Some factors affecting the distribution and apparent abundance of yellowfin and skipjack tuna in the Eastern Pacific Ocean

ENGLISH: Since 1951, the Inter-American Tropical Tuna Commission has been investigating the biology, ecology and population dynamics of the yellowfin tuna, Thunnus albacares, and the skipjack tuna, Katsuwonus pelamis, in the Eastern Pacific Ocean. Of particular importance has been the study of the effects of fishing and of fishery-independent factors on the abundance and distribution of these tunas. For yellowfin tuna there is, on the average, an inverse relationship between total fishing effort and apparent abundance (Schaefer, 1957a). For skipjack there is no evidence to suggest that fishing effort has ever been sufficiently intense to affect measurably the abundance (Schaefer, 1961). Rather, it appears that the year-to-year fluctuations in apparent abundance are independent of the activities of the fishing fleets. SPANISH: Desde 1951 la Comisión Interamericana del Atún Tropical se ha dedicado a la investigación de la biología, ecología y la dinámica de las poblaciones del atún aleta amarilla, Thunnus albacares, y del barrilete, Katsuwonus pelamis, en el Océano Pacífico del Este. De importancia especial ha sido el estudio de los efectos de la pesca y de los factores independientes de las pesquerías sobre la abundancia y la distribución de esos atunes. En cuanto al atún aleta amarilla, existe, en promedio, una relación inversa entre el esfuerzo total de pesca y la abundancia aparente (Schaefer, 1957a) . Con respecto al barrilete, no hay evidencia que haga pensar que el esfuerzo de pesca haya sido nunca lo suficientemente intenso como para afectar sensiblemente la abundancia (Schaefer, 1961). Más bien parece que las fluctuaciones de un año a otro en su abundancia aparente, son independientes de las actividades de las flotas pesqueras.

Primary production, chlorophyll, and zooplankton volumes in the tropical Eastern Pacific Ocean

ENGLISH: Between 1 October and 17 December 1955 investigations of the physical, chemical and biological oceanography of the Eastern Pacific Ocean in a region bounded approximately by 30° N. latitude, 9° S. latitude, 120° W. longitude and the mainland coast were conducted from the vessels Horizon and Spencer F. Baird of the Scripps Institution of Oceanography of the University of California. These were part of a cooperative operation, designated for convenience by the code name "Eastropic," in which a vessel of the U. S. Fish and Wildlife Service worked, during this same period, further west and a vessel of the Peruvian Navy worked further south, offshore from Peru. A vessel of the California State Fisheries Laboratory also conducted certain sub-surface tuna fishing operations and other studies in the same general region as the Scripps vessels. In addition to carrying out a number of special studies related to particular oceanographic features, the Scripps vessels occupied a considerable number of hydrographic stations. The locations of these stations, at each of which were made net-hauls for zooplankton, are shown in Figure 4 and Tables 2 and 3. At some of the hydrographic stations, and in Some places between stations, there were made from the Spencer F. Baird measurements of chlorophyll "a" and of primary production (by the C14 technique), both in situ and in a shipboard incubator. The purpose of this paper is to report on the results of these biological observations. SPANISH: Entre el 1° de octubre y el 17 de diciembre de 1955, a bordo de los barcos Horizon y Spencer F. Baird) de la Institución Scripps de Oceanografía de la Universidad de California, se hicieron investigaciones sobre la oceanografía física, química y biológica del Océano Pacífico Oriental, en una región limitada aproximadamente por los 30° N. de latitud, 9° S. de latitud, 120° O. de longitud y la costa continental. Estas investigaciones fueron parte de una operación que se realizó cooperativamente y a la que se convino darle el nombre codificado de "Eastropic". En ella, durante el mismo período, una embarcación del Servicio de Pesca y Vida Silvestre de los Estados Unidos (U. S. Fish and Wildlife Service) trabajó más hacia el oeste, y un barco de la armada peruana más hacia el sur, frente a la costa del Perú. También colaboró una nave del Laboratorio de Pesquerías del Estado de California (California State Fisheries Laboratory), realizando algunas operaciones de pesca de atún en aguas subsuperficiales, y otros estudios en la misma región general que recorrieron las embarcaciones de Scripps. Además de efectuar estudios especiales relacionados con las caracteristicas oceanográficas particulares de la región, las naves de Scripps establecieron un buen número de estaciones hidrográficas. La localización de estas estaciones se indica en la Figura 4 y en las Tablas 2 y 3; en cada una de ellas se hicieron rastreos con redes planctónicas para recoger muestras de zooplancton. En algunas de las estaciones hidrográficas, así como en algunos lugares entre estaciones, en el Spencer F. Baird se hicieron mediciones de la clorofila "a" y de la producción primaria (mediante la técnica del C14), tanto in situ como en una incubadora instalada a bordo. El propósito del presente trabajo es dar a conocer los resultados de estas observaciones biológicas. (PDF contains 44 pages.)

