850 resultados para Calonectris diomedea borealis
Resumo:
Pelagic juvenile rockfish (Sebastes spp.) collected in surveys designed to assess juvenile salmonids and other species in the Gulf of Alaska in 1998 and 2000–2003 provide an opportunity to document the occurrence of the pelagic juveniles of several species of rockfish. Often, species identification of rockfish is difficult or impossible at this stage of development (~20 to 60 mm), and few species indigenous to Alaska waters have been described. Use of mitochondrial DNA markers for rockfish species allowed unequivocal identification of ten species (S. aleutianus, S. alutus, S. borealis, S. entomelas, S. flavidus, S. melanops, S. pinniger, S. proriger, S. reedi, and S. ruberrimus) in subsamples from the collections. Other specimens were genetically assignable to groups of two or three species. Sebastes borealis, S. crameri, and S. reedi were identified using morphological data. Combining genetic and morphological data allowed successful resolution of the other species as S. emphaeus, probably S. ciliatus (although S. polyspinis cannot be totally ruled out), and S. polyspinis. Many specimens were initially morphologically indistinguishable from S. alutus, and several morphological groups included fish genetically identified as S. alutus. This paper details the characteristics of these pelagic juveniles to facilitate morphological identification of these species in future collections. (PDF file contains 32 pages.)
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This paper compiles available information on osteological and other anatomical specimens of at least 51 species of aquatic mammals (34 extant, one recently extinct and 16 fossil) collected in Mexico between 1868 and 1990 and housed in 29 scientific institutions (18 in the USA, nine in Mexico, one in the Netherlands, and one in England). These collections contain a total of 1427 specimens representing 10 families of odontocetes (Squalodontidaet , Rhabdosteidaet , Pontoporiidae, Albireonidaet , Monodontidae, Phocoenidae, Delphinidae, Ziphiidae, Kogiidae, and Physeteridae), three of mysticetes (Cetotheridaet , Eschrichtiidae, and Balaenopteridae), three of carnivores (Otariidae, Phocidae, and Mustelidae) and one of sirenians (Trichechidae). Of the aquatic mammals recorded from Mexico, seven species are not represented by specimens (Stenella frontalis, Lagenodelphis hosei, Feresa attenuata, Hyperoodon sp., Eubalaena glacialis, Balaenoptera borealis, and Enhydra lutris). (PDF file contains 40 pages.)
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Cephalopod remains (beaks, bodies, and parts of bodies) were collected from the stomachs of 157 sperm whales (Physeter macrocephalus) taken off central California (lat. 37°-39°N). At least 24 species representing 14 families were identified. Frequencies of occurrence of the six most numerous taxa were Moroteuthis robusta 72.0%, Gonatopsis borealis 66.2%, Histioteuthis dofleini 36.9%, Galiteuthis spp. (including G. phyllura and G. pacifica) 36.3%, Octopoteuthis deletron 35.0%, and Vampyroteuthis infernalis 27.4%. One find of two Mesonychoteuthis hamiltoni beaks strongly suggests transequatorial migration by one large male sperm whale. (PDF file contains 18 pages.)
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We have used the technique of non-redundant masking at the Palomar 200-inch telescope and radio VLBI imaging software to make optical aperture synthesis maps of two binary stars, β Corona Borealis and σ Herculis. The dynamic range of the map of β CrB, a binary star with a separation of 230 milliarcseconds is 50:1. For σ Her, we find a separation of 70 milliarcseconds and the dynamic range of our image is 30:1. These demonstrate the potential of the non-redundant masking technique for diffraction-limited imaging of astronomical objects with high dynamic range.
We find that the optimal integration time for measuring the closure phase is longer than that for measuring the fringe amplitude. There is not a close relationship between amplitude errors and phase errors, as is found in radio interferometry. Amplitude self calibration is less effective at optical wavelengths than at radio wavelengths. Primary beam sensitivity correction made in radio aperture synthesis is not necessary in optical aperture synthesis.
The effects of atmospheric disturbances on optical aperture synthesis have been studied by Monte Carlo simulations based on the Kolmogorov theory of refractive-index fluctuations. For the non-redundant masking with τ_c-sized apertures, the simulated fringe amplitude gives an upper bound of the observed fringe amplitude. A smooth transition is seen from the non-redundant masking regime to the speckle regime with increasing aperture size. The fractional reduction of the fringe amplitude according to the bandwidth is nearly independent of the aperture size. The limiting magnitude of optical aperture synthesis with τ_c-sized apertures and that with apertures larger than τ_c are derived.
