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Commerson’s dolphin (Cephalorhynchus commersonii), Peale’s dolphin (Lagenorhynchus australis), dusky dolphin (Lagenorhynchus obscurus), and hourglass dolphin (Lagenorhynchus cruciger) are closely related species occurring in the Southern Hemisphere. Even though they are partially sympatric, they have evolved towards diverse foraging strategies, prey, and habitat preferences. Size variation occurs both among and within species. Our goal was to study the allometric patterns and ontogenetic trajectories in the vertebral column of these dolphins related to their ecology. We choose nine functionally homologous vertebrae in each column and digitized five different tridimensional configurations, containing 28 to 41 landmarks depending on the functional region under analysis. We explored different levels of allometry (static, ontogenetic, and evolutionary) using multivariate regressions of shape vs. log-transformed centroid size. We compared ontogenetic allometry regression vectors to evidence differences in growth patterns. Finally, we calculated Procrustes distances of shape configurations to determine the timing of shape shifts. Of the studied species, When compared to the Lagenorhynchus species, Commerson’s dolphin showed the highest degrees of allometry, both static and ontogenetic. The macroevolutive trends indicate a high degree of evolutionary morphological change, which could be associated with the rapid evolutionary radiation proposed for the group. This is the first time that allometric changes are studied in small cetaceans by means of 3D geometric morphometrics. Fil: Marchesi, María Constanza. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico; Argentina Fil: Mora, Matias Sebastian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentina Fil: Dans, Silvana Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico; Argentina Fil: González-José, Rolamdo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

The Drake Passage (DP) is a dynamic oceanographic region influenced by the main frontal systems of the Southern Ocean, with little information about cetacean distribution and their relationship with environmental parameters. This study explored the use of generalized additive models (GAMs) to model the relationships of some cetacean species according to sea surface temperature (SST) and a suite of physiographic variables adjacent to the Antarctic Peninsula and DP during the austral summer. The results suggest that SST and distances from oceanographic boundaries, mainly the Southern Antarctic Circumpolar Current Front (SACCF) and Polar Front (PF), were the most significant parameters related to the presence/absence of cetaceans. SST showed an effect on humpback whale (Megaptera novaeangliae) presence around lower temperatures and sei whale (Balaenoptera borealis) and hourglass dolphin (Lagenorhynchus cruciger) at warmer waters. Four species of baleen whales prefer areas near SACCF and Elephant Island and two odontocetes in waters near the PF. Clustering analysis reflected three major groupings based on distances from oceanic fronts and coast: cetaceans that occurred in the northern sector of the DP but with the PF as the southernmost range; a second group with species occurring along the DP and not preferring Antarctic waters further south of the SACCF; and the third group, mainly baleen whales, mostly occupying Antarctic waters southern of the SACCF. We encourage further dedicated cetacean surveys in this particular dynamic region, based on in situ oceanographic data and krill acoustic sampling, and either taking into consideration cetacean species density or abundance.

