Assessing the atmospheric oscillations effects on the biology of the bullet tuna (Auxis rochei) and its possible linkage with global warming

Dissertação de mestrado, Biologia Marinha, Faculdade de Ciências e Tecnologia, Universidade do Algarve; Instituto Español de Oceanografia; 2015

Identification of small juvenile scombrids from northwest tropical Australia using mitochondrial DNA cytochrome b sequences

Small juveniles of the nine species of scombrids in Australian waters are morphologically similar to one another and, consequently, difficult to identify to species level. We show that the sequence of the mitochondrial DNA cytochrome b gene region is a powerful tool for identification of these young fish. Using this method, we identified 50 juvenile scombrids collected from Exmouth Bay, Western Australia. Six species of scombrids were apparent in this sample of fish: narrow-barred Spanish mackerel (Scomberomorus commerson), Indian mackerel (Rastrelliger kanagurta), frigate tuna (Auxis thazard), bullet tuna (Auxis rochei), leaping bonito (Cybiosarda elegans), and kawakawa (Euthynnus affinis). The presence of Indian mackerel, frigate tuna, leaping bonito, and kawakawa is the first indication that coastal waters may be an important spawning habitat for these species, although offshore spawning may also occur. The occurrence of small juvenile S. commerson was predicted from the known spawning patterns of that species, but other mackerel species (Scomberomorus munroi, Scomberomorus queenslandicus, Scomberomorus semifasiciatus) likely to be spawning during the sampling period were not detected among the 50 small juveniles analyzed here.

Abundance and biomass of near-surface ichthioplankton in the Western Pacific

During Cruise 50 of R/V Vityaz ichthyoplankton in surface waters was collected by a neuston otter trawl for many days in four study areas of the Western Tropical Pacific. Obtained results describe quantitative distribution of ichthyoplankton and small fishes in surface waters. The near-surface layer of the ocean (about 30-40 cm thick) can be considered as a special biotope, its population forms an independent biocoenosis - hyponeuston. Species composition of this community (particularly, composition of fish components) in the tropical zone has been studied to some degree, but structure of the biocoenosis as well as biomass and quantitative relationships of species have not been investigated at all. In this paper the authors discuss the method of collecting surface samples that is quite suitable for quantitative calculations and also present the first results obtained using this method, which described quantitative distribution of ichthyoplankton and small fishes in surface waters.

Observations on the spawning of four species on tuna (Neothunnus macropterus, Katsuwonus pelamis, Auxis thazard and Euthynnus lineatus) in the Eastern Pacific Ocean, based on the distribution of their larvae and juveniles

ENGLISH: Knowledge of spawning habits is useful in the elucidation of the life history, ecology and population structure of tropical tunas, and is essential to the sound management of these resources. Until recently, little was known concerning the spawning of tunas, or about the distribution of their larval and juvenile stages, in the Eastern Pacific Ocean. Nichols and Murphy (1944) reported the capture off Colombia of young scombroids ultimately identified as frigate mackerel, Auxis thazard (Schaefer and Marr, 1948a). Fowler (1944) reported the capture off Manzanillo, Mexico of two young tunas, one of which is definitely and the other most likely Neothunnus macropterus (Klawe, 1959). In 1947, young of N. macropterus, K. pelamis, A. thazard and E. lineatus were caught offshore from Central America (Schaefer and Marr, 1948a, 1948b, and Schaefer, 1948). Further collections of young N. macropterus, A. thazard and E. lineatus were made in the same general area in the spring of 1949 (Mead, 1951). In January and February 1955, Clemens (1956) carried Out experiments in rearing young tunas, E. lineatus and A. thazard, in shipboard aquaria, using fish caught off Central America. Matsumoto (1958) reported captures of larval N. macropterus and K. pelamis in the area along the 120th meridian of west longitude. Klawe (1958 and 1961b) reported captures of larval N. macropterus and Auxis from the Revillagigedo Islands. Captures of young Auxis and E. lineatus in the Gulf of Panama in January 1922 during the Dana Expedition have recently been reported by Matsumoto (1959). Capture of juveniles of K. pelamis, E. lineatus and Auxis in the area off tropical Mexico and in the area of outlying islands during the SCOT Expedition has been reported by Klawe (1960a). SPANISH: El conocimiento sobre los hábitos del desove es útil para el esclarecimiento de la historia natural, ecología y estructura de las poblaciones de atunes tropicales, y es esencial para la acertada administración de estos recursos. Hasta hace poco tiempo no se sabía mucho sobre el desove de los atunes o acerca de la distribución de sus larvas y juveniles en el Océano Pacífico Oriental. Nichols y Murphy (1944) informaron sobre la captura frente a Colombia de escómbridos jóvenes últimamente identificados como melva, Auxis thazard (Schaefer y Marr, 1948a). Fowler (1944) también informó sobre la captura de dos atunes jóvenes frente a Manzanillo, México, uno de los cuales era definitivamente Neothunnus macropterus y el otro era lo más probable que también lo fuera (Klawe, 1959). En 1947 se capturaron especímenes juveniles de N. macropterus, K. pelamis, A. thazard y E. lineatus frente a la América Central (Schaefer y Marr, 1948a, 1948b, y Schaefer, 1948). Otras recolecciones de ejemplares jóvenes de N. macropterus, A. thazard y E. lineatus fueron hechas en la misma área general durante la primavera de 1949 (Mead, 1951). En enero y febrero de 1955, Clemens (1956) efectuó experimentos de crianza de atunes jóvenes, E. lineatus y A.. thazard, en acuarios a bordo para lo que empleó peces capturados frente a la América Central. Matsumoto (1958) informó sobre capturas de larvas de N. macropterus y K. pelamis en el área a lo largo del meridiano 120 de longitud oeste. Klawe (1958 y 1961b) ha dado cuenta también de capturas de larvas de N. macropterus y Auxis en las Islas Revillagigedo. Matsumoto (1959) ha informado recientemente acerca de capturas de ejemplares jóvenes de Auxis y E. lineatus en el Golfo de Panamá en enero de 1922 durante la Expedición Dana. Klawe (1960a) informó así mismo que durante la Expedición SCOT se capturaron juveniles de K. pelamis, E. lineatus y Auxis en el área frente a la zona tropical de México y en la región de las islas alejadas del continente.

