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  • 1
    Digitale Medien
    Digitale Medien
    DIEL VARIATION IN MIGRATION RATES OF EASTERN PACIFIC GRAY WHALES MEASURED WITH THERMAL IMAGING SENSORS (1999)
    Oxford, UK : Blackwell Publishing Ltd
    Marine mammal science 15 (1999), S. 0 
    Details
    ISSN: 1748-7692
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: We recorded the blows of gray whales during their southbound migration past central California in January 1994, 1995, and 1996, using thermal imaging sensors. For our sampling purposes, we defined day (0730–1630) and night (1630–0730) to coincide with the on/off effort periods of the visual counts being conducted concurrently. We pooled data across the three years of sampling and tested for diel variation in surfacing interval, pod size, offshore distance, migration rate, and swimming speed by comparing paired day/night means for samples collected within the respective 24-h period. We performed these tests using data from the entire migration period and then repeated the tests for samples collected prior to and after the approximate median migration date (15 January). Over the entire migration period we observed larger diurnal pod sizes (x̄day= 1.75 ± 0.280, x̄night= 1.63 ± 0.232) and greater diurnal offshore distances (x̄day= 2.30 ± 0.328 km, x̄night= 2.03 ± 0.356 km) but found no diel variation in surfacing interval. For the entire migration period, the nocturnal migration rate (average number of whales passing per hour) was higher than the diurnal rate. During the first half of the migration we detected no diel variation in pod size or surfacing interval, but diurnal offshore distances were larger than at night (x̄day= 2.28 ± 0.273 km, x̄night= 1.96 ± 0.318 km). Diurnal and nocturnal migration rates prior to 15 January were not different. During the second half of the migration, there was no diel variation in surfacing interval, pod size, or distance offshore, but the nocturnal migration rate was higher (28%, SE = 11.6%) than the diurnal rate. We found no diel variation in swimming speed in any comparison. We propose that later migrants socialize more during the day, which effectively slows their diurnal rate of migration relative to nocturnal rates.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1748-7692.1999.tb00811.x
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  • 2
    Digitale Medien
    Digitale Medien
    GRAY WHALE CALF PRODUCTION 1994–2000: ARE OBSERVED FLUCTUATIONS RELATED TO CHANGES IN SEASONAL ICE COVER? (2002)
    Oxford, UK : Blackwell Publishing Ltd
    Marine mammal science 18 (2002), S. 0 
    Details
    ISSN: 1748-7692
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: We conducted shore-based sighting surveys to estimate the number of northbound migrating gray whale calves passing Piedras Blancas, California, for seven consecutive years (1994–2000). In addition, we conducted aerial surveys to determine offshore distribution of the migration in 1994 and 1995, measured day/night migration rates with thermal sensors in 1994–1996, and maintained concurrent replicate watches near the peak of each migration to estimate the proportion of the cow/calf pairs missed by the standard watch team. During good weather, we counted 325, 194, 407, 501, 440, 141, and 96 calves during 1994–2000, respectively. Correcting these counts for periods not on watch and for calves missed, produced final estimates of 945 calves (SE = 68.21) for 1994, 619 calves (SE = 67.19) for 1995, 1,146 calves (SE = 70.67) for 1996, 1,431 calves (SE = 82.02) for 1997, 1,388 calves (SE = 91.84) for 1998, 427 calves (SE = 41.10) for 1999, and 279 calves (SE = 34.79) for 2000. Calf production indices (calf estimate/total population estimate) are 4.2%, 2.7%, 4.8%, 5.8%, 5.5%, 1.7%, and 1.1% for the years 1994–2000, respectively. Fluctuations in calf production over this time period were positively correlated with the length of time that primary feeding habitat was free of seasonal ice during the previous year.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1748-7692.2002.tb01023.x
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  • 3
    Digitale Medien
    Digitale Medien
    COUNTING STELLER SEA LION PUPS IN ALASKA: AN EVALUATION OF MEDIUMFORMAT, COLOR AERIAL PHOTOGRAPHY (2001)
    Oxford, UK : Blackwell Publishing Ltd
    Marine mammal science 17 (2001), S. 0 
    Details
    ISSN: 1748-7692