In cetaceans, increased body flexibility is associated with increased maneuverability, this affects the animal’s swimming speed and foraging behavior. A more stable body form is associated with fast swimming and wide turns. One factor that affects the flexibility of a cetacean’s body is the structure and interaction of its vertebrae. Differences in vertebral morphology confer different muscular insertion sites and affect mechanical properties of swimming muscles. We studied vertebral morphology in four closely related and partially sympatric dolphin species from the Southern Hemisphere: Commerson’s dolphin (Cephalorhynchus commersonii), Peale’s dolphin (Lagenorhynchus australis), the dusky dolphin (Lagenorhynchus obscurus) and the hourglass dolphin (Lagenorhynchus cruciger). The former two species are usually considered coastal, associated with complex habitats where foraging strategies require greater maneuverability; they also show plasticity in their prey preferences. The latter two species are considered fastswimming cooperative feeders, with long distance movements reflecting prey availability in pelagic habitats. We employed three-dimensional (3D) geometric morphometric techniques and multivariate analyses to evaluate differences in vertebral morphology. Our analyses tested whether particular morphologies that limit or enhance flexibility were associated with preferred habitats and feeding strategies. We established links between morphology and behavioral patterns based on the biomechanical significance of specific vertebral morphological features. Principal component analyses (PCA) showed great differentiation between species in all the studied regions along the vertebral column. This was especially evident in the middle area, except in the case of dusky and hourglass dolphins which showed no discernible morphological difference in their mid-column vertebrae. PCA results were supported by statistically significant Mahalanobis distances (MD) between species. Species associated with complex habitats and behaviors possessed morphological features associated with greater flexibility of the column (i.e., spool-shaped vertebrae with short erect processes), whereas cooperative-feeder species possessed features associated with greater stability (i.e., disk-shaped vertebrae with long strongly bent processes). In these closely related and partially sympatric dolphins, vertebral morphology is distinctive and varies with the differential foraging strategies and habitat of each species. These findings reveal morphological plasticity among these dolphin species, highlighting the importance of behavioral complexity and of habitat use in the evolutionary development of morphological adaptations. Fil: Marchesi, María Constanza. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro para el Estudio de Sistemas Marinos; Argentina Fil: Mora, Matias Sebastian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentina Fil: Dans, Silvana Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro para el Estudio de Sistemas Marinos; Argentina Fil: Coscarella, Mariano Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro para el Estudio de Sistemas Marinos; Argentina Fil: Gonzalez-Jose, Rolando. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto Patagónico de Ciencias Sociales y Humanas; Argentina

Encased in a streamlined, flooded housing, a SoundTrap ST300HF hydrophone recording system was towed on voyages to South Georgia Island and the South Sandwich Islands and to the Antarctic Peninsula in December 2019–February 2020. Recordings were analyzed to identify acoustic detections of cetacean species. Acoustically identified species included sperm whales (Physeter macrocephalus), southern bottlenose whales (Hyperoodon planifrons), Arnoux's beaked whales (Berardius arnuxii), killer whales (Orcinus orca), and long-finned pilot whales (Globicephala melas). Acoustic detections also included several recognized types of beaked whale echolocation pulses (BW37/39 and BW58) as well as two likely beaked whale echolocation pulse types that do not match any previous descriptions. Narrow-band high-frequency echolocation signals (NBHF) (typical of porpoises and some dolphin species) were detected in many locations, and one of these coincided with a sighting of hourglass dolphins (Lagenorhynchus cruciger). This study shows the utility of an autonomous towed hydrophone system on a vessel of opportunity to study the distribution of cetaceans in rough seas that are difficult to study by visual survey methods.

Fast swimming pelagic cetacean species have osteological characteristics that promote a more stable spine in comparison to that of coastal species. The Peale?s dolphin (Lagenorhynchus australis) and the hourglass dolphin (Lagenorhynchus cruciger) have a close phylogenetic relationship and are found in coastal and pelagic waters in the Southern Hemisphere, respectively. The aim of this work was to study the relationship between the vertebral column?s morphology and its flexibility, across these species of contrasting habitats. Vertebral counts and multiple measurements of each vertebra were used to infer intervertebral flexibility. Bivariate plots and discriminant multivariate analyses were employed to compare each functional region along the vertebral column. Both species displayed a regionalization of the column into three stable regions and two flexible areas, which statistically differ in the proportion of the skeleton occupied in each species. While the Peale?s dolphin has rounder vertebrae, associated with higher flexibility, the hourglass dolphin has disk-shaped vertebrae and strongly inclined processes related to high stability. Although the species are closely related phylogenetically, vertebral morphology is influenced by a diverse set of ecological and behavioral factors, reflecting a high degree of vertebral plasticity within the genus. Fil: Marchesi, María Constanza. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina. Museo Acatushún de Aves y Mamíferos Marinos Australes; Argentina Fil: Mora, Matias Sebastian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencia Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentina Fil: Pimper, Lida Elena. Museo Acatushún de Aves y Mamíferos Marinos Australes; Argentina. Administración de Parques Nacionales. Delegación Regional Patagonia; Argentina Fil: Crespo, Enrique Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro para el Estudio de Sistemas Marinos; Argentina. Universidad Nacional de la Patagonia; Argentina Fil: Prosser Goodall, Rae Natalie. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina. Museo Acatushún de Aves y Mamíferos Marinos Australes; Argentina

