Volume 44 - Issue 5
In Memoriam: Jeanette A. Thomas Followed by Memories from Jeanette’s Family and Colleagues
- Written by Robert M. Timm et al.
- Hits: 517
Editor's Note: This tribute to Dr. Jeanette Thomas is presented first with a brief biography that lets the reader know about her diverse skill set and expertise, as well as her approach to science and the collection and sharing of knowledge. Her biography is followed by shared memories and contributions from her family, friends, and numerous colleagues who fondly remember Jeanette and share what she meant to their lives. These contributions were compiled by the team Jeanette assembled at Aquatic Mammals journal.
Please visit the Supplemental Material page on the website to watch two videos of Jeanette from her participation in the journal's Historical Perspectives series.
Also, Jeanette's publication list can be accessed at this link.
Page Numbers: 459-468
Depredation by Coastal Bottlenose Dolphins (Tursiops truncatus) in the Southwestern Gulf of Mexico in Relation to Fishing Techniques
- Written by Maria E. Rechimont, Ana L. Lara-Domínguez, Eduardo Morteo, Ibiza Martínez-Serrano, and Miguel Equihua
- Hits: 1059
Abstract: Cetacean–fishery interactions are a recurring problem. These interactions are conflict prone, especially between fishers and those seeking marine mammal conservation. In the southwestern Gulf of Mexico, a large fleet of artisanal fisheries operates using a range of different techniques. We recorded 90 fishing operations in two different fishing areas of Veracruz, Mexico, between 2009-2010 and 2014-2015, assessing whether dolphin interaction negatively affects fish catch and fish gear. These potential impacts were evaluated using three generalized linear models (GLMs) hypothesizing that (1) depredation decreases catch per unit effort (CPUE), (2) the predator presence modifies catch composition, and (3) prey species presence increases the likelihood of depredation. Of the gillnet hauls analyzed, 27 were subject to depredation by bottlenose dolphins, despite conditions and fishing methods varying among sites. Higher CPUE attracts larger pods, but a negative effect by depredation was not detected. We also found that depredation probability increased when there were higher capture volumes, when mackerels and jacks were present, and when operations were most southwesterly. Despite the short distance (< 80 km) between sites, we found that bottlenose dolphins on each site displayed different feeding behaviors towards fishing nets. Regarding conservation, bycatch caused by dolphins does not seem to be problematic. In fact, the increase in boat traffic and declining prey abundances due to overfishing could be the main causes of fishers’ economic loss. Dolphin–fishery interactions may not represent an actual challenge for marine conservation managers, but stakeholders, fisheries, and governmental institutions should be aware that diminishing returns due to overfishing could exacerbate the apparently false notion of dolphins competing for the fish.
Key Words: catch composition, fishing gear, CPUE, interactions, PNSAV-Marine Protected Area, Veracruz
Page Numbers: 469-481
Neonatal Critical Care and Hand-Rearing of a Bottlenose Dolphin (Tursiops truncatus) Calf
- Written by Jennifer E. Flower, Jennifer N. Langan, Benjamin N. Nevitt, Sathya K. Chinnadurai, Rita Stacey, Marina Ivančić, and Michael J. Adkesson
- Hits: 652
Abstract: Neonatal mortality is a recognized concern in cetaceans and, although infrequently documented, human intervention to provide neonatal care has been successful. Advancements in cetacean medical care now allow for enhanced neonatal care even with challenging circumstances. Herein, we describe neonatal care and hand-rearing of a male, 13 kg bottlenose dolphin (Tursiops truncatus) calf that was immediately rejected and traumatized by the dam following an uncomplicated parturition. Immediate intervention and restraint allowed for examination, medical stabilization, wound care, parenteral treatments, and diagnostics. Colostrum and milk were collected from the dam under manual and voluntary restraint. The calf was fed a combination of the dam’s milk and supplemental formula via a gastric tube, initially hourly with gradually decreasing frequency, for three months. Daily intensive care (e.g., blood sampling, topical wound care, and weights) was performed to monitor systemic health. The calf was originally housed alone but later was transitioned to a pool with visual and auditory access to other dolphins. When the calf reached 8 months of age, he was slowly introduced to another dam/calf pair. The calf is presently 4 years old and continues to thrive in a mixed social group of dam and calf pairs and young adult females comprised of two males and six females.