Biochemical differentiation between Ophidion Barbatum and o. Rochei (Pisces, Ophidiidae)

El gènere Ophidion esta representat al Mediterrani per dues espècies, 0. barbatum L. i O. rochei Müller. Són dues espècies molt similars en aspecte i difícils d'identificar només a partir dels seus caràcters morfològics externs. El treball descriu en primer lloc, i a partir de dades obtingudes per tècniques electroforètiques, alguns marcadors bioquímics que permeten diferenciar les dues espècies. En segon lloc, i a partir del càlcul de la 'Distància Genètica de Nei', es fa una estimació del temps de divergència entre O. barbatum i 0. rochei

Tunas and tuna fisheries of the World: an annotated bibliography, 1930-1953

This bibliography attempts to list, with descriptive annotations and a subject index, important literature published between 1930 and 1953 dealing with the tunas and their fisheries in all parts of the world. It is thus a continuation of Corwin's (1930) work, which extended with similar scope through 1929, and an extension of Shimada's (1951), which was limited to the biology of Pacific tunas. The tunas with which it deals are those fishes customarily so-called in commercial parlance and usually classified in the genera Thunnus, Neothunnus, Parathunnus, Germo, Katsuwonus, Euthynnus and Auxis and their various synonyms. All aspects of the biology of the tunas are dealt with, as are descriptions and histories of all types of tuna fisheries, commercial and exploratory tuna fishing methods and results, fishing gear, catch statistics, and fishery management, but processing technology, economics and marketing, folklore, and purely literary references have been excluded.

The distribution, abundance, and ecology of larval tunas from the entrance to the Gulf of California

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.)