A SoundTrap ST300HF hydrophone recorder in a streamlined, flooded towbody was towed behind expeditionary tourism vessels on trips to South Georgia and the South Sandwich Islands and to the Antarctic Peninsula in December 2019—February 2020. Recordings were analyzed to identify acoustic detections of cetacean species. Identified species included sperm whales (Physeter macrocephalus) and southern bottlenose whales (Hyperoodon planifrons). Acoustic detections also included echolocation pulses from several previously described beaked whale pulse types (BW37 and BW58) as well as a possibly new type of beaked whale echolocation pulse. Narrow-band high-frequency (NBHF) echolocation signals (typical of porpoises and some dolphin species) were detected at several locations, and one of these coincided with a sighting of hourglass dolphins (Lagenorhynchus cruciger). Unidentified large delphinids were also detected several times. This study shows the utility of a simple towed hydrophone system on a vessel of opportunity to study the distribution of cetaceans in rough seas that are difficult to study by visual survey methods. Additional research is needed to link the unidentified echolocation signals to known species throughout waters of the Southern Ocean.

Summary Hourglass dolphins are the most strikingly colored of the Lagenorhynchus genus, with dark black patterns alternating with pure white. They occur only in colder waters of the Southern Hemisphere, largely associated with the Antarctic convergence. They tend to be in small groups of 10 or fewer individuals, and often ride the bow and stern waves of open ocean vessels.

The hourglass dolphin, Lagenorhynchus cruciger, is one of the smallest cetaceans found in Antarctic waters. Although frequently observed, this is one of the least studied species of dolphin. In this study, we investigate the occurrence of hourglass dolphin in the South-West Atlantic and Southern Ocean from 42°S to 63°S and characterize the oceanographic and environmental features associated with their occurrence. Sighting data were collected during two scientific cruises in December 2009 and January and February 2011 and integrated into a geographical information system with environmental variables such as sea surface temperature, ocean colour, depth, distance to oceanographic fronts and distance from shore. We used a principal component analysis (PCA) to identify patterns in data and a non-hierarchic cluster analysis (K means) to classify observations into groups. A total of 19 sightings (96 individuals) were recorded. Group size ranged from one to twelve dolphins (mean 5.05). We could differentiate two groups in relation to the environmental conditions where animals were found, one group occurring in shallow coastal waters and the other occurring in deeper and colder waters further offshore. The present study contributes novel information on environmental measures associated with hourglass dolphin distribution in the South-West Atlantic and Southern Oceans. Additionally, it includes relatively high sighting clusters of this species in two highly productive and biodiverse areas (Burdwood Bank/Isla de los Estados and the South Shetland Islands).

We used stable carbon (δ 13 C) and nitrogen (δ 15 N) isotope analysis to investigate the trophic ecology of 8 small cetacean species of the southwestern South Atlantic Ocean: 6 delphinids (Grampus griseus, Lagenorhynchus cruciger, L. australis, Lissodelphis peronii, Pseudorca crassidens, and Cephalorhynchus commersonii) and 2 phocoenids (Phocoena dioptrica and P. spinipinnis). We also analyzed samples of possible prey collected from oceanic and coastal habitats adjacent to Tierra del Fuego. Cetacean bone-collagen δ 13 C and δ 15 N data revealed information on both habitat and prey preferences. We observed an isotopic continuum in which coastal species had the highest values of δ 13 C and δ 15 N (L. australis), while oceanic and southern species had the lowest values (L. cruciger and P. dioptrica), indicative of offshore foraging in cold oceanic waters near the Antarctic Conver- gence. Overlap in mean isotope values between C. commersonii and P. spinipinnis suggests that these species may have similar habitat and/or prey preferences. Isotope results for L. peronii, P. cras- sidens, and G. griseus suggest that at these latitudes (~54° S) they forage on the outer continental shelf. G. griseus show bimodal isotopic patterns, suggesting that 2 ecotypes that forage in different habitats and/or consume different prey items occur in this region of the southwestern Atlantic Ocean. The isotopic data presented here provide insight into the ecology of these cetaceans, with relevant implications for their successful management and conservation.

