physiological changes consistent with severe heat stroke appear rapidly, often within less than 30 minutes. This would

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help account for the low salvage rate even when apparently healthy animals are returned to the water fairly quickly. Whale Fisheries/Conservation The North American (Basques in Canada) whale fishery was in full bloom by the end of the fifteenth century, and may have begun as early as 1372. Shore-based whaling began in the U.S. in 1640, with pelagic whaling following in 1712. In 1789 the first U.S. whaler rounded Cape Horn. Whaling off Baja California occurred by 1809, although the gray whale calving grounds were not discovered until significantly later. In 1848 the Arctic bowhead was discovered. In 1856, Scammon discovered the gray whale calving grounds in Baja. Intense whaling began in 1858, and the stocks were depleted by 1865. In 1854 the first shore-based whaling station on the West Coast of the U.S went into operation in Monterey; by 1870, there were 11 such stations. By 1900, Monterey and most of the others had closed, although the Del Monte station in Richmond lasted until 1971. In 1868, pelagic whaling took a quantum leap forward with the invention of the modern harpoon gun by Svend Foyn. Another quantum leap occurred in 1924 with the introduction of the stern-loading factory ship. Pelagic whaling flourished both before and after World War II. The highest one-year catch occurred in 1961, after which whaling began a slow decline, due largely to stock depletion and the development of substitutes for the whale products of commercial importance. In 1969 Greenpeace was founded, and in 1972 the U.S. Congress passed the Marine Mammal Protection Act. Conservation efforts essentially put a halt to commercial whaling at the end of the 1960s. Unfortunately, a few nations have continued to hunt whales. In the mid-1960s, the Russians quietly exterminated an entire stock of southern right whales. Persistent Russian, Japanese, and Korean whaling have virtually exterminated the western Pacific stock of gray whales. In the 1990s, Japan resumed “scientific whaling,” allegedly to gather data on stocks of Minke whales for management purposes. However, DNA analysis done on whale meat purchased at the Tokyo Fish Market has shown the presence of other species as well (including fin and humpback whales). Of note also is the persistent aboriginal whale fishery. The Inuit are allowed subsistence hunting of gray whales (as well as bowhead), with a quota set at 124 animals. In 1995, they took 85. The right of the Makah to hunt whales was acknowledged in 1997, and the Nuu-Chuh-Nulth nation is now seeking similar acknowledgement. Whaling is not the only threat to Cetaceans. Recent research has demonstrated rising levels of environmental toxins in some marine mammal populations; pollution is an ubiquitous threat. A 20% decline in the resident population of Orcinus in the Pacific Northwest over the past five years may be the result of toxins concentrated up the food chain. A recent proposal by Mitsubishi to dramatically enlarge an existing saltworks in one of the gray whale calving lagoons was narrowly turned back in one of the few recent victories for marine mammal habitat.

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Research/Public Display Over the past two decades, research on marine mammals has exploded although, like all human interactions with marine mammals in this country, it is subject to the provisions of the Marine Mammal Protection Act. Telemetry devices and increased access to the underwater realm have allowed us to monitor marine mammals in ways previously only dreamed of. Molecular biology has given us new tools to explore not only the relationship of marine mammals to each other, but also to the rest of the phylogenetic tree. Dogged effort has turned photo-I.D. into a powerful tool: the work of John Calambokidis with blue whales in the Santa Barbara Channel and along the central California coast is certainly evidence of that. Our own efforts at the Santa Barbara Museum of Natural History have been directed toward the necropsies of all strandings along our coast whenever possible. We also maintain a live-sighting database as well as strong regional osteological and soft tissue collections. Debate about the public display of marine mammals has accelerated in the last several years. Recently the Vancouver Aquarium, an institution with enormous international respect, decided after several decades of display to remove their killer whales from exhibit. Educational benefits of keeping live marine mammals in collections will be increasing balanced against the cruelty of maintaining pelagic animals in extremely confined quarters. Some Comments on Blue Whales, Balaenoptera musculus. General: General characteristics of Balaenopteridae include a streamlined shape (Megaptera is the sole exception), small dorsal fins which vary widely among members of a given species in shape (in general, the larger the species, the more posterior the dorsal fin), and numerous throat grooves. External Morphology: B. musculus is the largest organism ever to inhabit the earth. As with all balaenopterids, females are larger than males. The largest individual ever measured (a female) was 33.6 m (110 ft) in length. The heaviest weighed was 190 tons (if lost blood volume were factored in, the weight would probably have been 200 tons). The mouth measures 6 m in length and the flukes 4.5 m in width. Dorsal fins are small (0.4m) and posterior. > 300 baleen plates (< 1 m in length) are in each upper jaw. The baleen and fringe bristles are black. 55-88 ventral pleats, of varying length, are found on the ventral surface. A single midline ridge extends from the blowhole to the rostrum. Blue whales are longer than 2 school buses laid end-to-end, and they are heavier than 1500 people. Their tongue weighs as much as an adult elephant, and their heart is larger than a VW Beetle. When they spout, their blow is 3 stories high (9 m). Their flukes are as wide as a soccer goal. Subspecies: Three subspecies have been recognized: B. musculus intermedia (the largest, inhabiting the Southern Hemisphere), B. musculus musculus (intermediate in size, inhabiting the North Atlantic and North Pacific), and B. musculus brevicauda (the shortest, inhabiting the tropical Southern Hemisphere in the Indian Ocean and Southeast Atlantic).