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: Estimates of Steller sea lion (Eumetopias jubatus) pup production are valuable for estimating population trend and size. Currently in Alaska, pups are counted by visiting rookeries, driving older animals into the water, then walking through the rookeries and counting the pups, a highly disruptive procedure. At smaller rookeries, with good vantage points, pups are occasionally counted from the periphery of rookeries without disturbing the sea lions. We evaluated counts made from medium-format, color, aerial photographs as an alternative to drive counts and peripheral counts. Neither the peripheral counts nor the aerial photographic counts disturbed animals on the rokeries. There were strong 1:1 linear relationships between photographic counts and drive counts (r2= 0.966, P 〈 0.001) and between photographic counts and peripheral counts (r2= 0.999, P 〈 0.001). Precision was similar for all three methods of counting. We suggest that medium-format, color, aerial photographs is appropriate for routine surveys of Steller sea lion pups in Alaska because it is not disruptive to the hauled-out sea lions and provides comparable estimates with similar precision to drive and peripheral counts. Large areas canbe rapidly surveyed during periods of good weather with a minimum of manpower.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1748-7692.2001.tb00984.x
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  • 4
    Digitale Medien
    Digitale Medien
    A NEW GEOGRAPHIC FORM OF THE SPINNER DOLPHIN, STENELLA LONGIROSTRIS, DETECTED WITH AERIAL PHOTOGRAMMETRY (1998)
    Oxford, UK : Blackwell Publishing Ltd
    Marine mammal science 14 (1998), S. 0 
    Details
    ISSN: 1748-7692
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: Analyses of skeletal and external morphology of spinner dolphins killed in to the yellowfin tuna purse-seine fishery in the eastern tropical Pacific led to the description of two subspecies of spinners from this region, the eastern spinnen dolphin and the Central American spinner dolphin (Perrin 1990). However, when we examined lengths of spinner dolphins taken from vertical aerial photographs from the same area, we found three unique morphotypes. Two of these forms correspond, at least in average length and distribution, to the existing subspecies. The third form is intermediate in length between the two recognized subspecies and is found along the edge of the continental shelf north of Cabo Corrientes, Mexico. We provisionally call this form the “Tres Marias spinner dolphin.” Our results demonstrate the value of a mix of fishery and fishery-independent data in studies of stock structure of impacted species.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1748-7692.1998.tb00689.x
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  • 5
    Digitale Medien
    Digitale Medien
    ARE GRAY WHALES HITTING “K” HARD? (2001)
    Oxford, UK : Blackwell Publishing Ltd
    Marine mammal science 17 (2001), S. 0 
    Details
    ISSN: 1748-7692
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1748-7692.2001.tb01310.x
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  • 6
    Digitale Medien
    Digitale Medien
    IDENTIFICATION OF GEOGRAPHIC FORMS OF COMMON DOLPHIN (Delphinus delphis) FROM AERIAL PHOTOGRAMMETRY (1993)
    Oxford, UK : Blackwell Publishing Ltd
    Marine mammal science 9 (1993), S. 0 
    Details
    ISSN: 1748-7692
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: Abstract: At least four morphologically distinct forms of common dolphins are found in the eastern Pacific, We compared length data for common dolphins photographed from the northern, central and southern regions as defined by Perrin et al. (1985) and found significant differences in average length for adult animals (〉150 cm) and for “adult females” defined for our purposes as animals accompanied by calves. Analyses of calculated birth dates for calves demonstrated differences in timing of reproduction between the geographically adjacent forms. Length distributions from aerial photographs and samples collected from the purse seine fishery were strikingly similar. This work demonstrates a new, non-invasive method for obtaining unbiased life history and morphological data.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1748-7692.1993.tb00438.x
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  • 7
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    Abundance and distribution of the eastern North Pacific Steller sea lion (Eumetopias jubatus) population (2021)