Toothed whales depend on echolocation for orientation and prey localization, and source parameters of echolocation clicks from free-ranging animals therefore convey valuable information about the acoustic physiology and behavioral ecology of the recorded species. Recordings of wild hourglass (Lagenorhynchus cruciger) and Hector's dolphins (Cephalorhynchus hectori) were made in the Drake Passage (between Tierra del Fuego and the Antarctic Peninsular) and Banks Peninsular (Akaroa Harbour, New Zealand) with a four element hydrophone array. Analysis of source parameters shows that both species produce narrow band high-frequency (NBHF) echolocation clicks. Coastal Hector's dolphins produce clicks with a mean peak frequency of 129 kHz, 3 dB bandwidth of 20 kHz, 57 micros, 10 dB duration, and mean apparent source level (ASL) of 177 dB re 1 microPa(p.-p.). The oceanic hourglass dolphins produce clicks with mean peak frequency of 126 kHz, 3 dB bandwidth of 8 kHz, 116 micros, 10 dB duration, and a mean estimated ASL of 197 dB re 1 microPa(p.-p.). Thus, hourglass dolphins apparently produce clicks of higher source level, which should allow them to detect prey at more than twice the distance compared to Hector's dolphins. The observed source parameter differences within these two NBHF species may be an adaptation to a coastal cluttered environment versus a deep water, pelagic habitat.

The information about cetacean occurrence around the Island of South Georgia is scarce. With the main goal of gathering information on a feeding ground of humpback whales (Megaptera novaeangliae) that winter in Brazilian waters, we conducted an expedition to South Georgia. We present here the information regarding cetacean sightings during the expedition. From 28 January to 2 March, 2006 we carried out 13 research cruises, covering 700 nautical miles and 110 h of observation. We registered 10 sightings, in 7 h of ad libitum observations, of the following species: Megaptera novaeangliae, Eubalaena australis, Balaenoptera physalus, Mesoplodon layardii, Orcinus orca and Lagenorhynchus cruciger. We present data on location, depth, group size, structure, and behavior for this geographical area of essential importance for cetacean conservation.

