962 resultados para Seasonal variations (Economics)


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Seventy percent of the world's catch of fish and fishery products is consumed as food. Fish and shellfish products represent 15.6 percent of animal protein supply and 5.6 percent of total protein supply on a worldwide basis. Developing countries account for almost 50 percent of global fish exports. Seafood-borne disease or illness outbreaks affect consumers both physically and financially, and create regulatory problems for both importing and exporting countries. Seafood safety as a commodity cannot be purchased in the marketplace and government intervenes to regulate the safety and quality of seafood. Theoretical issues and data limitations create problems in estimating what consumers will pay for seafood safety and quality. The costs and benefits of seafood safety must be considered at all levels, including the fishers, fish farmers, input suppliers to fishing, processing and trade, seafood processors, seafood distributors, consumers and government. Hazard Analysis Critical Control Point (HACCP) programmes are being implemented on a worldwide basis for seafood. Studies have been completed to estimate the cost of HACCP in various shrimp, fish and shellfish plants in the United States, and are underway for some seafood plants in the United Kingdom, Canada and Africa. Major developments within the last two decades have created a set of complex trading situations for seafood. Current events indicate that seafood safety and quality can be used as non-tariff barriers to free trade. Research priorities necessary to estimate the economic value and impacts of achieving safer seafood are outlined at the consumer, seafood production and processing, trade and government levels. An extensive list of references on the economics of seafood safety and quality is presented. (PDF contains 56 pages; captured from html.)

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ENGLISH: Knowledge of the kinds of organisms eaten by tunas, and the relative importance of different kinds of organisms in different situations, is of importance to our understanding of regional and local aggregations and of the behavior of the tropical tunas. Determination of the relative importance of benthic forms in the stomachs of tunas captured in the vicinity of islands and offshore banks, compared with the forms found in the stomachs of those from oceanic areas, distant from these shoal areas, is useful to the understanding of the mechanisms by which the islands and banks attract tuna. A thorough knowledge of the diet may also reveal more about the seasonal and annual variations in the distribution of these fish along the coasts of Mexico, Central America and elsewhere. A knowledge of the diet of the tunas is basic to quantitative studies of the zooplankton and nekton in the Eastern Pacific Ocean with reference to the production of tunas. Studies of the diet of the tropical tunas by examination of stomach contents was, therefore, commenced in late 1957. SPANISH: El conocimiento de las clases de organismos de que se alimentan los atunes, y la importancia relativa de las diferentes clases de organismos en situaciones diferentes, es de valor para nuestra comprensión de las agrupaciones regionales y locales, y de los hábitos de los atunes tropicales. La determinación de la importancia relativa de las formas bénticas en los estómagos de los atunes capturados en la vecindad de las islas y de los bancos apartados de la costa, comparadas con las formas encontradas en los estómagos de los atunes procedentes de áreas oceánicas, distantes de estas áreas poco profundas, es útil para comprender el mecanismo por el cual las islas y los bancos atraen al atún. Un conocimiento completo de la dieta puede revelar también algo más acerca de las variaciones estacionales y anuales en la distribución de estos peces a lo largo de las costas de México, América Central y otras partes. El conocimiento de la dieta del atún es básico para los estudios cuantitativos del zooplancton y del necton en el Océano Pacífico Oriental, con referencia a la producción de los atunes. El estudio de la dieta de los atunes tropicales mediante el examen del contenido estomacal, fué comenzado, por lo tanto, a fines de 1957.