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Specimens from elsewhere are often assigned to intermedia, but their true subspecies is unknown. B. m. brevicauda has a shorter tail than other subspecies, a proportionately longer body, and is less than 24.4 m (80 ft) in length. Although controversy accompanied the first description of brevicauda by the Japanese (many felt the separation into what was originally claimed as a new species was simply a ploy to exceed International Whaling Commission limits on blue whales), the subspecies is now widely accepted. The degree of hybridization among subspecies is unknown. Theoretically, the temporal displacement of migrations between Northern Hemisphere and Southern Hemisphere animals should prevent intermingling, but there is some interchange of animals. There is evidence of some hybridization between B. musculus and B. physalus. Communication: Vocalizations are in the 15-20 Hz range with intensities of 180-190 decibels. There are two components to the vocalization, each lasting approximately 10 seconds. The second component is at a lower frequency or ends in a downward mode. Vocalizations may be repeated at one-minute intervals. Geographic variations or dialects may exist, but the evidence is not substantial. Ultrasonic clicks have been recorded; echolocation (crude) has been postulated but not substantiated. Communication in this species can potentially occur over entire ocean basins, and it may be that widely spaced individuals are actually part of larger groups. Respiration/Diving: Blue whales make 10-12 shallow dives, of 10-20 seconds duration, in a row. 5-8 respirations are taken between dives. Deeper dives are of 10-30 minute duration. This species is not a particularly deep diver; it usually feeds in the top 100 m of the water column. The flukes are not regularly shown during diving, although the Makah refer to blue whales as kwakwe axtli, or “noisy tail.” Blue whales generate peak respiratory flows of 624,000 liters per minute during exhalation/inhalation (human maximum is 800 liters per minute). Feeding: Blue whales feed primarily on euphausids. In the North Pacific, the primary prey species are Euphausia pacifica and Thysanoessa sp. They also take in small fish, particularly sardines and capelin; this ingestion may be accidental. This species is considered a “swallower” or “gulper” as opposed to the Balaenidae (right whales), which are considered “skimmers.” Both side feeding and lunge feeding have been observed. Blue whales migrate on a north-south axis. They feed seasonally (spring, summer, fall) in high latitudes. The migrations correlate with euphausid abundance; timing may vary from year-to-year. Peak feeding is in the evening and early morning, which correlates with euphausid abundance in the water column. During their migration (and on their winter grounds) they may either feed or fast. Intake for a full-sized adult is 3-4 million calories per day, which corresponds to 4-5 tons of krill. The oral cavity of an adult blue whale can hold 2+ tons of water, while the stomach can hold 1-2 tons of krill. Reproduction: Blue whales mate in the fall and winter. Migratory phase differences prevent substantial Northern and Southern Hemisphere interbreeding. Gestation is 10-11 months, and sexually mature females usually bear a single calf every 2-3 years. Calves are 23-26 feet and 3 tons at birth. Calves receive approximately 130 gallons of milk per day. The milk is 41-50% milk fat (human milk is 3-4% milk fat). Calf weight gain is 4 kg per hour, and length gain is 4cm per day. Weaning occurs at 7 months, when calves average 16 m (53 ft) and 23 tons.

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The mother may lose 50 tons (one-third her body weight) while nursing. Northern Hemisphere females are 21-23 m at sexual maturity and 25m at physical maturity. Northern Hemisphere males are 20-21 m at sexual maturity and 24m at physical maturity. Sexual maturity occurs at 5-7 years; this has been lowered considerably by the population pressure exerted by hunting during the twentieth century. Miscellaneous: The maximum estimated life span for blue whales is 30-90 years (difficult to estimate). Individuals are usually solitary or found in groups of 2-3. Swimming speed is 2-6.5 km/hr for feeding animals, 5-33 km/hr for cruising or migrating animals, and 20-48 km/hr for chased animals. Maximum speeds cannot be maintained for sustained periods of time. Population: The pre-exploitation population of blue whales was approximately 350,000 animals. With the invention of the modern harpoon gun in the latter part of the 19th century and fast catcher vessels in the early 20th century, this species became the favored target of hunters (because of large size and high oil yield). Approximately 350,000 were taken in the 20th century, with 30,000 taken in 1930-31 alone. Approximately 9000 remain today, some 2000 of which summer off the coast of California. Disease/Mortality: Little is known about diseases in blue whales. They appear to be less parasitized than other species, which may be due to a diet low on the food chain. This may also account for the relatively low level of pollutants found in their tissues (although much more work is needed). The ventral surface of blue whales often becomes covered with diatoms, particularly in the Antarctic; this has given rise to the name “sulphurbottom.” Blue whales may also act as host to remoras. Shipping accidents and Orcinus attacks are causes of mortality. Research: Blue whales are the focus of intensive photoidentification work. The use of satellite tagging and “kritter kams” is also giving new insights into their world. Krill research is yielding additional insight into their life history. Much of this work is in progress in the Santa Barbara Channel. Some Comments on Gray Whales, Eschrichtius robustus General: Gray whales are not evident in the fossil record until 100,000 years ago (although many consider them to be a primitive balaenopterid of some antiquity). A North Atlantic population existed but became extinct in 1750. A Western Pacific population exists but has been nearly eliminated by Russian, Korean, and Japanese hunting. External Morphology: As with all Mysticetes, females are larger than males. Physical maturity is attained at approximately 20 years; the average male is 13.0 m (maximum 14.6 m) and the average female 14.1 m (maximum 15.0 m). Weight is approximately 20-35 tons. The skull is slightly more arched than balaenopterids. There is no dorsal fin, but there is a series of 6-12 ridges along the posterior third of the dorsum. Coloration is gray with white mottling, scarring, and a heavy ectoparasite burden that may reach several hundred pounds. 2-4 ventral grooves are present.