Monte Carlo simulations are also made to study the sensitivity and resolution of the bispectral analysis of speckle interferometry. We present the bispectral modulation transfer function and its signal-to-noise ratio at high light levels. The results confirm the validity of the heuristic interferometric view of image-forming process in the mid-spatial-frequency range. The signal-to- noise ratio of the bispectrum at arbitrary light levels is derived in the mid-spatial-frequency range.
The non-redundant masking technique is suitable for imaging bright objects with high resolution and high dynamic range, while the faintest limit will be better pursued by speckle imaging.
Resumo:
Der Beifang an kleinen Fischen beim Fang von Tiefseegarnelen (Pandalus borealis) ist sowohl aus Gründen des Bestandsschutzes als auch aus der Sicht des Fischers absolut unerwünscht. Diese Fische überleben zum größten Teil nicht die Fangprozedur, auch nicht, wenn sie unmittelbar nach dem Hol wieder über Bord gegeben werden. Sie sind damit für den Erhalt des betreffenden Bestandes verloren, kommerziell wertlos und verursachen in größeren Mengen einen erheblichen Sortieraufwand, der sich auf die finanzielle Bilanz einer Fangreise negativ auswirkt.
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Catch rates from surveys are used as indices of abundance for many fish species. Relative abundance estimates from surveys with longline gear do not usually account for possible effects of gear saturation, which potentially creates competition among fish for baited hooks and misrepresentations of abundance trends. We examined correlations between catch rates of sablefish (Anoplopoma fimbria) and giant grenadier (Albatrossia pectoralis) and between sablefish and shortraker (Sebastes borealis) and rougheye rockfish (Sebastes aleutianus) from 25 years of longline surveys in Alaska waters for evidence of competition for hooks. Sablefish catch rates were negatively correlated with giant grenadier catch rates in all management areas in Alaskan waters, and sablefish and rockfish were negatively correlated in five of the six areas, indicating that there is likely competition for hooks during longline surveys. Comparative analyses were done for trawl survey catch rates, and no negative correlations were observed, indicating that the negative correlations on the longline surveys are not due to differing habitat preferences or direct competition. Available adjustments for gear saturation may be biased if the probability of capture does not decrease linearly with baited hooks. A better understanding of each fish species’ catch probabilities on longline gear are needed before adjustments for hook competition can be made.
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Examination of hard parts recovered from scats (feces) is currently the most common method for determining the diet of pinnipeds. However, large or sharp prey remains may be spewed (regurgitated) biasing prey composition and size estimations in diet studies based on scats. Percent frequency of occurrence (FO%) and age or size of selected prey remains recovered from northern fur seal (Callorhinus ursinus) scat (n=3444) and spew samples (n=267) collected from rookeries on St. George Island and St. Paul Island, Alaska, between 1990 and 2000 were compared to determine if a bias in prey composition and age or size estimations existed between scats and spews. Overall prey composition was similar between sample type and location, but the relative FO% of primary prey (≥5%) varied by sample type and location. Age or size estimates of walleye pollock (Theragra chalcogramma) and of two species of gonatid squids (Gonatopsis borealis and Berryteuthis magister) were significantly larger in spews than in scats. Observed differences in FO% and estimated age or size of prey species whose remains were found in scats and spews likely result from size-selective digestion of prey remains. Scats were biased toward smaller prey remains, whereas spews were biased toward larger prey remains and cephalopod beaks. The percent overlap between age classes of walleye pollock caught by the commercial trawl fishery and age classes of walleye pollock consumed by northern fur seals varied noticeably between sample types for both islands (scats: St. George=15. 5%; St. Paul=4.1%; spews: St. George=94.6%; St. Paul=89.6%). These results demonstrate that the inclusion of multiple sampling methods allows for a more accurate assessment of northern fur seal prey occurrence and prey age and size.
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From December to February in most years from 1967 to 2007, observers counted gray whales, Eschrichtius robustus, from shore sites south of Carmel in central California. In addition to gray whales, other cetacean species were also recorded. These observations were summarized and compared among survey platforms and to ocean conditions. Eleven cetacean species were identified including eight odontocete species (killer whale, Orcinus orca; Pacific white-sided dolphin, Lagenorhynchus obliquidens; common dolphin, Delphinus spp.; bottlenose dolphin, Tursiops truncatus, northern right whale dolphin, Lissodelphis borealis; Risso’s dolphin, Grampus griseus; Dall’s porpoise, Phocoenoides dalli; and harbor porpoise, Phocoena phocoena) and three mysticete species (humpback whale, Megaptera novaeangliae; minke whale, Balaenoptera acutorostrata; and blue whale, Balaenoptera musculus). As expected, the detection of certain species among survey platforms (shore-based census watches, 25-power “Big Eye” binocular watches, and aerial surveys) was limited by species surfacing behavior and/or bathymetric preference. Comparisons among the shore-based census efforts showed a significant difference in sightings rates from 1967–84 (n = 14, mean = 0.11, SD = 0.11) to 1985–2007 (n = 11, mean = 1.48, SD = 0.47; t-Test: p < 0.001, df = 23). The warm period observed during the 1990’s may partially explain the increase in sighting rates and diversity of species observed at the census site compared to the much cooler temperatures of the 1970’s.
