Pacific White-sided Dolphin Lagenorhynchus Obliquidens Research Articles

Genomics reveals a genetically isolated population of the Pacific white-sided dolphin (Lagenorhynchus obliquidens) distributed in the Sea of Japan.

The processes by which animals become genetically isolated in an open environment such as the ocean have not yet been fully elucidated. Morphologically different populations of Pacific white-sided dolphin Lagenorhynchus obliquidens are observed sympatrically in the Sea of Japan. However, genetic studies that exclusively used limited mitochondrial loci or microsatellite DNA have failed to demonstrate the existence of genetically distinct populations. Here, to reveal the population structure, we analysed genome-wide population genetic data using single nucleotide polymorphisms (SNPs) gathered in 2018-2021 from all domestic captive individuals in aquaria, the majority of which originated from the wild, as well as from some stranded individuals, together covering a wide area of coastal water around Japan (n=123). Multiplexed intersimple sequence repeat genotyping-by-sequencing analysis was performed to obtain the SNP data. Principal coordinate analysis and the clustering method structure indicated that two genetically-distinct populations exist, with little interpopulation gene flow revealed. In addition, the genotypic segregation was reflected in differences in external morphotype. Furthermore, a population demographic analysis based on the whole-genome sequences of an individual from each population indicated that sea-level changes during the Last Glacial Period probably led to allopatric divergence of this species in a limited area of the Sea of Japan, with that group subsequently sharing a distribution area with the other population. These findings yield insights into the formation of genetically isolated sympatric populations in the ocean.

Epizootiology of a Cryptococcus gattii outbreak in porpoises and dolphins from the Salish Sea.

Cryptococcus gattii is a fungal pathogen that primarily affects the respiratory and nervous systems of humans and other animals. C. gattii emerged in temperate North America in 1999 as a multispecies outbreak of cryptococcosis in British Columbia (Canada) and Washington State and Oregon (USA), affecting humans, domestic animals, and wildlife. Here we describe the C. gattii epizootic in odontocetes. Cases of C. gattii were identified in 42 odontocetes in Washington and British Columbia between 1997 and 2016. Species affected included harbor porpoises Phocoena phocoena (n = 26), Dall's porpoises Phocoenoides dalli (n = 14), and Pacific white-sided dolphins Lagenorhynchus obliquidens (n = 2). The probable index case was identified in an adult male Dall's porpoise in 1997, 2 yr prior to the initial terrestrial outbreak. The spatiotemporal extent of the C. gattii epizootic was defined, and cases in odontocetes were found to be clustered around terrestrial C. gattii hotspots. Case-control analyses with stranded, uninfected odontocetes revealed that risk factors for infection were species (Dall's porpoises), age class (adult animals), and season (winter). This study suggests that mycoses are an emerging source of mortality for odontocetes, and that outbreaks may be associated with anthropogenic environmental disturbance.

Brucella ceti sequence type 23, 26, and 27 infections in North American cetaceans.

Brucella ceti infection is associated with a variety of disease outcomes in cetaceans globally. Multiple genotypes of B. ceti have been identified. This retrospective aimed to determine if specific lesions were associated with different B. ceti DNA sequence types (STs). Characterization of ST was performed on 163 samples from 88 free-ranging cetaceans, including common bottlenose dolphin Tursiops truncatus (T.t.; n = 73), common short-beaked dolphin Delphinus delphis (D.d.; n = 7), striped dolphin Stenella coeruleoalba (n = 3), Pacific white-sided dolphin Lagenorhynchus obliquidens (n = 2), sperm whale Physeter macrocephalus (n = 2), and harbour porpoise Phocoena phocoena (n = 1), that stranded along the coast of the US mainland and Hawaii. ST was determined using a previously described insertion sequence 711 quantitative PCR. Concordance with 9-locus multi-locus sequence typing was assessed in a subset of samples (n = 18). ST 26 was most commonly identified in adult dolphins along the US east coast with non-suppurative meningoencephalitis (p = 0.009). Animals infected with ST 27 were predominately perinates that were aborted or died shortly after birth with evidence of in utero pneumonia (p = 0.035). Reproductive tract inflammation and meningoencephalitis were also observed in adult T.t. and D.d. with ST 27, though low sample size limited interpretation. ST 23 infections can cause disease in cetacean families other than porpoises (Phocoenidae), including neurobrucellosis in D.d. In total, 11 animals were potentially infected with multiple STs. These data indicate differences in pathogenesis among B. ceti STs in free-ranging cetaceans, and infection with multiple STs is possible.

