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The Agoa protected marine area, located in the French West Indies, eastern Caribbean, holds several cetacean species, of which the pantropical spotted dolphin Stenella attenuata is the most commonly observed. This species is the focus of whale-watching activities off the leeward coasts of Guadeloupe and Martinique, which has allowed the development of a citizen science program to characterize individuals through the collection of photographic data. Here, we conducted a photo-identification study with a sample of 115,705 photos collected between 2014 and 2019, in which 290 marked individuals (179 in Guadeloupe and 111 in Martinique) were identified. Based on an Agglomerative Hierarchical Classification (AHC) analysis, dolphins from each island were separated into two residency clusters. The Catch–Mark–Release (CMR) POPAN statistical model for open populations estimated the pantropical spotted dolphin populations in Guadeloupe and Martinique at 657 (95% CI: 525–821) and 336 (95% CI: 253–446) individuals for frequent users, respectively, while occasional visitors were estimated at 3,063 (95% CI: 2,133–4,398) and 1,443 (95% CI: 1,024–2,033), respectively. The Martinique population tended to use a reduced coastal area and appeared to be smaller and stable, while the Guadeloupe population showed a slight decline in abundance throughout the study period. These results showed that the leeward coasts of Guadeloupe and Martinique are of particular importance for pantropical spotted dolphin populations, highlighting the need for continued monitoring through both scientific and citizen science programs to fill information gaps on this species in the eastern Caribbean.

The increase and diversification of vessel traffic worldwide has resulted in a variety of known disturbances to dolphins. As a remote island chain, the Hawaiian Islands rely heavily on the marine environment for transportation, recreation, and fishing that aggregates into significant levels of vessel traffic. Given the known presence of dolphins in this region, there is a gap in knowledge regarding the relative exposure risk that vessel traffic poses to island-associated dolphin populations in Hawai'i. This research identified the spatial distribution of pantropical spotted dolphins (Stenella attenuata) and common bottlenose dolphins (Tursiops trun-catus) and determined the extent of their overlap with various categories of vessel traffic in Maui Nui, Hawai'i. Species distribution was determined using kernel density estimates based on sighting data from 50 spotted dolphin sightings and 75 bottlenose dolphin sightings collected from 2013 to 2018. A combination of vessel GPS and Automatic Identification Systems (AIS) vessel tracks were used to quantify vessel traffic within the study area, resulting in 22,464 vessel tracks that were subsequently compiled into categories for analysis from 2014 to 2017. Risk of vessel exposure between vessels and dolphins, or co-occurrence, was determined by calculating the product of predicted dolphin density and predicted vessel density. Both species were exposed to vessel traffic risk over 100% of their distribution, but their highest exposure risk varied spatially, with high risk defined as > 0.25 on a normalized scale of low (0) to high (1) risk. The highest vessel exposure risk for spotted dolphins occurred in deeper, offshore waters, while the highest risk for bottlenose dolphins was in shallow, coastal waters. The vessel categories with the largest area of high risk to spotted dolphins were tour vessel and commercial fishing vessel traffic, while commercial transportation traffic had the highest exposure risk for bottlenose dolphins. This article provides baseline information for understanding the vulnerability of two island-associated dolphin populations to the threat of vessel traffic and highlights the differences in relative exposure risk based on species and vessel categories. [ABSTRACT FROM AUTHOR]

The Mexican Central Pacific (MCP) has complex oceanographic dynamics, with a well-defined seasonal pattern and influence of interannual sea surface temperature anomalies. The present study investigated the relationship between the distribution/abundance of spotted dolphins and the environmental conditions in the MCP. Dolphin sighting data were collected during January 2010-December 2015; distance to coast, sea surface temperature, and chlorophyll a (Chla) were obtained for each sighting location through georeferenced maps and satellite images. A total of 746 spotted dolphin sightings were obtained with a survey effort of 31,695 km. Spotted dolphins in the MCP showed a predominantly coastal distribution regardless of environmental conditions. Significant differences were detected concerning regional seasonal variation, with higher mean sighting rate during the stratified periods and higher density/abundance estimates during the mixed periods. Spotted dolphins showed preference for warmer conditions, with higher mean sighting rate, abundance, and distance to coast during the neutral and warm interannual periods. During the coolest conditions (cold periods), mean sighting rate and abundance decreased and spotted dolphins were located closer to the coast, where Chla concentration increased. These results suggest that changes in the distribution/abundance of these dolphins could be associated with habitat quality related to tropical (El Niño/Southern Oscillation) and extratropical (The Blob) oceanographic phenomena, which could be modulating their foraging activities. [ABSTRACT FROM AUTHOR]

