73 resultados para Filosofia - Portugal - séc.20


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One additional Chalci campaign that, in line with the previous Chalci campaigns 78-01, 78-02, and 79/01, has as its major objective the trawl exploration of the Ivoirian continental shelf at the depth of 10 to 120 metres.

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The small-spotted catshark (Scyliorhinus canicula) (Linnaeus, 1758) and the longnose spurdog (Squalus blainville) (Risso, 1826) are two species occurring in the European and western African continental shelves with a wide geographical distribution. In this study, the diet of S. blainville and S. canicula off the Portuguese western Atlantic coast was investigated in 2006 by collecting monthly samples of these two species from local fishing vessels. In the stomachs of both species, crustaceans and teleosts were the dominant prey items, and molluscs, polychaetes, echinoderms, and sipunculids were found in lower abundance. In S. canicula, urochordate and chondrichthyan species were also observed in stomachs and were classified as accidental prey items. Scyliorhinus canicula consumed a broader group of prey items than did S. blainville. A significant diet overlap was observed, despite both species occupying different depth ranges over the continental shelf. Scyliorhinus canicula exhibited a consistency in diet composition among seasons, sexes, and maturity stages. Nonetheless, for both adults and juveniles, an increase in relative abundance of teleosts in the diet was observed in the spring and summer. This study provides evidence of the importance of S. canicula and S. blainville as benthic and pelagic predators along the western Atlantic coast.

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Research on assessment and monitoring methods has primarily focused on fisheries with long multivariate data sets. Less research exists on methods applicable to data-poor fisheries with univariate data sets with a small sample size. In this study, we examine the capabilities of seasonal autoregressive integrated moving average (SARIMA) models to fit, forecast, and monitor the landings of such data-poor fisheries. We use a European fishery on meagre (Sciaenidae: Argyrosomus regius), where only a short time series of landings was available to model (n=60 months), as our case-study. We show that despite the limited sample size, a SARIMA model could be found that adequately fitted and forecasted the time series of meagre landings (12-month forecasts; mean error: 3.5 tons (t); annual absolute percentage error: 15.4%). We derive model-based prediction intervals and show how they can be used to detect problematic situations in the fishery. Our results indicate that over the course of one year the meagre landings remained within the prediction limits of the model and therefore indicated no need for urgent management intervention. We discuss the information that SARIMA model structure conveys on the meagre lifecycle and fishery, the methodological requirements of SARIMA forecasting of data-poor fisheries landings, and the capabilities SARIMA models present within current efforts to monitor the world’s data-poorest resources.

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Bottom trawl surveys were conducted in the southwest monsoon season in 1996 (survey 1) and in the northeast monsoon season in 1996-97 (survey 2) throughout Vietnamese waters. The surveys mainly covered the depth zone 50-200 m but in the northeast monsoon season the depth zone 20-50 m was included in the northern and southern areas. Overall, 273 trawl hauls were conducted. The total biomass for Vietnamese waters in the depth zone 20-200 m was estimated at 700 000 t . Biomass estimates are given for the most abundant species. A relatively higher mean catch-per-unit effort (CPUE) was obtained from survey 2 than from survey 1 and in partcular at depth ranges 50-100 and 100-200 m in south Vietnam. Overall, the dominant families were Monacanthidae (34%), Carangidae (15%), Trichiuridae (9%) and Synodontidae (6%).

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Over 20 years, successive openings and closures of the Sumilon Island marine reserve to fishers have provided unique opportunities to examine the effects of marine reserves on populations and communities of fishes and upon local fisheries. The history of the reserve also highlights the problems and frustrations of educating and convincing people of the need for rational management of renewable marine resources. Yet, it is a symbol of hope in that it has provided a unique example of the potential benefits of marine reserves in fisheries management, particularly in the developing world.

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•2011 PICES Science: A Note from the Science Board Chairman (pp. 1-6) •2011 PICES Awards (pp. 7-9) •Beyond the Terrible Disaster of the Great East Japan Earthquake (pp. 10-12) •A New Era of PICES-ICES Scientific Cooperation (p. 13) •New PICES Jellyfish Working Group Formed (pp. 14-15) •PICES Working Group on North Pacific Climate Variability (pp. 16-18) •Final U.S. GLOBEC Symposium and Celebration (pp. 19-25) •2011 PICES Rapid Assessment Survey (pp. 26-29) •Introduction to Rapid Assessment Survey Methodologies for Detecting Non-indigenous Marine Species (pp. 30-31) •The 7th International Conference on Marine Bioinvasions (pp. 32-33) •NOWPAP/PICES/WESTPAC Training Course on Remote Sensing Data Analysis (pp. 34-36) •PICES-2011 Workshop on “Trends in Marine Contaminants and their Effects in a Changing Ocean” (pp. 37-39) •The State of the Western North Pacific in the First Half of 2011 (pp. 40-42) •Yeosu Symposium theme sessions (p. 42) •The Bering Sea: Current Status and Recent Events (pp. 43-44) •News of the Northeast Pacific Ocean (pp. 45-47) •Recent and Upcoming PICES Publications (p. 47) •New leadership for the PICES Fishery Science Committee (p. 48)