Adult Whales Research Articles

Benefits of menopause: good fishing.

Humans can’t understand whale communication, but if they did, they might hear this familiar refrain: ‘‘Give Grandma some respect; she has been around! Post-menopausal killer whales (Fig. 1) are community leaders, with expertise in finding food when the salmon runs are poor, suggests an analysis of 751 hours of videos of resident whales in Washington and British Columbia [1]. The findings hint that the transfer of ecological knowledge to kin by older females may have partly driven the evolution of menopause. In only a handful of species do the females survive for decades after their reproductive years—humans, pilot whales, and killer (orca) whales. In humans, several studies have showcased the fitness benefits of being a grandmother—for instance, pre-modern Finnish and Canadian women who lived long lives had more grandchildren than women who died soon after menopause. As with human hunter-gatherer groups (our evolutionary crucible), the resident orca whales of Puget Sound and British Columbia have a tight-knit society. And perhaps whale bonds are even tighter—human hunter-gatherer girls and women were thought to eventually leave the group, say the researchers, whereas female and male whale offspring do not leave their mother’s pod. Previous studies have shown that adult whales are much more likely to die in the year after their mother’s death. In the new study, Lauren Brent et al. identified one key way older females contribute to the fitness of their offspring. They found that older females were much more likely than other whales to lead pods as they roamed through coastal waters, trolling for salmon—their primary source of food. What’s more, during years when salmon runs were scarce, the fraction of older females leading pods increased substantially. The findings suggest that older females serve as a repository of ecological information, enabling whales to survive when food is scarce. As a female ages, her relatedness to her group increases as her offspring reproduce, and her accumulated knowledge in turn benefits these kin. Whales have complex, fluid societies, which humans barely understand. For instance, some orca whales—not part of this study—live in migratory groups that hunt seals. As another example, male whales, who rarely live past 50, seem more dependent on their mothers than do females, and are more likely to die after she dies. Perhaps mom puts more resources into males since they mate outside the pod, increasing her reproductive success with less strain on the pod’s food resources, speculate the researchers. It is likely that menopause is about more than finding food, say the researchers. Throughout the long lives of these sophisticated creatures, older female whales may help younger animals navigate a complex range of social and environmental situations.

Microplastic and macroplastic ingestion by a deep diving, oceanic cetacean: The True's beaked whale Mesoplodon mirus

When mammals strand, they present a unique opportunity to obtain insights into their ecology. In May 2013, three True's beaked whales (two adult females and a female calf) stranded on the north and west coasts of Ireland and the contents of their stomachs and intestines were analysed for anthropogenic debris. A method for identifying microplastics ingested by larger marine organisms was developed. Microplastics were identified throughout the digestive tract of the single whale that was examined for the presence of microplastics. The two adult females had macroplastic items in their stomachs. Food remains recovered from the adult whales consisted of mesopelagic fish (Benthosema glaciale, Nansenia spp., Chauliodius sloani) and cephalopods, although trophic transfer has been discussed, it was not possible to ascertain whether prey were the source of microplastics. This is the first study to directly identify microplastics <5 mm in a cetacean species.

Results on photo identification for beluga whale &lt;i&gt;Delphinapterus leucas&lt;/i&gt; in the Anadyr estuary of the Bering Sea

