THREE MASS STRANDINGS OF SPERM WHALES (PHYSETER MACROCEPHALUS) IN SOUTHERN AUSTRALIAN WATERS

One hundred and fifteen sperm whales (97 female, 15 male, 3 unknown sex) were involved in three mass stranding events during the month of February 1998 along the west and northwest coastlines of Tasmania, Australia. Sixty-six of these whales stranded at Ocean Beach, Strahan; 35 at Greens Beach, Marrawah; and 11 at Black River Beach, Stanley. The remaining whales stranded singly along the coastline. Three mass strandings of this species in such close temporal proximity have not been reported in this area before, and this is the first time that data have been comprehensively collected from complete or near-complete groups of sperm whales from Tasmanian waters. Adult females dominated the three stranding groups. Total lengths ranged from 417 to 1,200 cm and ages ranged from 0.75 to 64 yr. Four females were lactating and four fetuses were found amongst the groups. Stomach contents were dominated by pelagic cephalopods.     

AN ASSESSMENT OF CHANGES WITH TIME IN THE MARKING PATTERNS USED FOR PHOTOIDENTIFICATION OF INDIVIDUAL SPERM WHALES, PHYSETER MACROCEPHALUS

We observed changes with time in the patterns of characteristic fluke markings used to identify sperm whales. Changes were categorized as minor, moderate, or major based on their severity. These change types were found to occur at rates of 0.9%, 11.8%, and 1.3% per individual per year, respectively. Gain and loss rates for each of seven different mark types were also calculated. The highest estimated rate was the gain of small nicks at 0.08 per individual per year. Most individuals identified by us possess at least a few characteristic marks and, therefore, changes of the type observed in this study are unlikely to severely affect their recognizability. For all but one mark type, gain rates were higher than loss rates, indicating that individuals may be accumulating marks with age. Over long periods this could eventually make individuals unrecognizable, with the result that population sizes calculated from these data may be overestimated. As long as photoidentification studies are conducted sufficiently often, and these changes are as gradual as they appear to be, this problem should be minimal.     

THE DIET OF GALÁPAGOS SPERM WHALES PHYSETER MACROCEPHALUS AS INDICATED BY FECAL SAMPLE ANALYSIS

Fecal samples were collected while following sperm whales ( Physeter macrocephalus ) off the Galápagos Islands, Ecuador. They contained 133 upper beaks and 164 lower beaks of cephalopods. Analysis of the lower beaks suggests that the sperm whales fed primarily on three genera of cephalopods; Histioteutbis (62%), Ancistrocbeirus (16%), and Octopoteutbis (7%). The beak dimensions indicate that the cephalopods ranged in mantle length from 5 to 54 cm and in mass from 12 to 650 g. Fecal samples varied significantly between five study years and over different parts of the study area, but the number of beaks collected per sample did not correlate significantly with defecation rate (a measure of feeding success). Using beak material from fecal samples gives a biased estimate of sperm whale diet, reducing the frequencies of very small and very large cephalopods. However, all other available methods of assessing sperm whale diet also possess biases.     

PATTERN SIMILARITY IN SHARED CODAS FROM SPERM WHALES (PHYSETER CATODON)

Abstract: Codas (patterned click sequences) produced by sperm whales ( Physeter catodon ) were recorded during four research cruises in the southeast Caribbean. Two coda patterns comprised more than 50% of the codas analyzed from 46 h of recording. These two patterns were called "shared" codas because they were produced by numerous whales throughout the area, both as repeated sequences by individual whales, at times simultaneously by two or more whales, and occasionally in overlapping series. Analyses of both the absolute timing and the relative timing of click intervals indicate equivalent variability in the temporal patterns of similar shared codas, whether produced by the same or different whales. The shared codas appear to have a function that is different from individual identification as hypothesized previously for some coda patterns.     

SEASONAL OCCURRENCE OF SPERM WHALE (PHYSETER MACROCEPHALUS) SOUNDS IN THE GULF OF ALASKA, 1999–2001

An acoustic survey for sperm whales was conducted in the Gulf of Alaska. Six autonomous hydrophones continuously recorded sound signals below 500 Hz from October 1999 to May 2001. After recovery, recordings were processed using an automatic process to detect usual clicks of sperm whales. The detection algorithm equalized background noise, summed the data in a frequency band, and then used autocorrelation to detect the whales' highly regular clicks. Detections were checked manually, revealing that 98% of detections did contain clicks. Results indicate that sperm whales are present in the Gulf of Alaska year-round; this result extends what is known from whaling data, which were gathered principally in summer. Sperm whales were more common in summer than winter by a factor of roughly two, and occurred less often at the westernmost site surveyed (52°N, 157°W) than elsewhere in the Gulf. This is the first study of sperm whales based exclusively on remote acoustic sensing. This methodology is feasible because sperm whale clicks extend to frequencies (∼100 Hz) low enough to be recorded by low-sample-rate instruments that operate continuously, and because the detection algorithm has a low false-detection rate. The methodology may be replicated to facilitate comparisons between different time periods and geographic regions.     

CHARACTERIZATION OF BEAKED WHALE (ZIPHIIDAE) AND SPERM WHALE (PHYSETER MACROCEPHALUS) SUMMER HABITAT IN SHELF-EDGE AND DEEPER WATERS OFF THE NORTHEAST U. S.