Introduction: Three species of cetaceans, the pantropical spotted dolphin (Stenella attenuata attenuata), the bottlenose dolphin (Tursiops truncatus) and the humpback whale (Megaptera novaeangliae), are important components of the marine fauna of the Guanacaste Conservation Area (ACG). However, basic biological information on the behavior and occurrence of these species remains scarce. Objective: The objective of this study is to determine the diurnal behavior of the three-mentioned species in the ACG. Methods: The north Pacific of Costa Rica, from Bahía Salinas to the Marine Sector of ACG was sampled between May 2005 and May 2006. The behavior scanning method was used to identify the general behavior of the cetacean groups. Results: Encounters were recorded for the three species, in a total of 36 sightings, but only for S. attenuata and M. novaeangliae for considerable periods of time. Stenella attenuata exhibited a wide variety of behaviors, being foraging (X2 = 29.42; d.f. = 1; P < 0.001) and travelling (X2 = 38.33; d.f. = 1; P < 0.001) significantly higher during the rainy season. Predominant behaviors for the humpback whale were mother-calf association, social and travelling; being the latter higher during the rainy season (X2 = 78.16; d.f. = 1; P < 0.001). Conclusions: Behaviors such as foraging and mother-calf were the most representative among species and the most frequent. This suggests that the area can be considered as a critical habitat for these species of cetaceans, with particular importance for highly migratory species such as humpback whales. [ABSTRACT FROM AUTHOR]

In Maui Nui, Hawai'i, limited information is available regarding the impact of fisheries interactions on two island-associated populations of common bottlenose (Tursiops truncatus) and pantropical spotted (Stenella attenuata) dolphins. To quantify the number of individuals with evidence of fisheries interactions, this study examined images of bottlenose and spotted dolphins' dorsal fins, mouthlines, and bodies that were photographically identified during survey efforts from 1996 to 2020. Our results reveal that 27% of the 255 identified bottlenose dolphins and 13% of the 374 identified spotted dolphins displayed one or more fishery gear-related scars. These data suggest that fisheries interactions may pose a serious threat to the population of bottlenose dolphins and is a concern for spotted dolphins in Maui Nui, Hawai'i. Our methodology of reviewing above- and underwater footage for mouthline and body images increased scar-detection rates by 51 and 40% for bottlenose and spotted dolphins, respectively. We recommend that future surveys expand dorsal fin photo-identification efforts to collect additional above- and underwater images of animals' mouthlines and bodies when in the field. In conjunction with the apparent decline in the Maui Nui bottlenose dolphin population, our findings highlight the need for further investigation regarding the level of impact fisheries interactions have on the status of these populations. [ABSTRACT FROM AUTHOR]

Although dolphins are mostly known to form single species groups of varying size, occasionally they aggregate in mixedspecies groups. The presence of mixed-species delphinid groups along the Peruvian coast is unknown. Herein, we report the presence of a single pantropical spotted dolphin (Stenella attenuata) within large groups of the long-beaked common dolphin (Delphinus delphis) at Los Organos in the northern coast of Peru. Sightings occurred on October 10th, 2016, January 7th, 2018 and September 21st, 2019. In one sighting the mixed group was feeding, while during the other two sightings the group was travelling. These records add new evidence about mixed-species delphinid groups in coastal waters of Peru. [ABSTRACT FROM AUTHOR]