Definition of individual beluga whales by the method of photo identification and selection of the main types of markers are presented for beluga whales in the Anadyr estuary, western Bering Sea. The study was conducted in the aggregation of beluga whales in three different sites at Anadyr - in the Anadyr sea port and at ferry docks № 8 and № 10 in the period from August 14 to September 6, 2013 (summer feeding of the whales). The maximum number of whales (40-70 animals) was observed at the ferry dock № 10, 2-6 whales were at the ferry dock № 8, and 1-2 ones - at the port. Mother-calf pairs were observed in all sites, but the portion of adult whales was the highest at the ferry dock № 10. Photocamera Nikon D90 and Nikkor lens (70-200 mm) were used for the photo ID. Mechanical skin damages, infections, spinal ridge traces, and age spots were used as individual markers. In total, 4400 images were obtained, including 155 ones with sides of beluga whales. The markers were observed both on the left side (32 cases) and right side (97 cases) of the whales, but both sides were identified for 13 whales only, including 3 females with calves. Taking into account the risk of reassessment in case of using two sides for identification, the identification is considered as successful for 110 individuals of beluga whale. Almost all identified individuals were met only once during the whole period of observation, only 6 of them were met twice, and only 4 - three times. One whale appeared 3 days in a row: on August 16, 17 and 18, and 5 individuals came 2 days in a row. Such few recurrent meetings may indicate a weak fidelity of beluga whales to certain water areas in the estuary, though maybe the length of study is insufficient, taking into account that a strong fidelity of mother-calf pairs of beluga whales to certain areas of the Anadyr estuary, considered as their hunting areas, was determined by visual observations of Shirshov Institute of Oceanology in the 1980s. Probably, the area at the dock № 10, where the whales form large aggregation, is not assigned to individual animals but is a common feeding area. This large aggregation is similar to the aggregation of beluga whales at Cape Beluzhy of Solovetsky Island in the White Sea. However, these aggregations are fundamentally different by their nature: the reproductive aggregation at Solovetsky Island is distinguished by various forms of social interactions, including sexual activity, while the search and hunting behavior prevail in the feeding aggregation at the ferry dock № 10. The main reason for the beluga whales concentration in this area is dense concentration of freshwater fish and salmons migrating for spawning. Reproductive aggregations of beluga whales are not known yet in the Far-Eastern Seas.

Biogeographic and trophic drivers of mesozooplankton distribution on the northeast continental shelf and in Hauraki Gulf, New Zealand

The northeast continental shelf of New Zealand and adjacent Hauraki Gulf were surveyed from early spring to late summer, to identify biogeographic and trophic factors influencing mesozooplankton community distribution and abundance. The outer shelf supported low-abundance oceanic species associated with the East Auckland Current which were also transported to the inner shelf during upwelling. Outer gulf sites, where gulf and shelf waters converged, supported a characteristic frontal assemblage. The inner gulf supported an abundant and diverse neritic community, with greater seasonal variability than offshore. Over spring to summer, succession of mesozooplankton taxa reflected an ecosystem shift from net autotrophic to heterotrophic states. These biogeographic and trophic effects defined the grazing impact mesozooplankton had on lower trophic levels, with grazing often matching primary production in spring and early summer. Greater mesozooplankton abundances in the gulf were supported by higher volume-specific primary productivity than on the shelf. The results have important implications for higher trophic levels, including larval fish survival, adult fish distributions and whale feeding.

Dynamics of whale shark occurrence at their fringe oceanic habitat.

Studies have shown that the whale shark (Rhincodon typus), a vulnerable large filter feeder, seasonally aggregates at highly productive coastal sites and that individuals can perform large, trans-boundary migrations to reach these locations. Yet, the whereabouts of the whale shark when absent from these sites and the potential oceanographic and biological drivers involved in shaping their present and future habitat use, including that located at the fringes of their suitable oceanic habitat, are largely unknown. We analysed a 16-year (1998–2013) observer dataset from the pole-and-line tuna fishery across the Azores (mid-North Atlantic) and used GAM models to investigate the spatial and temporal patterns of whale shark occurrence in relation to oceanographic features. Across this period, the whale shark became a regular summer visitor to the archipelago after a sharp increase in sighting frequency seen in 2008. We found that SST helps predicting their occurrence in the region associated to the position of the seasonal 22°C isotherm, showing that the Azores are at a thermal boundary for this species and providing an explanation for the post 2007 increase. Within the region, whale shark detections were also higher in areas of increased bathymetric slope and closer to the seamounts, coinciding with higher chl-a biomass, a behaviour most probably associated to increased feeding opportunities. They also showed a tendency to be clustered around the southernmost island of Santa Maria. This study shows that the region integrates the oceanic habitat of adult whale shark and suggests that an increase in its relative importance for the Atlantic population might be expected in face of climate change.

