996 resultados para Distribution circuits


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We present data on ichthyoplankton distribution, abundance, and seasonality and supporting environmental information for four species of coastal pelagics from the family Carangidae: blue runner Caranx crysos, Atlantic bumper Chloroscombrus chrysurus, round scad Decapterus punctatus, and rough scad Trachurus lathami. Data are from 1982 and 1983 cruises off Louisiana sponsored by the Southeastern Area Monitoring and Assessment Program (SEAMAP). Bioprofiles on reproductive biology, early life history, meristics, adult distribution, and fisheries characteristics are also presented for these species. Maximum abundances of larval blue runner, Atlantic bumper, and round scad were found in July inside the 4O-m isobath, although during the rest of the cruises these species were rarely found together. Larval Atlantic bumper were captured in June and July only; blue runner in May, June, and July; and round scad in all seasons. Atlantic bumper larvae, concentrated mostly off western Louisiana, were by far the most abundant carangid in 1982 and 1983. Larval blue runner were the second most abundant summer-spawned carangid in 1982 and 1983, but their abundance and depth distribution varied considerably between years. Relative abundance of larval round scad off Louisiana was low, and they were captured only west of the Mississippi River delta, although they are reported to dominate carangid populations in the eastern Gulf of Mexico. Rough scad were primarily winter/spring and outer-shelf (40-182 m) spawners. They ranked third in overall abundance, but were the most abundant target carangid on the outer shelf. Ecological parameters such as surface salinity, temperature, and station depth are presented from capture sites for recently hatched larvae <2.5 mm notochord length, except round scad) as well as for all sizes of fish below 14 mm standard length. (PDF file contains 44 pages.)

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We present data on ichthyoplankton distribution, abundance, and seasonality and supporting environmental information for four species of coastal pelagics from the family Clupeidae: round herring Etrumeus teres, scaled sardine Harengula jaguana, Atlantic thread herring Opisthonema oglinum, and Spanish sardine Sardinella aurita. Data are from 1982 and 1983 cruises across the northern Gulf of Mexico sponsored by the Southeastern Area Monitoring and Assessment Program (SEAMAP). This is the first such examination for these species on a multiyear and gulfwide scale. Bioproflles on reproductive biology, early life history, meristics, adult distribution, and fisheries characteristics are also presented for these species. During the summer, larval Atlantic thread herring and scaled and Spanish sardines were abundant on the inner shelf <40 m depth), but were rare or absent in deeper waters. Scaled sardine and thread herring were found virtually everywhere inner-shelf waters were sampled, but Spanish sardines were rare in the north-central Gulf. During 1982, larval Atlantic thread herring were the most abundant of the four target c1upeid species, whereas Spanish sardine were the most abundant during 1983. On the west Florida shelf, Spanish sardine dominated larval c1upeid populations both years. Scaled sardine larvae were the least abundant of the four species both years, but were still captured in 25% of inner-shelf bongo net collections. Round herring larvae, collected February-early June (primarily March-April), were abundant on the outer shelf (40-182 m depth) and especially off Louisiana. Over the 2-year period, outer-shelf mean abundance for round herring was 40.2 larvae/10 m2; inner-shelf mean abundances for scaled sardine, Atlantic thread herring, and Spanish sardine were 14.9, 39.2, and 41.9 larvae/l0 m2, respectively. (PDF file contains 66 pages.)

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Ichthyofauna of the coastal «10 m depth) habitat of the South Atlantic Bight were investigated between Cape Fear, North Carolina, and the St. John's River, Florida. Trawl collections from four nonconsecutive seasons in the period July 1980 to December 1982 indicated that the fish community is dominated by the family Sciaenidae, particularly juvenile forms. Spot (Leiostomus xanthurus) and Atlantic croaker (Micropogonias undulatus) were the two most abundant species and dominated catches during all seasons. Atlantic menhaden (Brevoortin tyrannus) was also very abundant, but only seasonally (winter and spring) dominant in the catches. Elasmobranch fIShes, especially rajiforms and carcharinids, contributed to much of the biomass of fishes collected. Total fish abundance was greatest in winter and lowest in summer and was influenced by the seasonality of Atlantic menhaden and Atlantic croaker in the catches. Biomass was highest in spring and lowest in summer, and was influenced by biomass of spot. Fish density ranged from 321 individuals and 12.2 kg per hectare to 746 individuals and 25.2 kg per hectare. Most species ranged widely throughout the bight, and showed some evidence of seasonal migration. Species assemblages were dominated by ubiquitous year-round residents of the coastal waters of the bight. Diversity (H') was highest in summer, and appeared influenced by the evenness of distribution of individuals among species. (PDF file contains 56 pages.)