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The increasingly intense competition between commercial and recreational fishermen for access to fish stocks has focused attention on the economic implications of fishery allocations. Indeed, one can scarcely find a management plan or amendment that does not at least refer to the relative food and sport values of fish and to how expenditures by commercial and recreational fishermen on equipment and supplies stimulate the economy. However, many of the arguments raised by constituents to influence such allocations, while having an seemingly "economics" ring to them, are usually incomplete, distorted, and even incorrect. This report offers fishery managers and other interested parties a guide to correct notions of economic value and to the appropriate ways to characterize, estimate, and compare value. In particular, introductory material from benefitcost analysis and input-output analysis is described and illustrated. In the process, several familiar specious arguments are exposed.(PDF file contains 34 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 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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The food habits of 20 species of pelagic nekton were investigated from collections made with small-mesh purse seines from 1979-84 off Washington and Oregon. Four species (spiny dogfish, Squalus acanthias; soupfin shark, Galeorhinus zyopterus; blue shark, Prionace glauca; and cutthroat trout, Salmo clarki) were mainly piscivorous. Six species (coho salmon, Oncorhynchus kisutch; chinook salmon, O. tshawytscha; black rockfish, Sebastes melanops; yellowtail rockfish, S. f1avidus; sablefish, Anoplopoma fimbria; and jack mackerel, Trachurus symmetricus) consumed both nektonic and planktonic organisms. The remaining species (market squid, Loligo opalescens; American shad, Alosa sapidissima; Pacific herring, Clupea harengus pallasi; northern anchovy, Engraulis mordax; pink salmon, O. gorbuscha; surf smelt, Hypomesus pretiosus; Pacific hake, Merluccius productus; Pacific saury, Cololabis saira; Pacific mackerel, Scomber japonicus; and medusafish, Icichthys lockingtom) were primarily planktonic feeders. There were substantial interannual, seasonal, and geographic variations in the diets of several species due primarily to changes in prey availability. Juvenile salmonids were not commonly consumed by this assemblage of fishes (PDF file contains 36 pages.)

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This report describes the proximate compositions (protein, moisture, fat, and ash) and major fatty acid profiles for raw and cooked samples of 40 southeastern finfish species. All samples (fillets) were cooked by a standard procedure in laminated plastic bags to an internal temperature of 70'C (lS8'F). Both summarized compositional data, with means and ranges for each species, and individual sample data including harvest dates and average lengths and weights are presented. When compared with raw samples, cooked samples exhibited an increase in protein content with an accompanying decrease in moisture content. Fat content either remained approximately the same or increased due to moisture loss during cooking. Our results are discussed in reference to compositional data previously published by others on some of the same species. Although additional data are needed to adequately describe the seasonal and geographic variations in the chemical compositions of many of these fish species, the results presented here should be useful to nutritionists, seafood marketers, and consumers.(PDF file contains 28 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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Expendable bathythermograph data collected by the Ships of Opportunity (SOOP) - Ocean Monitoring Program are analyzed for seasonal and inter-annual variations of the cold pool. Two major SOOP transects within the Middle Atlantic Bight (Southern New England and New York) have been analyzed for the years common to both (1977-81). During the years 1977-81, over 200 transects were occupied, and almost 3,000 XBT's were dropped. Results show that the cold pool is formed with the onset of spring warming and persists until fall overturn, is consistent year to year in both area and weighted average annual temperature, and advects water from the northeast to the southwest. Results also show a 100-d lag in minimum temperature between the Southern New England and New York transects. DitTerences in bathymetry between the two transects and their influence on the cold pool are also discussed. Plots of average (1977-81) bottom temperature for both transects are discussed and show consistent annual weighted mean temperature and areas. Bottom temperature plots for individual years, as well as maximum and minimum bottom temperature plots, are presented as Appendix figures. (PDF file contains 28 pages.)

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The California Department of Fish and Game's Natural Stocks Assessment Project (NSAP) collected water quality data at high tides on a monthly basis from February 1991 to October 1994, and during low tides from March 1992 to June 1994 in the Klamath River estuary to describe water quality conditions. NSAP collected data on water temperature, dissolved oxygen, salinity, depth of saltwedge, and Klamath River flow. Klamath River flows ranged from 44.5 cubic meters per second (1570 cfs) in August 1994 to 3832.2 cubic meters per second (135,315 cfs) in March 1993. Saltwater was present in the estuary primarily in the summer and early fall and generally extended 2 to 3 miles upstream. Surface water temperatures ranged from 6-8° C in the winter to 20-24° C in the summer. Summer water temperatures within the saltwedge were generally 5 to 8° C cooler than the surface water temperature. Dissolved oxygen in the estuary was generally greater than 6 to 7 ppm year-round. A sand berm formed at the mouth of the river each year in the late summer or early fall which raised the water level in the estuary and reduced tidal fluctuation so that the Klamath estuary became essentially a lagoon. I hypothesize the formation of the sand berm may increase the production of the estuary and help provide favorable conditions for rearing juvenile chinook salmon.