Very little is known about the foraging ecology of killer whales (Orcinus orca) in tropical oceans and on how these large apex predators affect prey communities. In most tropical waters, the presence of killer whales is unpredictable, and most information on their ecology is inferred from opportunistic records. This is particularly the case in the Indian Ocean where limited information is available. Between 2002 and 2017, killer whales were opportunistically encountered around the Mozambique Channel island of Mayotte in the eastern Comoros Archipelago (southwest Indian Ocean). A total of 15 killer whale sightings collected by various local experts were compiled and used to describe observed feeding events. Twenty-seven distinct individuals from four separate groups were identified by photo-identification, highlighting short-term site fidelity (minimum 7 days) to this area. Feeding was observed on seven occasions, and recorded prey included two species of elasmobranchs (Centroscymnus coelolepi and Mobula spp.) and two species of cetaceans: a humpback whale (Megaptera novaeangliae) calf and a pantropical spotted dolphin (Stenella attenuata). This study represents the first account of killer whales foraging on a combination of marine mammals and elasmobranchs in tropical waters, and describes the first presumed predation on a humpback whale calf in the southwest Indian Ocean. [ABSTRACT FROM AUTHOR]

We examined the incidence of bent or collapsed dorsal fins of eight species of odontocetes observed in the nearshore waters of Maui Nui, Hawaii. Between 1995 and 2017, 1,312 distinctive individual odontocetes were photographically documented. Our photo-identification catalogs include 583 spinner dolphins (Stenella longirostris longirostris), 164 bottlenose dolphins (Tursiops truncatus), 132 short-finned pilot whales (Globicephala macrorhynchus), 253 pantropical spotted dolphins (Stenella attenuata), 82 false killer whales (Pseudorca crassidens), 70 melon-headed whales (Peponocephala electra), 15 pygmy killer whales (Feresa attenuata), and 13 rough-toothed dolphins (Steno bredanensis). Of these, two false killer whales (2.44% of catalog), two spinner dolphins (0.34% of catalog), and three pantropical spotted dolphins (1.19% of catalog) displayed major dorsal fin disfigurements. Both spinner dolphins and two of the spotted dolphins had multiple resights spanning several years, with one spotted dolphin having a 16-year span between resights. The two false killer whales with bent dorsal fins did not have any resights and were only sighted once throughout the study period. We also present the first progression of dorsal fin collapse after a significant injury to the leading edge of a spinner dolphin. Results from this research expand our knowledge on injuries to marine mammals and the survivorship of wild dolphins with dorsal fin injuries and contribute to the management of odontocetes in Hawaii, where interactions with fishing gear are a significant conservation issue. [ABSTRACT FROM AUTHOR]

Abstract In the French West Indies (Caribbean), the insecticide Chlordecone (CLD) has been extensively used to reduce banana weevil (Cosmopolites sordidus) infestations in banana plantations. Previous studies have shown high CLD concentrations in freshwater and coastal communities of the region. CLD concentrations, however, have not yet been assessed in marine top predators. We investigated CLD concentrations in cetacean blubber tissues from Guadeloupe, including Physeter macrocephalus , Lagenodelphis hosei , Stenella attenuata and Pseudorca crassidens. Chlordecone was detected in all blubber samples analysed, with the exception of four P. macrocephalus. Concentrations (range: 1 to 329 ng·g−1 of lipid weight) were, however, lower than those found in species from fresh and brackish water. Ecological factors (open ocean habitat), CLD kinetics, and cetacean metabolism (high or specific enzymatic activity) might explain low concentrations found in cetacean blubber. Future analyses that include internal organ sampling would help to confirm CLD levels observed in this study. Highlights • This is the first report of chlordecone levels in the pelagic marine environment. • Chlordecone was present in the four cetacean species analysed. • Cetacean concentrations were lower than in species from fresh and brackish water. • Ecological factors and chlordecone kinetics explain the low concentrations found. [ABSTRACT FROM AUTHOR]

The embryology of cetaceans documents features that elucidate the interaction between form and function in modern species, as well as their evolution from extinct ones. Prenatal specimens of the dolphin Stenella attenuata demonstrate critical aspects of the embryonic and fetal development of cetaceans, the pharyngeal arches, ear ossicles, nasal opening, teeth, fore limb, hind limb, and flukes. In addition, specimens of the bowhead whale (Balaena mysticetus) illustrate the development of baleen and hair. [ABSTRACT FROM AUTHOR]