Whales sustain fisheries: Blue whales stimulate primary production in the Southern Ocean

AbstractIt has previously been asserted that baleen whales compete with fisheries by consuming potentially harvestable marine resources. The regularly applied “surplus‐yield model” suggests that whale prey becomes available to fisheries if whales are removed, and has been presented as a justification for whaling. However, recent findings indicate that whales enhance ecosystem productivity by defecating iron that stimulates primary productivity in iron‐limited waters. While juvenile whales and whales that are pregnant or lactating retain iron for growth and milk production, nonbreeding adult whales defecate most of the iron they consume. Here, we modify the surplus‐yield model to incorporate iron defecation. After modeling a simplistic trajectory of blue whale recovery to historical abundances, the traditional surplus‐yield model predicts that 1011 kg of carbon yr−1 would become unavailable to fisheries. However, this ignores the nutrient recycling role of whales. Our model suggests the population of blue whales would defecate 3 × 106 kg of iron yr−1, which would stimulate primary production equivalent to that required to support prey consumption by the blue whale population. Thus, modifying the surplus‐yield model to include iron defecation indicates that blue whales do not render marine resources unavailable to fisheries. By defecating iron‐rich feces, blue whales promote Southern Ocean productivity, rather than reducing fishery yields.

The anatomy of the larynx of the bowhead whale, Balaena mysticetus, and its sound‐producing functions

This study describes the morphology of the laryngeal apparatus in bowhead whales (Balaena mysticetus) with respect to respiration, deglutition, and vocalization. We also examined the intrinsic cricoarytenothyroid muscle (Musculus (M.) diverticuli laryngei) which forms the laryngeal diverticulum, to ascertain its interactions with the laryngeal cartilages during respiration and sound production. Five fetal larynges and four from adult whales were studied using noninvasive imaging, as well as macroscopic and microscopic techniques. The larynx extends from the skull base into the thoracic inlet. The dorsally curved laryngeal stalk, supported by epiglottis and the corniculate processes of arytenoid cartilages, is situated within the nasopharynx. The epiglottic cartilage exhibits a prominent medial ridge. The arytenoid cartilages are rod-shaped, and extend through the laryngeal cavity. The thyroid cartilage possesses a prominent caudal horn with a fibrous articulation to the ventrally incomplete cricoid cartilage. The M. thyroepiglotticus forms the connection between epiglottic and thyroid cartilages. The M. cricothyroideus lateralis connects the caudal horn of the thyroid cartilage with the cricoid cartilage and the M. cricothyroideus medialis connects the cricoid and thyroid cartilage. An extensive laryngeal diverticulum (Diverticulum laryngis), formed by the laryngeal mucosa and M. diverticuli laryngei, is positioned caudo-ventral to the laryngeal vestibule. The mucosa thickens into a fold medial to the vocal processes of the arytenoid cartilages. Experiments with airflow combined with histological and anatomical evidence strongly suggest a sound producing function for these (vocal) folds. This analysis provides the first account of sound producing structures and function in bowhead whales.

Metal Levels in Southern Right Whales (Eubalaena australis) from Península Valdés, Argentina.

Península Valdes, Argentina, is a nursing ground for a population of southern right whales (Eubalaena australis). In the last two decades this area has been subjected to an increase in population, tourism and industrial growth. This has raised the concern for exposure to chemical contaminants such as metals. In this study we measured nonessential metals (Ag, Al, As, Au, Ba, Be, Co, Cd, Cr, Hg, Li, Ni, Pb, Sb, Sn, Sr, U and Ti), essential metals (Cu, Fe, Mg, Mn, Mo and Zn) and an essential element (Se) in skin biopsies from female southern right whales (n=10). This is the first report on tissue concentrations of metals in adult southern right whales. Overall, tissue values were on the low end of the spectrum and similar to the values reported in studies of mysticetes from other regions. Measured values do not reflect substantial amounts of accumulation and thus serve as a baseline.

