Beaked Whale Ziphius Cavirostris Research Articles

Factors associated with the differential distribution of cetaceans linked with deep habitats in the Western Mediterranean Sea

Deep-habitat cetaceans are generally difficult to study, leading to a limited knowledge of their population. This paper assesses the differential distribution patterns of three deep-habitat cetaceans (Sperm whale—Physeter macrocephalus, Risso’s dolphin—Grampus griseus & Cuvier’s beaked whale—Ziphius cavirostris). We used data of 842 opportunistic sightings of cetaceans in the western Mediterranean sea. We inferred environmental and spatio-temporal factors that affect their distribution. Binary logistic regression models were generated to compare the presence of deep-habitat cetaceans with the presence of other cetacean species in the dataset. Then, the favourability function was applied, allowing for comparison between all the models. Sperm whale and Risso’s dolphin presence was differentially favoured by the distance to towns in the eastern part of the western Mediterranean sea. The differential distribution of sperm whale was also influenced by the stability of SST, and that of the Risso’s dolphin by lower mean salinity and higher mean Chlorophyll A concentration. When modelling the three deep-habitat cetaceans (including Cuvier’s beaked whale), the variable distance to towns had a negative influence on the presence of any of them more than it did to other cetaceans, being more favourable far from towns, so this issue should be further investigated.

A Comparative Study of Mini-FLOTAC With Traditional Coprological Techniques in the Analysis of Cetacean Fecal Samples.

Free-ranging cetaceans are considered sentinels for the marine ecosystem's health. New and non-invasive methods have been set up for the collection of fecal samples from free-ranging big whales at sea, permitting to gain an excellent epidemiological picture of parasitic infections in wild populations. To select the best protocol to be used for copromicroscopic examination in cetaceans stool samples, we evaluated the sensitivity of two commonly used techniques, i.e., a sedimentation-floatation method and the Mini-FLOTAC through validation by helminth isolation from the digestive tract. For this aim, gastrointestinal content and fecal samples were collected during necropsy from 44 cetaceans, including bottlenose dolphins (Tursiops truncatus), striped dolphins (Stenella coeruleoalba), sperm whales (Physeter macrocephalus), Risso's dolphins (Grampus griseus), Cuvier's beaked whales (Ziphius cavirostris), pilot whale (Globicephala melas), and fin whales (Balaenoptera physalus). Helminths were recovered through washing and filtering of the gastrointestinal contents and morphologically identified. Copromicroscopic examinations were performed on formalin-preserved fecal samples, using a sodium nitrate, sodium thiosulphate, and sucrose solution (s.g. = 1.450) for both methods. Helminths belonging to 9 taxa (i.e., the trematodes Synthesium tursionis, Synthesium delamurei, Campula palliata, Braunina cordiformis, Pholeter gastrophilus, the nematode Anisakis sp., cestodes of the family Tetrabothriidae and the acanthocephalan Bolbosoma sp.) were isolated. Eggs referable to the same taxa, with the exception of cestodes, were found in copromicroscopic analyses. Sensitivity of the Mini-FLOTAC method appeared higher or equal for all taxa, proving superior to the sedimentation-flotation method for the detection of all except Anisakis sp. The concordance of the two tests indeed revealed a moderate to perfect agreement (kappa values 0.42–1). Not excluding the limitations inherent to the techniques themselves, explanations for false-negative results at copromicroscopy could be linked to parasite-related factors, including prepatent infections, low parasitic burdens, or intermittent egg shedding. Notwithstanding these limitations, this study evidenced that the Mini-FLOTAC protocol approximates more accurately the composition of the gastrointestinal helminthic community of cetaceans from copromicroscopic examination, providing at the same time a quantitative estimation.

