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Cole C. Monnahan Jorge Acevedo A. Noble Hendrix Scott Gende Anelio Aguayo‐Lobo Francisco Martinez 《Marine Mammal Science》2019,35(4):1212-1231
In 2003 a feeding aggregation of southeastern Pacific humpback whales (Megaptera novaeangliae) was reported in the Magellan Strait. While Chile established its first marine national park in the Strait to protect humpback whale habitat, fatal ship strikes remain a concern because of overlap with a busy shipping lane. To better understand population risk, we estimated abundance and survival for this population using Bayesian robust‐design mark‐recapture models fit to photographic data from 2004 to 2016. Overall, the model estimated a total of 204 whales (95% CI: 199–210) during the last 12 yr, and 93 (95% CI: 86–100) in the 2016/2017 austral summer. The population grew at 2.3% (CI: 2.1%–3.1%), an annual increase of two whales. Annual survival (including calves) was estimated at 0.892 (CI: 0.871–0.910). Our results corroborate a persistent feeding population, but one that is increasing relatively slowly. Owing to its vulnerability stemming from its small size, coupled with significant overlap with a busy shipping lane, we argue this subpopulation is at significant risk from ship strikes and may be one of the few populations where anthropogenic mortalities could regulate population dynamics. We therefore encourage continued monitoring via photographic mark‐resighting surveys, and analyses explicitly investigating potential population‐level ship strike effects. 相似文献
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Laura Sanvicente-Añorve José Luis López-Sánchez Anelio Aguayo-Lobo Luis Medrano-González 《Acta zoologica》2004,85(4):223-232
External measurements and size differences between the sexes were examined in the coastal spotted dolphin, Stenella attenuata graffmani , in Bahía de Banderas, on the Mexican Pacific coast. The dolphins were collected by local fishermen and 29 external characteristics were measured by members of the Marine Mammals Laboratory, University of Mexico. The length of each characteristic with respect to total length was analysed through adjustment of the data to a power equation. A stepwise discriminant analysis was applied to the absolute values and to those expressed as proportions to analyse the differences between the sexes. Results indicate that growth in these dolphins is generally negatively allometric, and most of the characteristics measured were, in both absolute and proportional terms, greater in male dolphins than in female dolphins. As found in many species of odontocetes, the discriminant analysis showed that the main differences between the sexes for this coastal subspecies include the relative positions of the umbilicus, the genital aperture and the anus. The morphometric data provided by this study, corresponding to 29 specimens of S. a. graffmani collected in a restricted locality of the Mexican Pacific coast, are particularly interesting to studies documenting latitudinal morphological differences in the coastal spotted dolphin. 相似文献
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We investigated sex‐related site fidelity by humpback whales to the Fueguian Archipelago, a new feeding area in the eastern South Pacific, by examining the resighting histories of 45 males and 39 females recorded from 2003 to 2012. Results indicated an overall annual return to the feeding area of 74.8%, and annual sex ratio is roughly equal in the population. The probability of an individual being resighted across years and in subsequent years was not significantly different for both males and females, however, the proportion of resighting within a year was significantly higher for individual males compared to females. Potential sources of sex‐related bias were analyzed, but none were found to be significant. Greater intraannual resighting frequency for males may reflect sex‐based differences in spatial occupation and short‐range movements due to potential differences in energy budgets. 相似文献
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We document five cases of unusual colouration in Antarctic fur seals, Arctocephalus gazella, at Cape Shirreff, Livingston Island, from 1991–1992 to 2005–2006 austral summer seasons. This is the first time that these
colour patterns have been reported for this species. These included four rare light coloured animals and one piebald individual.