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Respiration/Diving: Shallow dives of 3-5 minutes are usually separated by 5-6 blows. Deeper dives may last up to 25 minutes and are usually accompanied by a display of flukes. Maximum depth is thought to be 120 m, although gray whales rarely go deeper than 100 m. Feeding: Alone among the Mysticetes, gray whales are bottom feeders, which they accomplish by suction. Most individuals feed with the right side down. Gray whales were formerly thought not to feed during their migration or calving period; multiple observations have now proven this to be false. Reproduction/Migration: Gray whales undertake an extraordinary migration of some 8000 miles, one of the longest migrations of any mammal. From the end of May through September, they feed on the shallow continental shelf of the Bering and Chukchi Seas. Beginning in October, they migrate to the calving lagoons of Baja California: Laguna Guerrero Negro, Laguna Ojo de Liebre, Laguna San Ignacio, and Estero Soledad. Pregnant females migrate first, followed by recently ovulated females, immature females, adult males, and immature males. Only about a week is spent in the calving lagoon itself, although the return north is not immediate. On the northward migration, pregnant females migrate first, followed by non-pregnant females, adult males, and immature males. Cow/calf pairs migrate last; their peak numbers pass Pt. Piedras Blancas on 1 May (on average). Calves are 4-5 m and 500-680 kg at birth. Milk intake is 40-50 gallsons/day. Weight gain is 90 kg/day. Calves are weaned at 6-9 (average 7) months. Gestation is 13 months females usually breed every other year. Miscellaneous: Swimming speed is 7-9 km/hr; speeds of 16 km/hr may be attained when individuals are chased. Gray whales may show aggression, particularly when calves are threatened; during the era of commercial whaling they were known as “devilfish.” Population: The current population of gray whales is approximately 22,000-25,000, which is probably higher than pre-contact levels. A history of aboriginal whaling in the Pacific Northwest and Alaska extends back several thousand years (it continues today). See comments under Whale Fisheries/Conservation. Disease/Mortality: Gray whales are among the most heavily parasitized of cetaceans. They are particularly noted for both barnacles and “whale lice” (actually Crustaceans) as ectoparasites, with parasite burdens often reaching several hundred pounds. Observations of predation by Orcinus are not uncommon. Some Comments on Humpback Whales, Megaptera novaeangiae General/External Morphology: The scientific name means “big-winged New Englander,” which refers to the large pectoral fins and the first scientific description of the species in New England in 1781. The species common name refers either to the back flexion while diving or the hump-like dorsal fin. Humpbacks are stockier than other balaenopterids. They lack a dorsal ridge and have a slender tail stock. The head constitutes almost 30% of body

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length and contains numerous dermal tubercles, which are actually hair follicles that contain well-innervated vibrissae (whiskers). The baleen plates are blackish-brown/gray, 85-104 cm in length, and number 270-400 in each upper jaw. The dorsal fin is 0.3 m and is highly variable in appearance. 12-36 pleats are present on the ventral surface, the least of any species of Balaenopterid. Basic coloration is black, with white patches on the chin, throat, abdomen, pectorals, and flukes. Some authors have remarked on the greater presence of white in Northern Hemisphere animals. The pectorals are the longest of any marine mammal and may reach onthird total body length. The rather slender flukes are unique in shape and coloration in each animal and are the basis for extensive research based on photoidentification Females are slightly larger than males; the largest measured is 19 m (62 ft), with a corresponding weight of probably 40-50 tons. Average length is 12-13 m. Average calf length is 4.2 m (14 ft). Communication: Songs are 2 or more notes repeated in a pattern. Units of sound are phrases; repeated phrases are themes. Singing occurs on the humpback whale wintering grounds. The “singers” appear to be sexually mature, isolated males. Although little is known about song function, it probably occurs in a breeding context. Humpback whale songs have 2-9 themes. The themes are sung in a specific order and last from a few minutes to one-half hour. The song is then repeated, which may continue for hours-days. All animals from the same population sing identical songs, although there may be subtle differences among subpopulations and individuals. There are major differences between different populations. The songs change annually, with each individual in the population somehow learning the differences. All individuals in a population learn the differences. Over a period of 5 years, the song will change almost entirely. Most frequencies are 40-5000 Hz. Other humpback vocalizations include clicks, chirps, moans, cries, and squeaks, which have often been bundled together as “social sounds.” Occasional song-type sounds are heard in northern feeding grounds. Although occasional higher-frequency clicks (2-14 kHz) are heard, there is no evidence for echolocation. Low frequency vocalizations in this and other Mysticetes may be important in orientation, navigation, and locating large prey aggregations. Respiration/Diving: Humpback whales undertake short dives of 2-4 minutes with surface intervals of 1 minute. In this dive pattern, the blows are irregular and the flukes are not shown. Longer dives are of 8-15 minute duration (30 minute maximum), with surface times of 4 minutes, regular blows, and flukes shown during dives. The longest dives occur on the shallow wintering grounds. During these dives, the animals may frequently be observed resting on or near the bottom. Feeding: Prey species vary among regions. Antarctic humpbacks feed almost entirely on euphausids, while North Pacific humpbacks feed on euphausids, mackerel, sand lance, capelin, and herring (and even an occasional gull). As with other Balaenopterids, this species is a “gulper” rather than a “skimmer.” Humpbacks demonstrate a wide variety of feeding techniques. They may create a ring of foam by circling prey while striking the water with their flukes, thus herding the prey by creating an acoustically opaque wall of bubbles. They may undertake bubble net feeding by (either alone or in groups) releasing bubbles from their blowhole while circling prey, then lunging up through the bubblenet cylinder. They may also

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employ bubble cloud feeding, in which one animal releases a large exhalation of bubbles, with the same result as above. Cooperative feeding may entail aggregations of up to 20 animals. North Pacific animals utilize more bubble net than bubble cloud feeding. Reproduction: Calves are born in well-defined tropical wintering grounds. Gestation is 11-11.5 months, and the calves are 4-5 m at birth. More than 43 kg milk is consumed daily. Weaning occurs at 5 months, when calves are 7.5-9 m. Sexual maturity is attained at 4-5 years (comments made for blue whales are applicable here also). Calving intervals average 2-3 years. As with most species of Cetacea, little is known regarding copulation. Females in estrous swim with sexually mature male “escorts.” Intense competition occurs for females, with occasional injuries to males. Competitors of the escorts may form cooperative groups of up to 20 individuals. Miscellaneous: Maximum age for humpback whales is estimated to be 40-50 years. Common swimming speeds are 3.8-14.3 km/hr, although wounded animals may swim as rapidly as 27 km/hr. Social behaviors are spectacular in this species and include breaching, lobtailing, tail slapping, and flippering. The functions for these behaviors are largely unknown but muchspeculated upon. Proposed reasons for breaching include excitation, aggression, communication of alarm, and dislodging of parasites. This species may show agonistic behavior toward boats during breeding season. Population/Migration: The pre-exploitation population of humpbacks was approximately 150,000. Over 250,000 were killed in the Antarctic in the first two-thirds of the twentieth century. Between 1910 and 1916, 60,000 were harvested. The aggregation of humpbacks in tropical calving grounds and their inshore winter feeding grounds made this species an easy target for whalers. Current population estimates are extremely difficult to come by, but the total world population is probably somewhere around 12,000 animals. The species appears to be extremely resilient, and the size of most populations is increasing. Current estimates for annual population increase in the North Pacific is 6-8%. In 1998, 911 humpbacks were estimated to summer off the California, Oregon, and Washington coast. Humpbacks undertake well-defined north-south migrations. During spring, summer, and fall they feed in cold, high latitude waters. In the winter they migrate to shallow, tropical waters to calve (but not feed). Winter populations were traditionally thought to winter off Mexico, Hawaii, and Japan. Recently, a previously unknown wintering ground in Costa Rica was discovered (there was some initial thought that this wintering ground might include a mixing of Northern and Southern Hemisphere individuals, but further research has not borne this out). The Hawaiian wintering ground is relatively new; anthropological research has shown that it has only been used for the past 200 years. The exchange rate with the Mexican population has led to speculation that it derives from the Mexican population, with the shift in breeding grounds perhaps induced by early commercial whaling. Most of the population that winters in Costa Rica feeds off California in summer. Recent DNA and photoidentification work has shown that humpback whales have extraordinary site fidelity to their feeding grounds. The population that summers off central California may be