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Fifteen fine-mesh (32-mm mesh) pelagic purse seine surveys were conducted between 1979 and 1984 off the Oregon and Washington coasts. Environmental conditions varied greatly among the years sampled, and even within years, due to variability in upwelling conditions and productivity and the effects of a strong El Nino from late 1982 to the middle of 1984. In the 843 sets made, a total of 115,891 specimens from 69 taxa was collected. Most individuals collected belonged to nine dominant taxa. Seasonal and interannual variations in the abundance and distribution patterns of these dominant taxa are presented in detail. A recurrent group analysis delineated four major groupings of nekton. (PDF file contains 91 pages.)

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In spite of over a century of research on cortical circuits, it is still unknown how many classes of cortical neurons exist. Neuronal classification has been a difficult problem because it is unclear what a neuronal cell class actually is and what are the best characteristics are to define them. Recently, unsupervised classifications using cluster analysis based on morphological, physiological or molecular characteristics, when applied to selected datasets, have provided quantitative and unbiased identification of distinct neuronal subtypes. However, better and more robust classification methods are needed for increasingly complex and larger datasets. We explored the use of affinity propagation, a recently developed unsupervised classification algorithm imported from machine learning, which gives a representative example or exemplar for each cluster. As a case study, we applied affinity propagation to a test dataset of 337 interneurons belonging to four subtypes, previously identified based on morphological and physiological characteristics. We found that affinity propagation correctly classified most of the neurons in a blind, non-supervised manner. In fact, using a combined anatomical/physiological dataset, our algorithm differentiated parvalbumin from somatostatin interneurons in 49 out of 50 cases. Affinity propagation could therefore be used in future studies to validly classify neurons, as a first step to help reverse engineer neural circuits.

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Low Voltage (LV) electricity distribution grid operations can be improved through a combination of new smart metering systems' capabilities based on real time Power Line Communications (PLC) and LV grid topology mapping. This paper presents two novel contributions. The first one is a new methodology developed for smart metering PLC network monitoring and analysis. It can be used to obtain relevant information from the grid, thus adding value to existing smart metering deployments and facilitating utility operational activities. A second contribution describes grid conditioning used to obtain LV feeder and phase identification of all connected smart electric meters. Real time availability of such information may help utilities with grid planning, fault location and a more accurate point of supply management.

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Covers the history of the study of boring sponges, taxonomy and distributions. Also includes identification of species, descriptions, key, references and plates. (PDF contains 30 pages)

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ENGLISH: The Inter-American Tropical Tuna Commission is engaged in scientific studies of the tuna resources of the Eastern Tropical Pacific Ocean. One of the most important aspects of these investigations is the evaluation of the effects of fishing upon the populations of yellowfin tuna (Neothunnus macropterus) and skipjack (Katsuwonus pelamis) of this region, based upon the analysis of quantitative records of fishing effort and catch. The systematic collection and compilation of statistical information on the operations and production of the tuna fishing Beet have, therefore, been essential parts of the research program since its inception in 1951. SPANISH: La Comisión Interamericana del Atún Tropical está dedicada al estudio cientifico de los recursos de atún del Océano Pacifico Oriental Tropical. Uno de los aspectos más importantes de las investigaciones es la evaluación de los efectos de la pesca sobre las poblaciones de atún aleta amarilla (Neothunnus macropterus) y barrilete (Katsuwonus pelamis) de esta región, sobre la base del análisis de los registros cuantitativos del esfuerzo de pesca y captura respectiva. La recolección sistemática y la compilación de informaciones estadisticas sobre las operaciones y producción de la flota pesquera de atún han sido, consecuentemente, de esencial importancia dentro de nuestro programa de trabajo desde su comienzo en 1951. (PDF contains 77 pages.)