4. Hourglass Dolphin Lagenorhynchus cruciger French: Dauphin sablier / German: Sanduhrdelfin / Spanish: Delfin cruzado Other common names: Sea Skunk, Springer, Wilson's Dolphin Taxonomy. Delphinus cruciger Quoy & Gaimard, 1824, “entre la Nouvelle-Hollande et le cap Horn [= between Australia and Cape Horn]...par 49 [S] de latitude,” southern Pacific Ocean. Taxonomy of Lagenorhynchus is currently in dispute; recent molecular analyses have revealed that the genus is not monophyletic. L. australis and L. cruciger appear to be most closely related to species of Cephalorhynchus and may be reassigned to this or another genus (Sagmatias) in the near future. Monotypic. Distribution. Circumpolar in subantarctic and Antarctic waters, primarily between 45° S and 65° S, but occasionally recorded N up to 33° S off Chile. Descriptive notes. Total length 160-190 cm (males) and 140-180 cm (females); weight up to 94 kg (males) and up to 88 kg (females). Neonates are ¢.100 cm long. The Hourglass Dolphin has robust body shape with short but well-defined beak. Dorsal fin is medium-sized and characteristically hooked in shape. In some individuals, mostly adult males, dorsal fin’s leading edge is bent backward. Males also have more keeled tailstock. Back and flanks are black, and belly and throat are white. Flanks are marked by wide white streaks that extend from base of flukes, arch over upper onehalf of body, and descend along sides of head to mouth in front of eyes, converging with white lower jaw and throat. Flank streaks taper into a thin white line mid-body just below dorsal fin, creating characteristic hourglass shape. Just in front of urogenital area, white belly pigmentation intrudesslightly into black pigmentation of lower lateral tailstock in the shape of a small hook. Dorsal fin, flippers, and flukes are black on both sides. Immature individuals have less pronounced hooks in dorsal fins and have more muted color pattern. There are 26-34 pairs of slender, conical teeth in upper jaw and 27-35 pairs in lower jaw. Habitat. Deep offshore waters, but sometimes in water less than 200 m deep around islands and banks off southern South America and the Antarctic Peninsula. The Hourglass Dolphin is the only small delphinid regularly observed south of the Antarctic Convergence. They may be observed within 160 km of the ice edge in some parts of Antarctica. In the Drake Passage, the Hourglass Dolphin seems to be most abundant at the southern boundary of the Antarctic Circumpolar Current and is often seen in areas with turbulent water. Preferred sea-surface temperatures seem to be 0-6-13°C. Food and Feeding. The Hourglass Dolphin preys on fish, squid, and crustaceans. Preferred prey includes Myctophidae (e.g. Krefftichthys anderssoni), hooked squid (Onychoteuthidae), lesser shining bobtail squid (Semirossia tenera), Patagonian squid (Doryteuthis gah), and juvenile Argentine hake (Merluccius hubbsi). The Hourglass Dolphin is primarily a surface species. They often forage in mixed-species aggregations with other cetaceans and seabirds. They sometimes feed among plankton swarms. Breeding. Very little is known about reproductive biology and life history of the Hourglass Dolphin. Females appear to reach sexual maturity at 180-185 cm in length, and males at 174 cm. Breeding seems to peak in January-February. Testes of mature males are large relative to body length, which may imply a promiscuous mating system and sperm competition. Activity patterns. The Hourglass Dolphin can swim at speeds of up to 22 km/h. They have been known to bow-ride and surf in stern wakes, and they are attracted to large ships. They may approach such ships even from long distances and remain with them for up to 30 minutes. The Hourglass Dolphin is also known to surf in high-sea waves. They can be acrobatic when leaping, sometimes spinning on their longitudinal axes. When traveling, they may also leap at long, low angles in a fashion similar to swimming penguins. Vocalizations are narrow-banded and high frequency, characteristic of species of Cephalorhynchus —perhaps suggesting a close evolutionary relationship between the Hourglass Dolphin and this genus. Movements, Home range and Social organization. Group sizes of Hourglass Dolphins are usually 1-14 individuals, but groups of up to 100 individuals have been observed. These are unusually small groups sizes for an oceanic delphinid. The Hourglass Dolphin often associates with the Fin Whale (Balaenoptera physalus), the Sei Whale (Balaenoptera borealis), the Southern Bottlenose Whale (Hyperoodon planifrons), Arnoux’s Beaked Whale (Berardius arnuxii), the Killer Whale (Orcinus orca), the Long-finned Pilot Whale (Globicephala melas), and the Southern Right-whale Dolphin (Lissodelphis peronii). There are currently no documented migrations, but in some areas, there may be seasonal north-south shifts. For example, abundance of Hourglass Dolphins around the Falkland Islands appears to decrease during winter (July-August), which may reflect movement into near-shore and subantarctic waters. Status and Conservation. CITES Appendix II. Classified as Least Concern on The [UCN Red List. Abundance of the Hourglass Dolphin is ¢.144,300 individuals south of the Antarctic Convergence. There is no known systematic exploitation of the Hourglass Dolphin. There are few reports of incidental catches, and it has never been taken for captivity. Overall, there are no known major threats to the Hourglass Dolphin. Bibliography. Brownell & Donahue (1999), Fernandez et al. (2003), Goodall (2009b), Hammond et al. (2008d), Jefferson et al. (2008), LeDuc et al. (1999), May-Collado & Agnarsson (2006), Santora (2012), Tougaard & Kyhn (2010)., Published as part of Russell A. Mittermeier & Don E. Wilson, 2014, Delphinidae, pp. 410-526 in Handbook of the Mammals of the World – Volume 4 Sea Mammals, Barcelona :Lynx Edicions on pages 490-491, DOI: 10.5281/zenodo.6610922