A model of the pelagic ecossystem in the eastern tropical Pacific Ocean

English: Recent calls for a more holistic approach to fisheries management have motivated development of trophic mass-balance models of ecosystems that underlie fisheries production. We developed a model hypothesis of the pelagic ecosystem in the eastern tropical Pacific Ocean (ETP) to gain insight into the relationships among the various species in the system and to explore the ecological implications of alternative methods of harvesting tunas. We represented the biomasses of and fluxes between the principal elements in the ecosystem with Ecopath, and examined the ecosystem's dynamic, time-series behavior with Ecosim. We parameterized the model for 38 species or groups of species, and described the sources, justifications, assumptions, and revisions of our estimates of the various parameters, diet relations, fisheries landings, and fisheries discards in the model. We conducted sensitivity analyses with an intermediate version of the model, for both the Ecopath mass-balance and the dynamic trajectories predicted by Ecosim. The analysis showed that changes in the basic parameters for two components at middle trophic levels, Cephalopods and Auxis spp., exert the greatest influence on the system. When the Cephalopod Q/B and Auxis spp. P/B were altered from their initial values and the model was rebalanced, the trends of the biomass trajectories predicted by Ecosim were not sensitive, but the scaling was sensitive for several components. We described the review process the model was subjected to, which included reviews by the IATTC Purse-seine Bycatch Working Group and by a working group supported by the National Center for Ecological Analysis and Synthesis. We fitted the model to historical time series of catches per unit of effort and mortality rates for yellowfin and bigeye tunas in simulations that incorporated historical fishing effort and a climate driver to represent the effect of El Niño-Southern Oscillation-scale variation on the system. The model was designed to evaluate the possible ecological implications of fishing for tunas in various ways. We recognize that a model cannot possibly represent all the complexity of a pelagic ocean ecosystem, but we believe that the ETP model provides insight into the structure and function of the pelagic ETP. Spanish: Llamamientos recientes hacia un enfoque más holístico al ordenamiento de la pesca han motivado el desarrollo de modelos tróficos de balance de masas de los ecosistemas que sostienen la producción pesquera. Desarrollamos una hipótesis modelo del ecosistema pelágico en el Océano Pacífico oriental tropical (POT) con miras a mejorar los conocimientos de las relaciones entre las distintas especies en el sistema y explorar las implicaciones ecológicas de métodos alternativos de capturar atunes. Con Ecopath representamos las biomasas de los elementos principales en el ecosistema, y los flujos entre los mismos, y con Ecosim examinamos el comportamiento dinámico del ecosistema con el tiempo. Parametrizamos el modelo para 38 especies o grupos de especies (denominados “componentes” del modelo), y describimos las fuentes, justificaciones, supuestos, y revisiones de nuestras estimaciones de los distintos parámetros, relaciones basadas en dieta, capturas retenidas de las pesquerías, y descartes de las mismas en el modelo. Realizamos análisis de sensibilidad con una versión intermedia del modelo, para el balance de masas de Ecopath y las trayectorias dinámicas predichas por Ecosim también. El análisis demostró que cambios en los parámetros básicos para dos componentes en niveles tróficos medianos, Cefalópodos y Auxis spp., ejercieron la mayor influencia sobre el sistema. Cuando se alteraron el Q/B de los Cefalópodos y el P/B de los Auxis spp. de sus valores iniciales y se balanceó el modelo de nuevo, las tendencias de las trayectorias de la biomasa predichas por Ecosim no fueron sensibles, pero la escala fue sensible para varios componentes. Describimos el proceso de revisión al que fue sujeto el modelo, inclusive revisiones por el Grupo de Trabajo sobre Captura Incidental de la CIAT y un grupo de trabajo apoyado por el Centro Nacional para Síntesis y Análisis Ecológicos. Ajustamos el modelo a series de tiempo históricas de capturas por unidad de esfuerzo y tasas de mortalidad de atunes aleta amarilla y patudo en simulaciones que incorporaron esfuerzo de pesca histórico e impulsos climáticos para representar el efecto de variaciones a escala de El Niño-Oscilación del Sur sobre el sistema. El modelo fue diseñado para evaluar las posibles implicaciones ecológicas de la pesca atunera de varias formas. Reconocemos la imposibilidad de que el modelo represente toda la complejidad de un ecosistema oceánico pelágico, pero creemos que el modelo del POT mejora los conocimientos de la estructura y función del POT pelágico.

Food habits and consumption rates of common dolphinfish (Coryphaena hippurus) in the eastern Pacific Ocean

An ecosystem approach to fisheries management requires an understanding of the impact of predatory fishes on the underlying prey resources. Defining trophic connections and measuring rates of food consumption by apex predators lays the groundwork for gaining insight into the role of predators and commercial fisheries in influencing food web structure and ecosystem dynamics.We analyzed the stomach contents of 545 common dolphinfish (Coryphaena hippurus) sampled from 74 sets of tuna purse-seine vessels fishing in the eastern Pacific Ocean (EPO) over a 22-month period. Stomach fullness of these dolphinfish and digestion state of the prey indicated that diel feeding periodicity varied by area and may be related to the digestibility and energy content of the prey. Common dolphinfish in the EPO appear to feed at night, as well as during the daytime. We analyzed prey importance by weight, numbers, and frequency of occurrence for five regions of the EPO. Prey importance varied by area. Flyingfishes, epipelagic cephalopods, tetraodontiform fishes, several mesopelagic fishes, Auxis spp., and gempylid fishes predominated in the diet. Ratios of prey length to predator length ranged from 0.014 to 0.720. Consumption-rate estimates averaged 5.6% of body weight per day. Stratified by sex, area, and length class, daily rations ranged up to 9.6% for large males and up to 19.8% for small dolphinfish in the east area (0–15°N, 111°W–coastline). Because common dolphinfish exert substantial predation pressure on several important prey groups, we concluded that their feeding ecology provides important clues to the pelagic food web and ecosystem structure in the EPO.

