Alternative Approach for Sectioning Beaked Whale Teeth for Ageing

Beaked whales are one of the least known groups of cetaceans and very little information is available on age for most species in this family. The paucity of age data is due to the availability of specimens and also a reluctance to allow the destructive sampling required to age these rare teeth. We examined teeth from four species of ziphiids that inhabit subantarctic waters to evaluate whether sections taken on a plane that was not mid-longitudinal would produce counts of cemental growth layer groups (GLGs) comparable to sections taken on the traditional mid-longitudinal plane. We used teeth of Cuvier?s beaked whale Ziphius cavirostris (n=12), Layard?s beaked whale Mesoplodon layardii (n=8), Gray?s beaked whale M. grayi (n=6) and Shepherd?s beaked whale Tasmacetus shepherdi (n=2) of different ontogenetic classes from the R. Natalie P. Goodall collection, held at the Museo Acatushún de Aves y Mamiferos Marinos Australes, Tierra del Fuego, Argentina. Teeth were initially cut on a low-speed saw into sections using pre-defined planes, one mid-longitudinal and 1-2 at different tangents at the edge of the tooth. At all selected locations, a 2-3mm thick section was cut, decalcified, and stained. Teeth from most specimens showed a clear layering pattern. GLGs in dentine were generally visible and similar to delphinids, but dentine became irregular at a relatively young age precluding use for age estimation. GLGs in cement varied among species but generally were distinct. In at least two species, M. grayi and M. layardii, it does appear that, from cemental GLGs, sections taken tangential to the mid-longitudinal plane can produce age estimates similar to mid-longitudinal sections. Finding a less destructive approach to sectioning teeth may facilitate ageing for beaked whale species.Fil: Dellabianca, Natalia Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; ArgentinaFil: Aleta A. Hohn. National Marine Fisheries Service; Estados Unidos22nd Biennial Conference on the Biology of Marine MammalsHalifaxCanadáSociety of Marine Mammalog

Spatial Models of Abundance and Habitat Preferences of Commerson’s and Peale’s Dolphin in Southern Patagonian Waters

Funding: This research was possible with the support of the Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET). Funding for travel to and accommodation for NAD in Aberdeen, Scotland was provided by CONICET and Cetacean Society International. The work of NAD was part of a postdoctoral fellowship funded by CONICET. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Peer reviewedPublisher PD

Age estimation and growth layer patterns in teeth of Commerson’s dolphins (\u3ci\u3eCephalorhynchus c. commersonii\u3c/i\u3e) in subantarctic waters

The Commerson’s dolphin, Cephalorhynchus c. commersonii, one of the world’s smallest cetaceans, occurs in the southwestern South Atlantic from about 41°30\u27S to near Cape Horn (56°S), including the central and eastern Strait of Magellan and the Falkland (Malvinas) Islands (Goodall 1978, Goodall et al. 1988). Along the coasts of Patagonia, northern Tierra del Fuego, Argentina, and the eastern Strait of Magellan, Chile, this is the cetacean most often seen near shore, where the animals feed and surf in the breakers. They seldom strand, but are commonly taken incidentally in shore-based gill nets set perpendicular to the coast over the wide tidal flats (Goodall 1978, 1994; Goodall et al. 1994, 2008; Iñíguez et al. 2003). Although there have been few aerial surveys, this is probably the most abundant small cetacean in these waters and is the most affected by bycatch in artisanal fisheries. Age estimation in marine mammals by counting incremental layers in teeth has been carried out since the 1950s (Scheffer and Myrick 1980). As mentioned in Hohn (2002), the importance of age estimation goes beyond population dynamic studies, and the information on age at sexual maturation and population age structure may help to adopt adequate policies in conservation management (Read and Hohn 1995, Hohn et al. 1996). Additional information can be obtained from teeth, such as life history or environmental events (Klevezal and Myrick 1984, Manzanilla 1989; Lockyer 1993, 1995; Klevezal 1996, Luque et al. 2009). Therefore, the description of a “basic or typical” pattern of a species gives us not only more accurate and precise age estimates, but also allows for the identification of accessory layers (ALs) and other tooth-tissue alterations, which could be correlated with intrinsic or extrinsic factors

Age estimation and growth layer patterns in teeth of Commerson's dolphins (Cephalorhynchus c. commersonii) in subantarctic waters

The Commerson’s dolphin, Cephalorhynchus c. commersonii, one of the world’s smallest cetaceans, occurs in the southwestern South Atlantic from about 41"30#S to near Cape Horn (56"S), including the central and eastern Strait of Magellan and the Falkland (Malvinas) Islands (Goodall 1978, Goodall et al. 1988). Along the coasts of Patagonia, northern Tierra del Fuego, Argentina, and the eastern Strait of Magellan, Chile, this is the cetacean most often seen near shore, where the animals feed and surf in the breakers. They seldom strand, but are commonly taken incidentally in shore-based gill nets set perpendicular to the coast over the wide tidal flats (Goodall 1978, 1994; Goodall et al. 1994, 2008; I˜n´ıguez et al. 2003). Although there have been few aerial surveys, this is probably the most abundant small cetacean in these waters and is the most affected by bycatch in artisanal fisheries.Fil: Dellabianca, Natalia Andrea. Museo Acatushún de Aves y Mamíferos Marinos Australes; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; ArgentinaFil: Hohn, Aleta A.. National Marine Fisheries. Service Southeast Fisheries Center; Estados UnidosFil: Prosser Goodall, Rae Natalie. Museo Acatushún de Aves y Mamíferos Marinos Australes; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentin

Sighting data base

This dataset has Commerson’s dolphin <i>Cephalorhynchus c. commersonii</i> and Peale’s dolphin <i>Lagenorhynchus australis</i> sightings collected during eight scientific cruises on board of the vessels <i>R/V Puerto Deseado</i> and <i>Tango SB-15 </i>of Argentina<i> </i>during austral summer and fall months (November-April) between 2009 and 2015, along the Patagonian shelf .<div>Cetacean sightings were recorded on a portable handheld computer with integrated GPS (Trimble Juno ST), using the free software CyberTracker (CyberTracker Software (Pty) Ltd Reg. no. 97/01908/07, http://www.cybertracker.co.za). Surveys were conducted daily during daylight hours (~ 12 hrs) at a mean vessel speed of 10 knots. During the surveys, two observers collected the data from both sides of the vessel, through naked eye scans supplemented by use of 7x50 binoculars<b> </b>with internal compass and reticle. A third observer assisted in the scans and recorded observations. Observers switched between the three positions at 2 hour intervals. Data recorded for each sighting included GPS position, date and time, sighting distance, sighting angle, species, group size and composition. Vessel speed, air temperature, wind speed and direction, Beaufort Sea State (BSS), cloud cover and visibility were recorded at the start of each day and updated whenever they changed.</div

Influence of climate oscillations on dentinal deposition in teeth of Commerson's dolphin

Effects of climatic oscillations on populations in marine environments are produced mainly through the lower trophic levels. Marine mammals, as top predators, are affected indirectly by these fluctuations, showing variations in their survival, growth and reproduction. The main objective of this study was to determine whether we could detect the effect of climatic oscillations on Commerson's dolphins (Cephalorhynchus c. commersonii) off Tierra del Fuego, Argentina, by examining the presence and proportion of anomalous dentinal growth layer groups (GLGs). The relative deposition of anomalous GLGs was determined using calendar years from 1960 to 2005, and related to the Southern Annular Mode (SAM) and El Niño Southern Oscillation (ENSO) events, and to mean annual sea surface temperatures (SST). Then, growth parameters between animals that did and did not show anomalous dentinal growth layer patterns in one or more of their GLGs were compared. The presence of anomalous GLGs was related to the SAM, increasing in frequency with negative values of the SAM. No relationship was found among anomalous GLGs, ENSO, and SST. There were no significant differences in growth parameters between animals with and without anomalous GLGs. Using recording structures such as teeth provided a unique way of reconstructing time series to evaluate the effects of these climatic patterns on a top predator species in an area where no similar studies have been conducted, primarily due to a lack of suitable long-term data sets.Fil: Dellabianca, Natalia Andrea. Museo Acatushún de Aves y Mamíferos Marinos Australes; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; ArgentinaFil: Hohn, Aleta A.. National Marine Fisheries Service Southeast Fisheries Center Beaufort Laboratory Beaufort; Estados UnidosFil: Prosser Goodall, Rae Natalie. Museo Acatushún de Aves y Mamíferos Marinos Australes; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; ArgentinaFil: Pousa, Jorge Lorenzo. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Laboratorio de Oceanografía Costera y Estuarios; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Macleod, Colin D.. University of Aberdeen; Reino UnidoFil: Lima, Mauricio. Pontificia Universidad Católica de Chile; Chil

Sighting data base

This dataset has Commerson’s dolphin Cephalorhynchus c. commersonii and Peale’s dolphin Lagenorhynchus australis sightings collected during eight scientific cruises on board of the vessels R/V Puerto Deseado and Tango SB-15 of Argentina during austral summer and fall months (November-April) between 2009 and 2015, along the Patagonian shelf

Records of Risso\u27s dolphin, Grampus griseus, in coastal waters of southern Argentina

We review the records of published and unpublished sightings and strandings for Risso's dolphin (Grampus griseus) in subantarctic waters of the Southwestern South Atlantic Ocean. Based on 59 sighting (n = 521 individuals) and 33 stranding records (n = 88 individuals), we identified three main areas of Risso's dolphin concentration in Patagonian waters, which have been observed mostly during the austral summer. We were unable to find published or unpublished reports of Risso's dolphin in offshore or over deep-water areas in this region. Future studies covering other potential areas of the species' distribution are important to improve the scarce information known for this dolphin in this area

Tracks of the different scientific cruises surveys during austral summer and fall months.

<p>Each single line of each cruise represents one day of survey effort. Black polygon indicates the region of study analyzed. White polygon indicates the primary range of distribution of Commerson’s dolphin in the southwest South Atlantic Ocean. Red polygon indicates the primary range of distribution of Peale’s dolphin in the southwest South Atlantic Ocean.</p

Autocorrelation of deviance residuals between segments (lags) for the fitted density surface model of Commerson’s dolphin.

<p>The dashed line represents the 95% confidence interval.</p