Tagging and recovery of tropical tunas 1955-1959

ENGLISH: Yellowfin and skipjack tuna occur in commercial quantities in the Eastern Pacific Ocean from California to Chile. They are captured in the high seas at distances from the mainland up to several hundred miles (see Alverson, 1960). The Inter-American Tropical Tuna Commission has been engaged for several years in research on the biology, ecology, and population dynamics of the stocks of these species supporting the commercial fishery, in order to elucidate the effects of the fishery and of fishery independent factors on their abundance and behavior, to provide the scientific basis for rational management of the fishery. An important aspect of this research is the investigation of the migrations of these species in the Eastern Pacific, and the determination of whether each consists of but a single population or is composed of various sub-populations. One direct means of approaching these problems is the tagging, and subsequent recovery, of specimens in the region of the commercial fishery. This also provides direct information on growth rates, by comparison of sizes of specimens at tagging and upon later recovery, and can furnish the basis of estimating rates of mortality. These are two of the important elements of the vital statistics of the tuna populations. SPANISH: El atún aleta amarilla y el barrilete se encuentran en cantidades comerciales en el Océano Pacífico Oriental, desde California hasta Chile. Estos peces son capturados en alta mar a varios cientos de millas de distancia de tierra firme (ver Alverson, 1960). La Comisión Interamericana del Atún Tropical ha estado dedicada durante varios años a la investigación de la biología, ecología y dinámica de las poblaciones de los stocks de las indicadas especies que mantienen la pesquería comercial, a fin de elucidar los efectos de ésta y de los factores independientes de la explotación sobre la abundancia y hábitos de estos peces, para obtener una base científica que permita una administración racional de la pesquería. Un aspecto importante de esta investigación es el estudio de los movimientos migratorios de estas especies en el Pacífico Oriental, y la determinación de que si cada una constituye una sola población o está compuesta de varias subpoblaciones. Un medio directo de abordar estos problemas es el de la marcación, y subsecuente recuperación, de especímenes en la región de la pesquería comercial. Esto también proporciona una información directa sobre la tasa de crecimiento, por la comparación de los tamaños de los especímenes al ser marcados y recuperados más tarde y puede proveer la base para estimar las tasas de mortalidad. Estos son dos de los elementos importantes de las estadísticas vitales de las poblaciones de atún.

Year class mortality, abundance and yield-per-recruit of yellowfin tuna in the eastern Pacific Ocean, 1954-1959

ENGLISH: One primary duty of the Inter-American Tropical Tuna Commission is to estimate the maximum sustainable catches of yellowfin tuna (Neothunnus macropterus) and skipjack (Katsuwonus pelamis), and to investigate and recommend proposals to maintain the stocks at levels which will permit these catches to be obtained. To do this, there is required some means of predicting yields relative to fishing intensity. . . The age composition of catch, and growth rate of yellowfin tuna for recent years have now been estimated (Hennemuth, 1961). In this paper, relative abundance at age of yellowfin tuna shall be estimated -and used, in turn, to estimate total mortality rate. Yield-per-recruit calculations, based on Beverton and Holt's (1957) simple equation, will be presented to compare present utilization with theoretical maxima under varying levels of fishing mortality and different ages at first capture. SPANISH: Uno de los principales deberes de la Comisión Interamericana del Atún Tropical es estimar las pescas máximas sostenibles de los atunes aleta amarilla (Neothunnus macropterus) y barrilete (Katsuwonus pelamis) , así como estudiar y recomendar proposiciones para mantener los stocks a niveles que permitan obtener estas pescas. Para lograr este propósito se requieren algunos medios que permitan predecir el rendimiento en relación con la intensidad de la pesca. . La composición de edades de la pesca y la tasa de crecimiento del atún aleta amarilla en años recientes han sido estimadas ahora (Hennemuth, 1961). En este trabajo, la abundancia relativa a una edad dada de esta especie será estimada y usada, a su vez, para estimar la tasa de mortalidad total. Los cálculos del rendimiento por recluta, basados en la ecuación simple de Beverton y Holt (1957), serán presentados para comparar la utilización actual con los máximos teóricos bajo valores variables de mortalidad por la pesca y a diferentes edades a la primera captura.

Measures of population density and concentration of fishing effort for yellowfin and skipjack tuna in the eastern Tropical Pacific Ocean 1951-1959

ENGLISH: In a previous Bulletin of this Commission, Griffiths (1960) discussed two indices of population density and an index of concentration of fishing effort of bait boats for yellowfin tuna in the Eastern Tropical Pacific for the 1951-1956 period. Yellowfin and skipjack tuna occur in the same general fishing areas and many of the commercial catches are composed of a mixture of the two species. It is desirable, therefore, to extend the investigation to skipjack and to the two species combined. SPANISH:En un Boletín anterior de esta Comisión, Griffiths (1960) se refiere a dos índices de la densidad de la población y a un índice de la concentración del esfuerzo de pesca de los barcos de carnada sobre el atún aleta amarilla en el Pacífico Oriental Tropical, correspondientes al período 1951-1956. Los atunes aleta amarilla y barrilete se encuentran en las mismas áreas generales de pesca y muchas de las pescas comerciales están compuestas de una mezcla de las dos especies. Es deseable, por lo tanto, ampliar la investigación en lo que se refiere al barrilete y a las dos especies combinadas.

