共查询到11条相似文献，搜索用时 0 毫秒
1.
Nancy A. Friday Tim D. Smith † Peter T. Stevick ‡ Judy Allen Tom Fernald 《Marine Mammal Science》2008,24(2):253-275
Capture‐recapture estimates of abundance using photographic identification data are sensitive to the quality of photographs used and distinctiveness of individuals in the population. Here analyses are presented for examining the effects of photographic quality and individual animal distinctiveness scores and for objectively selecting a subset of data to use for capture‐recapture analyses using humpback whale (Megaptera novaeangliae) data from a 2‐year study in the North Atlantic. Photographs were evaluated for their level of quality and whales for their level of individual distinctiveness. Photographic quality scores had a 0.21 probability of changing by a single‐quality level, and there were no changes by two or more levels. Individual distinctiveness scores were not independent of photographic quality scores. Estimates of abundance decreased as poor‐quality photographs were removed. An appropriate balance between precision and bias in abundance estimates was achieved by removing the lowest‐quality photographs and those of incompletely photographed flukes given our assumptions about the true population abundance. A simulation of the selection process implied that, if the estimates are negatively biased by heterogeneity, the increase in bias produced by decreasing the sample size is not more than 2%. Capture frequencies were independent of individual distinctiveness scores. 相似文献
2.
Peter T. Stevick 《Marine Mammal Science》1999,15(3):725-737
Strandings of previously identified individuals, while rare, provide an opportunity to examine age-length relationships in humpback whales (Megaptera novacangliae) from the North Atlantic. Ages and lengths of 23 individuals are presented: 11 females and 12 males, 9 of known age and 14 with estimated minimum ages. Lengths ranged from 853 to 1, 430 cm, ages 0.5–17 yr. These individuals were generally smaller and more variable in size at age than reported from commercial catches. Fifteen of the stranded individuals were four years of age or younger, while few of the animals taken by whalers were this young, and these probably represented the larger individuals in these age categories. Thus the data presented herein help to give more definition to the early growth curve for the humpback whale than has previously been available. Growth equations illustrate a difference of about one meter in asymptotic length through age five between stranding and catch data. The close fit of growth models to data from younger and older animals separately and the difficulty of fitting a single growth model to animals of all ages, could indicate that a dynamic or staged growth pattern exists in this species. 相似文献
3.
Whitlow W. L. Au Joseph Mobley William C. Burgess Marc O. Lammers Paul E. Nachtigall 《Marine Mammal Science》2000,16(3):530-544
A portable data logger controlled by a Tattletale 7 microcontroller was used to record humpback whale choruses during the 1998 humpback whale winter season in Hawaii. The data logger sampled the sounds for four minutes every half hour using a digitizing rate of 2 kHz, and the data were stored on a hard disk. The results between January and April showed a peak in the sound pressure level between mid-February and mid-March. This peak of approximately 120 dB re 1 μPa coincided with the peak in the number of whales sighted by aerial survey on 7 March 1998. The choruses had spectral peaks at 315 Hz and 630 Hz. Some of the sounds at 630 Hz were second harmonics of the 315 Hz peak and others were not. The data also indicated a diurnal pattern in the sound pressure level, with levels at night significantly louder than the daytime levels. The sound levels began to increase during sunset and remained relatively high until sunrise, when they progressively decreased to a minimum. The nighttime peak occurred within an hour before and after midnight, and the daytime minimum occurred between 1100 and 1500. That more humpback whales appear to sing at night may reflect a switch to sexual advertisement as the primary male mating strategy at this time. It may also indicate that daylight and vision play key roles in the formation of competitive groups. It is suggested that the relative number of humpback whales in a given locale may be estimated by monitoring changes in sound pressure levels. 相似文献
4.
Kathleen J. Vigness-Raposa Robert D. Kenney † M. Liliana Gonzalez ‡ Peter V. August § 《Marine Mammal Science》2010,26(1):161-175
Understanding the population structure of a species is critical to its effective management and conservation. The humpback whale ( Megaptera novaeangliae ) has been the target of numerous research projects in several ocean basins, but no clear picture of its population structure has emerged. In the North Atlantic Ocean, genetic analyses and photo-identification movements have shown significant heterogeneity among the summer feeding grounds. Building on this knowledge, we test the hypothesis that the feeding grounds represent distinct populations by analyzing the spatial pattern of summer humpback whale sightings and survey effort. Controlling for the spatial pattern of effort, sightings are clustered, with peaks at radial distances of 300 km, 600 km, and 1,500 km. These results provide insight into the spatial extent of the summer population structure of humpback whales in the North Atlantic Ocean. Fine-scale clustering at distances of 300 km and 600 km is compatible with multiple populations consisting of the Gulf of Maine, eastern Canada, western Greenland, and Iceland. Broad-scale clustering at distances of 1,500 km may represent divisions between the western and eastern North Atlantic populations. These results provide spatial bounds to the feeding grounds of humpback whales and emphasize their distinct nature as management units. 相似文献
5.
Louis M. Herman Adam A. Pack Kathryn Rose Alison Craig Elia Y. K. Herman Siri Hakala Aliza Milette 《Marine Mammal Science》2011,27(4):736-768
From a database of approximately 5,000 Hawaiian humpback whales identified photographically between 1976 and 2010, we extracted 71 males and 39 females having resighting spans of 10 or more years, from first to most recent sighting. Findings included: (1) the male‐biased sex ratio was like that found in breeding grounds worldwide; (2) the mean span for males of 20.7 yr (maximum = 32 yr) did not differ significantly from the mean of 19.8 yr (maximum = 29 yr) for females, but males were seen in significantly more years during their spans than were females; (3) the mean number of females seen with and without calf across 11 three‐year intervals from 1977 to 2009 did not differ significantly; (4) the calving rate for the 39 females was 0.48 and seven females produced two to eight calves over spans of 22–26 yr; (5) females attracted significantly more escorts in years without calf than in years with calf; (6) individuals showed great diversity in the social units they occupied over their sighting spans, but with the most frequently observed unit for both sexes being the trio of mother, calf, and escort. Males were also observed frequently in competitive groups centered about a female without calf. 相似文献
6.