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seen as far north as central Washington, but it rarely mixes with the population off British Columbia. Whether this holds for other species of balaenopterids remains to be determined. There is little (but some) mingling of Northern and Southern Hemisphere populations of humpbacks, as the migrations are 6 months out of phase. Disease/Mortality: Little is known about diseases in humpbacks. They are the most heavily parasitized of the Balaenopteridae (both endo- and ecto-parasites). Significant levels of DDT and chlorinated hydrocarbons have been found in tissues. There is also some evidence for fatalities from brevitoxin, the agent in paralytic shellfish poisoning.

Pinnipeds Pinnipeds (from the Latin for “feather-footed”) include the Family Otariidae (sea lions and fur seals), the Family Phocidae (the “true” seals), and the Family Odobenidae (the walrus). Historically, the families have usually been considered diphyletic—that is, descended from two different terrestrial ancestors. Otariids and Odobenids were considered descended from ursid (bear-like) ancestors and Phocids from mustelid (weasel-like) ancestors. Recent re-evaluation of morphologic evidence, as well as molecular evidence, now points toward a monophyletic origin with ursids as ancestors. Origins Pinnipeds first appear in the fossil record some 27 million years ago. Otariidae and Phocidae diverged shortly thereafter. Anatomy/Physiology General: Otariids have an external ear; phocids do not. Otariids can turn their hind flippers forward and use them to walk; phocids do not. Hearing: Pinniped ears show acoustical isolation similar to that of cetaceans. Additionally, phocids show modification of the middle ear bones (otariids do not). Echolocation/Sound Production: Pinnipeds lack the nasal sinuses and well-developed cranial fatty deposits of cetaceans. They emit a wide variety of vocalizations that probably serve a multitude of purposes. Some phocids may echolocate (the evidence is somewhat equivocal), but any echolocation is primitive at best. Navigation: Little is known, but species undertake long migrations between feeding and breeding grounds. Elephant seals have been tracked all the way from San Miguel Island to Hawaii.

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Miscellaneous senses: Eyes in pinnipeds are relatively large and can accommodate to allow them to see fairly well out of water. The oral vibrissae (whiskers) are well innervated. They greatly augment tactile sense and augment the reception of some sounds. Although pinnipeds have blubber, heat conservation is also aided by the presence of fur. All pinnipeds have both an outer layer of guard hairs and an inner layer of underfur hairs. Feeding: Pinnipeds have evolved a wide variety of feeding strategies. Those whose distribution overlap have also evolved niches which partition resources. Respiration: Much of the description of the cetacean respiratory system applies here also. Some species (Weddell seal) can dive to depths of 1500 m and stay submerged for over an hour. Cetaceans dive on full inspiration; pinnipeds tend to dive on full expiration. Circulation/Heat Conservation: Much of the comments regarding cetaceans apply here also. Pinnipeds have a large venous sinus posterior to the liver (cetaceans do not). Reproduction: Reproduction in pinnipeds is complex and may be either monogamous or polygynous. Monogamy occurs when the species does not aggregate into large breeding groups. When breeding aggregations occur, males may either defend territories (resource defense polygyny) or establish dominance hierarchies (female defense polygyny). California sea lions are an example of the former; elephant seals are an example of the latter. Renal Function: Pinniped kidneys are generally not as highly lobulated as those of cetaceans. Age: Maximum age is generally significantly lower for pinnipeds than it is for cetaceans. The energy expenditure in defending territories is a significant life stress in males. Intelligence: A great deal of work has been done on pinniped intelligence. In general, my comments on cetaceans apply here also. Pinniped Fisheries/Conservation Native American take of local pinnipeds was significant; it may well have grossly depleted the local elephant seal population prior to 1200 years ago. Commercial sealing depleted most stocks in the Southern California Bight (SCB) in the nineteenth century and rendered California sea lions, Guadalupe fur seals, and elephant seals almost extinct; these species passed through a significant genetic bottleneck on the road to recovery. Although all species are protected under the Marine Mammal Protection Act, ecosystem perturbations such as El Niño and epizootic diseases pose very real population threats. Some Comments on California Sea Lions, Zalophus californianus