Cuvier’s beaked whale foraging dives identified via machine learning using depth and triaxial acceleration

Knowledge of Cuvier’s beaked whale Ziphius cavirostris behavior has expanded through the utilization of animal-borne tags. However, many tag types do not record sound—thus preventing echolocation click detections to identify foraging—or have short deployments that sample a limited range of behaviors. As the quantity of such non-acoustic tag data grows, so too does the need for robust methods of detecting foraging from non-acoustic data. We used 692 dives from 5 sound-recording tags on Cuvier’s beaked whales in southern California, USA, to develop extreme gradient boosting tree models to detect foraging based on 1 Hz depth and 16 Hz triaxial acceleration data. We performed repeated 10-fold cross validation using classification accuracy to tune 500 models with randomly partitioned training and testing datasets. An average of 99.9 and 99.2% of training and testing dataset dives, respectively, were correctly classified across the 500 models. Dives without associated sound recordings (n = 2069 from 7 whales including 4 non-acoustic tags) were classified via a model that maximized training information using dive depth and duration, ascent and descent rates, bottom-phase average vertical speed, and roll circular variance during dive descents and bottom phases. Of all long, deep dives (conventionally assumed to include foraging), 2.4% were classified as non-foraging dives, while 0.3% of short, shallow dives were classified as foraging dives. Results confirm that conventional depth and/or duration classifiers provide reasonable estimates of longer-term foraging patterns. However, additional variables previously listed enhance foraging detections for unusual dives (notably non-foraging deep dives) for southern California Cuvier’s beaked whales.

An acoustic survey of beaked whale distribution at São Tomé and Príncipe, Gulf of Guinea, using an unmanned surface vessel

The first records of beaked whales, including Cuvier’s beaked whale Ziphius cavirostris, are reported from an acoustic baseline survey in the territorial waters of the Democratic Republic of São Tomé and Príncipe, Gulf of Guinea, West Africa. The survey was carried out between late 2018 and early 2019 using an AutoNaut unmanned surface vessel (USV), which is propelled by the motion of waves and operated remotely via a satellite link. The USV towed a hydrophone array on a cable, and over the course of 75 days the USV completed 1 772 km of acoustic survey effort. Beaked whale encounters were not uncommon and occurred on 28 of the 75 survey days. They were widespread on the shelf edge and in oceanic habitats above the abyssal plain. The average water depth at which acoustic detections were recorded was 2 519 (SD 555) m (n = 43). Beaked whales were evenly distributed across areas with different seabed characteristics: the number of encounters recorded in areas characterised by seabed gradient and ruggedness did not differ from that expected after accounting for survey effort. The majority of acoustic detections were attributable to Cuvier’s beaked whales, based on spectral and temporal characteristics of click-train vocalisations. The results provide baseline information on the distribution of beaked whales and suggest that passive acoustic methods using a small USV are well-suited to surveys of this species group, possibly because beaked whales, which are sensitive to disturbance associated with underwater sound sources, are less likely to avoid small, quiet vessels than larger vessels.

Cetacean strandings along the Pacific and Caribbean coasts of Nicaragua from 2014 to 2021

Documenting marine mammal strandings provides important information needed to understand the occurrence and distribution patterns of species. Here, we report on strandings of cetaceans on the Pacific (n = 11) and Caribbean (n = 2) coasts of Nicaragua, documented opportunistically from 2014 to 2021. Strandings included three species of baleen whale (blue whale Balaenoptera musculus, Bryde’s whale Balaenoptera edeni, humpback whale Megaptera novaeangliae) and five species of toothed whale (dwarf sperm whale Kogia sima, Guiana dolphin Sotalia guianensis, pantropical spotted dolphin Stenella attenuata, spinner dolphin Stenella longirostris, Cuvier’s beaked whale Ziphius cavirostris). These are the first published accounts of blue whales, Bryde’s whales, dwarf sperm whales, and Cuvier’s beaked whales in Nicaraguan waters. Limited resources and the advanced decomposition of animals prevented necropsies in most cases, the identification of the causes of mortality in all cases, and the species identification of two dolphins. Information derived from these stranding events offers new insights into the occurrence of marine mammals on the Pacific and Caribbean coasts of Nicaragua and Central America.

Causes of cetacean stranding and death on the Catalonian coast (western Mediterranean Sea), 2012-2019.