Exploitation of tunas in Ceylon's coastal waters

Ceylon’s fishery for the tunas is presently limited to the coastal waters which in the present context have an off-shore limit of 15 miles and our contribution to the world tuna production is a little over 1%. Four varieties of tuna are largely exploited in the coastal waters. Of these, Baleya or the skipjack (Katsuwonus pelamis Linn. 1758) is the predominant variety followed by attavalla or mackerel tuna (Euthynnus ajfinis, Cantor, 1850), kelawalla or yellowfin (Thunnus albacares, Bonnaterre, 1788) and alagoduwa or frigate mackerel (Auxis thazard Lacepede, 1802). Other varieties like the thora-baleya or bonito (Sarda orientalis) and asgedi kelawalla or big eye tuna (Thunnus obesus) are also landed frequently but in extremely small quantities. Figure 1 illustrates the relative composition of the tuna varieties in the catch and their percentage composition further sub-divided according to the type of effort applied. It is evident that Ceylon's coastal fishery for tunas is greatly influenced by the production of smaller varieties of the tunas.

Distribution and length-weight relationship of tunas and tuna-like fishes around Ceylon

Tunas and tuna-like fishes have contributed considerably towards the increase in fish production from Ceylon's coastal waters, during the last five years and in this blood fish group lies a potential resource for a further increase in production. Consequently considerable attention is being paid to the study of these species. Length frequency sampling of these species are being carried out and quite often it becomes necessary to convert catch in terms of weight to catch in terms of number, when estimating apparent abundance of the stock. The length-weight relationship in addition to its usefulness in converting length frequency data to weight frequency data for such purpose is of general value to biologists and even to fishermen. The six species studied are yellowfin tuna (Thunnus alacares, Bonneterre), skipjack tuna (Katsuwonus pelamis, Linnaeus), mackerel tuna (Buthynnus affinis, Cantor), frigate mackerel (narrow corseleted Auxis thazard, Lacepede and broad corseleted A. rochie, Risso) and bonito (Saida orientalis, T&S).

中国辽宁海洋放线菌资源、生物学特性及一株新种的鉴定命名

本论文在国内外首次报导了中国辽宁海洋放线菌资源考察研究结果。结果表明中国辽宁海洋放线菌资源丰富；在分离出的海洋放线菌中以链霉菌属居绝对优势，占所分离菌株总数的90%以上，此外尚有少量的海洋小单孢菌和海洋诺卡氏菌；所获提的海洋链霉菌可分为7个类群，已鉴定出11个种和1个新种。选择生长较快的链霉菌属13株菌株，对其形态特征、培养特征、生理生化特征、抗菌谱、细胞化学组分、DNA中的G+C mol%等内容进行系统研究。结果，全部13株菌株均能忍耐6%NaCl和pH13的碱性，5株菌株能耐受10%NaCl；G+C mol%均在69.5%-72.5%之间；均为细胞壁I型；但在形态特征、培养特征、生理生长特性、抗菌谱等方面各菌株之间又有差异。根据链霉菌鉴定手册，将13株菌株中的12株逐一定名：（1）将菌株H72-9定名为威德摩尔链德菌（S. wedmorensis, H72-9），（2）将菌株H73定名为细黄链霉菌（S. microflavus, H73）（3）将菌株H74-2定名为天蓝色链霉菌生天蓝亚种（S. coelicolor，subsp. coelicoferus, H74-2），（4）将菌株Hai-75定名为娄彻氏链霉菌（S. rochei, Hai-75），（5）将菌株H75-2定名为鲜黄链霉菌（S. galbus, H75-2），（6）将菌株H76定名为束丛链霉菌（S. fasciculus, H76），（7）将菌株H77定名为灰红链霉菌（S. griseoruber, H77），（8）将菌株H78-1定名为栗褐链霉菌（S. badius, H78-1），（9）将菌株J5定名为吡啶霉素链霉菌（S. pyridomyceticus, J5），（10）将菌株J7定名为锈亦链霉菌（S. rubiginosus, J7），（11）将菌株J10和J11定名为栗色浑圆链霉菌（S. castaneoglobosus）。将13株中的另一株海洋放线菌Hai-74确定为放线菌新种，它除了在形态特征、培养特征、生理生化特性等与已知近似种有明显的不同外，最主要的是在其独特的“索状”孢子丝结构，为国内外首次发现，故将此新种命名为索孢天蓝链霉菌（Strepomyces multisticho-cateniformis n. sp. Xie and Ding）。在研究中国辽宁海洋放线菌的抗菌性能中，我们还首次发现并报道了海洋细黄链霉菌H73的抗菌物质，它能显著减轻大豆连作障碍（重茬大豆根际土壤紫青霉菌及其毒素对大豆的危害），因此在今后它很有可能被用来研制一种能够减轻大豆连作障碍的新型农用抗生系。为此，我们对海洋细黄链霉菌H73的基因组DNA文库进行了构建，这将为今后研究有关抗菌基因方面的工作奠定基础。