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Estimates of incidental marine mammal, sea turtle, and seabird mortality in the California drift gillnet fishery for broadbill swordfish, Xiphias gladius, and common thresher shark, Alopias vulpinus, are summarized for the 7-year period, 1996 to 2002. Fishery observer coverage was 19% over the period (3,369 days observed/17,649 days fished). An experiment to test the effectiveness of acoustic pingers on reducing marine mammal entanglements in this fishery began in 1996 and resulted in statistically significant reductions in marine mammal bycatch. The most commonly entangled marine mammal species were the short-beaked common dolphin, Delphinus delphis; California sea lion, Zalophus californianus; and northern right whale dolphin, Lissodelphis borealis. Estimated mortality by species (CV and observed mortality in parentheses) from 1996 to 2002 is 861 (0.11, 133) short-beaked common dolphins; 553 (0.16, 103) California sea lions; 151 (0.25, 31) northern right whale dolphins; 150 (0.21, 27) northern elephant seals, Mirounga angustirostris; 54 (0.41, 10) long-beaked common dolphins, Delphinus capensis; 44 (0.53, 6) Dall’s porpoise, Phocoenoides dalli; 19 (0.60, 5) Risso’s dolphins, Grampus griseus; 11 (0.71, 2) gray whales, Eschrichtius robustus; 7 (0.83, 2) sperm whales, Physeter macrocephalus; 7 (0.96, 1) short-finned pilot whales, Globicephala macrorhychus; 12 (1.06, 1) minke whales, Balaenoptera acutorostrata; 5 (1.05, 1) fin whales, Balaenoptera physalus; 11 (0.68, 2) unidentified pinnipeds; 33 (0.52, 4) leatherback turtles, Dermochelys coriacea; 18 (0.57, 3) loggerhead turtles, Caretta caretta; 13 (0.73, 3) northern fulmars, Fulmarus glacialis; and 6 (0.86, 2) unidentified birds.
Resumo:
白垩纪末至第三纪初(K/T界限,距今约65Ma),恐龙大规模灭绝,爬行类的优势地位被哺乳动物所取代;裸子植物和蕨类急剧衰退,被子植物蓬勃发展,并逐渐成为地表植被的主体,研究这一时期的植物群的结构和特征进而揭示植物演化和环境变迁的规律及其相互关系是当今地球科学、生命科学和环境科学的重要研究内容。黑龙江省嘉荫地区的乌云组产有丰富的植物化石,其地质时代虽未定论,但不超出晚白垩世马斯特里赫特期至早第三纪古新世的范围,处于K/T界限,对其植物群的研究意义重大。乌云植物群以往的研究在古果实学研究方面明显不足、在植物群的性质的认识及乌云组时代的确定等方面存在很大争议。本文重点研究了乌云组的果实和种子化石,增添了新的植物类群,丰富了此植物群的研究内容,对乌云组的时代问题的确定提供了新的证据。 本文研究了乌云组的Nordenskioldia borealis(昆兰树科)、Nyssidium jianyinense sp. nov. (连香树科)、Hypericum zhuii sp. nov. (金丝桃科)、Amersinia obtrullate(广义山茱萸科)、Acer wuyunense sp. nov.(槭树科)等5种果实和种子化石。Nordenskioldia borealis的果无柄、为分果、小果瓣环绕中央柱轮状排列。Nyssidium jianyinense的果序为圆锥果序、蓇葖对生、蓇葖腹缝相对、果皮三层。Hypericum zhuii的种子外形呈长椭圆形、端部具乳突、表面网状、种脊明显、种皮两层、外种皮细胞的垂周壁明显加厚。Amersinia obtrullate果序头状、果镘形、3果室。Acer wuyunense果为翅果、小坚果被明显侧翼、翅强烈下延,包围小坚果。经修订和补充,乌云植物群目前共有维管植物48属60种,其中,蕨类植物4属6种、裸子植物7属7种、被子植物37属48种,被子植物占总种数的80%、占总属数的77%,被子植物占绝对优势。当时的群落类型湿生群落和中生群落类型为主,湿生群落主要有:由Sequoia、Metasequoia、Taxodium、Glyptostrobus等组成的针叶林;以Nyssidium、Trochodendroides占优势的阔叶林。 以Metasequoia占优势的针叶林和以Nyssidium、Trochodendroides等占优势的阔叶林。乌云植物群中热带和亚热带成分占种子植物总属数的54%,而温带成分则占36%,亚热带成分占优势,当时的气候-植被类型为亚热带常绿林或常绿夏绿混交林。Nordenskioldia、Nyssidium、Amersinia、Acer化石的地质分布不早于古新世的地层,这—证据不支持乌云组的地质时代划为晚白垩世,而支持划归古新世的观点。
Resumo:
早白垩世到早第三纪这段时期是松科早期起源和其后进行分支演化的关键时期。球果因为是重要的雌性生殖器官,而在松科演化问题上具有显著的研究价值。对早白垩世到早第三纪这段时间所发现的松科球果的研究经因一个半世纪的逐渐演变,现在划分为三个属:松属(Pinus),假南洋杉型属(Pseudoaraucaria),和松型球果属(Pityostrobus)。本文对采自辽宁义县早白垩世沙海组火山灰形成的凝灰质砂砾岩层中的一批硅化松科球果进行了详细的解剖学研究。将它们划分到松型球果属Pityostrobus中,并在此属下另立了4个新种:Pityostrobus hsuii, P. liaoningensis, P. yixianensis, P. borealis,以及五个暂时不能确切定种的类型。这些种以及类型根据鳞片基部树脂道的分布方式,划分为两类:一类包括Pityostrobus hsuii, P. liaoningensis,为在鳞片基部树脂道分布在鳞片迹的远轴面类型,它俩之间的区别主要在苞鳞复合体基部鳞片迹的形状上的显著差异,以及鳞片中上部树脂道的分布方式上的不同;另一类包括P. yixianensis以及与其相类似的四个类型和P. borealis以及一个与其相类似的类型,两个种在鳞片基部,树脂道分布在鳞片迹近轴面和远轴面,它们之间的差别主要在苞鳞复合体基部远轴面树脂道分布方式的不同而划分。通过与那些已发现的出产于欧洲和北美洲的种类进行对比,发现这批标本的结构性状上所体现出的多样性与欧美的标本有显著的不同。因此,在早白垩世,东亚为松科早期起源演化的一个重要中心。
