Bailey H.,National Oceanic and Atmospheric Administration |
Mate B.R.,Marine Mammal Institute |
Palacios D.M.,National Oceanic and Atmospheric Administration |
Palacios D.M.,University of Hawaii at Manoa |
And 3 more authors.
Endangered Species Research | Year: 2010
Baleen whale migrations typically consist of annual movements between productive, high-latitude feeding grounds and unproductive, low-latitude breeding grounds. However, the actual migratory path and whales' behaviour in these locations are poorly known. The objectives of this study were to apply a switching state-space model to the satellite tracks of blue whales Balaenoptera musculus in the Northeast Pacific to improve location estimation and gain insight into the migratory (transiting) and foraging (area-restricted search, ARS) behaviours of this population. During the period 1993 to 2007, Argos satellite tags were attached to 159 whales, mainly off the coast of California during late summer, of which 92 tracks were >7 d in duration. There was generally a southward movement during the winter to Baja California and to an area west of the Costa Rica Dome, in the eastern tropical Pacific (ETP). Travel speeds during transit were significantly faster than during ARS movements (mean = 3.70 and 1.05 km h-1, respectively). On average, 29% of the track time was spent in ARS, and the mean time within an ARS patch was 21 d. The occurrence of ARS behaviour throughout the migration cycle suggests that these animals may forage year-round, but could also indicate limited movements during the reproductive season. The extent of their northward migration from Baja California to Washington varied significantly interannually, likely in response to environmental changes affecting their prey. The long track durations obtained from electronic tagging have provided essential new information about the critical habitats of Northeast Pacific blue whales. © Inter-Research 2009. Source
Caballero S.,University of Los Andes, Colombia |
Duchene S.,University of Los Andes, Colombia |
Duchene S.,University of Sydney |
Garavito M.F.,University of Los Andes, Colombia |
And 2 more authors.
PLoS ONE | Year: 2015
A small number of cetaceans have adapted to an entirely freshwater environment, having colonized rivers in Asia and South America from an ancestral origin in the marine environment. This includes the 'river dolphins', early divergence from the odontocete lineage, and two species of true dolphins (Family Delphinidae). Successful adaptation to the freshwater environment may have required increased demands in energy involved in processes such as the mitochondrial osmotic balance. For this reason, riverine odontocetes provide a compelling natural experiment in adaptation of mammals from marine to freshwater habitats. Here we present initial evidence of positive selection in the NADH dehydrogenase subunit 2 of riverine odontocetes by analyses of full mitochondrial genomes, using tests of selection and protein structure modeling. The codon model with highest statistical support corresponds to three discrete categories for amino acid sites, those under positive, neutral, and purifying selection. With this model we found positive selection at site 297 of the NADH dehydrogenase subunit 2 (dN/dS>1.0,) leading to a substitution of an Ala or Val from the ancestral state of Thr. A phylogenetic reconstruction of 27 cetacean mitogenomes showed that an Ala substitution has evolved at least four times in cetaceans, once or more in the three 'river dolphins' (Families Pontoporidae, Lipotidae and Inidae), once in the riverine Sotalia fluviatilis (but not in its marine sister taxa), once in the riverine Orcaella brevirostris from the Mekong River (but not in its marine sister taxa) and once in two other related marine dolphins. We located the position of this amino acid substitution in an alpha-helix channel in the trans-membrane domain in both the E. coli structure and Sotalia fluviatilis model. In E. coli this position is located in a helix implicated in a proton translocation channel of respiratory complex 1 and may have a similar role in the NADH dehydrogenases of cetaceans. © 2015 Caballero et al. Source
News Article | March 5, 2016
An albino whale named “Gallon of Milk” made a rare appearance during a yearly whale census off Mexico’s Pacific coast. It was a welcome sight for conservation officials in the country as the extremely rare albino female gray whale had last been spotted in 2009. The National Commission of Natural Protected Areas (CONANP) posted a Facebook video showing the whale swimming in waters located near Baja California Sur in Mexico with a small calf in tow. The offspring did not appear to inherit her albino appearance. “Gallon of Milk” was first documented during the 2008-2009 season and belonged to an annual count of gray whales migrating to the area. According to CONANP, 2,211 gray whales showed up this year in the Ojo de Liebre lagoon of the El Vizcaíno Biosphere Reserve, the biological landscape of which researchers have been monitoring for 20 years now. Of those specimens, 1,004 are calves born in Mexico. The bright white whale’s condition albinism makes her of a special kind, since the gene mutation that leads to a sharp decrease in the pigment melanin – or the lack of it – is barely recorded among marine mammals. This condition has been better documented among land mammals, reptiles and birds, both in captivity and in the wild. The annual monitoring helps ensure the continuing survival of the gray whale species (Eschrichtius robustus), a highly endangered breed migrating every year between feeding and breeding sites. These majestic creatures can live up to 70 years, and grow to weigh 40 tons and reach 50 feet in length. Young whales grow to learn their parents’ migration patterns. “Usually calves follow their mothers from breeding areas to foraging grounds,” said Bruce Mate, director of Oregon State University’s Marine Mammal Institute. Gray whale populations were also decimated by commercial whaling. At present, their groups thrive in waters on the Pacific Ocean’s eastern and western sides, believed to be separated from each other. Those in the western Pacific – previously thought to be totally wiped out – are estimated to possibly be critically endangered at a 130-population count.