Abstract The presence of polybrominated diphenyl ethers (PBDEs) in the aquatic environment is an issue of major concern which may be a cause of increasing prevalence and severity of diseases in marine mammals. Although, cell culture model development and in vitro investigation approach is a prime need of time to progress immunotoxic research on aquatic mammals. In this study, we stablished fibroblast cell line (pantropic spotted dolphin) to assess the potential effects of PBDEs on cytokines response. Cells were grown in 6 well cell culture plate and complete media (DMEM and Ham's F12 nutrient mixture, fetal bovine serum, antibiotic and essential amino acids) was provided. The primary culture of (PSP-LWH) cells identification was achieved by vimentin (gene and protein) expressions. Karyotyping revealed pantropic spotted dolphin chromosomes 20 pairs with XX. Transfection was achieved by SV40 LT antigen and transfected cells were expended for passages. Stability of cell line was confirmed at various passages intervals using RT-PCR, western blotting and immunofluorescence methods. After confirmation, cell line was exposed to BDE-47 (250 ng/ml), BDE-100 (250 ng/ml) and BDE-209 (1000 ng/ml), with control group (PBS), positive control DMSO (0.1%) and negative control LPS (500 ng/ml) for 24 h. The ELISA results showed significant increase in IL-6 in BDE- 100 and BDE-209 while IL-1β and IL-8 were found higher in BDE-47 and BDE-100. TNFα and IL-10 secretion was noted higher in control and positive control groups. Altogether, these results emphasize importance of transfected (PSP-LWHT) cell line in aquatic research and potential effects of PBDEs on fibroblast provides evident to understand immune modulating effects of PBDEs in marine mammals. The impact of PBDEs on dolphin’s fibroblast cells immune response and altered cytokine response have been presented for the first time. [ABSTRACT FROM AUTHOR]

Bottlenose dolphins (Tursiops truncatus) and pantropical spotted dolphins (Stenella attenuata) co-occur in Golfo Dulce, a fjord-like embayment located in the southern Pacific coast of Costa Rica. We evaluated if spatial overlap by these dolphin species is associated with similar environmental requirements. Presence-only models based on niche theory were constructed by contrasting a set of spatial locations with the responses of the target species to abiotic ecogeographical variables (EGVs: depth, slope, distance to rivers, distance to 200 m isobath, mean sea surface temperature, and variation in sea surface temperature). Models were cross-validated with levels of discrimination that ranged from acceptable to excellent based on the area under the curve assessment (T. truncatus, rainy season: 0.76, dry season: 0.83; S. attenuata, rainy season: 0.84, dry season: 0.89). Both dolphin species occur in Golfo Dulce year-round; the lack of seasonality documented previously was supported by the models. Species distribution models showed no spatial overlap, with differences in EGVs affecting their distribution (T. truncatus: distance to river + distance to 200 m isobath, S. attenuata: depth + sea surface temperature). We argue that the coexistence of both predators in Golfo Dulce is linked to habitat heterogeneity, where critical habitats are spatially differentiated. The lack of fine-scale spatial overlap, along with influential abiotic variables, highlights a process of coexistence for dolphins that are sympatric at the scale of Golfo Dulce, but within the Gulf there is fine-scale allopatry [ABSTRACT FROM AUTHOR]

The population of Irrawaddy dolphins in Brunei Bay, Malaysia is little studied. This study aimed at contributing information on how abiotic and other factors influence different aspects of their behaviour displayed at the water surface. Several behaviours, i.e. foraging, travelling, foraging behind trawler, milling and socializing were observed during boat-based line transect surveys (2013-2016). The behaviours of individuals and groups were filmed or noted, and the abiotic factors of the habitat were registered at the same time. The number of “travelling” individuals was negatively correlated with surface water salinity (p value = 0.04) and positively correlated with turbidity (p value = 0.01). Fisher’s exact test also revealed that the behaviours of dolphin groups significantly differed with the ranges of several abiotic factors, i.e. foraging behind trawler with depth (p value = 0.001), travelling with surface water salinity (p value = 0.05), travelling and foraging behind trawler with turbidity (p value = 0.04, 0.01). The results for foraging behind trawler differed significantly between the groups with calves and those without calves (χ2 test, p value = 0.04), where groups with calves were less likely to forage behind trawlers. Significant differences were observed among group sizes for travelling, milling and socializing (χ2 test, p value < 0.05), with large groups (11-20 individuals) more frequently foraging, milling and socializing, compared to smaller ones. The current study is the first behavioural observation for Irrawaddy dolphins in Brunei Bay and these findings will help researchers, conservationists, local marine park managers and policy makers in developing effective conservation and management plans for the area. [ABSTRACT FROM AUTHOR]