The Heard Island Feasibility Test source transmitted a hum at 209-220 dB re: 1 microPa at 175-m depth, centered on 57 Hz with a maximum bandwidth of 30 Hz for 1 h of every 3. Experienced marine mammal observers conducted line-transect surveys and monitored marine mammal behavior visually and acoustically in a 70 x 70 km square centered on the transmission site. Thirty-nine groups of cetaceans and 19 of pinnipeds were sighted from both vessels before the start of transmissions. Thirty-nine groups of cetaceans and 23 of pinnipeds were sighted during transmissions. Blue (Balaenoptera musculus), fin (B. physalus), and sperm (Physeter macrocephalus) whales were sighted during the base line period; blue, sperm, and possibly sei (B. borealis) whales were sighted during the transmission period. More schools of hourglass dolphins (Lagenorhynchus cruciger) were sighted during transmissions, but fewer groups of pilot whales (Globicephala melas), southern bottlenose whales (Hyperoodon planifrons), and minke whales (B. acutorostrata). The density of all cetaceans was 0.0157 groups/km2 before the transmissions and 0.0166 groups/km2 during. Antarctic fur seals (Arctocephalus gazella) and southern elephant seals (Mirounga leonina) were seen, but not in sufficient numbers to estimate abundance. One blue whale tracked before, during and after a transmission changed respiration and reorientation rates, but did not avoid the source detectably. Sperm whales and pilot whales were heard in 23% of 1181 min of baseline acoustic surveys; but in none of 1939 min during the transmission period. Both species were heard within 48 h after the end of the test.

The hourglass dolphin Lagenorhynchus cruciger is the only regularly occurring small delphinid found south of the Antarctic Polar Front, yet little is known about its ecology and habitat use. This study uses 8 years (14 cruises) of standardized shipboard surveys during January–March (2003–2011) in southern Drake Passage near the South Shetland Islands to summarize the spatial distribution of hourglass dolphin sightings and quantify habitat use. Sighting data are linked to bathymetry (depth, slope) and distance to the average location of oceanographic features. A generalized linear model is used to examine the relationships between sightings and habitat features. Hourglass dolphins were sighted on 50% of surveys (n = 29); sightings were concentrated in February. Group size tended to be 2–6 individuals; there were only 2 sightings of larger groups, of 15 and 25 individuals. Sightings were distributed entirely within the deep pelagic waters north of the South Shetland Islands in southern Drake Passage and were closely associated with the southern boundary of the Antarctic Circumpolar Current. Information on occurrence and distribution reported in this study may be useful for refining habitat associations for hourglass dolphins at regional scales in the Southern Ocean.

Publisher Summary This chapter discusses the characteristics, taxonomy, distribution, abundance, and ecology of the hourglass dolphin or Lagenorhynchus cruciger. The hourglass dolphin is mainly black or dark with two elongated lateral white areas, in some animals joined with a fine white line that resembles an hourglass. The hourglass is a rather stocky dolphin with a large, recurved dorsal fin that is variable in shape from erect to hook. The hourglass dolphin is pelagic and circumpolar in the Southern Ocean, in both Antarctic and Subantarctic waters, near the ice pack. Exceptional northern sightings were in the South Atlantic and in the South Pacific off Valparaiso, Chile. Most specimens are found between the northernmost from New Zealand and the southernmost from the South Shetland Islands. Although oceanic, this dolphin is often sighted near islands and banks. It is most often seen in areas with turbulent waters. Hourglass dolphins are rapid swimmers with a forward, plunging movement. They commonly bow-ride ships, especially in rough weather. They often leap from the sea, porpoise like penguins, and have been observed to spin. They especially seem to enjoy wave surfing during very high seas.