Application of a novel method for age estimation of a baleen whale and a porpoise

AbstractEyeballs from 121 fin whales (Balaenoptera physalus) and 83 harbor porpoises (Phocoena phocoena) were used for age estimation using the aspartic acid racemization (AAR) technique. The racemization rate (kAsp) for fin whales was established from 15 fetuses (age 0) and 15 adult whales where age was estimated by reading growth layer groups (GLGs) in the earplugs. The (kAsp) for harbor porpoises was derived from 15 porpoises (two calves and 13 &gt; 1 yr old) age‐estimated by counting GLGs in the teeth and two calves classified to age based on length. The (kAsp) values were estimated by regression of GLGs against D/L ratios. For the fin whales an (kAsp) of 1.15 × 10−3/yr (SE ± 0.00005) and a D/L ratio at birth [(D/L)0] of 0.028 (SE ± 0.0012) were estimated, which is in agreement with rates for other mysticeti. For the harbor porpoises a (kAsp) of 3.10 × 10−3/yr (SE ± 0.0004) and a (D/L)0 value of 0.023 (SE ± 0.0018) were estimated, which is considerably higher than found for other cetaceans. Correlation between chosen age estimates from AAR and GLG counts indicated that AAR might be an alternative method for estimating age in marine mammals.

Registros de enredamentos de baleias-franca, Eubalaena australis (CETACEA, MISTICETI), na temporada reprodutiva de 2010, em Santa Catarina, Brasil doi: 10.5007/2175-7925.2011v24n2p109

Entanglements of right whales, Eubalaena australis (Cetacea, Mysticeti), in the 2010 breeding season in Santa Catarina state, Brazil. Right whales (Eubalaena australis) have been suffering with anthropogenic grows each breeding season on the southern coast of Santa Catarina state, and can cause strands and even death. During the 2010 breeding season, six entanglements among immature and adult whales were recorded. In most of the cases, the whales kept swimming slowly and didn’t want to approximate the whale watching boat. and injuries to the whales.

Recognition of killer whale individuals from multiple stereotyped call types.

Recognition of marine mammal individuals will be an essential tool for obtaining demographic information of populations as habitat monitoring is increasingly being conducted with passive acoustics. Our previous research established the potential to identify killer whale individuals with passive acoustic recordings with up to 78% accuracy. The data for this result consisted of 75 vocalizations from four adult (two male, two female) killer whales of Icelandic origin in residence at SeaWorld San Diego. The stereotyped vocalizations used were all SD1a or SD1b, and caller identification was known to a high degree of certainty allowing for quantifiable validation. Classification was performed with 12 mel-frequency cepstral coefficients, and 12 delta and 12 delta-delta cepstral coefficients as inputs to a Gaussian mixture model. We initially chose to use one call type as the SD1 call was frequently produced by all four individuals and it eliminated potential ambiguity from identifying call type instead of individual. In the research we now present, we extend our prior methods to be used with multiple call types. Because individuals in the wild will not have a known frequency of call type usage, we propose a normalization method for training a classifier that is unbiased with respect to call-type frequency.

Observations of Humpback Whales, Megaptera novaeangliae, in the Beaufort Sea, Alaska