Resumo:
Results of recent seabird bycatch studies in the International Commission for the Conservation of Atlantic Tunas Convention Area were combined to estimate total seabird bycatch of pelagic longline fishing in the Atlantic Ocean, and bycatch per selected species. Available studies do not apply to the full spatial and temporal extent of the fishing effort, so assumptions were made to account for missing information. Over the 4 years from 2003 to 2006 the total seabird bycatch estimate was 48,500. Results indicate that about 57% of the pelagic longline seabird bycatch was albatrosses (Diomedea, Phoebastria, Thalassarche, Phoebetria spp.). This mortality is at a level to cause concern for the smaller and more vulnerable albatross populations in the region. Variation in annual seabird bycatch was caused by variation in total fishing effort, and movement of effort away from areas of higher seabird bycatch rates.
Resumo:
Adaptive cluster sampling (ACS) has been the subject of many publications about sampling aggregated populations. Choosing the criterion value that invokes ACS remains problematic. We address this problem using data from a June 1999 ACS survey for rockfish, specifically for Pacific ocean perch (Sebastes alutus), and for shortraker (S. borealis) and rougheye (S. aleutianus) rockfish combined. Our hypotheses were that ACS would outperform simple random sampling (SRS) for S. alutus and would be more applicable for S. alutus than for S. borealis and S. aleutianus combined because populations of S. alutus are thought to be more aggregated. Three alternatives for choosing a criterion value were investigated. We chose the strategy that yielded the lowest criterion value and simulated the higher criterion values with the data after the survey. Systematic random sampling was conducted across the whole area to determine the lowest criterion value, and then a new systematic random sample was taken with adaptive sampling around each tow that exceeded the fixed criterion value. ACS yielded gains in precision (SE) over SRS. Bootstrapping showed that the distribution of an ACS estimator is approximately normal, whereas the SRS sampling distribution is skewed and bimodal. Simulation showed that a higher criterion value results in substantially less adaptive sampling with little tradeoff in precision. When time-efficiency was examined, ACS quickly added more samples, but sampling edge units caused this efficiency to be lessened, and the gain in efficiency did not measurably affect our conclusions. ACS for S. alutus should be incorporated with a fixed criterion value equal to the top quartile of previously collected survey data. The second hypothesis was confirmed because ACS did not prove to be more effective for S. borealis-S. aleutianus. Overall, our ACS results were not as optimistic as those previously published in the literature, and indicate the need for further study of this sampling method.
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A new species Norileca borealis belonging to the family Cymothoidae is described in detail and illustrated. The new species is distinguished from the other members of the genus by the details of maxilla 2, maxilliped, pleotelson and pereopod 1.