RésuméDes observations nouvelles et quelques échouages complètent le premier bilan faunistique établi en 1989 pour les îles Kerguelen. Aux neuf espèces identifiées précédemment ( Eubalaena glacialis , Balaenoptera acutorostrata , Megaptera novaeangliae , Physeter macrocephalus , Mesoplodon layardii , Cephalorhynchus commersonii , Lagenorhynchus cruciger , Orcinus orca , et Globicephala melas ) s'ajoutent, grâce à des échouages, deux nouvelles espèces: Ziphius cavirostris et Hyperoodon planifrons . En outre, la présence occasionnelle de Phocoena dioptrica est confirmée. L'événement le plus marquant est cependant le grand nombre d'observations (n=1649) de cachalots ( Physeter macrocephalus ) faites depuis 1989 au delà du plateau des îles, dans une zone peu fréquentée autrefois par les bateaux de pêche. Pour le dauphin de Commerson ( Cephalorhynchus commersonii ), espèce la plus commune, des données biologiques et écologiques s'ajoutent aux données faunistiques. Nous faisons également état, pour trois espèces ( Physeter macrocephalus , Orcinus orca , et Globicephala melas ), d'interactions avec la pêcherie à la palangre de la légine australe ( Dissostichus eleginoides ).

This note reviews new and historical sightings of Lagenorhynchus-like dolphins in tropical and sub-tropical waters of the Indian and Pacific Oceans. Given the distributions of the three Southern Hemisphere species, it seems probable that these sightings refer to an unrecognised species in tropical and sub-tropical waters. It is recommended that observers on future surveys in these regions are especially vigilant for sightings of these dolphins.

Lagenorhynchus cruciger (Quoy and Gaimard, 1824). Voy. autour du Monde...l'Uranie et la Physicienne, Zool., p. 87, pl. 2. TYPE LOCALITY: Pacific Ocean, "entre la Nouvelle-Hollande et le cap Horn [= between Australia and Cape Horn],..par 49° [S] de latitude". DISTRIBUTION: Southern Hemisphere: antarctic and cold-temperate waters. STATUS: CITES - Appendix II. SYNONYMS: albigena, bivattus, clanculus, wilsoni. COMMENTS: Formerly included australis and obscurus, see Hershkovitz (1966«) and comments under australis and obscurus., Published as part of James G. Mead & Robert L. Brownell, Jr., 1993, Order Cetacea, pp. 349-364 in Mammal Species of the World (2 nd Edition), Washington and London :Smithsonian Institution Press on page 353, DOI: 10.5281/zenodo.7352970

The source properties of toothed whale echolocation clicks are essential for evaluating the performance of biosonar systems. However, such data only exist for a small number of free ranging toothed whale species. Here we present a quantitative analysis of the first recordings of echolocation sounds from hour glass dolphins (Lagenorhynchus cruciger) made in the Drake Strait. Recordings were made with a vertical array of four broad‐band, calibrated hydrophones that allows for acoustic localization and source parameter derivation. Only apparent on‐axis clicks were used for analysis. Hour glass dolphins produce clicks with a mean peak and centroid frequency around 128kHz, a narrow, mean RMS bandwidth of 10kHz with no energy below 100kHz and a mean signal duration of 161μs. Echolocation clicks of hour glass dolphins are thus of the high frequency narrow band‐width type (NBHF type) found in porpoises, a few delphinids of the Cephalorhynchus genus and the pygmy sperm whale Kogia breviceps, but are strikingly dif...

