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.)

Seasonal Climatologies and Variability of Eastern Tropical Pacific Surface Waters

Interannual variability caused by the El Nino-Southern Oscillation in the eastern tropical Pacific Ocean (ETP) is analogous to seasonal variability of comparable magnitude. Climatological spatial patterns and seasonal variability of physical variables that may affect the ETP ecosystem are presented and discussed. Surface temperature, surface salinity, mixed layer depth, thermocline depth, thermocline strength, and surface dynamic height were derived from bathythermograph, hydrocast, and CTD data. Surface current velocity, divergence, and upwelling velocity were derived from ship drift reports. Surface wind velocity, wind stress, wind divergence, wind stress curl, and Ekman pumping velocity were derived from gridded pseudostress data obtained from Florida State University. Seasonal maps of these variables, and their deviations from the annual mean, show different patterns of variation in Equatorial (S°S-SON) and Tropical Surface Water (SOlS0N). Seasonal shifts in the trade winds, which affect the strength of equatorial upwelling and the North Equatorial Countercurrent, cause seasonal variations in most variables. Seasonal and interannual variability of surface temperature, mixed layer depth, thermocline depth and wind stress were quantified. Surface temperature, mixed layer depth and thermocline depth, but not local wind stress, are less variable in Tropical Surface Water than in Equatorial Surface Water. Seasonal and interannual variability are close to equal in most of the ETP, within factors of 2 or less. (PDF file contains 70 pages.)

Marine Flora and Fauna of the Eastern United States: Dicyemida

This manual treats the six species of dicyemid mesozoans that have been reported in three species of hosts (Octopus vulgaris, O. joubini, and O. briareus) from the eastern coast of North America and the Gulf of Mexico, including the Florida Keys. All are parasites of species of Octopus and are in the genus Dicyema, family Dicyemidae. In the introduction, the life cycle, as known, and the general morphology of dicyemids are briefly described, and methods are given for collecting and preparing material for study. These are followed by a key to species and by an annotated checklist, which includes data, some hitherto unpublished, on their known prevalence in hosts from various localities including Bimini and Bermuda.(PDF file contains 20 pages.)

Marine Flora and Fauna of the Eastern United States: Copepoda, Cyclopoida: Archinotodelphyidae, Notodelphyidae, and Ascidicolidae

This manual includes an introduction to the general biology, a selected bibliography, and an illustrated key to 11 genera and 17 species of copepods of the Crustacea, Subclass Copepoda, Order Cyclopoida, Families Archinotodelphyidae, Notodelphyidae and Ascidicolidae, associated with ascidians from the Atlantic Coast of the United States. Species distributed from the Gulf of Maine to Long Island Sound are emphasized. An annotated systematic list, with statements of the world distribution and new records of association with hosts, and a systematic index are also provided. (PDF file contains 44 pages.)

Marine flora and fauna of the eastern United States Mollusca: Cephalopoda

The cephalopods found in neritic waters of the northeastern United States include myopsid and oegopsid squids, sepiolid squids, and octopods. A key with diagnostic illustrations is provided to aid in identification of the eleven species common in the neritic waters between Cape Hatteras and Nova Scotia; included also is information on two oceanic species that occur over the continental shelf in this area and that can be confused with similar-looking neritic species. Other sections comprise a glossary of taxonomic characters used for identification of these species, an annotated systematic checklist, and checklists of the 89 other oceanic species and 18 Carolinian and subtropical neritic species that might occur occasionally off the northeastern United States. (PDF file contains 30 pages.)