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Village tanks are put to a wide range of uses by the rural communities that depend on them for their survival. As the primacy of irrigation has decreased under these tanks due to a variety of climatic and economic reasons there is a need to reevaluate their use for other productive functions. The research presented in this paper is part of a programme investigating the potential to improve the management of living aquatic resources in order to bring benefits to the most marginal groups identified in upper watershed areas. Based on an improved typology of seasonal tanks, the seasonal changes and dynamics of various water quality parameters indicative of nutrient status and fisheries carrying capacity are compared over a period of one year. Indicators of Net (Primary) Productivity (NP): Rates of Dissolved Oxygen (DO) change, Total Suspended Solids (TSS): Total Suspended Volatile solids (TVSS) ratios are the parameters of principle interest. Based on these results a comparative analysis is made on two classes of ‘seasonal’ and ‘semi-seasonal’ tanks. Results indicate a broad correlation in each of these parameters with seasonal trends in tank hydrology. Highest productivity levels are associated with periods of declining water storage, whilst the lowest levels are associated with the periods of maximum water storage shortly after the NW monsoon. This variation is primarily attributed to dilution effects associated with depth and storage area. During the yala period, encroachment of the surface layer by several species of aquatic macrophyte also has progressively negative impacts on productivity. The most seasonal tanks show wider extremes in seasonal nutrient dynamics, overall, with less favourable conditions than the ‘semi-seasonal’ tanks. Never the less all the tanks can be considered as being highly productive with NP levels comparable to fertilised pond systems for much of the year. This indicates that nutrient status is not likely to be amongst the most important constraints to enhancing fish production. Other potential management improvements based on these results are discussed. [PDF contains 19 pages]

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ENGLISH: The Inter-American Tropical Tuna Commission has maintained a hydro-biological station in the Gulf of Panama located at 8°45'N, 79°23'W in connection with their ecological investigation of the anchoveta (Cetengraulis mysticetus), a tuna baitfish (see Peterson, 1961, for references) . The depth is approximately 42 meters at mean low water at this station. Routine hydrographic and biological observations have been made (Schaefer, Bishop and Howard, 1958; Schaefer and Bishop, 1958; Forsbergh, 1963), including the collection of quantitative phytoplankton samples from November 1954 through May 1957 (Smayda, 1959; unpublished). The seasonal and regional variations in phytoplankton growth in the Gulf of Panama have also been investigated (Smayda, 1963). The relationships existing between C1 4 assimilation as determined by 24 hour in situ experiments and diatom standing crop at 10 meters when expressed as cell numbers, cell volume, cell surface area and cell plasma volume have been assessed for 30 observations made between November 1954 and May 1957 at 8°45'N, 79°23'W. The average cell volume and cell surface area characteristics for 110 diatom species and varieties are presented. SPANISH: Las relaciones existentes entre la asimilación del C14 , determinadas después de 24 horas de experimentos in situ, y la cosecha estable de las diatomeas a 10 metros, expresando el número de células, volumen celular, área de la superficie celular y volumen del plasma celular, han sido determinadas por medio de 30 observaciones hechas entre noviembre de 1954 y mayo de 1957, a los 8°45'N, 79°23'W. Se presenta, para 110 especies y variedades de diatomeas, el promedio de las características del volumen celular y del área de la superficie celular. (PDF contains 67 pages.)