Environmental enrichment is a crucial element of promoting welfare for animals in captivity. However, enrichment programs are not always formally evaluated for their efficacy. Furthermore, there is little empirical evidence of enrichment evaluation for species of small cetaceans in zoological settings. A wide range of variables may potentially influence enrichment efficacy and how it in turn affects behavior. The purpose of this study was to determine the most preferred environmental enrichment, and method of presentation, for a species that has not been well studied in captivity, the pantropical spotted dolphin (Stenella attenuata). In order to determine which enrichment items and method of presentation were most effective at eliciting enrichment interaction, we systematically examined how several variables of enrichment influenced enrichment interaction. The results suggested that presenting enrichment after training sessions influenced interaction with the enrichment. The results also indicated preference for enrichment type and a specific enrichment device. Finally, factors that influenced interaction were also found to influence aberrant behavior. The results support the premise that enrichment be "redefined" for each species and each individual. [ABSTRACT FROM AUTHOR]

The article presents the study on delphinid vocal behavior with the use of digital acoustic recording tag (DTAG) along with the information on whistle repertoire of pantropical spotted dolphins Stenella attenuata. Topics discussed include data collection opportunities on small delphinids being limited due to active behavior, impacts of noise or other anthropogenic activities on delphinids; and evaluation of communication and behavior of cetaceans.

Con la finalidad de conocer las especies de mamíferos marinos que se encuentran en la costa central de Oaxaca, se elaboró un listado comentando las características de los registros obtenidos. Se incluyeron las observaciones hechas a lo largo de 30 recorridos por mar, entre junio de 1999 y enero de 2004, realizadas entre las bahías de Huatulco y la playa de La Escobilla. Adicionalmente se incluyeron registros de animales varados, así como observaciones realizadas desde la costa. Se presentan comentarios sobre el registro de 8 especies en la zona, incluyendo las localidades y fechas de los avistamientos. Stenella attenuata es la especie más abundante, y la zona de Zipolite-Isla Roca Blanca la localidad con el mayor número de avistamientos. Dado el crecimiento turístico del lugar, es importante contar con este tipo de registros ya que es poco lo que se sabe sobre estas especies en esta porción de la costa oaxaqueña.With the aim of documenting the species of marine mammals that occur along the central coast of Oaxaca, a list with the characteristics of the records was elaborated based on observations made throughout 30 surveys from Huatulco Bays to La Escobilla beach between June 1999 and January 2004. Additional records from stranded animals are included, as well observations from the coast. Comments on 8 species are presented, including localities and dates of sightings. Stenella attenuata is the most abundant species. Zipolite-Roca Blanca island was the locality with the highest number of sightings. This records are important to promote conservation due growth of tourism in the area, given that Oaxaca coast is poorly known regarding marine mammals.