Greenland turbot Reinhardtius hippoglossoides of the eastern Bering Sea and Aleutian Islands region

Greenland turbot (Reinhardtius hippoglossoides) is a commercially important flounder in both the North Atlantic and North Pacific Oceans. In the latter, its center of abundance is in the eastern Bering Sea and along the Aleutian Islands chain where its population is managed as a single stock. Harvest levels in this region of the North Pacific during the period 1970-81 were comparable with those in the northwest and northeast Atlantic, with annual average catches of 53,000 metric tons (t). However, the catch in 1984 dropped sharply to 23,100 t, in part because of reduced quotas arising from concern over continued poor recruitment and declining catch-per-unit-effort. Recruitment failure was manifested in 1) the sharp decline in the catch rate of young flsh in annual research trawl surveys on the continental shelf of the eastern Bering Sea and 2) an increasing proportion of older and larger fish in the commercial catch from the continental slope of both the eastern Bering Sea and Aleutian Islands. The cause ofthe decline in recruitment could not be clearly identifled. Greenland turbot of the Bering Sea-Aleutian Islands share certain distributional features with the North Atlantic form. There is an apparent bathymetric change in the size and age of fish, with younger animals occupying continental shelf depths and the older individuals residing at depths of the continental slope. At shallow depths the young are exposed to temperature fluctuations, whereas older animals along the slope are exposed to relatively stable temperatures. A hypothesis is proposed for describing the temporal and spatial paths by which young animals reach the mature or spawning portion of the population. (PDF file contains 38 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.)

Congrid eels of the Eastern Pacific and key to their leptocephali

This study indicates that 13 species of congrid larvae belonging to 8 genera occur in the eastern Pacific. The species are: Ariosoma gilberti; Paraconger californiensis; Paraconger sp.; P. dentatus; Chiloconger labiatus; Taenioconger digueti; T. canabus; Gorgasia punctata; G. obtusa; Gnathophis catalinensis; Hildebrandia nitens; Bathycongrus macrurus; and B. varidens. The morphological and anatomical changes undergone during metamorphosis are useful in the identification of the larvae. Larvae are distributed closer to the coastal waters, and are more common from January to May than from June to December. A key to the larvae was developed based on the myotomal counts, adult vertebral counts, pigmentation patterns, and the nature of the teeth and tail tip to distinguish the genera and species. This study shows that Garman's unidentified larvae, Atopichthys acus and A. cingulus, are two different larval stages of Ariosoma gilberti, and points out that Atopichthys dentatus and A. obtusus belong to Paraconger and Gorgasia, respectively. (PDF file contains 25 pages.)

Variability in the air-sea interaction patterns and timescales within the south-eastern Bay of Biscay, as observed by HF radar data

Two high-frequency (HF) radar stations were installed on the coast of the south-eastern Bay of Biscay in 2009, providing high spatial and temporal resolution and large spatial coverage of currents in the area for the first time. This has made it possible to quantitatively assess the air-sea interaction patterns and timescales for the period 2009-2010. The analysis was conducted using the Barnett-Preisendorfer approach to canonical correlation analysis (CCA) of reanalysis surface winds and HF radar-derived surface currents. The CCA yields two canonical patterns: the first wind-current interaction pattern corresponds to the classical Ekman drift at the sea surface, whilst the second describes an anticyclonic/cyclonic surface circulation. The results obtained demonstrate that local winds play an important role in driving the upper water circulation. The wind-current interaction timescales are mainly related to diurnal breezes and synoptic variability. In particular, the breezes force diurnal currents in waters of the continental shelf and slope of the south-eastern Bay. It is concluded that the breezes may force diurnal currents over considerably wider areas than that covered by the HF radar, considering that the northern and southern continental shelves of the Bay exhibit stronger diurnal than annual wind amplitudes.

First occurrence of Mosasauridae (Squamata) in the Maastrichtian (latest Cretaceous) of Alicante (Valencia Community, Eastern Spain)

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Monthly charts of surface salinity in the Eastern Tropical Pacific Ocean

ENGLISH: Mean monthly maps of surface salinity of the eastern Pacific Ocean were prepared using all available data. Charts were also made of the distribution by one-degree quadrangles of the number of surface salinity observations for each month. Features of interest in the surface salinity distribution are discussed briefly, especially with reference to temporal changes. SPANISH: Se prepararon mapas mensuales sobre la salinidad media de superficie del Océano Pacifico oriental tropical, usando todos los datos disponibles. También se ejecutaron cartas por cuadrángulos de un grado, según el número de las observaciones mensuales de la distribución de la salinidad superficial. Las caracteristicas de interés de las distribuciones de la salinidad superficial se discuten brevemente, especialmente con referencia a los cambios estacionales. (PDF contains 44 pages.)