Key Words: neonate, nutrition, hand-rearing, calf, critical care, cetacean, bottlenose dolphin, Tursiops truncatus
Page Numbers: 482-490
Cookiecutter Shark Bite Wounds on Cetaceans of the Gulf of Mexico
- Written by Mark A. Grace, Laura Aichinger Dias, Katherine Maze-Foley, Carrie Sinclair, Keith D. Mullin, Lance Garrison, and Lauren Noble
- Hits: 616
Document: Short Note
Page Numbers: 491-499
Young Belugas (Delphinapterus leucas) Exhibit Sex-Specific Social Affiliations
- Written by Lauren Mazikowski, Heather M. Hill, and Michael Noonan
- Hits: 479
Abstract: The present study investigated the social affiliations of young beluga whales (ages 1 to 5 years). The results indicated that young males were found significantly more often in the proximity of other males (both juvenile and adult) than found in the proximity of females. Young females were found less often with other whales than were males, and they did not show a difference based on sex. These results mimic the male-affiliative patterns found in both wild and captive adult belugas, suggesting that the tendency for males to group together develops at an early age in this species.
Key Words: beluga, Delphinapterus leucas, sex segregation, social affiliation, juvenile
Page Numbers: 500-505
Lens Lipidomes Among Phocidae and Odobenidae
- Written by Raphaela Stimmelmayr and Douglas Borchman
- Hits: 467
Abstract: Why do seals develop cataracts after living 40 years, rats after 2 years, and humans after 70 years, while whales do not develop cataracts even after 100 years of age? To address that question, lenses from pinnipeds—walrus, spotted seals, ringed seals, bearded seals, and a ribbon seal—were studied. The cholesterol and phospholipid content of the lenses were measured using 1H and 31P-NMR spectroscopy, respectively. Lens lipid structure was measured using FTIR spectroscopy. We found that in Phocidae, similar to various terrestrial species, lifespan is related to lens sphingolipid, and lens sphingolipid is related to lens membrane order and cholesterol. Shifting lens lipid composition toward increased levels of sphingolipids has been proposed as an adaptive evolutionary molecular mechanism to limit reactive oxygen species lens damage (oxi¬dative stress) and, thus, age-related cataract formation. Additional comparative studies of lens lipid composition of pinnipeds across taxa with various foraging and diving strategies are needed to further explore and test underlying assumptions for the observed divergent sphingolipid content between Phocidae and Odobenidae. While the causes of the lens compositional differences between Phocidae and Odobenidae remain undetermined, our study provides novel physiological data on lens lipid composition in marine mammals and largely complements lens lipid compositional findings in terrestrial and other aquatic species that demonstrate a linkage between lifespan, sphingolipids, and cataracts.
Key Words: pinnipeds, seals, walruses, cataract, lens, lifespan, lipids
Page Numbers: 506-518
Whale Poaching Detection Based on Microscopic Characteristics of Bottlenose Dolphins’ (Tursiops truncatus) Bone Fragments
- Written by Manuela Zadravec, Zvonimir Kozarić, Snježana Kužir, Mario Mitak, Tomislav Gomerčić, Miroslav Benić, and Martina Đuras
- Hits: 577
Abstract: Although many countries prohibit whaling, it remains a significant cause of whale population decline. Whale meal, likely from whales killed during illegal whaling or caught accidentally, can appear in a fish meal as a contaminant detectable by microscopic examination of bone fragments. To provide a rigorous basis for such a detection, microscopic characterization of bone fragments of 10 female and 10 male, less than a year old to 21-year-old bottlenose dolphins (Tursiops truncatus), a widespread cetacean species herein used as a whale model, was performed and compared to the reference bone fragments of fish, ruminants, poultry, and pigs. The processing of bones mimicked the process used in the production of meat and bone meals, while their description was based on qualitative characteristics (i.e., the shape of a bone fragment; the shape, density, and distribution of osteocyte lacunae; and the distribution and density of canaliculae). Bottlenose dolphin bone fragments are smoothly contoured. Their elliptical osteocyte lacunae are clearly visible, while the canaliculae radiate from the lacunae in all directions. The comparison of these qualitative bone characteristics with that of other vertebrata under study revealed that bottlenose dolphin bone fragments can definitely be differentiated from that of fish, may be differentiated from that of poultry and pig, but cannot be differentiated from that of ruminants. Measurements of the osteocyte lacunae showed the lacunar length to be strongly associated with an animal’s age and lacunar shape, while their width was strongly associated with an animal’s gender and lacunar shape. The results indicate the possibility of detecting a whale meal admixture in a fish meal using light microscopy, which should be followed by PCR to allow for the identification of the admixture source.