The causes of cetacean stranding and death along the Catalan coast between 2012 and 2019 were systematically investigated. Necropsies and detailed pathological investigations were performed on 89 well-preserved stranded cetaceans, including 72 striped dolphins Stenella coeruleoalba, 9 Risso's dolphins Grampus griseus, 5 bottlenose dolphins Tursiops truncatus, 1 common dolphin Delphinus delphis, 1 Cuvier's beaked whale Ziphius cavirostris and 1 fin whale Balaenoptera physalus. The cause of death was determined for 89.9% of the stranded cetaceans. Fisheries interaction was the most frequent cause of death in striped dolphins (27.8%) and bottlenose dolphins (60%). Cetacean morbillivirus (CeMV) was detected on the Catalan coast from 2016 to 2017, causing systemic disease and death in 8 of the 72 (11.1%) striped dolphins. Chronic CeMV infection of the central nervous system was observed from 2018-2019 in a further 5 striped dolphins. Thus, acute and chronic CeMV disease caused mortality in 18% of striped dolphins and 14.6% of all 89 cetaceans. Brucella ceti was isolated in 6 striped dolphins and 1 bottlenose dolphin with typical brucellosis lesions and in 1 striped dolphin with systemic CeMV. Sinusitis due to severe infestation by the nematode parasite Crassicauda grampicola caused the death of 4 out of 6 adult Risso's dolphins. Maternal separation, in some cases complicated with septicemia, was a frequent cause of death in 13 of 14 calves. Other less common causes of death were encephalomalacia of unknown origin, septicemia, peritonitis due to gastric perforation by parasites and hepatitis caused by Sarcocystis spp.

Ingestion of macroplastics by odontocetes of the Greek Seas, Eastern Mediterranean: Often deadly!

Plastic pollution is an omnipresent problem that threatens marine animals through ingestion and entanglement. Marine mammals are no exception to this rule but their interaction with plastic remains understudied in the Mediterranean Sea. Here we highlight this problem by analyzing the stomach contents of 34 individuals from seven odontocete species stranded in Greece. Macroplastic (>5 mm) was found in the stomachs of nine individuals from four species (harbour porpoise Phocoena phocoena, Risso's dolphin Grampus griseus, Cuvier's beaked whale Ziphius cavirostris and sperm whale Physeter macrocephalus) with the highest frequency of occurrence in sperm whales (60%). Gastric blockage from plastic was presumably lethal in three cases, with plastic bags being the most common finding (46%). Plastic ingestion is of particular conservation concern for the endangered Mediterranean sperm whales. A regular examination of stranded cetaceans with a standardised protocol is critical for allowing spatiotemporal comparisons within and across species.

Taxonomic status and epidemiology of the mesoparasitic copepod Pennella balaenoptera in cetaceans from the western Mediterranean.

Pennella balaenoptera is a mesoparasitic copepod that has been reported in at least 17 cetacean species. Subtle morphological differences in the first antennae of adult females have been used to discriminate this species from P. filosa, a species infecting fishes. Other morphological traits are unreliable because of their high plasticity, and no molecular data are available to confirm the taxonomic status of P. balaenoptera as an independent species. We found no consistent morphological differences of the first antennae between P. balaenoptera and P. filosa collected from cetaceans and fish in the western Mediterranean. Molecular data on the mitochondrial cytochrome oxidase subunit I failed to show reciprocal monophyly for the 2 species, and nucleotide divergence between them was low (mean ± SD [range]: 4.1 ± 0.006% [0.5-8.9]). Thus, P. balaenoptera and P. filosa are considered conspecific. We also obtained data on infection parameters of P. balaenoptera based on 450 individuals of 6 cetacean species stranded on the Spanish Mediterranean coast between 1980 and 2017. Prevalence was significantly lowest in the most coastal species, the bottlenose dolphin Tursiops truncatus (3.6%) and highest in the most oceanic species, Cuvier's beaked whale Ziphius cavirostris (100%). This suggests that the life cycle of P. balaenoptera is primarily oceanic. Interestingly, P. filosa also occurs in the oceanic realm infecting large fishes. This ecological similarity further supports the hypothesis that P. balaenoptera and P. filosa are conspecific.

Physiological, morphological, and ecological tradeoffs influence vertical habitat use of deep-diving toothed-whales in the Bahamas.