Distribution of fishing effort and resulting tuna catches from the Eastern Tropical Pacific Ocean, by quarters of the year, 1959-1962

ENGLISH: This report is a sequel to one previously published by the Commission (Alverson, 1960) which covered the years 1951 through 1958. It is based entirely on information collected from the logbooks of purse-seiners and baitboats engaged in the fishery for yellowfin (Thunnus albacares) and skipjack (Katsuwonus pelamis) tuna in the Eastern Pacific from 1959 through 1962. SPANISH: Este informe es una secuela de uno publicado previamente por la Comisión (Alverson, 1960) que cubrió los años de 1951 a 1958. Se basa enteramente en la información recoleetada ,de los diarios de pesca de los barcos rederos y de carnada, que se ocupande la pesquería del atún aleta amarilla (Thunnus albacares) y del barrilete (Katsuwonus pelamis) en el Pacífico Oriental, desde 1959 a 1962.

Estimation of the number of purse-seiner sets on tuna associated with dolphins in the Eastern Pacific Ocean during 1959-1980

ENGLISH: Annual estimates of the number of purse-seine sets made on tunas associated with dolphins are needed to estimate the total number of dolphins killed incidentally by the eastern Pacific tuna fishery. The most complete source of data, the Inter-American Tropical Tuna Commission's logbook data base, was used in this study. In the logbook data base, most sets are identified as being either associated with dolphins or not associated with dolphins. Some sets are not identified in this respect. However, the number of these unidentified sets which were associated with dolphins have been estimated by stratifying the logbook data according to whether or not any tuna were caught, whether or not the nearest identified set was associated with dolphins, and the distance to the nearest identified set. Most of the unidentified sets fell in strata characterized by a proportion of sets on tuna associated with dolphins that was lower than the overall unstratified proportion. Landings data were used to estimate the number of sets on tunas associated with dolphins from fishing trips not included in the logbook data base. SPANISH: Se necesitan las estimaciones anuales de la cantidad de lances realizados sobre atunes asociados con delfines para calcular todo el número de delfines muertos accidentalmente en la pesca atunera del Pacífico oriental. Se empleó en este estudio la fuente más completa-los datos de la Comisión Interamericana del Atún Tropical, proveniente de los cuadernos de bitácora. En éstos, la mayoría de los lances han sido identificados ya sea como asociados o no asociados con delfines. Algunos de los lances no han sido identificados a este respecto. Sin embargo, se ha estimado el número de estos lances asociados con delfines que no se habían identificado, al estratificar los datos de bitácora de acuerdo a si se había o no capturado atún, a si el lance identificado más próximo era o no un lance asociado con delfines y al averiguar la distancia del lance identificado más cercano. La mayoría de los lances sin identificar se colocan en los estratos caracterizados por una proporción de lances sobre atunes asociados con delfines, inferior a la proporción general sin estratificar. Se usaron los datos de los desembarques para calcular la cantidad de lances sobre atunes asociados con delfines en viajes pesqueros que no fueron incluídos en la base de los datos de bitácora. (PDF contains 73 pages.)

A temperature atlas of the Gulf of Panama, 1955-1959

The interests of the Inter-American Tropical Tuna Commission in the hydrography and biology of the Gulf of Panama have been adequately stated in the Commission's Bulletin series (Forsbergh, 1963; Howard, 1954; Howard and Landa, 1958; Peterson, 1961; Schaefer, 1953; Schaefer and Bishop, 1958; Schaefer, Bishop and Howard, 1958). The present report deals with data collected on 10 surveys made by Tuna Commission personnel for the purpose of describing seasonal upwelling by means of a study of the temperature structure of the Gulf of Panama, and a comparison of the thermal pattern during the dry, upwelling season (January to April) with that of the rainy season (May to December). Considerations of upwelling in the Gulf have been shown to be of interest and of probable biological consequence by Schaefer (1951) and by Simpson (1959). (PDF contains 60 pages.)

