Short-finned Pilot Whales Globicephala Macrorhynchus Research Articles

An assessment of behavioral criteria used to estimate aerobic dive limit: the influence of body size, group membership, and location on dive durations of short-finned pilot whales Globicephala macrorhynchus

An assessment of behavioral criteria used to estimate aerobic dive limit: the influence of body size, group membership, and location on dive durations of short-finned pilot whales Globicephala macrorhynchus

Insights into the Relative Abundance, Life History, and Ecology of Oceanic Sharks in the Eastern Bahamas

Fisheries-independent data on the diversity, relative abundance, and demographic structure of poorly studied, threatened oceanic sharks are absent from much of the western North Atlantic Ocean, where multiple oceanic shark species have experienced significant population declines. Resource-limited management approaches require the identification of critical habitats or aggregation sites worthy of protection and enforcement. Data were collected on oceanic sharks using pelagic longline surveys, targeted baiting, and opportunistic encounters in oligotrophic open-ocean habitats of north-eastern Exuma Sound (NES), The Bahamas. The oceanic epipelagic shark community was also characterized using targeted baiting off Columbus Point, Cat Island (CI), a seamount north of San Salvador (SSSM), and the northwestern tip of Mayaguana. Pelagic longline surveys suggested that the relative abundance of sharks at NES was low (shark catch-per-unit-effort: 0.0007 sharks hook−1 h−1; 2.3 sharks per 1000 hooks). Silky sharks Carcharhinus falciformis, particularly juveniles (134 ± 39 cm stretched total length; mean ± SD STL), were the most common. Targeted baiting suggested oceanic whitetip sharks C. longimanus were abundant at CI, where large adults (245 ± 23 cm STL), most of which were females (83.8%, n = 98 of 117) that were gravid (65.7%; n = 46 of 70 assessed for pregnancy), dominated the aggregation. Many (20.5–26.5%, n = 24–31 of 117 depending on assumptions regarding tag loss) were recaptured or resighted at CI for up to five years. Silky sharks dominated catches at SSSM. Oceanic sharks, particularly adults, were sometimes caught or observed alongside short-finned pilot whales Globicephala macrorhynchus or tunas. Although The Bahamas offers threatened oceanic sharks refuge from fishing across its entire jurisdiction, these data suggest that some fixed features, including sites such as CI and potentially SSSM, are important aggregation sites with high regional conservation value and should be prioritized by fisheries managers and enforcement officials.

Marine mammals used as bait for improvised fish aggregating devices in marine waters of Ecuador, eastern tropical Pacific

Fish aggregating devices (FADs) are floating objects typically used to attract and capture pelagic fish in industrial tuna fisheries. This study documents 9 cases, involving 31 marine mammals, of incidentally captured, killed or otherwise retrieved cetaceans and pinnipeds which were used, or presumably used, as bait for improvised fish aggregation devices (IFAD) by artisanal fishers in coastal Ecuador. At least 3 species of small cetaceans were affected, including pantropical spotted dolphinStenella attenuata, short-finned pilot whaleGlobicephala macrorhynchus, pygmy killer whaleFeresa attenuataand an unidentified small delphinid, as well as South American sea lionsOtaria byroniawhich were reportedly killed on purpose for this fishing practice. A sperm whalePhyseter macrocephalusand a humpback whaleMegaptera novaeangliaewere presumably found floating at sea and opportunistically exploited as FADs. The South American sea lion represented 80.6% of marine mammals used as bait associated with FADs (25 sea lions out of 31 marine mammals), while the remaining 5 (possibly 6) cetacean species represented 19.4%. This is the first report of baited FADs in Ecuador, the extent of which is still unknown. This fishing technique has not been documented in other nations along the west coast of South America, although baiting of gillnets with marine mammal parts is common in Peru. Without fisheries management and regulation, this illegal fishing practice could rapidly expand and lead to further direct kills and conservation problems for targeted marine mammal populations in the eastern tropical Pacific. A bottom-up fisheries policy in concert with community-based conservation to ban the use of marine mammals as FAD bait is recommended.