Dive capacity among toothed whales (suborder: Odontoceti) has been shown to generally increase with body mass in a relationship closely linked to the allometric scaling of metabolic rates. However, two odontocete species tagged in this study, the Blainville’s beaked whale Mesoplodon densirostris and the Cuvier’s beaked whale Ziphius cavirostris, confounded expectations of a simple allometric relationship, with exceptionally long (mean: 46.1 min & 65.4 min) and deep dives (mean: 1129 m & 1179 m), and comparatively small body masses (med.: 842.9 kg & 1556.7 kg). These two species also exhibited exceptionally long recovery periods between successive deep dives, or inter-deep-dive intervals (M. densirostris: med. 62 min; Z. cavirostris: med. 68 min). We examined competing hypotheses to explain observed patterns of vertical habitat use based on body mass, oxygen binding protein concentrations, and inter-deep-dive intervals in an assemblage of five sympatric toothed whales species in the Bahamas. Hypotheses were evaluated using dive data from satellite tags attached to the two beaked whales (M. densirostris, n = 12; Z. cavirostris, n = 7), as well as melon-headed whales Peponocephala electra (n = 13), short-finned pilot whales Globicephala macrorhynchus (n = 15), and sperm whales Physeter macrocephalus (n = 27). Body mass and myoglobin concentration together explained only 36% of the variance in maximum dive durations. The inclusion of inter-deep-dive intervals, substantially improved model fits (R2 = 0.92). This finding supported a hypothesis that beaked whales extend foraging dives by exceeding aerobic dive limits, with the extension of inter-deep-dive intervals corresponding to metabolism of accumulated lactic acid. This inference points to intriguing tradeoffs between body size, access to prey in different depth strata, and time allocation within dive cycles. These tradeoffs and resulting differences in habitat use have important implications for spatial distribution patterns, and relative vulnerabilities to anthropogenic impacts.

Nowhere to go: noise impact assessments for marine mammal populations with high site fidelity

ESR Endangered Species Research Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials ESR 32:391-413 (2017) - DOI: https://doi.org/10.3354/esr00820 Theme Section: 21st century paradigms for measuring and managing the effects of anthropogenic ocean noise Nowhere to go: noise impact assessments for marine mammal populations with high site fidelity Karin A. Forney1,*, Brandon L. Southall2,3,4, Elisabeth Slooten5, Steve Dawson6, Andrew J. Read4, Robin W. Baird7, Robert L. Brownell Jr.8 1Marine Mammal and Turtle Division, Southwest Fisheries Science Center, National Marine Fisheries Service, NOAA, c/o MLML Norte, 7544 Sandholdt Rd, Moss Landing, CA 95039, USA 2Southall Environmental Associates, Inc., 9099 Soquel Dr, Suite 8, Aptos, CA 95003, USA 3University of California, Institute of Marine Science, Long Marine Laboratory, 100 McAllister Way, Santa Cruz, CA 95060, USA 4Nicholas School of the Environment, Duke University, 135 Duke Marine Lab Rd, Beaufort, NC 28516, USA 5Department of Zoology, University of Otago, PO Box 56, Dunedin, 9054, New Zealand 6Department of Marine Science, University of Otago, PO Box 56, Dunedin, 9016, New Zealand 7Cascadia Research Collective, 218 1/2 4th Ave W, Olympia, WA 98501, USA 8Southwest Fisheries Science Center, National Marine Fisheries Service, NOAA, 34500 Highway 1, Monterey, CA 93940, USA *Corresponding author: karin.forney@noaa.gov ABSTRACT: As awareness of the effects of anthropogenic noise on marine mammals has grown, research has broadened from evaluating physiological responses, including injury and mortality, to considering effects on behavior and acoustic communication. Most mitigation efforts attempt to minimize injury by enabling animals to move away as noise levels are increased gradually. Recent experiences demonstrate that this approach is inadequate or even counterproductive for small, localized marine mammal populations, for which displacement of animals may itself cause harm. Seismic surveys within the ranges of harbor porpoise Phocoena phocoena in California and Māui dolphin Cephalorhynchus hectori maui in New Zealand highlight the need to explicitly consider biological risks posed by displacement during survey planning, monitoring, and mitigation. Consequences of displacement are poorly understood, but likely include increased stress and reduced foraging success, with associated effects on survival and reproduction. In some cases, such as the Critically Endangered Māui dolphin, displacement by seismic activities risks exposing the remaining 55 dolphins to bycatch in nearby fisheries. Similar concerns about military and industrial activities exist for island-associated species such as melon-headed whales Peponocephala electra in Hawai'i; shelf-break associated species such as Cuvier’s beaked whales Ziphius cavirostris off the US Atlantic coast, and whales foraging in coastal habitats, such as the Critically Endangered western gray whale Eschrichtius robustus. We present an expanded framework for considering disturbance effects that acknowledges scientific uncertainty, providing managers and operators a more robust means of assessing and avoiding potential harm associated with both displacement and direct effects of intense anthropogenic noise exposure. KEY WORDS: Anthropogenic noise · Marine mammals · Impact assessment · Mitigation · Monitoring · Small populations Full text in pdf format PreviousNextCite this article as: Forney KA, Southall BL, Slooten E, Dawson S, Read AJ, Baird RW, Brownell RL Jr (2017) Nowhere to go: noise impact assessments for marine mammal populations with high site fidelity. Endang Species Res 32:391-413. https://doi.org/10.3354/esr00820 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in ESR Vol. 32. Online publication date: May 08, 2017 Print ISSN: 1863-5407; Online ISSN: 1613-4796 Copyright © 2017 Inter-Research.