Las características del hábitat que influyen en las especies animales varían de un lugar a otro. Al mismo tiempo, toda especie es rodeada por una serie de factores ambientales que interactúan entre sí, pero la influencia que una característica ambiental particular pueda ejercer sobre una especie depende no sólo de las demás variables, sino de las condiciones morfológicas, fisiológicas y sociales de esa especie. En este estudio, desarrollado de junio 1996 a julio 1997, la pregunta fue enfocada a determinar si comportamientos específicos en el delfín bufeo (Tursiops truncatus) y el delfín manchado (Stenella attenuata) están relacionados con áreas de distribución y factores ambientales particulares. El área de estudio fue cubierta siguiendo transectos lineares oblicuos predeterminados y cada grupo fue observado de 15 min a 5 h. Las variables ambientales fueron medidas al inicio y al final de cada avistamiento junto con la determinación de la posición geográfica y el comportamiento llevado a cabo por los delfines. Para el bufeo, las actividades de forrajeo/ alimentación mostraron coincidencia exclusiva con bocas de ríos y áreas de coral y manglar, y las actividades sociales y de merodeo, se asociaron a áreas cercanas a los sitios de forrajeo. El desplazamiento ocurrió a lo largo de diferentes puntos paralelos a la costa, con un bajo porcentaje de casos a través del golfo (16.56 %), lo cual sugiere que el bufeo rara vez cruza el golfo. En el caso del manchado, no fue posible asociar zonas comportamientos particulares, pues todo el grupo se mueve junto; sin embargo, si fue observada la presencia de distintos comportamientos en un mismo momento, llevados a cabo por grupos específicos dentro de la manada. Se consideraron factores ambientales tales como la profundidad, la temperatura, la salinidad y la distancia respecto a la costa, entre otros. El ANDEVA de bloques no reveló una relación marcada entre actividades y zonas variables ambientales particulares, sin embargo, los resultados mostraron información valiosa sobre tendencias muy interesantes. La falta de significancia, en relación con los aspectos ambientales, fue atribuida a tres aspectos: (a) las transiciones entre actividades se dieron generalmente dentro de un área poco variable, (b) fue común que los delfines se desplazaran cubriendo grandes áreas sin cambiar de actividad y (c) las condiciones ambientales en el Golfo son bastante homogéneas. En ambas especies el mayor promedio en el número de individuos por grupo correspondió a la categoría de socialización activa, seguido en forma decreciente por el desplazamiento, la socialización pasiva y la alimentación. En el caso del bufeo, el menor tamaño promedio de grupo estuvo asociado a las actividades de alimentación (ANDEVA, F= 2.624, p=0.037, gl= 4), mientras que en el manchado correspondió a los momentos de merodeo (ANDEvA, F= 3.817, p=0.009, gl= 4).Distribution and environmental conditions related to the behavior in the bottlenose dolphin (Tursiops truncatus) and the spotted dolphin (Stenella attenuata) (Cetacea: Delphinidae) in Golfo Dulce, Costa Rica. Habitat characteristics influencing behavior in animal species vary locally. The influence that a particular environmental characteristic can have on a species depends not only on other variables, but on morphological, physiological and social conditions of that species. in this study, developed from June 1996 to July 1997, I studied whether specific behaviors are related to particular distribution areas and environmental factors in the bottlenose (Tursiops truncatus) and the spotted dolphin (Stenella attenuata). The study area was covered along oblicuous linear transects, and the behavior of single groups was observed from 15 min to 5 h. Environmental factors such as depth, temperature, salinity and distance from shore, among others, were considered. For the bottlenose dolphin, foraging/feeding activities showed exclusive coincidence with river mouths, coral reef and mangrove areas, while social and milling activities where seen close to feeding areas. Traveling occurred along different points parallel to the coast, with a low percentage of cases across the gulf (16.56 %), suggesting that the bottlenose rarely crosses from one side to the other. in the spotted dolphin, several behaviors were observed simultaneously in the schools and it was not possible to associate areas with particular behaviors. The lack of significant relationships among activities and particular environmental variables (ANOVA tests) is attributed to three aspects: (a) transitions among activities generally occurred into a low variable area, (b) dolphins often traveled along large areas without changing activities and (c) environmental conditions in Golfo Dulce are homogeneous. in the two species the highest average in the number of individuals per group corresponded to the category of active socializing, followed by traveling, passive socializing and feeding. in the case of the bottlenose dolphin, the smallest group size was associated with feeding activities (ANOvA, F= 2.624, p=0.037, n= 156, df= 4), while in the spotted dolphin the smallest group size corresponded to milling activities (ANOvA, F= 3.817, p=0.009, n=51, df= 4). Rev. Biol. Trop. 55 (2): 549-557. Epub 2007 June, 29.

Phylogenetic relationships in the family Delphinidae have been widely debated. We examined 347 skulls of Tursiops, Stenella, Delphinus, Steno, Lagenodelphis, and Sousa in order to resolve the phylogenetic position of Australian species of Tursiops. Five Tursiops type specimens were included. Cranial morphology was described using 2-dimensional (2-D) and 3-dimensional geometric morphometrics (3- GM), counts and categorical data. Analyses showed a clear morphological separation of Tursiops, including type specimens, from other genera. The three Stenella species did not cluster together. Stenella attenuata clustered with Delphinus delphis, and Stenella coeruleoalba with Lagenodelphis hosei. Length and width of the skull and rostrum were important discriminators in both methods. For 3-D data, round vs. angular posterior skull shape distinguished some genera. Taxa that overlapped in the multivariate analyses had different mean tooth counts. Our study challenges genetic studies that identified Tursiops as polyphyletic, with T. aduncus closer to S. attenuata. [ABSTRACT FROM AUTHOR]