Lunar cycles influence the diving behavior and habitat use of short-finned pilot whales around the main Hawaiian Islands

The availability of light, both solar and lunar, is likely to influence the behavior of vertically migrating aquatic animals and their predators. However, the influence of light level on the diving behavior and habitat use of deep-diving cetaceans is not well understood. We used data from 28 depth-transmitting satellite tags deployed on short-finned pilot whales Globicephala macrorhynchus around the main Hawaiian Islands to examine movements and diving behavior in relation to lunar cycles and oceanographic season. During a full moon, dives were deeper (48.1%) and longer (16.7%) than during a new moon. This change appeared to be driven primarily by an increase (25.2%) in the depth of deep dives (>200 m) completed at night and an increase in the proportion of deeper daytime and twilight dives during a full moon. Dives occurred a mean of 18.3 km farther offshore (more than twice as far from shore) during a full moon compared to a new moon. During the oceanographic season with the shortest day length (fall), dives were shallower (25.4%) and shorter (14.2%) than seasons with longer days (summer). This suggests that changes in light level, both solar and lunar, affect the depth of prey targeted by pilot whales, which in turn influences pilot whale diving behavior and distribution. Future research should determine how these changes influence the feeding success and energetics of pilot whales.

Validation of the photogrammetric method to assess body condition of an odontocete, the shortfinned pilot whale Globicephala macrorhynchus

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 620:185-200 (2019) - DOI: https://doi.org/10.3354/meps12971 Validation of the photogrammetric method to assess body condition of an odontocete, the shortfinned pilot whale Globicephala macrorhynchus S. R. Noren1,*, L. Schwarz1, K. Chase2, K. Aldrich3, K. McMahon-Van Oss3, J. St. Leger2 1Intitute of Marine Science, University of California Santa Cruz, Santa Cruz, CA 95060, USA 2SeaWorld San Diego, San Diego, CA 92109, USA 3SeaWorld Orlando, Orlando, FL 32821, USA *Corresponding author: snoren@ucsc.edu ABSTRACT: Validated metrics to monitor body condition of free-ranging animals are critical to track population stability. We tested repeatability and reliability of body width and body length measurements taken from overhead photographs and validated the assumptions upon which the photogrammetric method to monitor cetacean body condition are based. Short-finned pilot whales Globicephala macrorhynchus served as models. Variability was low for multiple measurements taken from 1 photograph and across photographs of the same animal; standard deviations represented 1.2 ± 1.2% and 2.5 ± 1.3% of mean estimates, respectively. To account for body length variations across whales, we calculated mass, width, and blubber indexes as the residual values of these variables regressed against length. Across the sites examined (anterior pectoral fin, anterior dorsal fin, and posterior dorsal fin), only photogrammetric body width at the posterior dorsal fin site showed consistent significant positive relationships with measured condition indexes (i.e. width and blubber index slope = 0.10, p = 0.005; width and mass index slope = 18.1, p < 0.01). Moreover, only the body width to body length ratio at this site predicted mass index (slope = 3105, p = 0.05). Thus, changes in photogrammetrically measured body width posterior of the dorsal fin at approximately 47% of total body length from the rostrum are related to changes in underlying blubber thickness and body mass. The width:length ratio at this site can be used to monitor condition. Additional studies are warranted to determine if body width at this site reliably predicts condition across odontocete species with varying body morphologies. KEY WORDS: Photogrammetry · Body condition · Blubber · Pilot whale · Odontocete · Disturbance Full text in pdf format PreviousNextCite this article as: Noren SR, Schwarz L, Chase K, Aldrich K, McMahon-Van Oss K, St Leger J (2019) Validation of the photogrammetric method to assess body condition of an odontocete, the shortfinned pilot whale Globicephala macrorhynchus. Mar Ecol Prog Ser 620:185-200. https://doi.org/10.3354/meps12971 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 620. Online publication date: June 18, 2019 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2019 Inter-Research.