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ENGLISH: In a previous Commission Bulletin, Shimada (1957) has described the geographical distribution of the yearly catches of yellowfin tuna (Neothunnus macropterus) and skipjack (Katsuwonus pelamis) from the Eastern Pacific Ocean for the period 1952 to 1955 inclusive, based on information obtained from logbook records of baitboats and purse-seiners. In view of the seasonal nature of the fishery in different areas, a summary of the catches by smaller time units may be of additional value. Accordingly, statistical data employed earlier by Shimada have been retabulated by quarters of the year and form the basis of the present report. SPANISH: En un Boletín anterior de la Comisión, Shimada (1957) hizo un estudio sobre la distribución geográfica de las pescas anuales de atún aleta amarilla (Neothunnus macropterus) y barrilete (Katsuwonus pelamis) del Océano Pacifico Oriental, en el perlado comprendido por los años 1952 a 1955 inclusive. Dicho estudio fué hecho sobre la base de la información obtenida en los registros de las bitácoras de los barcos carnaderos y rederos. Pero en vista de la naturaleza que imprimen las estaciones a la pesquería en las diferentes áreas se ha considerado que podría tener valor complementario un resumen de las pescas en unidades de tiempo menores. De acuerdo con este criterio, los datos estadísticos empleados antes por Shimada, se han tabulado de nuevo ahora, por trimestres, y constituyen siempre la base del presente informe. (PDF contains 49 pages.)

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Fish assemblage structure of Maryland's coastal lagoon complex was analyzed for spatial and seasonal patterns for the period 1991-2000. Data was made available by Maryland Department of Natural Resources from their MD Coastal Bays Finfish Survey. Dominant species from separate trawl and wiw surveys included blue crab Callinectes sapidus (erroneously included here as a "fish" due to its dominance and commercial importance), bay anchovy Anchoa mitchilli, spot Leiostomous xanthurus, silver perch Bairdiella ehrysoura, and Atlantic menhaden Brevwrtia tyrannus. Ninety-four fish species were identified in the two surveys, a diversity substantially higher than other survey records for Middle Atlantic Bight estuarine and lagoon systems (richness=26 to 78 species). Total species richness for the trawl survey was highest in Chincoteague and lowest in Assawoman and Sinepuxent. On the other hand, mean richness per tow (-area) and related Shannon Weiner Diversity Index were significantly higher in the northern two bays (Assawoman and Isle of Wight Bays) than in the two southern bays (Chincoteague or Sinepuxent Bays). For the seine survey, effort-adjusted diversity indices were significantly lower for Chincoteague Bay than for the other three bays. Higher relative abundances were observed in the northern bays than in the southern bays. The trawl survey exhibited the lowest catch-per-site in Sinepuxent Bay and the highest in Assawoman Bay. The seine survey had the lowest catch-per-site in Chincoteague Bay while the other three embayments were of similar magnitude. There was clear seasonality in assemblage structure with peak abundance and diversity in the summer compared to other seasons. Blue crabs in particular showed a c. 2-fold decline in relative abundance from early summer to fall, which is likely attributable to harvest removals (i.e., an exploitation rate of c. 50%). Seagrass coverage, although increasing over the course of the 10 year survey, did not have obvious effects on species diversity and abundance across or within the embayments, although it did have positive associations with two important species: bay anchovy and summer flounder Pavalich thys dentatus. Atlantic menhaden were most dominant in Assawoman Bay, which could be related to higher primary production typically observed in this Bay in comparison to the other three. (PDF contains 99 pages)

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ENGLISH: Logbook records of tuna vessels fishing in the eastern Pacific Ocean were used to prepare charts showing the distribution of yellowfin and skipjack tuna catches by 1-degree area, by quarter of the year, and by gear for the years 1963-1966. Recent changes in the geographical distribution of yellowfin catches are illustrated. The size composition of the U. S. tuna fleet is given, and recent changes are discussed. SPANISH: Los registros de los cuadernos de bitácora de los barcos atuneros que pescan en el Océano Pacifico oriental, se emplearon para preparar los gráficos que indican la distribuci6n de las capturas de atún aleta amarilla y de barrilete por área de 1 grado, por trimestre del ano y por aparejo de pesca para los anos de 1963-1966. Se ilustran los cambios recientes en la distribucion geográfica de las capturas de atún aleta amarilla. Se da la composición de tamaño de la flota atunera de los E. U. y se discuten los cambios recientes. (PDF contains 76 pages.)