The probability of detecting echolocating delphinids on a near-seafloor sensor was estimated using two Monte Carlo simulation methods. One method estimated the probability of detecting a single click (cue counting); the other estimated the probability of detecting a group of delphinids (group counting). Echolocation click beam pattern and source level assumptions strongly influenced detectability predictions by the cue counting model. Group detectability was also influenced by assumptions about group behaviors. Model results were compared to in situ recordings of encounters with Risso's dolphin (Grampus griseus) and presumed pantropical spotted dolphin (Stenella attenuata) from a near-seafloor four-channel tracking sensor deployed in the Gulf of Mexico (25.537°N 84.632°W, depth 1220 m). Horizontal detection range, received level and estimated source level distributions from localized encounters were compared with the model predictions. Agreement between in situ results and model predictions suggests that simulations can be used to estimate detection probabilities when direct distance estimation is not available. [ABSTRACT FROM AUTHOR]

This study characterizes daytime acoustic and dive behavior of pantropical spotted dolphins (Stenella attenuata) in Hawai'i using 14.58 h of data collected from five deployments of digital acoustic recording tags (DTAG3) in 2013. For each tagged animal, the number of whistles, foraging buzzes, dive profiles, and dive statistics were calculated. Start, end, minimum, and maximum frequencies, number of inflection points and duration were measured from 746 whistles. Whistles ranged in frequency from 9.7±2.8 to 19.8±4.2 kHz, had a mean duration of 0.7±0.5 s and a mean of 1.2±1.2 inflection points. Thirteen foraging buzzes were recorded across all tags. Mean dive depth and duration were 16±9m and 1.9±1.0 min, respectively. Tagged animals spent the majority of time in the upper 10m (76.9%±16.1%) of the water column. Both whistle frequency characteristics and dive statistics measured here were similar to previously reported values for spotted dolphins in Hawai'i. Shallow, short dive profiles combined with few foraging buzzes provide evidence that little spotted dolphin feeding behavior occurs during daytime hours. This work represents one of the first successful DTAG3 studies of small pelagic delphinids, providing rare insights into baseline bioacoustics and dive behavior. [ABSTRACT FROM AUTHOR]

Acoustic recordings of two closely related species, spinner dolphin ( Stenella longirostris) and pantropical spotted dolphin ( Stenella attenuata), were investigated from four different geographic locations: two in the Central Tropical Pacific, one in the Eastern Tropical Pacific and one in the Indian Ocean. The two delphinid species occur in tropical and warm temperate waters, with overlapping ranges. They produce very similar vocalizations, but at the same time their calls exhibit a certain degree of intraspecific variation among different geographic locations as has been observed in other delphinid species. Oscillatory whistles (whistles with at least two oscillations in their frequency contours) were identified and manually extracted from the recordings. Whistles with four or more maxima (oscillations) occurred only in spinner dolphins and they were present in all geographic regions investigated. In addition, the oscillatory whistles with two and three maxima were significantly more frequent in spinner than in spotted dolphins. The differences in oscillatory whistles for these two species seem to be consistent across study areas and therefore, could be used in addition to other whistle features to help distinguish between them. [ABSTRACT FROM AUTHOR]

Paralelo a un estudio de zooplancton (1999-2000), se hicieron observaciones a bordo de un bote inflable, sobre la presencia o ausencia de delfines a lo largo de un transecto (~8 km long) en la parte central de Bahía Culebra (24 km² ), Golfo de Papagayo. Se realizaron 34 muestreos en total y hubo avistamientos de delfines en 20 de ellos. La única especie de cetáceo observado en la Bahía fue el delfín manchado (Stenella attenuata). Estos avistamientos fueron más frecuentes durante la época lluviosa, en particular durante el mes de mayo de ambos años. La presencia de S. attenuata en Bahía Culebra podría estar asociada a la abundancia de presas potenciales como peces y moluscos (calamares), como se evidencia por las estadísticas pesqueras disponibles para la zona Pacífica de Costa RicaParallel to a zooplankton study (1999-2000) observations were made (from an inflatable boat), on the presence of dolphins along a transect (~8 km long) on the axis of Culebra Bay (24 km² ), Gulf of Papagayo, Pacific coast of Costa Rica. Dolphins were found during 20 of the 31 boat surveys conducted. The only species of cetacean found in the bay was Stenella attenuata, the spotted dolphin. These sightings were more frequent during the rainy season, particularly during the month of May of both years. The presence of S. attenuata in Culebra Bay might be associated to the abundances of fish and mollusks (their presumed prey: for example, squids), as evidenced by fishery statistics available for this zone of the Pacific coast of Costa Rica