Key Words: whale poaching, bottlenose dolphin, Tursiops truncatus, osteocyte
Page Numbers: 519-528
Relative Growth of the Skull of the Common Minke Whale (Balaenoptera acutorostrata) Using a 3D Laser Surface Scanner
- Written by Giacomo Franci and Annalisa Berta
- Hits: 615
Abstract: Growth-related morphological changes in the skulls of an ontogenetic series of 11 North Pacific common minke whales (Balaenoptera acutorostrata) were investigated using a three-dimensional (3D) surface laser scanner. Landmark coordinate measurements were taken at 30 points on the skull to extract individual allometric equa¬tions relating the length and zygomatic width of the skull. Comparisons were made with estimates of the surface areas of various skull components. The results revealed that the anatomical components involved in feeding (i.e., rostrum) increased in size relative to skull length. In contrast, sensory organs and the anatomical regions involved in neu¬rological function (i.e., orbit, tympanic bullae, and foramen magnum) were fully developed at birth, and their relative size decreased over the course of development. Geometric morphometric studies such as the one described herein benefit from the capture of 3D images of specimens, making the process of sample acquisition faster, less expensive, and more readily available to researchers.
Key Words: geometric morphometrics, 2D and 3D images, allometry, minke whale, Balaenoptera acutorostrata
Page Numbers: 529-537
Redefinition and Sexual Difference of Contact Calls in Belugas (Delphinapterus leucas)
- Written by Yuka Mishima, Tadamichi Morisaka, Yuki Mishima, Tadashi Sunada, and Yoshinori Miyamoto
- Hits: 552
Abstract: Previous studies have suggested that belugas (Delphinapterus leucas) use pulsed calls both with and without tone-like components for contact calls. However, call classification differs among researchers, and the definition of contact calls remains ambiguous. The objective of this study is to organize and integrate this information to redefine the contact calls of belugas. Our previous studies termed their contact call as PS1, which was exchanged among the belugas and was the predominant call type in isolation. PS1 is a broadband pulsed call that sounds like a door creaking and has a duration of 0.15 to 1.5 s. Individual distinctiveness was found within a typical pulse repetition pattern of PS1. The PS1 characteristics initially described were based on one captive population. In this study, calls from another population of seven belugas of both sexes and various ages at Shimane Aquarium, Japan, were recorded from October 2014 to March 2015. The PS1 definition was expanded to broadband pulsed calls continuing for > 0.15 s, and the PS1 calls were explored from their calls. The belugas exchanged PS1 calls, but the pulse repetition pattern had various forms instead of the typical pattern suggested in previous PS1 studies. Additionally, all the PS1 calls contained a tone-like component. By reflecting on these results and referring to other previous studies, we renamed these contact calls creaking calls. Moreover, this study shows sex differences in the creaking calls. The females and juvenile male had creaking calls with an individually distinct pulse repetition pattern, while adult males had variations in pattern during free swimming. Each adult male, however, used only an individually distinct stereotype of pulse repetition pattern in a visual reunion and first-sighting context. This suggests that adult males have individualized and non-individualized creaking calls, and they use the former to advertise identity in separation, reunion, or greeting contexts.