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ENGLISH: All available longline data on skipjack captured in the Pacific Ocean by Japanese research vessels (1949-1965) and from incidental skipjack catches by Japanese commercial vessels (1956-1964) were analyzed. As skipjack are not specifically sought by longline vessels, the data are limited. Considering this it was found that: longline gear captures skipjack of wider size-range and is more selective for larger skipjack than conventional fishing methods, i.e. pole-and-line and purse-seine; skipjack are widely and almost continuously distributed across the Pacific; throughout the year average hook-rates are greater in the southeastern Pacific than in the northwestern Pacific; areas of high hook-rate shift south during the second and third quarters and north during the first and fourth quarters; in the western Pacific the north-south range of the catch distribution was greatest in the first and fourth quarters; skipjack hook-rates are relatively high in the northwestern Pacific east of Japan only during the first and fourth quarters; the highest hook-rates were recorded in extensive areas along the equator (from lO°N to 20°8 between approximately 155°W-100°W); generally more skipjack were captured by research longline gear in water temperature ranges approaching both the upper and lower temperature limits of skipjack distribution (18-21C and 26-28C), than is the case in surface skipjack fisheries; tentative comparisons of longline skipjack catch distributions with Pacific current systems, suggests low skipjack abundance in both North Pacific Central and North Pacific Equatorial water; the sex ratio was 95 males : 63 females in a small sample of skipjack examined; longlines capture skipjack of three, and possibly more, age groups; in skipjack size-composition samples studied, the smaller modal group (65 cm) observed in January-March in the northwestern Pacific (1600E-180oE and 20oN-45°N) corresponds in size to the larger modal group appearing in the late-summer surface fishery off the Izu-Bonin Islands southeast of Japan, and also compares in modal size to the skipjack taken in the Hawaiian fishery in spring time; the analysis of skipjack catches by hook position on the longline and by death-rate studies, indicates that part of the catch is made while the gear is in motion near the surface, and a lesser part of the catch is made when the gear is stabilized at a depth of 70 to 140 m. A brief discussion is given, in the light of new information presented, on several hypotheses by other authors concerning the population structure and migration of skipjack in the Pacific Ocean. SPANISH: Se analizaron todos los datos disponibles de la pesca con palangre de barriletes capturados en el Océano Pacífico por barcos japoneses de investigación (1949-1965) y por las capturas incidentales de los barcos comerciales japoneses (1956-1964). Como los barcos palangreros específicamente, no persiguen al barrilete, los datos son limitados. Considerando ésto, se encontró: que el arte palangrero obtiene barriletes con una distribución más amplia de tallas, y es más selectivo en cuanto a los barriletes de mayor talla, que los métodos convencionales de pesca, Le. cañas de pescar y redes de cerco; el barrilete se encuentra amplia y casi continuamente distribuido a través del Pacífico; en todo el año, las tasas promedio de captura por anzuelo son superiores en el Pacífico sudoriental que las del Pacífico noroeste; las áreas con una tasa alta de captura por anzuelo, se cambian hacia el sur durante los trimestres segundo y tercero, y durante los trimestres primero y cuarto hacia el norte; en el Pacífico occidental la amplitud de la distribución de captura norte-sur, fue superior en los trimestres primero y cuarto; las tasas de captura por anzuelo de barrilete, son relativamente altas en el Pacífico noroeste al este del Japón, únicamente durante los trimestres primero y cuarto; las tasas de captura por anzuelo más altas fueron registradas en extensas áreas a lo largo del ecuador (desde los 10°N hasta los 20°S, aproximadamente entre los 155°W-100°W) ; generalmente las artes palangreras de investigación capturaron más barrilete en aguas en las que la temperatura se aproximaba a los límites más altos o bajos de la temperatura en la distribución del barrilete (18-21 C y 26-28 C), que en el caso de la pesca superficial de barrilete; las comparaciones tentativas de la captura de barrilete con palangre, con el sistema de las corrientes del Pacífico, sugieren una abundancia inferior de barrilete tanto en las aguas del Pacífico central del norte como en las del Pacífico ecuatorial del norte; la proporcíon sexual examinada en una pequeña muestra de barriletes, fue de 95 machos y 63 hembras; los palangreros capturan barriletes de tres grupos de edad y posiblemente de más; en las muestras estudiadas de la composición de las tallas de barrilete, el grupo modal más pequeño (65 cm), observado en enero-marzo en el Pacífico noroeste (160 0E-180° y 20 oN-45°N), corresponde en talla al grupo modal más grande que aparece en la pesca de superficie a fines del verano frente a las Islas Izu-Bonín al sudeste del Japón, y se compara también con la talla modal del barrilete obtenido en la pesca hawaiana en la época de primavera; el análisis de las capturas de barrilete por medio del estudio de la posición de los anzuelos en el palangre y por la tasa de mortalidad, indica que parte de la captura se efectúa cuando el equipo está en movimiento cerca a la superficie y una parte inferior de la captura se realiza, cuando las artes se estabilizan a una profundidad de 70 a 140 m. Se ofrece una breve discusión sobre varias hipótesis de otros autores, en vista de la nueva información presentada referente a la estructura poblacional y a la migración del barrilete en el Océano Pacífico. (PDF contains 100 pages.)