Stocks of Dolphins (Stenella spp. and Delphinus delphis) in the Eastern Tropical Pacific: A Phylogeographic Classification

Current information is reviewed that provides clues to the intraspecific structure of dolphin species incidently killed in the yellowfin tuna purse-seine fishery of the eastern tropical Pacific (ETP). Current law requires that management efforts are focused on the intraspecific level, attempting to preserve local and presumably locally adapted populations. Four species are reviewed: pantropical spotted, Stenella attenuata; spinner, S. longirostTis; striped, S. coeruleoalba; and common, Delphinus delphis, dolphins. For each species, distributional, demographic, phenotypic, and genotypic data are summarized, and the putative stocks are categorized based on four hierarchal phylogeographic criteria relative to their probability of being evolutionarily significant units. For spotted dolphins, the morphological similarity of animals from the south and the west argues that stock designations (and boundaries) be changed from the current northern offshore and southern offshore to northeastern offshore and a combined western and southern offshore. For the striped dolphin, we find little reason to continue the present division into geographical stocks. For common dolphins, we reiterate an earlier recommendation that the long-beaked form (Baja neritic) and the northern short-beaked form be managed separately; recent morphological and genetic work provides evidence that they are probably separate species. Finally, we note that the stock structure of ETP spinner dolphins is complex, with the whitebelly form exhibiting characteristics of a hybrid swarm between the eastern and pantropical subspecies. There is little morphological basis at present for division of the whitebelly spinner dolphin into northern and southern stocks. However, we recommend continued separate management of the pooled whitebelly forms, despite their hybrid/intergrade status. Steps should be taken to ensure that management practices do not reduce the abundance of eastern relative to whitebelly spinner dolphins. To do so may lead to increased invasion of the eastern's stock range and possible replacement of the eastern spinner dolphin genome.(PDF file contains 24 pages.)

Structure and Historical Changes in the Groundfish Complex of the Eastern Bering Sea

The eastern Bering Sea is a major marine ecosystem containing some of the largest populations of groundfish, crabs, birds, and marine mammals in the world. Commercial catches of groundfish in this region have averaged about 1.6 million tons (t) annually in 1970-86. This report describes the species and relative importance of species in the eastern Bering Sea groundfish complex, the environment in which they live, and the history of the fisheries and management during the years 1954 - 1985. Historical changes in abundance and the condition of the principal species at the end of this first 30 years of exploitation are also examined. Results suggest that the biomass of the groundfish complex is characterized by variability rather than stability. The most reliable data (1979 to 1985) suggests that the biomass of the complex fluctuated between 11.8 and 15.7 million t. Even greater variability is suggested by the less reliable data from earlier years. Because of its dominance in the complex and wide fluctuations in abundance, walleye pollock (Theragra chalcogramma) is primarily responsible for the major variations in abundance of the complex. After 30 years of exploitation, the complex was generally in excellent condition. (PDF file contains 100 pages.)

Review of geographical stocks of tropical dolphins (Stenella spp. and Delphinus delphis) in the eastern Pacific

Information on geographical variation is reviewed for Stenella attenuata, S. longirostris, S. coeruleoalba, and Delphinus delphis in the eastern tropical Pacific, and boundaries for potential management units are proposed. National Marine Fisheries Service and Inter-American Tropical Tuna Commission sighting records made from 1979 to 1983 which were outside boundaries used in a 1979 assessment were examined for validity. Tagging returns and morphological data were also analyzed. Several stock ranges are expanded or combined. Three management units are proposed for S. attenuata: the coastal, northern offshore, and southern offshore spoiled dolphins. Four management units are proposed for S. longirostris: the Costa Rican, eastern, northern whitebelly, and southern whitebelly spinner dolphins. Two provisional management units are proposed for S. coeruleoalba: the northern and southern striped dolphins. Five management units (two of which are provisional) are proposed for D. delphis: the Baja neritic, northern, central, southern, and Guerrero common dolphins. Division into management units was based on morphological stock differences and distributional breaks. (PDF file contains 34 pages.)

Observations on the taxonomy, biology, and ecology of the Engraulid and Clupeid fishes in the Gulf of Nicoya, Costa Rica.