C. Scott Baker Louis M. Herman Anjanette Perry William S. Lawton Janice M. Straley John H. Straley 《Marine Mammal Science》1985,1(4):304-323
A total of 326 humpback whales (Megaptera novaeangliae) were individually identified in southeastern Alaska during five summer seasons (July to September) and four late seasons (November to February) spanning the years 1979 to 1983. Peak numbers of whales were found late in August or early in September. Whales arrived 1–2 wk later in 1982 than in 1981. Whales sighted in both the summer and late seasons of 1981 and 1982 remained about 3.7 mo and one whale remained for at least 4.9 mo. Humpback whales from southeastern Alaska wintered in Hawaiian or Mexican waters, but generally did not travel to other feeding regions. The most rapid migratory transit between Hawaii and southeastern Alaska was 79 d. Based on mark-recapture analyses of the photographic data, we estimate a population of 270–372 whales in the southeastern Alaska feeding herd. 相似文献
7.
Jay Barlow John Calambokidis Erin A. Falcone C. Scott Baker Alexander M. Burdin Phillip J. Clapham John K. B. Ford Christine M. Gabriele Richard LeDuc David K. Mattila Terrance J. Quinn II Lorenzo Rojas‐Bracho Janice M. Straley Barbara L. Taylor Jorge Urbán R. Paul Wade David Weller Briana H. Witteveen Manami Yamaguchi 《Marine Mammal Science》2011,27(4):793-818
We estimated the abundance of humpback whales in the North Pacific by capture‐recapture methods using over 18,000 fluke identification photographs collected in 2004–2006. Our best estimate of abundance was 21,808 (CV = 0.04). We estimated the biases in this value using a simulation model. Births and deaths, which violate the assumption of a closed population, resulted in a bias of +5.2%, exclusion of calves in samples resulted in a bias of ?10.5%, failure to achieve random geographic sampling resulted in a bias of ?0.4%, and missed matches resulted in a bias of +9.3%. Known sex‐biased sampling favoring males in breeding areas did not add significant bias if both sexes are proportionately sampled in the feeding areas. Our best estimate of abundance was 21,063 after accounting for a net bias of +3.5%. This estimate is likely to be lower than the true abundance due to two additional sources of bias: individual heterogeneity in the probability of being sampled (unquantified) and the likely existence of an unknown and unsampled breeding area (?8.7%). Results confirm that the overall humpback whale population in the North Pacific has continued to increase and is now greater than some prior estimates of prewhaling abundance. 相似文献
8.
9.
Sally A. Mizroch Michael F. Tillman Susan Jurasz Janice M. Straley Olga Von Ziegesar Louis M. Herman Adam A. Pack Scott Baker Jim Darling Debbie Glockner‐Ferrari Mark Ferrari Dan R. Salden Phillip J. Clapham 《Marine Mammal Science》2011,27(1):217-229
Invasive tags designed to provide information on animal movements through radio or satellite monitoring have tremendous potential for the study of whales and other cetaceans. However, to date there have been no published studies on the survival of tagged animals over periods of years or decades. Researchers from the National Marine Mammal Laboratory and the Woods Hole Oceanographic Institution tracked five humpback whales with implanted radio tags in southeastern Alaska in August 1976 and July 1977, and tracked two humpback whales in Prince William Sound, Alaska, in June 1978. All seven of these individually identified humpback whales were resighted at least 20 yr after first being tagged, and five of the seven have been observed for more than 30 yr; some of them are among the most resighted humpback whales in the North Pacific. Photos of tagging sites taken during and subsequent to tagging operations show persistent but superficial scarring and no indication of infection. These pioneering field studies demonstrated both long‐term survival of the whales and the short‐term effects of deploying radio tags, which at the time were larger and more invasive than those typically used today. 相似文献
10.
Olga V. Titova Olga A. Filatova Ivan D. Fedutin Ekaterina N. Ovsyanikova Haruna Okabe Nozomi Kobayashi Jo Marie V Acebes Alexandr M. Burdin Erich Hoyt 《Marine Mammal Science》2018,34(1):100-112
Humpback whales migrate seasonally from high latitude feeding areas to lower latitude breeding areas for mating and calving. In 2004–2006, a North Pacific basin‐wide study called SPLASH was conducted as an international collaboration among various groups of researchers. The Russian Far East consists of multiple high latitude feeding areas and during SPLASH, 102 whales were identified and compared to catalogs from breeding areas. Our goal in this study was to further investigate the migratory destinations of whales from the Russian Far East using a total of 1,459 photographs of whales identified from 2004 to 2014. We compared the latest Russian catalog with the SPLASH catalog from wintering areas (2004–2006) and with two additional regional catalogs from Okinawa (1989–2006) and the northern Philippines (2000–2006). We found a total of 152 matches: 106 with Asian, 35 with Hawaiian, and 11 with Mexican breeding grounds. The match rate was higher in mainland Kamchatka and consisted mostly of whales from the Asian breeding ground. In the Commander Islands, the proportion of whales from Asia was twice that of Hawaii and six times higher than Mexico. The total match rate was low, supporting the hypothesis of some undiscovered humpback whale breeding location in the North Pacific. 相似文献
11.
Briana H. Witteveen Graham A. J. Worthy Robert J. Foy Kate M. Wynne 《Marine Mammal Science》2012,28(3):E233-E250