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ENGLISH: This study is based on collections of larvae of Thunnus albacares, Euthynnus llneatus, and Auxis sp. obtained from surface and oblique net tows made during seven cruises, each along a comparable track in the entrance of the Gulf of California and each during a different month. Concomitant measurements of surface temperature, salinity, and zooplankton were made at each of the plankton stations. The catches of larval Auxis sp. were examined by analysis of variance techniques to determine which environmental features were associated with the spawning of this tuna as indicated by the distribution of larvae and to gain some insight into the behavior of the larvae themselves. The testing indicated that the spawning of Auxis sp. varied significantly among the different months of the cruises. The testing also indicated that if the larvae were capable of avoiding the sampling apparatus, this ability was not related to features associated with time of day such as light conditions. The analysis did not detect any change in the vertical distribution of the larvae among the months of the experiment. It was concluded that the larvae did not exhibit a diel vertical movement. The measurements of temperature, salinity, and zooplankton volumes were treated as covariates in the analysis. The surface temperature proved to be a highly important factor in explaining the distribution of larvae, but salinity and zooplankton volumes were not. Catches of Thunnus albaeares and Euthynnus lineatus were rare during the course of the study; these are discussed in qualitative terms with respect to the time of the year and the surface temperature. The distribution of larval tunas in the area of study was compared with the distribution of surface water masses. It appeared that these masses had no influence per se on the distribution of larvae. SPANISH: Este estudio está basado en las recolecciones de larvas de Thunnus albacares, Eutbynnus lineatus, y Auxis sp. obtenidas según los arrastres superficiales y oblicuos de la red, realizados durante siete cruceros, cada uno a la entrada del Golfo de California a lo largo de un derrotero comparable, y cada uno durante distintos meses. Las mediciones correspondientes de la temperatura superficial, salinidad y de zooplancton se realizaron en cada una de las estaciones de plancton. Las capturas de larvas Auxís sp. fueron examinadas mediante el análisis de la varianza para determinar cuales características ambientales se encontraban asociadas con el desove de este atún según lo indicaba la distribución de las larvas, y para obtener alguna idea del comportamiento de las larvas en sí mismas. Las pruebas indicaron que el desove de Auxis sp. varió significativamente entre los diferentes meses de los cruceros; indicaron también que si las larvas eran capaces de evitar el aparato de muestreo, esta habilidad no se relacionaba a las características asociadas con la hora del día de acuerdo a las condiciones de luz. El análisis no demostró ningún cambio en la distribución vertical de las larvas durante los meses del experimento. Se determinó que las larvas no exhiben un movimiento vertical diario. Las mediciones de temperatura, salinidad, y de los volúmenes de zooplancton fueron tratadas como covariables en el análisis. La temperatura superficial demostró ser un factor altamente importante en la explicación de la distribución de las larvas, pero la salinidad y los volúmenes de zooplancton no lo fueron. Las capturas de Thunnus albacares y Eutbynnus lineatus fueron pocas durante el curso de este estudio; éstas se discuten en términos cualitativos respecto a la época del año y a la temperatura superficial. La distribución de los atunes larvales en el área de estudio fue comparada con la distribución de las masas superficiales de agua. Parece que estas masas no tienen influencia per se en la distribución de las larvas. (PDF contains 40 pages.)