Humpback Whales, Megaptera novaeangliae, are found in all of the world’s oceans (Reeves and others 2002). Humpback Whales, however, have generally not been found in the Arctic Ocean with the exception of the Barents Sea where warmer waters from the North Atlantic Drift provide rich nutrients for food resources, and ice free zones in the summer (Zabavnikov and others 2005). In the North Pacific, Asian stocks of Humpback Whales summer in the eastern Bering Sea, with some individuals occasionally entering the Arctic Ocean via the Bering Strait and summering along the Siberian coast of the Chukchi Sea (Tomilin 1937; Sleptsov 1961; Johnson and Wolman 1984; Angliss and Allen 2008). Further penetration into the Arctic Ocean, especially into the Beaufort Sea, has probably been prevented by the whales’ natural avoidance of colder waters and associated polar pack ice (Chittleborough 1965; Dawbin 1966). We report on the 1st confirmed sighting of Humpback Whales for the Beaufort Sea, Alaska. During August 2007, FEX LP contracted Agvik Marine LLC to barge oil drilling equipment from Cape Simpson to West Dock (Prudhoe Bay), Alaska, as part of a demobilization of onshore drilling activities conducted the previous 2 winters. On 1 August 2007, at UTM 454911E, 7879755N (WGS84) (about 87 km east of Point Barrow), KAH observed a whale at about 250 m from the barge, and initially identified the individual as a Humpback Whale based on the unique characteristics of the dorsal fin and flukes, and characteristic arching back. Five minutes later the same whale (presumably) approached to within about 75 m of the barge where it was photographed (Fig. 1) and confirmed by BA, an experienced Inupiat hunter, to be a Humpback Whale. During this close encounter, the whale turned on its side revealing the characteristic long pectoral flipper. At this time KAH and the barge’s captain observed a calf with the adult whale. The adult was last seen about 3 min later about 175 m from the barge, slowly traveling to the east. No photographs were taken of the calf or the undersides of the adult’s flukes. At the time of the encounter, the sea state was a Beaufort 3 (large wavelets with occasional whitecaps), the wind was from the east at 10 knots (about 19 km/hr), and visibility was excellent. The barge, hampered by the loss of an outboard engine, was reduced to traveling at ,6 km/hr. Other than approaching the barge, the whales showed no undue reaction to the vessel. Although adult whales were sighted at 3 locations during an 8-min period, we could not positively ascertain whether more than 1 adult whale was present. We believe that we observed only a single cow/calf pair, although it was possible some of the sightings were of an additional Humpback Whale. Further, 2 Gray Whales (Eschrichtius robustus) were observed minutes before the 1st Humpback Whale sighting. While an extralimital sighting of a Humpback Whale in the Beaufort Sea is unusual in itself, the presence of a calf is particularly noteworthy. Based on limited understanding of whales in the North Pacific, it is possible that the whales we observed were part of the Western North Pacific stock that breeds in Asian waters, especially near the Mariana, Ryukyu, and Bonin islands, and summers in the Bering Sea; although the Central North Pacific stock, which breeds among the Hawaiian Islands (Angliss and Allen 2008), may also summer in portions of the Bering Sea. Regardless of origin (Asia or NORTHWESTERN NATURALIST 90:160–162 AUTUMN 2009 160 NORTHWESTERN NATURALIST 90(2)

Concentrations of Organotin Compounds in the Stranded Killer Whales from Rausu, Hokkaido, Japan

We measured the concentrations of butyltin (BT) and phenyltin (PT) compounds in blubber, liver, lung, and muscle of seven stranded killer whales (Orcinus orca) collected from Rausu, Hokkaido, Japan. BTs in blubber (n = 6), liver (n = 4), lung (n = 1), and muscle (n = 4) of adult whale were in the range of 37-90, 385-676, 15, and 26-53 microg kg(-1) wet weight, respectively. Concentrations of PTs in blubber, liver, lung, and muscle were <1 to 58, <1 to 14, 7 and <1 to 4 microg kg(-1) wet weight, respectively. Detected frequencies of PTs were low in all tissues. Higher percentages of monobutyltin (MBT) in blubber, lung, and muscle were observed, while the percentage of dibutyltin (DBT) was high in liver. Detected frequencies of triphenyltin (TPT) were highest among tissues. Total BT concentrations in blubber and liver of a whale calf were lower than those in adult whales. MBT and DBT in the liver of the calf were the same (42%). MBT in blubber was the dominant compound among BTs.