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The Northern Pacific population of this species is almost 160,000. Almost 90,000 are in the Southern California Bight (SCB), with a breeding population on San Miguel Island of approximately 80,000 animals. Significant sexual dimorphism exists. Mature males average 2.25m and 325 kg, females average 1.8m and 110 kg. California sea lions breed from the Channel Islands to Mexico. After breeding, males undertake a northward migration; females are less migratory. Breeding season is June-July. This species was rare in SCB prior to 1930. It is now growing at the rate of 12% per year but has suffered significant losses due to El Niño events. Some Comments on Stellar Sea Lions, Eumetopias jubata The population of this pinniped has crashed in the North Pacific over the past two decades. It was formerly the most abundant pinniped in the SCB, with a substantial rookery on San Miguel Island. The last pup was born on San Miguel in 1982, and the last confirmed sighting of an adult was in 1984. Ecosystem disruption by fishing appears to be a major factor in the decline of this species both locally and in its current range. This species is much larger than the California Sea Lion. Males average 2.9 m and 1000 kg. Some Comments on Guadalupe Fur Seals, Arctocephalus townsendii The historical range of this species was from the Farallones to the Islas Revillagigedos, with a major rookery on San Miguel Island. They were hunted intensively in the nineteenth century and were considered extinct by 1900. Carl Hubbs discovered a small breeding colony on Guadalupe Island in 1954. The species breeds primarily on Guadalupe Island and is increasing by 10% per year. Occasional visitors are seen on San Miguel and San Nicholas Islands. The first adult female was seen on San Miguel Island in 1997; it gave birth in June of that year and reared the pup to weaning age. Some Comments on Northern Fur Seals, Callorhinus ursinus San Miguel Island was colonized by this pinniped in the 1960s, 5500 km south of its only other breeding areas. Population size has increased at slightly more than 10% per year, but El Niño events (primarily 1983 and 1997) have caused dramatic population declines in recent years. 1997 population size on San Miguel Island was approximately 12,000 animals. Total North Pacific population is more than 1 million animals.

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This species weans its young at 120 days, which is much earlier than most other North Pacific otariids. Some Comments on Harbor Seals, Phoca vitulina The North Pacific population of this species is 312,000. The SCB contains 5000, 75% of which occur around the northern Channel Islands. This is the only west-coast pinniped that occurs in the Atlantic also. It is usually found within 10 km of land. The population in the North Pacific is stable and is increasing at the rate of 10% per year. Some Comments on Northern Elephant Seals, Mirounga angustirostris This is the largest of the extant pinnipeds. Males average 4.5 m and 2500 kg; females average 3 m and 900 kg. Breeding Season occurs from December to mid-March. Females and juveniles molt from mid-March through May. Males molt in July and August. Juveniles haul out from September through November. Elephant seals were hunted intensively in the nineteenth century and by the end of the century were presumed extinct. The 1890 population has been estimated at 20-100 individuals limited to Guadalupe Island. By 1968, it bred also at the western tip of San Miguel Island. Today, it breeds all the way around San Miguel Island, on Santa Rosa Island, and on the mainland at San Simeon. Current population is approximately 140,000. The largest breeding population, approximately 50,000 animals, occurs on San Miguel Island. Elephant seals have been intensively studied. They are noted for deep diving.

Sea Otters, Enhydra lutris This species is a member of the mustelid family. Its former range was from Alaska to Mexico, and it occurred on both sides of the Pacific Rim. Pre-hunting populations were approximately 150,000-300,000 animals. Hunting began in 1741, and by 1900 there were probably only 1000-2000 animals left. The Russian and Alaskan populations have experienced a significant recovery and until recently numbered 100,000-150,000 animals. The California population numbers approximately 1900; it is descended from a colony of approximately 30 animals known since 1915. The Russian and Alaskan populations are now experiencing dramatic declines. With the decline of some pinniped populations (especially Stellar sea lions), killer whales have increased predation on otters.

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This species has been extremely controversial from a resource management standpoint. The California population is extremely tenuous and passed through a genetic bottleneck. Otters were transplanted to San Nicholas Island (part of their former range) in attempt to increase dispersal of the species, but the transplant was a disaster. Sea otters have no blubber. They depend on an extremely dense layer of underfur (it functions by trapping air) and a high basal metabolic rate for insulation. Sea otters are the only marine mammals to use tools.

References Berta, Annalisa and J L Sumich. Marine Mammals: Evolutionary Biology. New York: Academic Press, 1999. This is a great, current, highly technical general treatise on marine mammals. Mark Carwardine, ed. Whales, Dolphins, and Porpoises (2nd ed.). New York: Facts on File, 1999. I am not always enthusiastic about natural history volumes from this publisher, but this is probably the best one-volume summary of Cetacean biology for the informed layperson. Highly recommended despite its “coffee-table” size. Calambokidis, John, and G Steiger. Blue Whales. Grantown-on-Spey (Scotland): Colin Baxter Photography, 1997. See comments for Clapham below. Clapham, Phil. Humpback Whales. Stillwater, MN: Voyageur, 1996. This is one in the Worldlife Library series. Typical of the series, the coverage is broad but superficial and the pictures are great. The series is aimed at the informed layperson. Dierauf, Leslie, and F M D Gulland. The CRC Handbook of Marine Mammal Medicine. New York: CRC Press, 2001. This is probably the most up-to date reference in the bibliography. The quality of some of the chapters is a bit uneven, but the volume is indispensable. It includes a chapter on electronic databases. Heyning, John. Masters of the Ocean Realm: Whales, Dolphins, and Porpoises. Seattle: University of Washington Press, 1995. This is a brief, but masterful, overview of marine mammal biology. The author is a marine mammal anatomist, authority on the Ziphiidae (beaked whales), and the Associate Director of the Los Angeles County Museum of Natural History. Jones, Mary Lou, S Swartz, and S Leatherwood. The Grey Whale. New York: Academic Press, 1984. This volume is now somewhat outdated, but is remains the best single volume treatise on the grey whale.