Marine mammal density and behavior were measured in a 70‐×70‐km square centered on the site of the Heard Island feasibility test 4 days before and throughout the transmissions. Observers were stationed on two large vessels; they conducted line‐transect surveys, and monitored marine mammal behavior during transmissions. Observers surveyed 590 nm of tracklines before and 598 nm during transmissions; they made 123 h of observations before and 149 h during. Transmission source characteristics are described elsewhere. Forty schools of cetaceans and 18 pinnipeds were sighted before the transmissions; 40 schools and 25 pinnipeds were sighted after. Sightings of endangered cetaceans were equally common before and during transmissions (3 schools each), but the number of hourglass dolphin (Lagenorhynchus cruciger) schools increased and schools of midsized whales, chiefly southern bottlenose whales (Hyperoodon planifrons) and minke whales (Balaena acutorostrata), decreased. These changes could be explained by the transmissions, the survey vessel, or unknown natural factors. Cetacean school size may have changed during transmissions, but there were no consistent changes in direction of travel or calling behavior. Endangered whales showed changes in respiration rate and rate of reorientation. However, these whales were able to aggregate and probably feed during transmissions.

Summary Records of four species of Delphinidae, Delphinus delphis, Lissodelphis peroni, Lagenorhynchus obscurus, and Lagenorhynchus cruciger in waters to the east and south‐east of New Zealand are discussed in relation to surface temperatures. In this region D. delphis appears to be largely confined north of the Subtropical Convergence and a minimum surface temperature of about 14°c, and near New Zealand from Hawke Bay southward in the warm water of the East Cape Current; L. peroni to the Subtropical Convergence and the subantarctic water to the south of it, between surface temperatures of 9°c and 16°c; L. obscurus to the immediate vicinity of the Subtropical Convergence and surface temperatures in summer of about 14° to 15°c, and L. cruciger across the Antarctic Convergence region, in a surface temperature range of 2° to 9°c.

SYNOPSIS The histology is described, for the first time, of the liver, kidney, and heart muscle of the rare and primitive cetacean Caperea (Neobalœna) marginata Gray, 1844. Observations are also submitted on the hepatic histology of Physeter catodon, Megaptera novœangliœ and Lagenorhynchus cruciger, and a tentative hypothesis is advanced concerning the mode of venous drainage of the cetacean liver lobule. Attention is drawn to a hitherto undescribed histological feature of the kidney of Caperea, Physeter, Phocœna and Lagenorhynchus, and its interpretation is attempted in terms of renal structure and function.

Lagenorhynchus cruciger (Quoy and Gaimard, 1824). Voy. Autour du Monde, sur Uranie et la Physicienne, Paris, Zool., p. 87. TYPE LOCALITY: Pacific Ocean, 49° S., between Cape Horn and Australia. DISTRIBUTION: Antarctic and cold temperate waters of the Atlantic and Pacific coasts of South America. COMMENT: Formerly included australis and obscurus; see Rice, 1977. PROTECTED STATUS: CITES - Appendix II as Order Cetacea. ISIS NUMBER: 5301411002012004001., Published as part of James H. Honacki, Kenneth E. Kinman & James W. Koeppl, 1982, Order Cetacea, pp. 290-304 in Mammal Species of the World (1 st Edition), Lawrence, Kansas, USA :Alien Press, Inc. & The Association of Systematics Collections on page 293, DOI: 10.5281/zenodo.7352983, {"references":["Rice, D. W. 1977. A list of the marine mammals of the world. Third ed. NOAA Technical Report, NMFS SSRF- 711: 1 - 15."]}

The systematic positions of the various dolphins now described under Lagenorhynchus have recently been studied by Bierman and Slijper (19471948). It is "highly probable," they state, that obscuruts, fitzroyi, sup:rci'iosuY, cruciger, wilsoni, and australis all belong to the same species, LagEnorhynchus cruciger (Quoy et Gaimard, 1824). However, "it is still doubtfull [sic! whether Lag. obliquidens Gill from North Pacific belongs to this species or not" (1948, p. 17). In view of the fact that several thousands of miles, and the equatorial belt, scparate the known ranges of cruciger (in the sensz of Bierman and Slijper) and obliquidens I believe that we can safely consider the two as distinct species until evidence to the contrary appears.