Serum thyroid hormone concentrations and thyroid histomorphology as biomarkers in bowhead whales (Balaena mysticetus)

Serum thyroid hormone (TH) concentrations have been used alone or with other measurements to assess health status or effects of toxicant exposure in marine mammals. Histological sections from thyroid glands of the bowhead whale ( Balaena mysticetus L., 1758) were examined in conjunction with serological TH analyses. Serum was assayed for total and free triiodothyronine and total and free thyroxine via radioimmunoassay. Histomorphology of thyroid tissue was assessed by light microscopy and the utilization of an epithelial-follicular index (EFI). Age, sex, or season did not significantly affect serum TH levels. However, TH concentrations in pregnant or lactating females were found to be significantly lower than in the other sex and reproductive groups investigated. The EFI and epithelial height (EH) were greater in spring subadult and adult whales compared with those that were landed in the fall. No correlation was found between serum TH concentrations and serum, blubber, or liver levels of select polychlorinated biphenyl metabolites and organochlorine congeners examined. Low variability in concentrations of the serum THs across age, season, and sex and reproductive groups supports the existence of strong homeostatic mechanisms for maintaining TH concentrations in these presumably healthy animals. Departures from these ranges may indicate a disturbance in these regulatory mechanisms and may be a useful indication of toxicity or other health disorders.

Temporal pattern of humpback whale (Megaptera novaeangliae) group structure around Abrolhos Archipelago breeding region, Bahia, Brazil

To characterize temporal patterns of humpback group structure around Abrolhos Archipelago, Brazil, seven years (1998–2004) of data obtained from July through November were analysed. During one-hour scans, observers determined group composition within 9.3 km around a land-based station. A total of 930 scans, comprising 4288 groups were analysed. Seven group categories were identified and their frequencies were 14.6% of 1AD (lone whale), 25.2% of DYAD (two adult whales), 7.3% of TRIO (three adult whales), 5.2 of TRIO+ (more than three adults), 24.9% of MOC (mother and calf), 19.6% of MOCE (mother, calf and one escort), and 3.1% of MOCE+ (mother, calf and more than one escort). Proportions of whale-group categories did not change between morning and afternoon, nor among years. However, as the season progressed, groups with calves increased while groups without calves decreased. This progression may be explained by the segregated migration patterns of humpback whales and also by changes in the social status of individuals. The Abrolhos Reef provides protection from the prevailing winds, which may explain the higher proportion of groups with calves in the area.

Attempt at Intracytoplasmic Sperm Injection of In Vitro Matured Oocytes in Common Minke Whales (Balaenoptera acutorostrata) Captured During the Kushiro Coast Survey

The present study was conducted during the Kushiro Coast Survey in an attempt to produce common minke whale embryos. In Experiment 1, we attempted to determine the appropriate culture duration (30 or 40 h) for in vitro maturation (IVM) of immature oocytes using the Well of the Well method. In Experiment 2, and intracytoplasmic sperm injection (ICSI) was applied to matured oocytes from prepubertal and adult common minke whales after IVM culture (40 or 48 h), and then their embryonic development was assessed. In Experiment 1, the maturation rate of oocytes cultured for 40 h (30.4%) was significantly higher than that of oocytes cultured for 30 h (6.8%; P<0.01). In Experiment 2, a total of 35 and 46 immature oocytes derived from adult (n=2) and prepubertal (n=6) minke whales, respectively, were cultured for 40 or 48 h. The maturation rate in the oocytes from the adult whales (34.2%) tended to be higher than that of the oocytes from the prepubertal whales (19.6%), but there was no significant difference. Following ICSI, 3 out of the 10 inseminated and cultured oocytes from the adult whales cleaved (2-, 8-, and 16-cell stages); all of these oocytes had been matured for 40 in culture. However, these oocytes did not develop to further stages. Only one of the 6 oocytes derived from the prepubertal whales, IVM cultured for 40 h and inseminated, developed to the 4-cell stage. The present results indicate that a 40 h IVM culture produces significantly higher rates of in vitro maturation than a 30 h IVM culture for common minke whale oocytes. Following ICSI, some oocytes cleaved to the 16-cell stage, but no further development was observed.