    In:  http://aquaticcommons.org/id/eprint/8935 | 403 | 2012-06-27 16:56:11 | 8935 | United States National Marine Fisheries Service
    Details
    Publikationsdatum: 2021-06-29
    Beschreibung: The eastern Steller sea lion (Eumetopias jubatus) populationcomprises animals that breed along the west coast of North America between California and southeastern Alaska. There are currently 13 major rookeries (〉50 pups): five insoutheastern Alaska, three in British Columbia, two in Oregon, and three in California. Overall abundance hasincreased at an average annual rate of 3.1% since the 1970s. These increases can largely be attributed to population recovery from predator-control kills and commercial harvests, and abundance is now probably as high as it has been in the last century. The number of rookeries has remained fairly constant (n=11 to 13) over thepast 80 years, but there has been a northward shift in distribution of both rookeries and numbers of animals.Based on the number of pups counted in a population-wide survey in 2002, total pup production was estimated to be about 11,000 (82% in southeastern Alaska and British Columbia), representing a total population size as approximately 46,000−58,000 animal
    Schlagwort(e): Biology ; Ecology ; Fisheries
    Repository-Name: AquaDocs
    Materialart: article , TRUE
    Format: application/pdf
    Format: application/pdf
    Format: 102-115
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  • 8
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    Photogrammetry of blue whales with an unmanned hexacopter (2016)
    John Wiley & Sons
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    Publikationsdatum: 2022-05-25
    Beschreibung: Author Posting. © Society for Marine Mammalogy, 2016. This article is posted here by permission of Society for Marine Mammalogy for personal use, not for redistribution. The definitive version was published in Marine Mammal Science 32 (2016):1510–1515, doi:10.1111/mms.12328.
    Beschreibung: Baleen whales are the largest animals ever to live on earth, and many populations were hunted close to extinction in the 20th century (Clapham et al. 1999). Their recovery is now a key international conservation goal, and they are important in marine ecosystems as massive consumers that can promote primary production through nutrient cycling (Roman et al. 2014). However, although abundance has been assessed to monitor the recovery of some large whale populations (e.g., Barlow et al. 2011, Laake et al. 2012) many populations are wide-ranging and pelagic, and this inaccessibility has generally impeded quantitative assessments of recovery (Peel et al. 2015). To augment traditional abundance monitoring, we suggest that photogrammetric measures of individual growth and body condition can also inform about population status, enabling assessment of individual health as well as population numbers. Photogrammetry from manned aircraft has used photographs taken from directly above whales to estimate individual lengths (Gilpatrick and Perryman 2008) and monitor growth trends (Fearnbach et al. 2011), and shape profiles can be measured to assess body condition to infer reproductive and nutritional status (e.g., Perryman and Lynn 2002, Miller et al. 2012). Recently, Durban et al. (2015) demonstrated the utility of an unmanned hexacopter for collecting aerial photogrammetry images of killer whales (Orcinus orca); this provided a noninvasive, cost-effective, and safe platform that could be deployed from a boat to obtain vertical images of whales. Here we describe the use of this small, unmanned aerial system (UAS) to measure length and condition of blue whales (Balaenoptera musculus), the largest of all whales.
    Beschreibung: María Francisca Cortés Solari; Rafaela Landea Briones; MERI Foundation; Woods Hole Oceanographic Institution Access
    Repository-Name: Woods Hole Open Access Server
    Materialart: Article
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  • 9
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    Body shape changes associated with reproductive status, nutritive condition and growth in right whales Eubalaena glacialis and E. australis (2012)
    Inter-Research
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    Publikationsdatum: 2022-05-25
    Beschreibung: Author Posting. © Inter-Research, 2012. This article is posted here by permission of Inter-Research. The definitive version was published in Marine Ecology Progress Series 459 (2012): 135-156, doi:10.3354/meps09675.