Key Words: acoustic communication, vocal exchange, individuality, repertoire, classification, Delphinidae, cetacean
Page Numbers: 538-554
Movements and Dive Patterns of Pygmy Killer Whales (Feresa attenuata) Released in the Gulf of Mexico Following Rehabilitation
- Written by Eric E. Pulis, Randall S. Wells, Gregory S. Schorr, David C. Douglas, Mystera M. Samuelson, and Moby Solangi
- Hits: 1640
Abstract: The habits and habitats of pygmy killer whales (Feresa attenuata) in the Gulf of Mexico (GoM) are poorly known outside of strandings and line-transect surveys. Two adult male pygmy killer whales were found live-stranded in the state of Mississippi (USA) on 1 September 2015 and were subsequently rehabilitated and returned to the offshore waters of the GoM on 11 July 2016. To monitor the animals post-release, both were tagged with satellite-linked location and dive behavior tags. Tags were programed to record and transmit dive duration and depth (when dives were ≥ 30 m deep for ≥ 30 s), duration of time spent above 30 m depth, and estimate locations using the Argos system. The tags transmitted for 15 and 88 days, respectively, providing a total of 1,027 filtered locations and 3,150 dive duration and maximum depth records. The animals began diving after two and four days, respectively, post-release. More than 96% of dives occurred at night. The longest recorded dive was more than 9 min in duration, and the deepest was to 368 m. More than 98% of the locations were over the GoM shelf break, spanning water 200 to 1,200 m deep. Diving patterns indicate that this species is most active at night in the GoM, suggesting its prey species are likely diel migrators that are below reachable depths during daylight hours. Near simultaneous location data from both animals confirmed that they stayed in close proximity but did not dive synchronously. Success of the rehabilitation and release was inconclusive for pygmy killer whale ID 30IMMS, whereas 31IMMS met the established criteria for success with ≥ 6 weeks of documented post-release survival. Follow-up monitoring through satellite-linked telemetry provided not only important data for evaluating the success of the rehabilitation but also for documenting the activity and habitat use of these seldom-observed cetaceans.
Key Words: cetacean tag, dive behavior, pygmy killer whale, Feresa attenuata, marine mammal, post-release monitoring, satellite-linked telemetry
Page Numbers: 555-567
Antibiotic Susceptibility Patterns of Bacteria Isolated from Cetaceans Stranded in the Philippines
- Written by Marie Christine M. Obusan, Lemnuel V. Aragones, Windell L. Rivera, and Maria Auxilia T. Siringan
- Hits: 545
Abstract: As sentinels, cetaceans provide the link between ocean and human health by indicating the emergence of disease threats, pathogenic microorganisms, and antimicrobial resistance. Cetaceans that stranded in the Philippines from January 2012 to March 2013 were screened for antibiotic resistance. The susceptibility patterns of Achromobacter xylosidans, Acinetobacter spp., Aeromonas spp., Burkholderia cepacia, Enterococcus faecalis, Enterococcus sp., Moraxella sp., Proteus mirabilis, Providencia stuartii, Rhizobium radiobacter, Serratia marcescens, Sphingomonas sp., Staphylococcus epidermidis, and Vibrio spp. isolated from nine cetaceans representing the species Globicephala macrorhynchus, Kogia sima, Kogia breviceps, Stenella attenuata, and Steno bredanensis were determined using a selection of antibiotics. More than half of these isolates showed either single or multiple resistances to the antibiotics tested. Development of antibiotic resistance in a rough-toothed dolphin (S. bredanensis) was observed after the administration of antibiotics during the course of rehabilitation. The findings of the study can serve as a basis for providing medical intervention during management and rehabilitation of stranded cetaceans, and have implications relevant to zoonotic transmission of potentially pathogenic or antibiotic resistant bacteria from cetaceans to other marine species and humans. Investigating stranded cetaceans for the occurrence of bacteria and antibiotic resistance is one way of monitoring the health of their counterparts in the wild, offering insights as to the possible involvement of bacterial infections in local stranding events.
Key Words: antibiotic resistance, bacteria, stranding events, cetaceans, Philippines
Page Numbers: 568-579
Historical Perspectives: The History and Future of Marine Mammal Ecology
- Written by James P. Estes
- Hits: 561
Document: Historical Perspectives Essay
Page Numbers: 580-594