ENGLISH: In 1952 and 1953, during the course of a study of the abrupt decline and apparent disappearance from the Gulf of Nicoya of the population of anchovetas (Cetengraulis mysticetus), an important tuna bait fish, considerable material was collected on the taxonomy, biology, and ecology of the several anchovies and the herrings inhabith1g the Gulf. The Gulf of Nicoya, approximately 50 miles long and varying in width from about 5 to 35 miles, is located on the Pacific coast of Costa Rica. The family Engraulididae is represented by four genera comprising fourteen species, and nine species were identified as members of eight genera of the family Clupeidae. All of the species inhabit other coastal areas of the tropical Eastern Pacific. SPANISH: En 1952 Y 1953, durante el curso de un estudio sobre la declinación abrupta y la aparente desaparición en el Golfo de Nicoya de la población de anchovetas (Cetengraulis mysticetus) un pez de importancia para la pesca del atún, se recolectó material considerable relacionado con la taxonomía, biología y ecología de las diversas especies de anchoas y arenques que habitan dicho Golfo. El Golfo de Nicoya, que mide aproximadamente 50 millas de largo y varía en su anchura entre 5 y 35 millas, se encuentra en la costa del Pacífico de Costa Rica. La familia de los Engráulidos está representada por cuatro géneros que comprenden catorce especies, y otras nueve fueron identificadas como miembros de ocho géneros de la familia Clupeidae. Todas estas especies habitan otras áreas costeras del Pacífico Oriental tropical. (PDF contains 144 pages.)

A study of changes in fishing effort, abundance, and yield for yellowfin and skipjack tuna in the Eastern Tropical Pacific Ocean

ENGLISH: The rapid growth of the Eastern Pacific fishery for yellowfin and skipjack tuna since the end of World War II has given rise to questions concerning the rational utilization of these resources. As part of the Inter-American Tropical Tuna Commission's program of research designed to investigate these problems, a study was undertaken to determine from the historical records of the fishery the effects of fishing upon the stocks of yellowfin and skipjack tuna of the Eastern Pacific region and to evaluate the present condition of these stocks with respect to the maximum equilibrium yield. SPANISH: EI rápido crecimiento, desde la terminación de la Segunda Guerra Mundial, de la pesquería de atún aleta amarilla y barrilete en el Pacifico Oriental, ha dado lugar a que se hagan algunos comentarios sabre la racional utilización de estos recursos. Como parte del programa de la Comisión Interamericana del Atún Tropical designado para la investigación de estos problemas, un estudio fué llevado a cabo para determinar, de los informes historicós de la pesquería, los efectos de la pesca sobre los stocks de atún aleta amarilla y barrilete de la región del Pacifico Oriental y para evaluar la presente condición de estos stocks con respecto al máximo rendimiento de equilibria. (PDF contains 123 pages.)

Influence of the Azores high on sea level pressure and wind, and on precipitation, in the Eastern Tropical Pacific Ocean

ENGLISH: Intensification of the Azores high pressure cell in mid-year, with concomitant air flow from the Caribbean into the Pacific, is shown to be responsible for a secondary minimum of precipitation observed along the tropical Pacific coast of the Americas, and to have a measurable effect on wind and precipitation several hundred kilometers offshore. SPANISH: La intensificación de la célula de alta presión de las Azores a mediados del año, y la corriente de aire concomitante que entra al Pacífico procedente del Caribe, se demuestra que es la causante de un mínimo secundario de precipitación observado a lo largo de la costa tropical de las Américas en el Pacífico y que tiene un efecto mensurable sobre el viento y la precipitación varios cientos de kilómetros mar afuera. (PDF contains 23 pages.)

Geographical distribution of yellowfin tuna and skipjack catches in the Eastern Pacific Ocean, by quarters of the year, 1963-1966

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.)

Geographical catch distribution of yellowfin and skipjack tuna in the Eastern Pacific Ocean, 1967-1970, and fleet and total catch statistics, 1962-1970

ENGLISH: Logbook records of tuna vessels fishing in the eastern Pacific Ocean were used to prepare charts showing the distribution of yellowfin tuna and skipjack catches by i-degree area, by quarter of the year, and by gear, for the years 1967-1970. Recent changes in the geographical distribution of yellowfin catch are illustrated. Also given are annual catch statistics and the composition of the international tuna fishing fleets which operated in the Commission's Yellowfin Regulatory Area each year, 1962-1970. SPANISH: Los registros de los cuadernos de bitácora de los barcos pesqueros de atún en el Océano Pacífico oriental se usaron para preparar gráficos que presentan para los años de 1967-1970, la distribución de captura del atún aleta amarilla y barrilete por área de 1 grado, trimestre del año y, por las artes. Se ilustran los recientes cambios en la distribución geográfica de la captura del atún aleta amarilla. Se presentan también las estadísticas de captura anual y la composición de la flota internacional de pesca, que explota cada año el Area Reglamentaria de la Comisión, 1962-1970. (PDF contains 95 pages.)