Sperm whales ( Physeter macrocephalus ) and beaked whales ( Mesoplodon spp. and Ziphius cavirostris ) are deep-diving cetaceans that frequent shelf-edge and Gulf Stream waters off the northeast U. S. coast. Sighting data collected during seven summer (1990, 1991, 1993, and 1995–1998) shipboard surveys were analyzed using a geographic information system to determine habitat use based on bathymetric and oceanographic features. Although sighting rates were lower for beaked whales, both taxa occupied similar habitats. Beaked whales were concentrated at the colder shelf edge, whereas sperm whales were associated with warmer off-shelf water. Mean sighting rates for both taxa were higher in canyon features, but only beaked whale sighting rates were significantly different between canyon and non-canyon habitat (Wilcoxon signed rank test P = 0.007). Within the shared habitat, the two taxa were separated at fine-scale based on oceanographic features.     

SPERM WHALES TAGGED WITH TRANSPONDERS AND TRACKED UNDERWATER BY SONAR

Abstract: Two sperm whales tagged with acoustic transponder tags were tracked by sonar during a cruise from 16 to 30 October 1991 in the southeast Caribbean west of Dominica Island. The whales dove to depths of 400–600 m and more, including a dive to 1,185 m and one possibly to 2,000 m. They were tracked for periods of 3–14 h, over distances of 8.5–40 km. The tagged whales were found together four and eight days after tagging, and were tracked simultaneously for 13 h, over 31 km. Whale movements on different days at the surface averaged from 0.68 to 0.82 m/set, with dive descent rates from 0.82 to 1.13 m/set, ascent rates from 0.74 to 1.16 m/set, and horizontal movement during dives from 0.76 to 1.29 m/set. Dives lasted from 18 min to 1 h and 13 min, averaging 33 and 41 min on different days. Every track ended when tag signals became obscured at night by dense biological scatterers concentrated in offshore areas where the whales were diving. Both tagged whales appear to have been males of 15 and 11m, each dominant in different groups; but when together the larger whale was dominant, as evidenced by chases and agonistic vocalizations. The whales did not appear to react to the tags or to the sounds associated with tracking (30, 32, and 36 kHz).     

BILIARY BILE ACID COMPOSITION OF THE PHYSETERIDAE (SPERM WHALES)

Abstract: The bile acid composition of bile obtained from the hepatopancreatic ducts of three species of sperm whales (Cetacea: Physeteridae) was investigated. Bile acids were isolated by adsorption chromatography and analyzed by sequential HPLC, SIMS, and GLC-MS. In each species the dominant bile acids were deoxycholic acid (a secondary bile acid formed by bacterial 7α-dehydroxylation of cholic acid), and chenodeoxycholic acid (a primary bile acid) which together composed more than 86% of biliary bile acids in all three species. In Physeter catodon (sperm whale) deoxycholic acid constituted 79%, and in Kogia breviceps (pygmy sperm whale) it was 61% of biliary bile acids. The sperm whale, which differs from other whales in having a remnant of a large intestine, is the second mammal identified to date in which deoxycholic acid is the predominant bile acid. The high proportion of deoxycholic acid indicates that in the Physeteridae, anaerobic fermentation occurs in its cecum, and that bile acids undergo enterohepatic cycling. Also found were minor proportions of cholic acid, as well as bacterial derivatives of chenodeoxycholic acid (ursodeoxycholic acid, lithocholic acid, and the 12β-epimer of allo-deoxycholic acid). Bile acids were conjugated with taurine in all species; however, in the sperm whale ( Physeter ) glycine conjugates were present in trace proportions. The bile acid hydroxylation pattern (12α- but not 6α-hydroxylation), lack of primary 5α- (allo) bile acids, and presence of glycine conjugated bile acids suggests the possibility that sperm whales originated from ancient artiodactyls.     

THE MICROSCOPIC AND IMMUNOHISTOLOGIC ANATOMY OF THE ENDOCRINE PANCREAS OF PYGMY AND DWARF SPERM WHALES (KOGIIDAE)

Histologic studies of pancreatic tissues of one pygmy sperm whale, Kiogia breviceps , and one dwarf sperm whale, K. simus , demonstrated rather typical exocrine pancreatic anatomy. Peroxidase-antiperoxidase (PAP) techniques determined that the cell composition of the islets of Langerhans resembled that of other mammals. Within islets, cells secreting insulin (B-cells) and glucagon (A-cells), were clearly demonstrated, but, surprisingly, isolated A- and B-cells were also found among pancreatic acinar cells. PAP techniques demonstrated the presence of neuron-specific enolase within islets, but failed to provide a sufficiently clear reaction to demonstrate the presence of somarostatin-producing D-cells. No positive PAP reaction for serotonin occurred.     

DIETS OF FIN, SEI, AND SPERM WHALES IN BRITISH COLUMBIA: AN ANALYSIS OF COMMERCIAL WHALING RECORDS, 1963–1967

Diets of fin ( Balaenoptera physalus ), sei ( Balaenoptera borealis ), and sperm whales ( Physeter macrocephalus ) were estimated from the stomach contents of individuals killed along the British Columbia coast from 1963 to 1967. The dominant prey types of fin whales were euphausiids, with minor contributions from copepods and fish. Sei whale stomachs contained primarily copepods in three years, whereas euphausiids or a variety of fish dominated the diet in the other two years. Sperm whales consumed primarily North Pacific giant squid ( Moroteuthis robusta ), but secondary prey differed between males and females. Female sperm whales frequently consumed ragfish ( Icosteus spp.) and other fish, whereas the male diet also contained rockfish ( Sebastes spp.). The high abundance of euphausiids along the British Columbia coast likely contributed to the presence of a summer resident population of fin whales. The high abundance of large copepods farther north probably influenced the migration of sei whales through the offshore waters of British Columbia. Sperm whale stomach contents differed by sex reflecting location and possibly breeding behaviors.