Spatial niche partitioning among three small cetaceans in the eastern coastal area of Hokkaido, Japan

Spatial niche partitioning of marine mammals is thought to be caused by dietary differences. However, due to the difficulty involved with conducting simultaneous marine predator and prey distribution surveys at the same scale, marine mammals have not been studied alongside their prey distribution. To understand the spatial niche overlap between 3 small cetaceans observed in the eastern coastal waters of Hokkaido, Japan (Pacific white-sided dolphinLagenorhynchus obliquidens, Dall’s porpoisePhocoenoides dalli, and harbor porpoisePhocoena phocoena), and the mechanisms behind the differences in their distributions, visual and hydroacoustic surveys using a quantitative echosounder were concurrently conducted. A clear spatial niche overlap was observed between the Pacific white-sided dolphin and Dall’s porpoise, whereas the spatial overlap was moderate between the harbor porpoise and the other 2 species. In areas where Pacific white-sided dolphins were observed, potential prey was abundant in a shallower layer, at approximately 80-90 m depth. On the other hand, potential prey was more abundant in deeper layers in areas where Dall’s and harbor porpoises were observed. Water depth affected the potential prey abundance at all depth layers (0-300 m), as potential prey were more abundant in areas with a shallower water depth. Additionally, potential prey were more abundant in shallower layers (3-200 m) than in deeper layers (200-300 m), where the maximum water depth was 3000 m. The differences in spatial niche among Pacific white-sided dolphin, Dall’s porpoise, and harbor porpoise might cause their dietary differences, as they are epipelagic feeders, midwater feeders, and both epipelagic and midwater feeders, respectively.

Predicting seasonal density patterns of California cetaceans based on habitat models