Migrations of yellowfin and skipjack tuna in the Eastern Pacific Ocean as determined by tagging experiments, 1952-1964

ENGLISH: Totals of 59,547 tagged yellowfin and 90,412 tagged skipjack were released during 1952-1964 throughout the range of the fishery in the eastern Pacific Ocean during that period. Most of the fish were released from commercial baitboats, either on regular fishing trips or on chartered trips to catch fish for tagging. There we re 8,397 yellowfin and 4,381 skipjack returned from these releases. There appear to be two main groups of yellowfin in the eastern Pacific Ocean. There is considerable intermingling among the fish of the two groups, however. The fish of the northern group (west coast of Baja California, Gulf of California, and Revillagigedo Islands) first appear in the Revillagigedo Islands in about April, and migrate north along the Baja California coast during the spring and summer and south along that coast during the fall. Recruits to the southern group (Tres Marias Islands to northern Chile) appear at many points or continuously along most of the coast. The fish which first appear in the northern Panama Bight in April migrate rapidly northwest to Central America and Mexico and south to the Gulf of Guayaquil. There also appear to be two main groups of skipjack in the eastern Pacific Ocean. The fish of the northern group (west coast of Baja California, Gulf of California, and Revillagigedo Islands ) perform about the same migration as do the yellowfin of the same area, but most of the skipjack apparently then migrate to the central Pacific Ocean during the fall and/or winter. Recruits to the southern group (Central America to northern Chile) appear mostly in or near the Panama Bight. The fish which first appear in the northern Panama Bight in April migrate rapidly northwest to Central America and south to the Gulf of Guayaquil. The proportions which migrate in these directions vary considerably from year to year, this perhaps being dependent on differences in the sea-surface temperatures. SPANISH: Durante el período de 1952-1964 se liberó a través de todos los límites de distribución de la pesquería en el Océano Pacífico oriental un total de 59,547 aleta amarilla y 90,412 barriletes marcados. La mayoria de los peces fueron liberados de barcos de carnada comerciales, o en viajes regulares de pesca o en viajes en los que se fletaron los barcos para capturar atunes y marcarlos. De estas líberaciones se recapturaron 8,397 aleta amarilla y 4,381 barriletes. Parece que haya dos grupos principales de aleta amarilla en el Océano Pacífico oriental. Sin embargo, existe una entremezcla considerable entre los peces de los dos grupos. Los peces del grupo septentrional (costa occidental de Baja California, Golfo de California y Islas Revillagigedo) aparecen primero en las Islas Revillagigedo alrededor de abril, y durante la primavera y el verano se desplazan al norte a lo largo de la costa de Baja California y durante el otoño al sur a lo largo de la costa. Los reclutas del grupo meridional (Islas Tres Marias hasta el norte de Chile) aparecen en muchas partes o continuamente a lo largo de la mayoría de la costa. Los peces que aparecen primero en la región septentrional del Panamá Bight en abril se desplazan rápidamente al noroeste a la América Central y México y al sur al Golfo de Guayaquil. Parece también que existen dos grupos principales de barrilete en el Océano Pacífico oriental. Los peces del gr upo septentrional (costa occidental de Baja California, Golfo de California e Islas Revillagigedo ) realizan casi la misma migración que el atún aleta amarilla de la misma área, pero aparentemente la mayor parte del barrilete se desplaza luego al Océano Pacífico central durante el otoño y/o en el invierno. Los reclutas al grupo meridional (América Central al norte de Chile) aparecen en su mayoría en el Panamá Bight o cerca a este lugar. Los peces que aparecen primero en la región septentrional del Panamá Bight en abril se desplazan rápidamente al noroeste a la América Central y al sur al Golfo de Guayaquil. Las proporciones que se desplazan en estas direcciones varían considerablemente de año a año; tal vez esto depende en las diferencias de temperatura de la superficie del mar. (PDF contains 227 pages.)

Lake Chad fisheries and its importance in the Green Revolution Programme

Lake Chad fisheries contributes about 13% of all fish produced by the inland and coastal states of the nation and supports a large population of fishermen and allied workers. The species of freshwater fish produced from the Lake such as Gymnarchus, Clarias and Heterotis are very popular with the fish consumers in Nigeria; hence Lake Chad processed fish is transported long distances to southern Nigerian markets. Lake Chad thus contributes significantly to the provision of fish protein and to the Green Revolution Programme

Transport Properties And Induced Voltage In The Structure Of Water-Filled Single-Walled Boron-Nitrogen Nanotubes

Density functional theory/molecular dynamics simulations were employed to give insights into the mechanism of voltage generation based on a water-filled single-walled boron-nitrogen nanotube (SWBNNT). Our calculations showed that (1) the transport properties of confined water in a SWBNNT are different from those of bulk water in view of configuration, the diffusion coefficient, the dipole orientation, and the density distribution, and (2) a voltage difference of several millivolts would generate between the two ends of a SWBNNT due to interactions between the water dipole chains and charge carriers in the tube. Therefore, this structure of a water-filled SWBNNT can be a promising candidate for a synthetic nanoscale power cell as well as a practical nanopower harvesting device.

Failure detectors and communication efficiency in the crash and general omisión failure models

122 p.