Survey of Brucella spp. and Leptospira spp. antibodies in cetaceans and manatees of the Amazon basin and Atlantic Ocean, Brazil

Aquatic mammals can act as sentinels of emerging and resurging pathogens in the environment. Brucella spp. and Leptospira spp. are 2 zoonotic pathogens relevant to aquatic mammals, and their detection can be used to assess pathogen exposure. In this study, serum from 84 individuals-63 cetaceans (families Iniidae, n = 37; Delphinidae, n = 22; and Kogiidae, n = 4) and 21 West Indian manatees Trichechus manatus-was tested by the Rose Bengal Test (RBT) and a commercial competitive enzyme-linked immunosorbent assay (c-ELISA) for detecting Brucella spp. antibodies, and the microscopic agglutination test (MAT) for screening Leptospira spp. exposure. Overall, 4.8% (3/63) of cetaceans were positive by RBT and 15.9% (10/63) by c-ELISA for Brucella spp. Serum from 8 c-ELISA positive cetaceans (with available serum) was further tested via serum agglutination test (SAT) and 1 individual was positive. c-ELISA was more sensitive than RBT. Exposure to Brucella spp. was found in 5 cetacean species: Clymene dolphin Stenella clymene, short-finned pilot whale Globicephala macrorhynchus, pygmy killer whale Feresa attenuata, melon-headed whale Peponocephala electra and Atlantic bottlenose dolphin Tursiops truncatus in the Atlantic Ocean, Brazil, expanding the range of known Brucella seropositive aquatic hosts. No evidence of Brucella spp. exposure was found in Iniidae and Kogiidae odontocetes and manatees. Antibodies against Leptospira spp. were not detected in cetaceans and sirenians by MAT. These results contribute to the evaluation of different Brucella spp. serological methods in cetaceans and manatees and highlight the epidemiology of zoonotic pathogens in aquatic mammals of the southwestern Atlantic Ocean and the Amazon basin.

The autumn occurrence and spatial distribution of cetaceans in the waters of Mauritania during a geophysical survey in 2012

This study aimed to identify the occurrence and spatial distribution of cetaceans in Mauritanian waters (eastern Atlantic). A geophysical survey was conducted over 92 days between September and December 2012. Over 967 km was surveyed, with 1 017 h of observer effort recorded. Visual watches for marine mammals resulted in 228 cetacean sightings of 16 different species, including 12 odontocetes and 4 mysticetes. The short-finned pilot whale Globicephala macrorhynchus was the most frequently encountered odontocete, followed by the Atlantic spotted dolphin Stenella frontalis. Of the mysticetes, the sei whale Balaenoptera borealis and blue whale B. musculus were encountered most frequently. We used generalised additive models and generalised linear models to examine the relationships between environmental factors and cetacean distribution. The results showed depth had a significant influence on presence of the short-finned pilot whale, which preferred waters deeper than 1 800 m. The model for mysticetes identified bathymetry as a significant environmental predictor, whereas slope of the ocean floor had a positive effect but was not significant. This study contributes to our understanding of cetaceans in Mauritanian waters, using data from a platform of opportunity.

Morbillivirus infection in Risso's dolphin Grampus griseus: a phylogenetic and pathological study of cases from the Canary Islands.

The earliest evidence of cetacean morbillivirus (CeMV) infection dates from 1982, when the dolphin morbillivirus strain (DMV) was identified in bottlenose dolphins Tursiops truncatus stranded in the mid-Atlantic region. Since then, CeMV has been detected globally in at least 26 species of mysticetes and odontocetes, causing widespread mortality and a wide range of pathological effects. In the Canary Islands, DMV and pilot whale morbillivirus have been detected in cetacean species, including short-finned pilot whales Globicephala macrorhynchus and bottlenose dolphins. Risso's dolphins Grampus griseus have been reported year-round in waters of the Canary Islands and are considered a resident species. No information is currently available on CeMV prevalence in this species in this ocean region. We searched for evidence of CeMV infection in 12 Risso's dolphins stranded in the Canary Islands from 2003 to 2015 by means of histopathology, PCR and immunohistochemistry. PCR revealed 2 CeMV-positive animals (16.6%). Phylogenetic analysis showed that the strains from the 2 positive specimens were phylogenetically quite distant, proving that more than 1 strain infects the Risso's dolphin population in this region. We also determined that the strain detected in one of the specimens mainly circulated in the northeastern Atlantic Ocean from 2007 to 2013.