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Leatherwood, Stephen, R R Reeves, W E Perrin, et al. Whales, Dolphins, and Porpoises of the Eastern North Pacific and Adjacent Arctic Waters. NOAA Technical Report NMFS Circular 444, 1982. Since reprinted by Dover and widely available, this is an excellent reference. It is filled with data on distribution and identifying characteristics, and the black-and-white photos are very good. Leatherwood, Stephen and R R Reeves. The Sierra Club Handbook of Whales and Dolphins. San Francisco: Sierra Club Books, 1983. This is an outgrowth of the reference above and a companion volume covering the Atlantic. It offers excellent color drawings (supplemented by good black-and-white pictures) and a terse, well-informed text. It is aimed at the informed layperson and is global in scope. It is an excellent choice for carrying into the field anywhere in the world. Leatherwood, Stephen and R R Reeves, eds. The Bottlenose Dolphin. New York: Academic Press, 1990. This is a thorough, well-written treatise on the biology of this species. Le Boeuf, Burney J and R M Laws, eds. Elephant Seals: Population Ecology, Behavior, and Physiology. Berkeley: University of California Press, 1994. This is another single-species volume, well written, and edited by the dean of elephant seal biology. Orr, Robert T and R C Helm. Marine Mammals of California. Berkeley: University of California Press, 1989 (revised). This is a volume in the California Natural History Guides series. It features line drawings and concise text and covers both cetaceans and pinnipeds. Reeves, Randall R, B S Stewart, and S Leatherwood. The Sierra Club Book of Seals and Sirenians. San Francisco: Sierra Club Books, 1992. This is a companion volume to the Leatherwood volume above. The comments offered above apply here also. Reynolds, John and S A Rommel, eds. Biology of Marine Mammals. Washington, D.C.: Smithsonian Institution Press, 1999. This is another good, technical, current text on the biology of marine mammals. Reynolds, John, R S Wells, and S D Eide. The Bottlenose Dolphin: Biology and Conservation. Gainesville: University Press of Florida, 2000. Rice, Dale. Marine Mammals of the World: Systematics and Distribution. Special Publication no. 4, The Society for Marine Mammalogy, 1998. This is a list of all known species and subspecies of marine mammals and their distribution. Riedman, Marianne. The Pinnipeds. Berkeley: University of California Press, 1990. Overview of pinniped biology with emphasis on behavior. Ridgway, Sam H and R Harrison. Handbook of Marine Mammals, vol. 1-vol. 6. New York: Academic Press, 1985-1999. These volumes provide excellent summary accounts of all species of cetaceans and pinnipeds.

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Slijper, E J. Whales. New York: Basic Books, 1962 (republished by Cornell in 1979). The date of publication might lead one to consider this volume long outdated, but it remains the single most indispensable text on cetacean biology. What was often only speculation in Professor Slijper’s day has usually been proven true. Many of us still use slides made from the drawings in this text to illustrate papers presented at technical meetings. Tonnessen, J N and A O Johnsen. The History of Modern Whaling. Berkeley: University of California Press, 1982.

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Marine Mammal Migration in the Santa Barbara Channel

Mammal Blue Whales Bottlenose Dolphins California Sea Lions Common Dolphins Dall's Porpoises Gray Whales Harbor Seals Humpback Whales Minke Whales Northern Elephant Seals Northern Right Whale Dolphins Orcas (Killer Whales) Pacific White Sided Dolphins Risso's Dolphins Sperm Whales

Jan

Feb

Mar

Apr

** ** ** ** ** ** * * ** *

** ** ** ** ** ** * * ** *

** ** ** ** ** ** * * ** *

** ** ** ** ** ** * * * *

* * * *

* * * *

* * *

* * *

May * ** ** ** ** * ** ** *

Jun ** ** ** ** ** ** ** ** *

July ** ** ** ** **

** ** ** **

Aug ** ** ** ** **

** ** ** **

* * * *

* * **

* * ** *

** Frequently seen in the channel

** * ** *

Sep ** ** ** ** **

Oct * ** ** ** **

** * ** * *

** * *

* * ** *

* * ** *

*

Nov

Dec

** ** ** **

** ** ** **

** * * * *

** * * ** *

* * *

* * *

*Occasionally seen in the channel

(Based on information provided by Condor Whale Watching)

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MARINE MAMMALS OCCURRING IN THE WATERS OF CALIFORNIA Charles J. Rennie, III Channel Islands National Park ORDER CETACEA Suborder Mysticeti (Baleen whales) Family Balaenidae (Right whales)* Eubalaena glacialis (Northern right whale) Family Balaenopteridae (Rorquals) Balaenoptera acutorostrata (Minke whale) Balaenoptera borealis (Sei whale) Balaenoptera brydei (Bryde’s whale)** Balaenoptera musculus (Blue whale) Balaenoptera physalus (Fin whale) Megaptera novaeangliae (Humpback whale) Family Eschrichtidae Eschrichtius robustus (Gray whale) Suborder Odontoceti (Toothed whales) Family Physeteridae Kogia breviceps (Pygmy sperm whale) Kogia simus (Dwarf sperm whale) Physeter macrocephalus (Sperm whale) Family Ziphiidae Berardius bairdii (Baird’s beaked whale) Mesoplodon carlhubbsi (Hubbs’ beaked whale) Mesoplodon densirostris (Blainville’s beaked whale) Mesoplodon ginkgodens (Ginkgo-toothed beaked whale)*** Mesoplodon perrini (Perrin’s beaked whale) Mesoplodon stejnegeri (Stejneger’s beaked whale) Ziphius cavirostris (Cuvier’s beaked whale)

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Family Delphinidae Delphinus delphis (Short-beaked common dolphin) Delphinus capensis (Long-beaked common dolphin) Globicephala macrorhynchus (Short-finned pilot whale) Grampus griseus (Risso’s dolphin) Lagenorhynchus obliquidens (Pacific white-sided dolphin) Lissodelphis borealis (Northern right whale dolphin) Orcinus orca (Killer whale) Pseudorca crassidens (False killer whale) Stenella attenuata (Pantropical spotted dolphin) Stenella coeruleoalba (Striped dolphin) Steno bredanensis (Rough-toothed dolphin) Tursiops truncatus (Bottlenose dolphin) Family Phocoenidae (Porpoises) Phocoena phocoena (Harbor porpoise) Phocoenoides dalli (Dall’s porpoise) ORDER CARNIVORA Family Mustelidae Enhydra lutris (Sea otter) Suborder Pinnipedia Family Otariidae (Fur seals and sea lions) Arctocephalus townsendi (Guadalupe fur seal) Callorhinus ursinus (Northern fur seal) Eumetopias jubatus (Steller sea lion)**** Zalophus californianus (California sea lion) Family Phocidae (True seals) Mirounga angustirostris (Northern elephant seal) Phoca vitulina (Harbor seal) This list is accurate as of December 2007. However, as DNA-based research proliferates and field work increases, some of these taxonomies will undergo significant revision. The status of Bryde’s whales is a case in point. Two species were recently delineated from the previously accepted one, and it’s likely that more species will be split off (the local species has been changed from Balaenoptera edeni to Balaenoptera brydei). *Known from very limited sightings. **Species recently revised. ***Known from skeletal material only in this range. ****The last reliable sighting of this species in the Santa Barbara Channel was in 1984. CHANNEL ISLANDS NATURALIST CORPS TRAINING MANUAL CHAPTER 7