ESR Endangered Species Research Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials ESR 23:1-22 (2014) - DOI: https://doi.org/10.3354/esr00548 Theme Section: Geospatial approaches to support pelagic conservation planning and adaptive management Predicting seasonal density patterns of California cetaceans based on habitat models Elizabeth A. Becker1,2,*, Karin A. Forney1, David G. Foley3,4, Raymond C. Smith5, Thomas J. Moore6, Jay Barlow6 1Marine Mammal and Turtle Division, Southwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, 110 Shaffer Rd, Santa Cruz, California 95060, USA 2Ocean Associates Inc., 4007 N. Abingdon Street, Arlington, Virginia 22207, USA 3Institute of Marine Sciences, University of California at Santa Cruz, 1000 Shaffer Rd, Santa Cruz, California 95060, USA 4Environmental Research Division, Southwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, 1352 Lighthouse Ave, Pacific Grove, California 93950, USA 5Environmental Research Institute, UCSB, Santa Barbara, California 93106, USA 6Marine Mammal and Turtle Division, Southwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, 8901 La Jolla Shores Dr., La Jolla, California 92037, USA *Corresponding author: ebecker77@cox.net ABSTRACT: Temporal variability in species distribution remains a major source of uncertainty in managing protected marine species, particularly in ecosystems with significant seasonal or interannual variation, such as the California Current Ecosystem (CCE). Spatially explicit species–habitat models have become valuable tools for decision makers assisting in the development and implementation of measures to reduce adverse impacts (e.g. from fishery bycatch, ship strikes, anthropogenic sound), but such models are often not available for all seasons of interest. Broad-scale migratory patterns of many of the large whale species are well known, while seasonal distribution shifts of small cetaceans are typically less well understood. Within the CCE, species–habitat models have been developed based on 6 summer-fall surveys conducted during 1991 to 2008. We evaluated whether the between-year oceanographic variability can inform species predictions during winter-spring periods. Generalized additive models were developed to predict abundance of 4 cetacean species/genera known to have year-round occurrence in the CCE: common dolphins Delphinus spp., Pacific white-sided dolphin Lagenorhynchus obliquidens, northern right whale dolphin Lissodelphis borealis, and Dall’s porpoise Phocoenoides dalli. Predictor variables included a combination of temporally dynamic, remotely sensed environmental variables and geographically fixed variables. Across-season predictive ability was evaluated relative to aerial surveys conducted in winter-spring 1991 to 1992, using observed:predicted density ratios, nonparametric Spearman rank correlation tests, and visual inspection of predicted and observed distributions by species. Seasonal geographic patterns of species density were captured effectively for most species, although some model limitations were evident, particularly when the original summer-fall data did not adequately capture winter-spring habitat conditions. KEY WORDS: Cetacean abundance · Habitat-based density model · California Current · Remote sensing · Common dolphin · Pacific white-sided dolphin · Northern right whale dolphin · Dall’s porpoise Full text in pdf format NextCite this article as: Becker EA, Forney KA, Foley DG, Smith RC, Moore TJ, Barlow J (2014) Predicting seasonal density patterns of California cetaceans based on habitat models. Endang Species Res 23:1-22. https://doi.org/10.3354/esr00548 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in ESR Vol. 23, No. 1. Online publication date: January 28, 2014 Print ISSN: 1863-5407; Online ISSN: 1613-4796 Copyright © 2014 Inter-Research.

목시조사(2000-2010)에 의한 한국 연안 고래류의 종류 및 분포

In the late 1970s, the National Fisheries Research & Development Institute (NFRDI) started cetacean research to submit the Korean whale catch record to the International Whaling Commission. This continued until the moratorium on commercial whaling in 1986. The NFRDI resumed cetacean research with a pilot whale sighting survey in 1999. Subsequently, the NFRDI has conducted 53 cetacean sighting surveys within the Korean exclusive economic zone between 2000 and 2010. The surveys took a total of 760 days and cruising for 23,866 nautical miles. The finless porpoise Neophocaena asiaeorientalis was sighted most frequently (735 times), followed by the minke whale Balaenoptera acutorostrata (396 times), the long-beaked common dolphin Delphinus capensis (102 times), and the Pacific white-sided dolphin Lagenorhynchus obliquidens (27 times). Minke whales were distributed in the Yellow Sea and coastal area of the East Sea from spring to fall. Pacific white-sided dolphin sightings were restricted to the middle and upper coastal areas of the East Sea in summer. Common dolphins were sighted from east of the southern coast to the eastern coast of the Korean Peninsula from spring to fall. Finless porpoise occurred in all Korean coastal areas, except the middle and upper eastern coast.

The relationship between the estimated migrated population of Pacific White-sided dolphins Lagenorhynchus obliquidens and abundance of prey species

The relationship between the estimated migrated population of Pacific White-sided dolphins Lagenorhynchus obliquidens and abundance of prey species

Risso’s and Pacific white-sided dolphin habitat modeling from passive acoustic monitoring

