The prevalence of ectoparasitic barnacles discriminates stocks of Atlantic common bottlenose dolphins (Tursiops truncatus) at risk of entanglement in coastal gill net fisheries
Kim W. Urian, Rachel Kaufmann, Danielle M. Waples, Andrew J. Read
In North Carolina, USA, estuarine and coastal bottlenose dolphins mix in nearshore ocean waters, complicating efforts to estimate stock size and determine which stocks interact with fisheries. We examined digital photographs of the dorsal fins of dolphins of known stock identity and calculated the proportion of their fins covered by barnacles. We refer to this proportion as the Infestation Index, which was eight times greater for coastal than estuarine dolphins. This approach allows us to assign groups of dolphins to either coastal or estuarine stocks and to identify the stock of entangled or stranded dolphins.
Distribution, demography, and behavior of North Atlantic right whales (Eubalaena glacialis) in Cape Cod Bay, Massachusetts, 1998–2013
Charles A. Mayo, Laura Ganley, Christine A. Hudak, Solange Brault, Marilyn K. Marx, Erin Burke, Moira W. Brown
North Atlantic right whales were documented in Cape Cod Bay during aerial surveys conducted between January and May of 1998 to 2013. As the number of cataloged right whales in the population increased, the number of individual whales visiting the Bay increased, but the rate of increase in the Bay was greater than that of the cataloged population indicating a change in habitat preference. The maximum number of whales documented in the Bay (277 individuals in 2011) represents 56.9% of the cataloged population. We also demonstrated a preference for or rejection of the Bay by individual right whales
Mitochondrial DNA diversity and population structure in the Irrawaddy dolphin (Orcaella brevirostris) from the Gulf of Thailand and the Mekong River
Susana Caballero, Verné Dove, Justine Jackson‐Ricketts, Chalatip Junchompoo, Sarah Cohen, Ellen Hines
Dolphins from the genus Sotalia have been recognized recently as two separate species, the tucuxi (Sotalia fluviatilis) found in the Amazon Basin, and the Guiana dolphin (Sotalia guianensis) found along the Caribbean and Atlantic coasts of South America. However, no information is currently available regarding the taxonomic identity of Sotalia dolphins found in the Orinoco River in Venezuela. Such taxonomic clarification is important in order to be able to classify species under the IUCN categories and to manage and protect them. In early 2015, we collected seven samples from dolphins found about 200 Km up from the river mouth. DNA was extracted from these samples and we sequenced five gene fragments. These were compared with available sequences from the same gene fragments from the two described species Sotalia fluviatilis and Sotalia guianensis. Taking into consideration the molecular diagnostic characters described for each species, we determined these dolphins to belong to Sotalia guianensis. Additionally, we investigated the evolutionary relationship between dolphins from the Orinoco and other locations along the South American Coast and the Amazon Basin and we hypothesize that these dolphins colonized the Orinoco River from the Caribbean Sea around 640,000 years ago, in a single relatively recent event, when sea level was higher than today.
Response to capture stress involves multiple corticosteroids and is associated with serum thyroid hormone concentrations in Guadalupe fur seals (Arctocephalus philippii townsendi)
Eugene J. DeRango, Denise J. Greig, Casandra Gálvez, Tenaya A. Norris, Lorraine Barbosa, Fernando R. Elorriaga‐Verplancken, Daniel E. Crocker
Guadalupe fur seals are a threatened species that can be susceptible to stress in their environment. We present the first study to determine stress hormones in this species when they are captured to gather scientific information. Fur seal adult females and pups expressed hormones differently during capture, which likely reflects the differences in their diving ability. Cortisol, a common stress hormone in mammals, was also associated with thyroid hormones, which are known to regulate growth and metabolism. Together these findings can be applied to how fur seals respond to human-induced stressors.
Accuracy and precision of dolphin group size estimates
Tim Gerrodette, Wayne L. Perryman, Cornelia S. Oedekoven
Estimates of dolphin group size from a ship were compared to counts from aerial photographs. Most people tended to underestimate dolphin group size, and the tendency increased with group size. On average, groups of 25, 50, 100, and 500 dolphins were underestimated by <1%, 16%, 27%, and 47%. Estimates of group size were also highly variable. Studies which depend on group size estimates will be improved if the tendency to underestimate group size and the high uncertainty of group size estimates are accounted for.
Characterization of milk protein composition of the Yangtze finless porpoise
Xianyuan Zeng, Minmin Chen, Zhigang Liu, Daoping Yu, Shiang‐Lin Huang, Jiwei Yang, Fei Fan, Ding Wang, Yujiang Hao, Ghulam Nabi
Mammary glands provide energy and nutrients via milk to offspring during the beginning of their life, playing a vital role in neonatal growth and survival in mammals. We applied the ultrasonography to investigate appearances and measurements of mammary glands at different reproductive stages. Our findings revealed the mammary glands developed little until the final phase of gestation, probably to reduce swimming drag and that the mammary glands increased milk production from the mid- to late lactation stages, likely to meet the increasing energy requirement for thermal insulation and body growth in the winter.