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Evolution of Marine Mammals 45 – 50 million years ago a hoofed animal resembling pigs and cows, called mesonychids, began feeding along the shores of ancient seas, as the number of animals increased some were forced to deeper water to feed. This in turn created pressure on these animals to dive for food and plants in deeper water, which led to the development of the archaeocete (40 million years ago). The archaeocete’s blowholes started to move further back on its head, and the front legs developed into flippers, and the tail developed a paddle-like structure. Baleen whales emerged in fossil records some 20 –25 million years during the Oligocene period. A modern day example of the process of adaptation to aquatic life can be found on the Tokelau islands in the South Pacific where pigs feed on the coral reefs at low tide. Genetically, todays closest relative to whales are cows, pigs, and horses. Diving for food filled a new niche in evolutionary development, and has allowed for the development of the largest animal on earth. A total of 79 species of cetaceans now roam the world’s oceans. Pinnipeds evolved from a “bear-like”, carnivorous ancestor ~30 million years ago Oligocene/ Miocene. Sea otters more recent ~ 5-7 million years ago Miocene/Pliocene. However, it is still unclear whether or not the seals, sea lions and walruses evolved from a common ancestor such as the cetaceans (monophyletic vs. diphyletic).

Facts on the evolution of whales: • • • • • • • • • • • • • • • • •

Returned to the sea 30-70 million years ago Hairless, streamlined bodies Modified arms created flippers loss of all external evidence of hind legs No Sebaceous glands (produce oil and lubricants for hair and skin of terrestrial mammals) No sweat glands No scent glands No ear flaps Nipples of females retract into slits on either side when not in use Nostrils (blowholes) situated on top of head Pair of blowholes in baleen whales Single blowhole in toothed whales Upper and lower jaw elongated Thick layer of body fat, to protect from loss of body heat. Up to 1/3 of body mass can be fat Respiratory and circulatory systems specialized to withstand long periods underwater The number of red blood corpuscles per millimeter is twice that of terrestrial mammals Pulse rate during a dive can drop to 1/8 of what it may be at the surface

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Whale, Dolphin, and Porpoise Terms

ADAPTATION

Physical and behavioral changes that occur slowly over time that help an organism live more easily in its environment

AMBERGRIS

Wax like substance found in the intestines of Sperm whales, used in perfumes.

BALEEN

Rows of triangular plates that hang from the upper jaws of Mysticetes. The plates of baleen are composed of a material which is very similar to fingernails. The baleen is used to filter the planktonic prey and fish from the water.

BLOWHOLE

The nasal opening of a whale, which is located on the top of the head. Baleen whales have two external nasal openings while toothed whales have only one.

CALF

A new born or young whale that is still dependent on its mother for protection and of nourishment.

CETACEAN

Marine mammals of the order Cetacea which includes the great whales, dolphins and porpoises. Generally, all members of this order are considered whales.

COW

A mature female whale.

DOLPHIN

A toothed whale having sharp, conical teeth, and a beak.

DORSAL FIN

A triangular structure found along the back of many whales, thought to help stabilize the whale during swimming, diving and regulation of body temperature.

ECHOLOCATION The process employed by toothed whales to locate distant objects by use of sound waves that are reflected back to the whale from the object. EVOLUTION

A process of continuous growth and change over millions of years.

FLIPPER

A famous dolphin from the television program of the same name and the distinctive structures found on either side of the whale’s body. These are for steering, turning, and controlling the whale's vertical position in the water.

KRILL

The common name for euphausiid shrimp, upon which are small crustaceans that many species of baleen whales feed.

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Whale, Dolphin, and Porpoise Terms MELON

A wax-like organ, located in the front of the skull of toothed whales, used for echolocation.

MYSTICETE

A sub-order of whales that possess baleen instead of teeth. These whales strain their food from the water with their baleen. The Mysticete include the largest animals on earth, such as the Blue and the Finback whale.

ODONTOCETE

A sub-order of whales which have teeth of uniform shape and function. Dolphins, porpoises, and the Sperm whale are all Odontocete. These whales eat primarily fish and squid.

PORPOISE

A toothed whale having rounded teeth and no beak.

SPOUT

The expired air of a whale that forms "steam," (a cloud of condensed water vapor) often called the “blow."

A series of pleats found along the underside of most Mysticetes. VENTRAL GROOVES These grooves are related to the feeding behavior of the whales which requires them to expand and accommodate large volumes of water. VERTEBRAE

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The bones that make up the backbone of vertebrate animals.

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Porpoises vs Dolphins Characteristics

Porpoises

Dolphins

Family

Phocoenidae

Delphinidae

Length

Seldom exceed 7 feet

Many can exceed 10 feet

Shape

More robust, chubby

Lean sleek body

Triangular

Sickle-shaped

Lack a rostrum or a beak.

Very prominent rostrum (often)

Spade-shaped

Cone-shaped

Life span

Rarely to 20 years

Up to 50 years

Behavior

Shy (usually)

Ride bow waves

Harbor porpoise Dall's porpoise

Common dolphin Bottlenose dolphin Pacific white-sided dolphin Risso's dolphin Killer whale (Orca) Pilot whale

Dorsal fin "Nose" Teeth

Examples

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Page 1

Marine Mammal Identification Keys, © Peter Howorth

Key to Identifying Seals, Sea Lions and Sea Otters in the Ocean Seals: No external earlobes; heads smooth Dive by descending vertically until snout disappears Very short, stubby tails Swim with hind flippers

Pacific harbor seal Phoca vitulina richardsi

Northern elephant seal Mirounga angustirostris

Round head profile

Round head profile

Ear holes

Smooth head; no visible ear holes

Long whiskers

Long black whiskers

Short fore flippers with claws

Short fore flippers with claws

Short hind flippers with claws

Short hind flippers without claws

Mottled coat: silver, tan, brown, and/or black

Uniform tan or brown

Coastal

Coastal and pelagic

Sometimes rafts in kelp with hind flippers out of water

Males and females:

Male:

Female:

Very little difference in size, shape, length, or weight

Massive head

Large, wide skull

Both up to about 300 pounds and 6 feet

Pronounced snout

Up to 2000 pounds

Up to 5000 pounds

Notes: The main differences between the two species are the massive size, thicker head, and uniform color of the northern elephant seal. CHANNEL ISLANDS NATURALIST CORPS TRAINING MANUAL CHAPTER 7

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Marine Mammal Identification Keys, © Peter Howorth

Key to Identifying Seals, Sea Lions and Sea Otters in the Ocean Sea lions, fur seals and sea otters: External earlobes Dive by swimming forward, then submerging headfirst Sea lions: Yellowish tan, brown or black coat Very short, stubby tails Swim with fore flippers Coastal out to about 200 miles; sometimes raft in kelp or float on surface with front and/or hind flippers out of water

California sea lion Zalophus californianus c.

Steller sea lion Eumetopias jubatus

Concave head profile, long head

Concave head profile, boxlike, thicker head features

Short, stubby ears

Short, stubby ears

Tan to black whiskers about length of snout

Tan to black whiskers about length of snout

Long fore flippers edged with black

Long fore flippers edged with black

Short hind flippers

Short hind flippers

Male:

Female:

Male:

Female:

Prominent crest on head

Long, streamlined head

Massive shoulders & head

Large, wide skull

Crest white or light tan

Yellowish tan to brown

Thicker fur around shoulders Yellow or tan fur

Very dark brown or black

175-350 pounds

Yellow or tan fur

5-6 feet long

1600-2000 pounds

body

350-500 pounds

600-1200 pounds CHANNEL ISLANDS NATURALIST CORPS TRAINING MANUAL CHAPTER 7

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Marine Mammal Identification Keys, © Peter Howorth

6-8 feet long

Notes: The main differences between the two species are the massive size, thicker, boxier head, and yellow to tan color of the Steller sea lion.

Key to Identifying Seals, Sea Lions and Sea Otters in the Ocean Sea lions, fur seals and sea otters: External earlobes Dive by swimming forward, then submerging headfirst Fur Seals: Reddish brown, brown or black coat Very short, stubby tails Swim with fore flippers Pelagic; sometimes raft in kelp or float on surface with front and/or hind flippers out of water Often roll and rub themselves with flippers

Northern fur seal Callorhinus ursinus

Guadalupe fur seal Arctocephalus townsendi

Convex head profile

Concave head profile

Short, stubby snout

Long, collie-like snout

Very long, down-turned ears

Medium length ears

Very long, often white whiskers

Long tan whiskers

White patches on cheeks and breast

Generally similar to California sea lion

Large, round eyes

Hind flippers short

Hind flippers long and flexible; equal to 1/3 body length

Male:

Female:

Male:

Female:

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Marine Mammal Identification Keys, © Peter Howorth

Thick neck and shoulders

125-175 pounds

Thick neck and shoulders

125-175 pounds

Up to 450 pounds

5 feet

450 pounds

5 feet

6 feet

6 feet

Notes: The main differences between the two species are the short, stubby snouts and very long whiskers and hind flippers of the northern fur seal, which contrast with the collie-like snout of the Guadalupe.

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Marine Mammal Identification Keys, © Peter Howorth

Key to Identifying Seals, Sea Lions and Sea Otters in the Ocean Sea lions, fur seals and sea otters: External earlobes Dive by swimming forward, then submerging headfirst Southern sea otters

Enhydra lutris nereis Brown or black coat; white heads in older animals Long, bushy tails Swim with hind flippers Stay very close to coast; sometimes raft in kelp or float on surface with front and/or hind flippers out of water Often roll and rub themselves with flippers Often place prey on bellies Whiskers end in horizontal line beneath snouts

Male:

Female:

Up to 80 pounds

Up to 50 pounds or so

Up to 5 feet

Up to about 4 feet

Notes: The main difference between sea otters and pinnipeds is the small size of the otter. Also, sea otters only stay down from a few seconds to a few minutes at most; pinnipeds can remain submerged much longer. Finally, sea otters generally remain very close to shore in water 120 feet in depth or less.

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Marine Mammal Identification Keys, © Peter Howorth

Key to Identifying Large Whales off California Species

Blow

Dorsal

Flukes

Habitat

Key features

Blue

Tall and straight Very small (up to 1 foot), very far back, appears after blow

Huge, straight when seen from rear Near escarpments; open Glows turquoise, mottled sea; subtemperate in CA blue-gray, wide, flat head

Fin

Similar to above, Larger (18 to 24”); appears with smaller blow or immediately afterward

Virtually never seen

Near escarpments & open ocean; subtemperate & temperate in CA

Sei

Medium, bushy

Large (24” or more), 1/3 forward of flukes

Virtually never seen

Tropical to subtemperate; Dorsal large, third rare off CA of length forward from flukes, gray with oval white patches

Bryde’s

Short, bushy

Medium (18-24”) appears to sink when diving

Virtually never seen

Tropical to temperate; extremely rare off CA

Three ridges on snout

Minke

Short, bushy

Small (12-18”)

Virtually never seen

Fairly common near escarpments and plains

Smallest rorqual whale (35’); white stripe on each flipper, sharp, pointed snout

Humpback

Tall and straight, Misshapen, bumpy sometimes bushy

Large, down-turned at tips

Common near escarpments

Down-turned tips of flukes, long flippers, warty snout

Gray

Heart-shaped

None, but bumpy ridges

Straight when diving

Coastal

Mottled gray color, heartshaped blow

North Pacific right

short, bushy

None

Large

Extremely rare off CA

No dorsal, high arch to lower jaw

Sperm

Short, bushy, forward and to left

None, but bumpy

Hang straight up for long time

Offshore canyons and seamounts

Boxy head shape; blow forward and to left

Baird’s beaked

Short, bushy

Triangular; 1/3 forward of flukes

Sometimes shown

Continental borderline; rare

Bulbous head; dolphinlike snout

Lower right jaw white, rest gray or black, sometimes gray or white chevron behind head.

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