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

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

False killer whale and short-finned pilot whale acoustic identification

False killer whales Pseudorca crassidens and short-finned pilot whales Globicephala macrorhynchus are known to interact with long-line fishing gear in Hawaiian waters, causing eco- nomic loss and leading to whale injuries and deaths. The main Hawaiian Islands' insular popula- tion of false killer whales is listed as endangered and the offshore population is considered 'strate- gic' under the Marine Mammal Protection Act due to relatively high bycatch levels. Discriminating between these species acoustically is problematic due to similarity in the spectral content of their echolocation clicks. We used passive acoustic monitoring along with data from satellite tags to dis- tinguish signals from these 2 species. Acoustic encounters recorded with autonomous instruments offshore of the islands of Hawai'i and Kaua'i were matched with concurrent and nearby location information obtained from satellite tagged individuals. Two patterns of echolocation clicks were established for the 2 species. The overall spectral click parameters were highly similar (22 kHz peak and 25 kHz center frequency), but false killer whales had shorter duration and broader bandwidth clicks than short-finned pilot whales (225 µs, 8 kHz (�3 dB bandwidth) and 545 µs, 4 kHz, respectively). Also, short-finned pilot whale clicks showed distinct spectral peaks at 12 and 18 kHz. Automated classification techniques using Gaussian mixture models had a 6.5% median error rate. Based on these findings for echolocation clicks and prior published work on whistle classification, acoustic encounters of false killer whales and short-finned pilot whales on auto - nomous instruments should be identifiable to species level, leading to better long-term monitoring with the goal of mitigating bycatch.

Behaviour of Short-finned Pilot Whales Globicephala macrorhynchus (Gray, 1846) (Mammalia: Cetartiodactyla: Delphinidae) in the southeastern Arabian Sea

We report the presence and behaviour of a pod of short-finned pilot whale Globicephala macrorhynchus in the southeastern Arabian Sea. The pod was observed in the southeastern side of Minicoy Island, in the Nine degree channel (09°219′23′′N;74°39′529′′E) on 03.02.2013. Later, on 06.02.2013,the same pod of pilot whales were observed near Kalpeni Island (10°02′402′′N; 73°39′579′′E) 130 km northwest of the previous location. The average length of the whales was estimated as 550 cm and weight as approximately 1200 kg. They were travelling in a northwesterly direction. The pod size of the whales sighted was twelve and several species specific behaviour such as side rolling, spyhopping, lobtailing, peduncle arching and movement patterns such as synchronous travelling and logging could be observed. The occurrence of scars and injuries on the body of four whales in the pod are also reported.

Vessel noise effects on delphinid communication

Increasing numbers and speeds of vessels in areas with populations of cetaceans may have the cumulative effect of reducing habitat quality by increasing the underwater noise level. Here, we first use digital acoustic tags to demonstrate that free-ranging delphinids in a coastal deep- water habitat are subjected to varying and occasionally intense levels of vessel noise. Vessel noise and sound propagation measurements from a shallow-water habitat are then used to model the potential impact of high sound levels from small vessels on delphinid communication in both shallow and deep habitats, with bottlenose dolphins Tursiops sp. and short-finned pilot whales Globicephala macrorhynchus as model organisms. We find that small vessels travelling at 5 knots in shallow water can reduce the communication range of bottlenose dolphins within 50 m by 26%. Pilot whales in a quieter deep-water habitat could suffer a reduction in their communication range of 58% caused by a vessel at similar range and speed. Increased cavitation noise at higher speeds drastically increases the impact on the communication range. Gear shifts generate high-level transient sounds (peak- peak source levels of up to 200 dB re 1 µPa) that may be audible over many kilometres and may dis- turb close-range animals. We conclude that noise from small vessels can significantly mask acousti- cally mediated communication in delphinids and contribute to the documented negative impacts on animal fitness.