Managing wildlife-human interactions demands reliable information about the likely consequences of management actions. This requirement is a general one, whatever the taxonomic group. We describe a method for estimating population dynamics and decision analysis that is generally applicable, extremely flexible, uses data efficiently, and gives answers in a useful format. Our case study involves bycatch of a protected species, the Northeastern Offshore Spotted Dolphin (Stenella attenuata), in the tuna fishery of the eastern Pacific Ocean. Informed decision-making requires quantitative analyses taking all relevant information into account, assessing how bycatch affects these species and how regulations affect the fisheries, and describing the uncertainty in analyses. Bayesian analysis is an ideal framework for delivering information on uncertainty to the decision-making process. It also allows information from other populations or species or expert judgment to be included in the analysis, if appropriate. Integrated analysis attempts to include all relevant data for a population into one analysis by combining analyses, sharing parameters, and simultaneously estimating all parameters, using a combined objective function. It ensures that model assumptions and parameter estimates are consistent throughout the analysis, that uncertainty is propagated through the analysis, and that the correlations among parameters are preserved. Perhaps the most important aspect of integrated analysis is the way it both enables and forces consideration of the system as a whole, so that inconsistencies can be observed and resolved.

On October 1, 2009, sixteen dolphins were obtained from fishermen by incidental catching in the Yellow Sea, China. As the dolphins' skin color was ambiguous, morphological parameters were measured, and mitochondrial DNA cytochrome b (Cyt b) gene sequence was studied to identify the species. Morphological characteristics were consistent with Pantropical spotted dolphins, Stenella attenuata. Furthermore, a partial mitochondrial DNA cytochrome b (Cyt b) gene sequence as long as 328-bp was studied by extracting genomic DNA from the skins, and six haplotypes were detected in the sixteen dolphins. By comparing homologous sequences available in GenBank (), all the six haplotypes had maximal genetic similarity with Pantropical spotted dolphin. Eight species of cetacean (whales and dolphins) are now recognised in the Yellow Sea. To the best of our knowledge, this is the first record of Pantropical spotted dolphins from this region. Despite this species being listed as a Grade II National Key Protected Animal since 1988, little is known of its biology in Chinese waters. We recommend remedial research be undertaken to ensure appropriate management. [ABSTRACT FROM AUTHOR]

The article presents the first report of sperm whale (Physeter macrocephalus) attacks by killer whales (Orcinus orca) in the Gulf of Mexico. It states that an interaction between sperm whales and killer whales was observed using a vessel doing mid-water trawling operations in the gulf. It also says that killer whales have been observed attacking other marine mammals including pantropical spotted dolphins (Stenella attenuata).

A total of 24 stranded or bycatch cetaceans, including Balaenoptera omurai , Lagenodelphis hosei , Kogia sima , Stenella attenuata , Grampus griseus , Neophocaena phocaenoides , and Sousa chinensis, were collected from 2001 to 2011 in Taiwan. Using the muscular δ 13 C and δ 15 N data, three ecological groups were identified as the oceanic baleen whale, the neritic, and the coastal toothed whale groups, coinciding with their taxonomy, feeding habits and geographical distribution. A horizontal inshore to offshore distribution was found for the sympatric neritic toothed dolphins, G. griseus , K. sima , S. attenuata , and L. hosei in the outermost offshore waters, accompanying their growth. For the first time we identify Taiwan’s Chinese white dolphin, S. chinensis, as an exclusive fish eater. Cd and As bioaccumulated in the G. griseus , L. hosei and S. attenuata increase as they grow. Prey-derived As- and Cd-induced health threats were found in L. hosei , and G. griseus . [ABSTRACT FROM AUTHOR]

The article focuses on an attack by smooth hammerhead sharks on some pantropical spotted dolphins in waters off Brazil, and discusses some features of group antipredation tactics. A linear regression model was used to examine the relationship between distances from adult dolphins followed by sharks to subgroups.