Strandings of Beaked Whales (Ziphiidae) in Galicia (NW Spain) between 1990 and 2013

In the coast of Galicia an average of 200 stranded cetaceans are reported annually. From 1990 to 2013, 21 individuals of four species of the family Ziphiidae were found: 15 Cuvier's beaked whales (Ziphius cavirostris), two Sowerby's beaked whales (Mesoplodon bidens), one True's beaked whale (Mesoplodon mirus) and one Blainville's beaked whale (Mesoplodon densirostris), as well as two unidentified ones. These were the first records in Galicia for True's beaked whale and Blainville's beaked whale. The study of the distribution of oceanic species considering only stranded animals has limitations, but is a good approach to this not well-known cetacean family. Due to the small number of individuals of the different species, statistical analyses for geographic or seasonal patterns were only carried out for the Cuvier's beaked whales. Between the periods of 1990–2002 and 2003–2013 significant differences were found for geographic and seasonal occurrence patterns. Over the last decade strandings were located only in the north area of the region, mainly during the spring season, while in the previous decade they were located along the three considered areas and only in autumn and winter.

Trackline and point detection probabilities for acoustic surveys of Cuvier's and Blainville's beaked whales

Acoustic survey methods can be used to estimate density and abundance using sounds produced by cetaceans and detected using hydrophones if the probability of detection can be estimated. For passive acoustic surveys, probability of detection at zero horizontal distance from a sensor, commonly called g(0), depends on the temporal patterns of vocalizations. Methods to estimate g(0) are developed based on the assumption that a beaked whale will be detected if it is producing regular echolocation clicks directly under or above a hydrophone. Data from acoustic recording tags placed on two species of beaked whales (Cuvier's beaked whale-Ziphius cavirostris and Blainville's beaked whale-Mesoplodon densirostris) are used to directly estimate the percentage of time they produce echolocation clicks. A model of vocal behavior for these species as a function of their diving behavior is applied to other types of dive data (from time-depth recorders and time-depth-transmitting satellite tags) to indirectly determine g(0) in other locations for low ambient noise conditions. Estimates of g(0) for a single instant in time are 0.28 [standard deviation (s.d.) = 0.05] for Cuvier's beaked whale and 0.19 (s.d. = 0.01) for Blainville's beaked whale.

Species identity and human consumption of beaked whales in the Gilbert Islands, Republic of Kiribati

AbstractWe investigated the species identity and local use of cetaceans on the Gilbert Islands, Republic of Kiribati. Working with the Kiribati Ministry of Environment, Lands and Agricultural Development and Fisheries Division, we visited the islands of Tarawa, Tabiteuea (North), Butaritari and Onotoa from June to July 2009, and collected 24 bones, bone fragments or teeth attributed to recent strandings. The mitochondrial DNA control region or cytochrome b was successfully amplified from 12 bones or bone fragments and used to identify four species: Mesoplodon sp. representing a new species or subspecies of beaked whale, the dense‐beaked whale Mesoplodon densirostris, Cuvier's beaked whale Ziphius cavirostris and the pygmy sperm whale Kogia breviceps. This is the first confirmed identification of the dense‐beaked, Cuvier's and pygmy sperm whales from the Gilbert Islands. All specimens were reportedly used for human consumption.

Herpesvirus infection with severe lymphoid necrosis affecting a beaked whale stranded in the Canary Islands

This report describes the pathologic findings in a single, adult female Cuvier's beaked whale Ziphius cavirostris stranded in the Canary Islands. The study indicated that this whale died with a severe, systemic, herpesviral infection and clearly exhibited lesions different from those of the fat and gas embolic syndrome described in beaked whale mass strandings associated with sonar exposure. This is the first report of a cetacean alphaherpesvirus infection of the lymphoid system in a beaked whale.