    Beschreibung: Mammalian reproduction is metabolically regulated; therefore, the endangered status and high variability in reproduction of North Atlantic right whales Eubalaena glacialis necessitate accurate assessments at sea of the nutritional condition of living individuals. Aerial photogrammetry was used to measure dorsal body width at multiple locations along the bodies of free-swimming right whales at different stages of the female reproductive cycle (E. glacialis) and during the initial months of lactation (mother and calf Eubalaena australis) to quantify changes in nutritional condition during energetically demanding events. Principal components analyses indicated that body width was most variable at 60% of the body length from the snout. Thoracic, abdominal and caudal body width of E. australis thinned significantly during the initial months of lactation, especially at 60% of body length from the snout, while their calves’ widths and width-to-length ratios increased. The body shape of E. glacialis that had been lactating for 8 mo was significantly thinner than non-lactating, non-pregnant E. glacialis. Body shape of E. glacialis measured in the eighth month of lactation was significantly thinner than that of E. australis in the first month, but did not differ from that of E. australis in the third and fourth months. Body width was comparable with diameter calculated from girth of carcasses. These results indicate that mother right whales rely on endogenous nutrient reserves to support the considerable energy expenditure during the initial months of lactation; therefore, photogrammetric measurements of body width, particularly at 60% of body length from the snout, are an effective way to quantitatively and remotely assess nutritional condition of living right whales.
    Beschreibung: This project was made possible with funds provided by the National Oceanic and Atmospheric Administration (NOAA), National Marine Fisheries Service, the Northeast Consortium, and the Hussey Foundation through the Ocean Life Institute at Woods Hole Oceanographic Institution.
    Schlagwort(e): Right whale ; Body shape ; Body condition ; Aerial photogrammetry ; Reproduction ; Energetics ; Eubalaena
    Repository-Name: Woods Hole Open Access Server
    Materialart: Article
    Format: application/pdf
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  • 10
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    The use of aerial photographs for estimating school sizes of cetaceans (2021)
    In:  http://aquaticcommons.org/id/eprint/3459 | 8 | 2011-09-29 17:26:25 | 3459 | Inter-American Tropical Tuna Commission
    Details
    Publikationsdatum: 2021-06-26
    Beschreibung: ENGLISH: The accuracy and precision of dolphin school size estimates based on aerial photograph counts were examined using data collected on recent aerial and ship surveys. These estimates were found to be accurate during a 1979research cruise aboard a tuna purse-seiner; dolphin schools were photographed from the ship’s helicopter, encircled with the purse-seine, and then counted as the dolphins were released from the net. A comparison of photographic estimates with these counts indicated that the relationship was fairly close and gave no indication of significantly differing from 1:1. During a 1980 aerial study, photographic estimates from different schools, passes, and camera formats were compared and were found to be quite precise with a standard deviation of approximately 60/0 of school size. Photographic estimates were also compared with estimates made by aerial observers. Most observers tended to underestimate school size, particularly for large schools. The variability among observers was high, indicating that observers should be individually calibrated. SPANISH: Se examinó la exactitud y la precisión de las estimaciones de la magnitud de los cardúmenes de delfines basadas en el cálculo de las fotografías aéreas, usando los datos obtenidos en los últimos reconocimientos aéreos y de los barcos. En 1979, durante un crucero de investigación en un cerquero atunero, se encontró que estas estimaciones eran acertadas; se fotografiaron los cardúmenes de delfines desde un helicóptero del barco, cercados con la red y luego se contaron a medida que se libraban los delfines de la red. Una comparación de las estimaciones fotográficas con estos cálculos indicó que la relación era bastante aproximada y no hubo indicación que se diferenció significativamente de la razón 1:1. Durante un estudio aéreo en 1980, se compararon las estimaciones fotográficas de diferentes del cardúmenes, en los pases y los formatos de las cámaras y se encontró que eran bastante precisos, con una desviación normal de cerca del 60/0 de la magnitud cardumen. Se compararon también las estimaciones fotográficas con las estimaciones realizadas por los observadores aéreos. La mayoría de los observadores tienden a subestimar la magnitud de los cardúmenes, especialmente los cardúmenes grandes. La variabilidad entre los observadores fue elevada, lo que indica que se deben calibrar individualmente los datos de observadores.(PDF contains 39 pages.)
    Beschreibung: This article is bilingual and contains both Spanish and English translations.
    Schlagwort(e): Management ; Oceanography ; aerial photography ; school size ; cetacean ; fotografias aereas ; los cardúmenes ; los cetaceos
    Repository-Name: AquaDocs
    Materialart: article
    Format: application/pdf
    Format: application/pdf
    Format: 381-419
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