The incidence of this atypical colouring was low and the lack of resightings in previous and subsequent seasons suggests that
these morphs are not common in Antarctic fur seals. Although the causes of these atypical light colour patterns are uncertain
the subject is interesting for study and more observations on these atypical colourations are required for a proper assessment
of the ecological and physiological implications of this condition in otariids can be conducted in the future. 相似文献
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From observations of the spatial distribution of humpback whales in the Mexican Pacific between 1981 and 1986, it is possible to recognize four subregions: 1) the southern coast of Baja California; 2) the northern Gulf of California, including the Midriff Islands; 3) the mainland coast of Mexico, including the Isla Isabel and Islas Tres Marias and 4) the Revillagigedo Archipelago. The seasonal distribution of whales near the Mexican mainland and the Revillagigedo Archipelago extends from November to May and is similar to that of other winter breeding grounds, including the Hawaiian Islands. Along the southern coast of Baja California, whales have been observed from September to April, possibly indicating a shorter migratory route. In the northern Gulf of California, however, humpback whales have been reported throughout the year and are occasionally observed feeding during both summer and winter months. The degree of individual movement between the four subregions is still unknown. The number of individual humpback whales identified photographically in recent years suggests that there ate more whales in the Mexican Pacific than previously reported. 相似文献
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Luis A. Pastene Jorge Acevedo Mutsuo Goto Alexandre N. Zerbini Paola Acu?a Anelio Aguayo-Lobo 《Conservation Genetics》2010,11(4):1553-1558
Mitochondrial DNA control region sequences were analyzed to investigate population structure and possible migratory links
of common minke whales (Balaenoptera acutorostrata) in two ocean basins: western South Atlantic (WSA) and western South Pacific (WSP). The results of several different phylogenetic
estimations consistently grouped all haplotypes but one (n = 1) from these two ocean basins into two separate clades. South and North Atlantic haplotypes were more closely related
to each other than either was to haplotypes from the WSP. The interpopulation genetic distance between WSA and WSP whales
was similar to that reported between North Pacific and North Atlantic common minke whales (0.0234). The migration rate between
the two ocean basins was estimated at near-zero using MDIV. The genetic evidence presented here was consistent with the hypothesis
of migratory links among Brazil, Chilean Patagonia and the Antarctic Peninsula, and between low-latitude and Antarctic waters
of the WSP. The results suggest multiple populations of common minke whales in the Southern Hemisphere, which may have conservation
as well as taxonomic implications. Our single locus results should be corroborated by additional analyses in a larger number
of samples and at more genetic markers. 相似文献
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MIGRATORY DESTINATIONS OF HUMPBACK WHALES FROM THE MAGELLAN STRAIT FEEDING GROUND, SOUTHEAST PACIFIC
Jorge Acevedo Kristin Rasmussen † Fernando Félix ‡ Cristina Castro § Martha Llano ¶ Eduardo Secchi # Marco T. Saborío Anelio Aguayo-Lobo ††† Ben Haase Meike Scheidat †† Luciano Dalla-Rosa ‡‡ Carlos Olavarría §§ Paul Forestell ¶¶ Paola Acuña ## Gregory Kaufman Luis A. Pastene 《Marine Mammal Science》2007,23(2):453-463
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Jorge Acevedo Carlos Olavarr��a Jorge Plana Anelio Aguayo-Lobo Antonio Larrea Luis A. Pastene 《Polar Biology》2011,34(2):313-318
The occurrence of dwarf minke whales (Balaenoptera acutorostrata subsp.) around the Antarctic Peninsula was examined based on 406 sightings of minke whales recorded during the Chilean Antarctic
Scientific Expeditions and other opportunistic cetacean surveys. Identification of the species was made only for the whales
sighted in the proximity of the vessels when the specific diagnostic characters could be confirmed. Of the 406 sightings,
296 were assigned to Antarctic (519 individuals), nine (11 individuals) to dwarf and 101 to unidentified minke whales (149
individuals). Dwarf minke whales were identified by the reported external diagnostic characters for this species. Seven animals
occurred around the South Shetland Island and four in the Gerlache Strait. In addition, another two animals were identified
as dwarf minke whales in the Bellinghausen Sea in winter 1993, being these the most southern records for this species. These
results confirm the occurrence of dwarf minke whales around the Antarctic Peninsula during the summer seasons, as well as
in the Bellinghausen Sea in winter. The geographical range of these sightings was comprised between 61°03′ and 69°25′S and
between 55°29′ and 86°53′W. These results also suggest that some dwarf minke whales remain in the Antarctic during the austral
winter. 相似文献