Morphological analysis of the foramen magnum in finless porpoise (genus Neophocaena) using postmortem computed tomography 3D volume rendered images
Brian Chin Wing Kot, Derek Kam Ping Chan, Adams Hei Long Yuen, Francis Ho Man Wong, Henry Chun Lok Tsui
Variations in foramen magnum (FM) size and shape could be of clinical and diagnostic importance. Deviations from the normal FM structure may correlate with neurological deficits. We described the variability and provide baseline morphometric data of the FM and adjacent occipital indices in 2 finless porpoise species using postmortem computed tomography. Taxonomic differences and sexual dimorphism were noted in some FM morphometric values. Six distinct FM shapes were identified in the 2 porpoise species. This study provides important baseline FM morphometric values, which may aid corrective diagnosis, classification, and treatment of neurological diseases in cetaceans.
Sexual maturity and estimated fecundity in female Indo‐Pacific bottlenose dolphins (Tursiops aduncus) from South Australia: Combining field observations and postmortem results
Catherine Kemper, Mauro Talamonti, Michael Bossley, Aude Steiner
It is important to know when dolphins become mature and how many calves a female produces. Carcasses of 88 females were studied, including some seen alive for many years. Dolphins were aged using their teeth, and reproductive organs were collected. Average age at maturation was 7 years. Ovaries grew between birth and maturity, and usually had evidence of less than 11 conceptions during a lifetime. These conceptions matched the number of calves some females gave birth to. Estimated interbirth period was 4 years. Two females had unusual reproductive histories and were either chronically diseased or had high heavy metal burdens.
Survival rate and population size of Indo‐Pacific humpback dolphins (Sousa chinensis) in Xiamen Bay, China
Bingyao Chen, Huili Gao, Thomas A. Jefferson, Yi Lu, Lin Wang, Shanshan Li, Hui Wang, Xinrong Xu, Guang Yang
Xiamen is a beautiful garden city with perfect harmony between man and nature, and the Indo-Pacific humpback dolphins inhabit there. The dolphins were well known in the Xiamen public and protected at the highest priority by Xiamen government. However, survival rate remains unclear and the population size has not been monitored since 2004. Here, A research team from Nanjing Normal University provided a latest estimation of population size of 70 individuals (63-88) and survival of 0.947(0.922-0.966). This small population size indicated its “critically endangered” status and emphasizes urgency of the need for protection of the population.
Heard but not seen: Occurrence of Kogia spp. along the western North Atlantic shelf break
Lynne E. W. Hodge, Simone Baumann‐Pickering, John A. Hildebrand, Joel T. Bell, Erin W. Cummings, Heather J. Foley, Ryan J. McAlarney, William A. McLellan, D. Ann Pabst, Zachary T. Swaim, Danielle M. Waples and Andrew J. Read
Dwarf and pygmy sperm whales strand frequently along the southeastern U.S. but are rarely detected during visual surveys. These relatively small whales often lie motionless at the surface and dive without showing their tails. To better understand their distribution, we compared detections of these two species along the Atlantic shelf break using visual survey and passive acoustics methods. Our results demonstrate that these animals are much more common along the Atlantic shelf break and slope waters than suggested by visual surveys, highlighting the value of passive acoustic monitoring for describing the occurrence and distribution of cryptic species.
Large dugong (Dugong dugon) aggregations persist in coastal Qatar
Christopher D. Marshall, Mehsin Al Ansi, Jennifer Dupont, Christopher Warren, Ismail Al Shaikh and Joshua Cullen
A gulf-wide survey conducted in 1986 for dugongs, or sea cows, in the Arabian Gulf discovered the largest population outside Australia. The largest group of dugongs ever recorded was found during these surveys between Qatar and Bahrain. Our team rediscovered several large herds of sea cows in this region. The largest group size we report is 508 individuals, but helicopter surveys also detected large herds of 226 and 166 individuals each. Large groups of dugongs still frequent coastal waters of Qatar during the winter months. These observations provide a solid foundation to expand conservation efforts in this region in Qatar.
Environmental evidence for a pygmy blue whale aggregation area in the Subtropical Convergence Zone south of Australia
Maria I. Garcia‐Rojas, K. Curt S. Jenner, Peter C. Gill, Micheline‐Nicole M. Jenner, Alicia L. Sutton and Robert D. McCauley
The importance of the Subtropical Convergence zone south of Australia as a feeding area to the pygmy blue whales of the eastern Indian Ocean was investigated. A combination of satellite tagging studies and acoustic and visual surveys confirmed the presence of pygmy blue whales in the Subtropical Convergence zone and provided evidence for feeding throughout the region. Pygmy blue whales were acoustically detected in proximity to sea surface temperature fronts and high chlorophyll concentrations. Oceanographic features present throughout the Subtropical Convergence zone continue to support the world’s largest living mammals during migratory movements between the Southern Ocean and Indonesia.
Comparing depth and seabed terrain preferences of individually identified female humpback whales (Megaptera novaeangliae), with and without calf, off Maui, Hawaii
Adam A. Pack, Louis M. Herman, Alison S. Craig, Scott S. Spitz, James O. Waterman, Elia Y. K. Herman, Mark H. Deakos, Siri Hakala and Carley Lowe
We studied individual female humpback whales over 12 years in Hawaii so that we could investigate what water depth and seabed terrain type they preferred when they had a calf versus when they had no calf. At each sighting, we photographed the female’s unique tail fluke pattern and determined her water depth and whether she was associated with rugged or flat seabed terrain. We found that 35 females who were sighted with a calf and without a calf in different years preferred significantly shallower water when they had a calf, but they had no preference for particular seabed terrain.