Habitat characterization allows prediction of dolphin distributions in response to oceanographic processes and can be used to understand and predict effects of anthropogenic disturbances. Many habitat models focus on contemporary dolphin occurrence and environmental predictor data, but time-lagged oceanographic data may increase a model's predictive power due to ecological successional processes. Using hourly occurrence of Risso's dolphin Grampus griseus clicks and 2 types of Pacific white-sided dolphin Lagenorhynchus obliquidens clicks in autonomous passive acoustic recordings, we investigate the importance of time-lagged predictor variables with general- ized additive models. These models relate dolphin acoustic activity from recordings at 6 sites in the Southern California Bight between August 2005 and December 2007 to oceanographic variables including sea surface temperature (SST), SST coefficient of variation (CV), sea surface chlorophyll concentration (chl), chl CV, upwelling indices, and solar and lunar temporal indices. The most consis- tently selected variables among the trial models evaluated during cross-validation were SST (100% of models) and SST CV (80%) for Risso's dolphin clicks; solar indices (100%) and SST and SST CV (60% each) for Pacific white-sided type A (PWS A) clicks; and SST CV (100%), solar indices (100%) and SST (80%) for Pacific white-sided type B (PWS B) clicks. Best predictive models for Risso's dolphins and PWS A clicks included time-lagged variables, suggesting the importance of ecological succession between abiotic variables and dolphin occurrence, while best models of PWS B clicks were for current conditions, suggesting association with prey-aggregating features such as fronts and eddies.

Spatio-temporal comparison of Pacific white-sided dolphin echolocation click types

A comparison of temporal and geographical trends in different echolocation click types produced by Pacific white-sided dolphin Lagenorhynchus obliquidens can lead to insights into the significance of their usage by the dolphins. Using autonomous seafloor recording packages, the spa- tial, diel and seasonal patterns of Pacific white-sided dolphin echolocation click activity are described for 6 locations in the Southern California Bight. Click bouts of the 2 types of Pacific white-sided dol- phin echolocation clicks are identified based on their unique spectral characteristics in long-term spectral averages. Type A clicks were detected on 317 of 1959 recording days and were heard at all 6 sites, with the majority of detections occurring at San Clemente Island and Point Conception. Type B clicks were detected on 130 recording days and were only heard at the 2 southern inshore sites. Significant diel patterns were evident for both click types: Type A click bouts were detected during more hours and with higher click rates at night than during the day, while Type B click bouts exhib- ited the opposite behavior, with greater activity during the day. At the southern sites, both click types exhibited a fall-winter peak in seasonal occurrence. At Point Conception, where only Type A was detected, peak occurrence was during spring. The described spatial and seasonal patterns support the hypothesis that click types are population-specific, while diel patterns suggest differences in prey preferences.

Climate change and a poleward shift in the distribution of the Pacific white-sided dolphin in the northeastern Pacific

Increasing water temperatures due to global warming mean that specific isotherms are shifting polewards. This may cause the poleward shifts in the range limits of species that are only found in specific thermal habitats. Such range shifts have been recorded in a number of plant and animal species. In the last 3 decades, we observed a decline in the presence of Pacific white-sided dolphin Lagenorhynchus obliquidens in the southwest Gulf of California (GOC), which is considered the southern boundary of their distribution. Considering that the thermal environment is physiologi- cally important to animals, we believe that this poleward shift in the usual geographic range of the Pacific white-sided dolphin is due to long-term changes in the local climate. To obtain the conceptual framework needed to discuss such a hypothesis, we summarize and analyze current knowledge about Pacific white-sided dolphins in the southwest GOC, and sea surface temperature variability at a regional scale.

Temporal change of school size on Pacific white-sided dolphin Lagenorhynchus obliquidens in the Tsugaru Strait, Japan

Temporal change of school size on Pacific white-sided dolphin Lagenorhynchus obliquidens in the Tsugaru Strait, Japan

Cetacean distributions relative to ocean processes in the northern California Current System