Size composition, growth and sexual maturity of bigeye tuna, Thunnus obesus (Lowe), from the Japanese long-line fishery in the Eastern Pacific Ocean

Size composition data of bigeye tuna taken from the eastern tropical Pacific Ocean by Japanese Prefectural experimental training vessels from 1958 to 1964 are examined. A gradient of increasing fish size from east to west is noted. Males increase in ratio over females for the entire range of lengths examined, and beyond 170 cm comprise more than 75 per cent of the total. The first semester of the year is important as a bigeye spawning season. A general relationship between sexual maturity and thermal structure of the water is discussed. At the end of their 12th quarter of life bigeye are about 114 cm long, by the 16th quarter, 137 cm and at the end of 20 quarters, about 153 cm. The long-line fishery in the eastern Pacific has had a marked effect on the size composition of the stocks of bigeye, but whether the fishing has driven the stocks below a point which could afford a maximum sustainable yield could not be determined. (PDF contains 55 pages.)

Geographical distribution of the annual catches of yellowfin and skipjack tuna from the Eastern Tropical Pacific Ocean from vessel logbook records, 1952-1955

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.)

Studies of the sexual development and spawning of yellowfin tuna, Neothunnus macropterus, and skipjack, Katsuwonus pelamis, in three areas of the Eastern Pacific Ocean, by examination of gonads.

ENGLISH: Knowledge of the size and age at maturity, spawning seasons, and spawning areas of the tropical tunas supporting the fishery in the Eastern Pacific is an important part of the basic information required for understanding their life history, population structure, and fishery dynamics. Until a few years ago nothing was known of these matters. In 1947 the senior author and one of his colleagues (Schaefer and Marr 1948, Schaefer 1948) were able to demonstrate that both yellowfin tuna and skipjack spawn offshore from Central America at least during the late winter and spring months. During January to April many yellowfin tuna over about 70 cm. total length in commercial catches from that region were found to have gonads in advanced stages of maturity, and specimens caught during late June were found to be spent. Maturing skipjack were collected in late February, and spawned-out fish were observed in late March. Numerous very young juveniles of the yellowfin, down to 10 mm. in length, and two very young juvenile skipjack, were captured in this area between January and May. SPANISH: El conocimiento del tamaño y la edad que corresponden a la primera madurez sexual, así como de las estaciones y áreas de desove de los atunes tropicales que mantienen las pesquerías del Pacífico Oriental, constituyen parte importante de la información que es menester para comprender la historia natural, la estructura de la población y la dinámica de la pesquería. Hasta hace pocos años nada se sabía sobre el particular. En 1947 el autor principal y uno de sus colegas (Schaefer y Marr, 1948; Schaefer, 1948) pudieron demostrar que tanto el atún aleta amarilla como el barrilete desovan en el mar abierto, frente a América Central, por lo menos durante la última parte del invierno y en la primavera. De enero a abril encontraron que muchos de los atunes aleta amarilla de más de 70 cm. de longitud total, procedentes de las pescas comerciales de dicha región; tenían gónadas en avanzados estados de madurez, mientras que ejemplares pescados hacia fines de junio ya habían desovado. Se recolectaron barriletes en vías de maduración a fines de febrero, al paso que en los últimos días de marzo se encontraron especímenes que ya habían desovado. Numerosos ejemplares muy juveniles del atún aleta amarilla, tan pequeños como 10 mm., y dos barriletes también muy juveniles, fueron pescados en esta región entre enero y mayo. (PDF contains 65 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.)