Occurrence of a herd of female sperm whales and their calves (Physeter catodon), off Monaco, in the Ligurian Sea

A herd of female sperm whales with calves was observed for the first time off the coast of Monaco in mid December 2001. The herd was composed of more than ten animals: the adults were foraging; the calves were resting. The adult whales measured less than 12 m in length and the calves were estimated to be 5 m. This occurrence is discussed.

Transfer of fatty acids from mothers to their calves during lactation in white whales Delphinapterus leucas

Blubber biopsies, through the entire blubber layer, were collected from the members of 4 mother-calf pairs of white whales Delphinapterus leucas from Storfjorden, Svalbard, Norway. In addition, milk samples were collected from all 4 adult females. The calves ranged in age/size from newborn (with the umbilical cord still attached; 140 cm in length) up to a 1 yr old (body length of 255 cm). Since white whale calves consume only milk during their first year of life, free-living mother-calf pairs provide an interesting opportunity to study the deposition of lipids (calf blubber) when the diet (i.e. milk) is known precisely. The blubber of the newborn calves had fatty-acid (FA) compositions that differed significantly from the FA compositions of both the milk and the blubber of their respective mothers. The FA composition of the blubber of calves changed gradually with age, coming to resemble the FA composition of the blubber of their mothers more closely, rather than shift- ing towards the FA composition of the milk, i.e. their diet. The largest calf in the study had a blubber FA composition similar to that of the adult whales. Analyses also showed that the FA composition of the milk was significantly different from the FA composition of the maternal blubber.

Comparative Studies on Lipid Analysis and Ultrastructure in Porcine and Southern Minke Whale (Balaenoptera Bonaerensis) Oocytes

The present study was conducted to clarify the difference in the color of the cytoplasm in immature follicular oocytes from prepubertal and adult minke whales. The four lipid contents (triglyceride, total cholesterol, phospholipids and non-esterified fatty acids) in vitrified immature oocytes from prepubertal and adult minke whales, and also in fresh and vitrified immature porcine oocytes, were measured. The lipid contents in vitrified-warmed minke whale oocytes were similarly high compared with those in vitrified-warmed porcine oocytes. In particular, the total cholesterol and phospholipid contents in the vitrified immature oocytes from prepubertal and adult minke whales were significantly (P<0.05) higher than those from prepubertal pigs. Furthermore, the distribution of lipid droplets in fresh and vitrified immature oocytes was observed in transmission electron microscopy. Lipid droplets in the prepubertal minke whale oocytes were distributed throughout the cytoplasm. In contrast, adult minke whales had larger lipid droplets which were distributed mainly in the central portion of the cytoplasm. The lipid droplets of immature oocytes from prepubertal pigs were larger than those in minke whale oocytes. These results indicated that the difference in the distribution of the cytoplasmic lipid droplets may result in the difference in the color tone of both prepubertal and adult whale oocyte cytoplasm.

Levels and probable origin of predatory scarring on humpback whales (Megaptera novaeangliae) in east Australian waters

To investigate the incidence of non-lethal predation in Southern Hemisphere whales, more than 3400 fluke-identification photographs from resight histories of 1436 east Australian humpback whales were examined for evidence of predatory markings. Photographs were obtained from 1984 to 1996 at various locations along the east coast of Australia, from northern Queensland to southern New South Wales. Photographs were classified in terms of the level and type of scarring. The possible predator and whether the markings appeared fresh were also noted. In all, 17% of identified east Australian humpbacks possessed some form of predatory scarring, 57% of which was minor and 43% major. Almost all predatory scarring was consistent with that inflicted by killer whales. Only three whales demonstrated an increase in the level of predatory scarring after their first sightings. Two incidents of fresh scarring were recorded, and one fatal killer whale attack on a humpback whale calf was directly observed. The overall level of predatory scarring found in this study is comparable to those found in studies for Northern Hemisphere humpback whales. The low incidence of adult whales showing their first sign of predatory scarring after their initial sighting, and the small number possessing recent scarring, support the idea that east Australian humpback whales experience most predatory attacks early in life.