Partitioning of the Pelagos Sanctuary (north-western Mediterranean Sea) into hotspots and coldspots of cetacean distributions

This study used Monte Carlo methods to generate simulations that considered the effort distribution to determine the locations of significant aggregations of cetacean sightings inside the northern Pelagos Sanctuary (north-western Mediterranean Sea). For three years, monitoring has been conducted from five motor vessels covering about 30,050 km. The most frequently encountered species were the striped dolphinStenella coeruleoalbarepresenting 64.7% of all sightings, the fin whaleBalaenoptera physalus(17.0%), Cuvier's beaked whaleZiphius cavirostris(9.9%), Risso's dolphinGrampus griseus(4.3%) and the sperm whalePhyseter catodon(2.2%). Sightings' positions and effort coverage were distributed over a grid of 5′ longitude and 5′ latitude. Spatial concentrations of sightings were analysed according to the distribution of effort to identify ‘hotspots’ (locations where the species occurred at a significantly greater frequency than expected), and ‘coldspots’ (locations with a significantly lower frequency than expected). Most fin whale hotspots (14) were located on the bathyal plain between 2000 and 2500 m, four hotspots were around the 1000 m isobaths, and one is located close to the seamount off Genoa. Fin whale coldspots were mainly along the coast. Striped dolphin hotspots were widely distributed over two main areas, in waters with depths between 2000 and 2500 m and at the continental slope; coldspots for this species were also mainly along the coast in the northern part of the study area. Many hotspots were found in the Genoa Canyon, and hotspots of striped dolphins, Cuvier's beaked whales, sperm whales and Risso's dolphins overlapped in this region. Some of the hotspots of Cuvier's beaked whales were identified at the seamount in the study area, where no other species was sighted frequently. Risso's dolphin hotspots were mainly near the 1000 m isobath. For sperm whales, several hotspots were identified: three associated with steep slope features (such as canyons or the continental slope), and one was in the centre of the flat area of Pelagos where the depth is 2500 m. This study highlights the ecological importance of particular locations inside the Pelagos Sanctuary—locations that should be protected from anthropogenic degradations for marine mammal conservation.

SOUND PATHWAYS REVEALED: SIMULATED SOUND TRANSMISSION AND RECEPTION IN CUVIER'S BEAKED WHALE ZIPHIUS CAVIROSTRIS USING THE VIBRO-ACOUSTIC TOOLKIT

Our team has pioneered a combination of techniques that add synergistically to produce a flexible computational environment for acoustic simulations. We combine the anatomic geometry obtained from industrial CT scanners; tissue property measurements; and custom FEM software, the Vibro-acoustic Toolkit. Mass stranding events suggest that Cuvier’s beaked whale Ziphius cavirostris may be heavily impacted by exposure to high-intensity sound, so we have concentrated our initial efforts on them.

Simulating the effect of high-intensity sound on cetaceans: Modeling approach and a case study for Cuvier’s beaked whale (Ziphius cavirostris)

A finite element model is formulated to study the steady-state vibration response of the anatomy of a whale (Cetacea) submerged in seawater. The anatomy was reconstructed from a combination of two-dimensional (2D) computed tomography (CT) scan images, identification of Hounsfield units with tissue types, and mapping of mechanical properties. A partial differential equation model describes the motion of the tissues within a Lagrangean framework. The computational model was applied to the study of the response of the tissues within the head of a neonate Cuvier's beaked whale Ziphius cavirostris. The characteristics of the sound stimulus was a continuous wave excitation at 3500 Hz and 180 dB re: 1 microPa received level, incident as a plane wave. We model the beaked whale tissues embedded within a volume of seawater. To account for the finite dimensions of the computational volume, we increased the damping for viscous shear stresses within the water volume, in an attempt to reduce the contribution of waves reflected from the boundaries of the computational box. The mechanical response of the tissues was simulated including: strain amplitude; dissipated power; and pressure. The tissues are not likely to suffer direct mechanical or thermal damage, within the range of parameters tested.