Age and growth of some delphinids in south-eastern Brazil

This study provides the first compilation on age and growth of some delphinids in south-eastern Brazil (18°25′S–25°45′S). A total of 154 delphinids were reported: 44 Atlantic spotted dolphin Stenella frontalis; 36 bottlenose dolphin Tursiops truncatus; 26 ‘Brazilian’ common dolphin Delphinus sp.; 20 rough-toothed dolphin Steno bredanensis; 16 Fraser's dolphin Lagenodelphis hosei; 3 false killer whale Pseudorca crassidens; 3 unidentified Stenella sp.; 2 pantropical spotted dolphin Stenella attenuata; 2 short-finned pilot whale Globicephala macrorhynchus; 1 spinner dolphin Stenella longirostris; and 1 striped dolphin Stenella coeruleoalba. Age was estimated by counting the number of growth layer groups present in the dentine in 74.5% of the sample. The growth of 92 individuals of the first five species was determined by the Gompertz model to length-at-age data. Stenella frontalis—the oldest specimen was 23 y and the asymptotic length of 224.4 cm predicted by growth curve occurred at about 20 y; T. truncatus—the oldest specimen was 26 y and the asymptotic length of 301.3 cm predicted by growth curve occurred at about 20 y; Delphinus sp.—the oldest dolphin was 18 y and the asymptotic length of 215.9 cm predicted by growth curve occurred at about 5–6 y; S. bredanensis—the oldest specimen was 24 y and the asymptotic length of 258.1 cm predicted by growth curve occurred at about 10 y; L. hosei—the oldest specimen was 19 y and the asymptotic length of 231.2 cm predicted by growth curve occurred at about 7–8 y. Only age was estimated for the other species. The age-at-length data for S. frontalis, Delphinus sp., S. bredanensis and L. hosei were consistent, suggesting a good agreement with previous work on these species. For T. truncatus, the age at asymptotic length obtained in this study might be confirmed by increasing the sample size. The information currently presented will contribute to further life history research of delphinids on the western south Atlantic coast.

Molecular and functional characterization of a urea transporter from the kidney of a short-finned pilot whale.

Cetaceans (whales and dolphins) always excrete urine with an osmolality markedly higher than that of plasma. Although the mechanisms by which cetaceans concentrate urine have not been elucidated, data support a role for medullary urea accumulation in this process, as is the case for terrestrial mammals. Therefore, we hypothesized that facilitated urea transporters are present in the kidney of cetaceans. Using 5'/3'-rapid amplification of cDNA ends, we cloned a 2.7-kb cDNA from the kidney of the short-finned pilot whale Globicephala macrorhynchus. The putative open-reading frame encoded a 397-amino acid protein [pilot whale urea transporter A2 (whUT-A2)] that has 94% amino acid sequence identity to the A2 isoform of the human urea transporter (hUT-A2). Heterologous expression of whUT-A2 cRNA in Xenopus oocytes induced phloretin-inhibitable urea transport. Although Northern analysis and RT-PCR indicated that whUT-A2 was exclusively expressed in kidney, Western blotting using a polyclonal antibody to rat UT-A1/UT-A2 detected various immunoreactive proteins in kidney and other tissues. Furthermore, RT-PCR analysis suggested the presence of alternatively spliced UT-A transcripts in the kidney as well as extrarenal tissues. We conclude that renal urea transporters are highly conserved among mammals inhabiting terrestrial and pelagic environments. A urea-based concentrating mechanism, presumably evolved to meet the demands of an arid terrestrial environment, may have contributed a fortuitous preadaptation that enabled the ancestors of cetaceans to reinvade the sea.