Abstract Associations between cetacean distributions, oceanographic features, and bioacoustic backscatter were examined during two process cruises in the northern California Current System (CCS) during late spring and summer 2000. Line-transect surveys of cetaceans were conducted across the shelf and slope, out to 150 km offshore from Newport, Oregon (44.6°N) to Crescent City, California (41.9°N), in conjunction with multidisciplinary mesoscale and fine-scale surveys of ocean and ecosystem structure. Occurrence patterns (presence/absence) of cetaceans were compared with hydrographic and ecological variables (e.g., sea surface salinity, sea surface temperature, thermocline depth, halocline depth, chlorophyll maximum, distance to the center of the equatorward jet, distance to the shoreward edge of the upwelling front, and acoustic backscatter at 38, 120, 200 and 420 kHz) derived from a towed, undulating array and a bioacoustic system. Using a multiple logistic regression model, 60.2% and 94.4% of the variation in occurrence patterns of humpback whales Megaptera novaeangliae during late spring and summer, respectively, were explained. Sea surface temperature, depth, and distance to the alongshore upwelling front were the most important environmental variables during June, when humpbacks occurred over the slope (200–2000 m). During August, when humpbacks concentrated over a submarine bank (Heceta Bank) and off Cape Blanco, sea surface salinity was the most important variable, followed by latitude and depth. Humpbacks did not occur in the lowest salinity water of the Columbia River plume. For harbor porpoise Phocoena phocoena, the model explained 79.2% and 70.1% of the variation in their occurrence patterns during June and August, respectively. During spring, latitude, sea surface salinity, and thermocline gradient were the most important predictors. During summer, latitude and distance to the inshore edge of the upwelling front were the most important variables. Typically a coastal species, harbor porpoises extended their distribution farther offshore at Heceta Bank and at Cape Blanco, where they were associated with the higher chlorophyll concentrations in these regions. Pacific white-sided dolphin Lagenorhynchus obliquidens was the most numerous small cetacean in early June, but was rare during August. The model explained 44.5% of the variation in their occurrence pattern, which was best described by distance to the upwelling front and acoustic backscatter at 38 kHz. The model of the occurrence pattern of Dall's porpoise Phocoenoides dalli was more successful when mesoscale variability in the CCS was higher during summer. Thus, the responses of cetaceans to biophysical features and upwelling processes in the northern CCS were both seasonally and spatially specific. Heceta Bank and associated flow-topography interactions were very important to a cascade of trophic dynamics that ultimately influenced the distribution of foraging cetaceans. The higher productivity associated with upwelling near Cape Blanco also had a strong influence on the distribution of cetaceans.

A review of virus infections of cataceans and the potential impact of morbilliviruses, poxviruses and papillomaviruses on host population dynamics.

Viruses belonging to 9 families have been detected in cetaceans. We critically review the clinical features, pathology and epidemiology of the diseases they cause. Cetacean morbillivirus (family Paramyxoviridae) induces a serious disease with a high mortality rate and persists in several populations. It may have long-term effects on the dynamics of cetacean populations either as enzootic infection or recurrent epizootics. The latter presumably have the more profound impact due to removal of sexually mature individuals. Members of the family Poxviridae infect several species of odontocetes, resulting in ring and tattoo skin lesions. Although poxviruses apparently do not induce a high mortality, circumstancial evidence suggests they may be lethal in young animals lacking protective immunity, and thus may negatively affect net recruitment. Papillomaviruses (family Papovaviridae) cause genital warts in at least 3 species of cetaceans. In 10% of male Burmeister's porpoises Phocoena spinipinnis from Peru, lesions were sufficiently severe to at least hamper, if not impede, copulation. Members of the families Herpesviridae, Orthomyxoviridae and Rhabdoviridae were demonstrated in cetaceans suffering serious illnesses, but with the exception of a 'porpoise herpesvirus' their causative role is still tentative. Herpes-like viruses and caliciviruses (Caliciviridae) give rise to cutaneous diseases in Monodontidae and Delphinidae. Antibodies to several serotypes of caliciviruses were found in odontocetes and mysticetes. An unrecognized Hepadnaviridae was detected by serology in a captive Pacific white-sided dolphin Lagenorhynchus obliquidens with chronic persistent hepatitis. Adenoviruses (Adenoviridae) were isolated from the intestinal tracts of mysticeti and a beluga Delphinapterus leucas but were not associated with any pathologies. We discuss the potential impact of Paramyxoviridae, Poxviridae and Papovaviridae on the dynamics of several odontocete populations.