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We study the language choice behavior of bilingual speakers in modern societies, such as the Basque Country, Ireland andWales. These countries have two o cial languages:A, spoken by all, and B, spoken by a minority. We think of the bilinguals in those societies as a population playing repeatedly a Bayesian game in which, they must choose strategically the language, A or B, that might be used in the interaction. The choice has to be made under imperfect information about the linguistic type of the interlocutors. We take the Nash equilibrium of the language use game as a model for real life language choice behavior. It is shown that the predictions made with this model t very well the data about the actual use, contained in the censuses, of Basque, Irish and Welsh languages. Then the question posed by Fishman (2001),which appears in the title, is answered as follows: it is hard, mainly, because bilingual speakers have reached an equilibrium which is evolutionary stable. This means that to solve fast and in a re ex manner their frequent language coordination problem, bilinguals have developed linguistic conventions based chie y on the strategy 'Use the same language as your interlocutor', which weakens the actual use of B.1

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ENGLISH: Year-class composition of catch, virtual population size and yearclass strength were determined from serial samples of size composition of catches and catch records. Murphy's Solution to the catch equation, which is free from the effects caused by changes in fishing pressure, was used to estimate year-class strength, i.e. the total population of fish age 3/4 years. The resultant estimates indicated that the X55, X56, X57, X62 and X63 year classes were above average and the X58, X59, X60, X61 and X64 year classes were below average. The year-class designation refers to the year of actual entry or presumed year of entry into the commercial fishery (at approximately 1 year of age). The strongest and poorest year classes were the X57 and X61 classes, respectively. The ratio of the strongest to the weakest year class was 2.6. This amount of variation is small compared to that found for other species of fish. It was found that the relationship between stock size and yearclass strength is of no value in predicting year-class strength. As a by-product of the analysis, estimates of the catchability coefficients (qN) of the age groups in the fishery were obtained, These estimates were found to vary with age and time. Age-two fish apparently showed the greatest vulnerability to fishing gear, followed by ages three and one, respectively. The average estimate of the catchability coefficient in weight was calculated and found to compare favorably with Schaefer's estimate. The influence of sea-surface water temperature upon year-class strength was investigated to determine whether the latter can be predicted from a knowledge of sea-surface temperatures prevailing during and following spawning. No correlation was evident. SPANISH: La composición de la clase anual en la captura, el tamaño de la población virtual y la fuerza de clase anual, fueron determinados según una serie de muestras de la composición de tamaño de las capturas y de los registros de captura. La Solución de Murphy de la ecuación de captura, que está libre de los efectos causados por los cambios de la presión de pesca, fue usada para estimar la fuerza de la clase anual, i.e. la población total de peces de 3/4 años. Las estimaciones resultantes indican que las clases anuales X55, X56, X57, X62 y X63 fueron superiores al promedio y que las clases anuales X58, X59, X60, X61 y X64 fueron inferiores al promedio. La designación de la clase anual se refiere al año actual de entrada o al año supuesto de entrada en la pesca comercial (aproximadamente a la edad de 1 año). Las clases anuales más fuertes y más pobres fueron la X57 y X61 respectivamente. La razón de la clase anual más fuerte en relación a la más débil fue 2.6. Esta cantidad de variación es pequeña comparada con la encontrada para otras especies de peces. Se encontró que la relación entre en tamaño del stock y la fuerza de la clase anual no tiene valor en predecir la fuerza de la clase anual. Se obtuvieron estimaciones de los coeficientes de capturabilidad (qN) de los grupos de edad en la pesquería como un producto derivado del análisis. Se encontraron que estas estimaciones variaron con la edad y tiempo. Los peces de edad dos aparentemente presentaron la vulnerabilidad más grande en relación al arte pesquero, seguidos por las edades tres y una, respectivamente. La estimación promedio del coeficiente de capturabilidad en peso fue calculada y se encontró que podía compararse favorablemente con la estimación de Schaefer. La influencia de la temperatura del agua superficial del mar sobre la fuerza de la clase anual fue investigada para determinar si se podía predecir esta última según el conocimíento de las temperaturas superficiales del mar prevalecientes durante el desove y después de éste. No hubo correlación evidente. (PDF contains 44 pages.)