Report of the Inter-American Tropical Tuna Commission for the year 1959

ENGLISH: The Inter-American Tropical Tuna Commission was established under authority of a Convention, between the Governments of the Republic of Costa Rica and the United States of America, which entered into force in 1950. The Convention provides for the adherence, by exchange of correspondence with existing members, of other governments having an interest in the tuna and tuna-bait resources of the Eastern Tropical Pacific Ocean. The Republic of Panama adhered to the Convention in 1953. SPANISH: La Comisión Interamericana del Atún Tropical fue establecida en virtud de una Convención suscrita entre los Gobiernos de la Republica de Costa Rica y de los Estados Unidos de America, que entro en vigencia en 1950. La Convención esta abierta para que otros gobiernos interesados en los recursos de atún y de carnada para la pesca de este en el Océano Pacifico Oriental Tropical puedan adherirse a la misma mediante intercambio de correspondencia con los Gobiernos Miembros. La Republica de Panamá se adhirió a la Convención en 1953. (PDF contains 156 pages.)

The predatory feeding of Acanthocyclops viridis (Jur.) (Copepoda, Cyclopoida). [Translation from: Trudy Inst.Biol.Vodokhranil. 2(5) 117-127, 1959. ]

The feeding of freshwater copepods, especially cyclopoida, has been poorly covered in research so far. The majority of existing special works on the feeding of cyclopoida illustrate this question only from the qualitative side. The food content of the nauplius of freshwater cyclops has not been studied at all, as also the feeding of adult entomostracans on bacteria. Moreover the question of the suitability of vegetable food for Cyclops is not clear enough. This article aims to elucidate as fully as possible the nutrition of Acanthocyclops viridis (Jur.) - a large cyclops, inhabiting the mass of demersal layers of the open parts of the Rybinsk reservoir and its foreshore. The present work is devoted only to the predatory feeding of A. viridis, and includes data from the content of the intestines of cyclops, collected in natural conditions, and also the results of experimental observations carried out in a laboratory during 1958.

Chilodonella cyprini (Moroff, 1902) [Translation from: Izv.gos.nauchno-issled.Inst.ozer.i rech.ryb.kh-va 49 25-28, 1959]

The ciliated protozoan Chilodonella cyprini is described. Chilodon parasitizes the body, gills and fins of fishes. The infusoria produce irritation of the integument and strengthened mucous secretion. The sparse knowledsge of the ecology of chilodon is summarised and some advice on the struggle against cholodoniasis in carp given.

On the character of the phytoplankton of the Yakimvarskii Gulf (Lake Ladoga) [Translation from: Botanicheskii Zhurnal, T. 44, No. 9, 1311-1314, 1959]

The Laboratory of Lake Studies of the Academy of Sciences of the USSR in 1956 undertook this complicated study of Lake Ladoga. The plan of the laboratory made allowance for the detailed investigation of the phytoplankton of the lake during a series of years. In the present article are given the preliminary results of observations on the phytoplankton of the Yakimvarskii Bay from 1956 to 1957. Details are also given on the concentration of dissolved gases and biogenic substances of the bay.

Das deutsche Einschiff-Schwimmschleppnetz. (Entwicklung seit 1959 und derzeitiger Stand Anfang 1968)

Herrn Professor Dr. Andres v. BRANDT Ltd.Dir. und Prof. des Instituts für Fangtechnik, Hamburg, zum 60. Geburtstag gewidmet.

Species Trends in Sport Fisheries, Monterey Bay, Calif., 1959-86

Three surveys spanning 28 years were examined for changes in species caught by recreational fishermen from small boats (skiffs) and commercial passenger fishing vessels (CPFV's) in California's Monterey Bay region. As fishing effort increased, the catch of certain nearshore species of rockfish, Sebastes spp., declined. CPFV fishing was conducted farther from port and in deeper water to compensate for declining abundance while most skiffs remained in traditional areas close to port. The trend toward deeper water CPFV fishing has been interrupted only temporarily by increased availability of nearshore species. Life history characteristics of rockfish including residential behavior, variable recruitment, and natural longevity contribute to a vulnerability to localized overfishing for several species.

Comparisons of Shark Catch Rates on Longlines Using Rope/Steel (Yankee) and Monofilament Gangions

During the months of June through September in 1991 and 1992, 71 shark longlines were fished in the Chesapeake Bight region ofthe U.S. mid-Atlantic coast with a combination of rope/steel (Yankee) and monofilament gangions. A total of 288 sharks were taken on 3,666 monofilament gangions, and 352 sharks were caught on 6,975 Yankee gangions. Catch rates between gear types differed by depth strata, by month, and by species. Analyses were divided between efforts in the nursery ground ofthe sandbar shark, Carcharhinus plumbeus, in Chesapeake Bay and efforts outside the Bay. Mean catch per unit effort (CPUE) ± SE, as sharks caught per 100 hooks fished, was significantly (P<0.05) lower for Yankee gangions. Mean CPUE's for sandbar sharks in the nursery ground were 20.6 ± 3.8 for Yankee gangions and 26.0 ± 3.0 for monofilament gangions, and mean CPUE's for all species combined outside the Bay were 3.7 ± 0.7 for Yankee gangions, and 6.9 ± 1.2 for monofilament gangions.