TETRAPHYLLIDEAN PLEROCERCOIDS FROM WESTERN MEDITERRANEAN CETACEANS AND OTHER MARINE MAMMALS AROUND THE WORLD: A COMPREHENSIVE MORPHOLOGICAL ANALYSIS

Tetraphyllidean plerocercoids have occasionally been reported in marine mammals, but they have rarely been described in detail, and the ecological significance of these infections is unclear. We described plerocercoids collected from the mucosa of the terminal colon and rectum, the anal crypts, and the hepatopancreatic ducts of 7 striped dolphins Stenella coeruleoalba, 1 Cuvier's beaked whale Ziphius cavirostris, and 3 Risso's dolphins Grampus griseus from the Spanish Mediterranean. We also examined undescribed plerocercoids from 3 cetacean species from the Atlantic and the Pacific. All plerocercoids had a lanceolate body, and a scolex with an apical sucker and 4 sessile monolocular bothridia. The bothridia had free posterior edges and an accessory sucker at their anterior end. Under light microscopy, the bothridia of some Mediterranean specimens looked bilocular without accessory suckers, but a true accessory sucker was observed in histological sections. A principal component analysis revealed 2 stable clusters of specimens along the first principal component regardless of host species. These "large" and "small" morphotypes are thought to represent early migratory stages of Phyllobothrium delphini and Monorygma grimaldii. The similarity in scolex morphology, the observation of plerocercoids buried in intestinal regions close to the sites where M. grimaldii and P. delphini occur, and the coexistence of all larval forms in the same individual hosts would support this hypothesis. Future molecular analysis may confirm it.

A NEW SPECIES OF BEAKED WHALE MESOPLODON PERRINI SP. N. (CETACEA: ZIPHIIDAE) DISCOVERED THROUGH PHYLOGENETIC ANALYSES OF MITOCHONDRIAL DNA SEQUENCES

Abstract Mesoplodon perrini, a new species of beaked whale is described on the basis of five animals stranded on the coast of California (between 32°55′N, 117°15′W and 36°37′N, 121°55′W) from May 1975 to September 1997. Four of these animals were initially identified as Hector's beaked whales M. hectori based on cranial morphology (Mead 1981). A fifth specimen was initially identified as a neonate Cuvier's beaked whale Ziphius cavirostris based on external features. These specimens were first recognized as representatives of an undescribed species through phylogenetic analysis of mitochondrial (mt) DNA control region and cytochrome b sequence data. Although similar morphologically, the genetic data do not support a close evolutionary relationship between M. perrini and M. hectori. Instead, these data suggest a possible sister species relationship with the lesser beaked whale M. peruvianus. Sightings of two small beaked whales off California in the 1970s which were tentatively identified as M. hectori are also likely to be M. perrini. We suggest that M. hectori is confined to the Southern Hemisphere, while M. perrini is known to date only from the North Pacific.

Feeding ecology of Cuvier's beaked whale (Ziphius cavirostris): a review with new information on the diet of this species

Published information on the diet of Cuvier's beaked whales Ziphius cavirostris (Odontoceti: Ziphiidae) is reviewed and new information on the stomach contents of three animals: two stranded in Galicia (north-west Spain) in February 1990 at A Lanzada, and in February 1995 at Portonovo; and the third stranded in February 1999 in North Uist (Scotland), is presented. The whale stranded in 1990 was a male; the other two were adult females. All animals were >5 m long. The limited published information on the diet of this species indicates that it feeds primarily on oceanic cephalopods although some authors also found remains of oceanic fish and crustaceans. Food remains from the three new samples consisted entirely of cephalopod beaks. The Scottish sample set is the largest recorded to date for this species. The prey identified consisted of oceanic cephalopods, mainly squid (Cephalopoda: Teuthoidea). The most frequently occurring species were the squid Teuthowenia megalops, Mastigoteuthis schmidti and Taoniuspavo (for the Galician whale stranded in 1990), Teuthowenia megalops and Histioteuthis reversa (for the second Galician whale) and T. megalops, Gonatus sp. and Taoniuspavo (for the Scottish whale). Other prey included the squid Histioteuthis bonnellii, Histioteuthis arcturi and Todarodes sagittatus as well as Vampiroteuthis infernalis (Cephalopoda: Vampyromorpha), Stauroteuthis syrtensis and Japetella diaphana (Cephalopoda: Octopoda). The squid eaten (estimated from the measurement of the lower beaks) included juvenile and mature individuals of the most important species (Teuthowenia megalops, Gonatus sp.). The range of species found in the diet of Z. cavirostris is greater than that reported for sperm whales and bottlenosed whales in the north-east Atlantic.