294 research outputs found

    The Fed and the Stock Market

    Get PDF
    The Fed closely monitors the stock market and the stock market continuously forms expectations about the Fed decisions. What does this imply for the relation between the fed funds rate and the S&P500? We find that the answer depends on the conditions prevailing on the financial market. During periods of high (low) volatility in asset price inflation an unexpected 5 fall in the stock market index implies that the Fed cuts the interest rate by 19 (66) basis points while an unanticipated policy tightening of 50 basis points causes a 4.7 (2.3) decline in the S&P500. The Fed reaction to asset price return is however statistically different from zero only in the high volatility regime, whereas the fall in asset price return following an interest rate rise is highly significant during normal times onlyasset price volatility, nonlinear policy, threshold SVAR, system GMM.

    Influencia de la temperatura del fondo del mar y profundidad en la estimación del área de barrido en sistemas de arrastre

    Get PDF
    The methodological approach to data collection and analysis in Mediterranean bottom trawl surveys has changed considerably since their beginnings in the mid-1980s. The introduction of new technologies in surveys greatly improved knowledge on trawl underwater geometry, but also raised a question on the reliability of the data obtained. The most commonly used trawl monitoring systems in the Mediterranean use the constant speed of sound when calculating horizontal distance from one sensor to another. However, the speed of the sound in seawater is not constant because it depends on water temperature, pressure, and salinity. This is known to affect the performance of the horizontally transmitting sonars, and it is reasonable to assume that unless it is properly compensated for, the readings from trawl monitoring systems can be incorrect, resulting in biased swept area estimates, and hence potentially producing bias in abundance estimates. In the knowledge that speed of sound depends on temperature, salinity and pressure, the Del Grosso (1974) equation was used to calculate the compensation coefficient for a series of theoretical depth and temperature data. A simple model is proposed in the current paper for the manual correction of the horizontal net opening and swept area estimates. Temperature and depth data obtained from the MEDATLAS project are used to show seasonal and spatial variation in the near-bottom speed of sound, and the results demonstrate that, unless compensated for properly, the error in the horizontal net spread ranges from –1.5% to 2.9%.El enfoque metodológico para la recopilación de datos y análisis en estudios de arrastre de fondo del Mediterráneo ha cambiado considerablemente desde sus inicios en los años ochenta. La introducción de nuevas tecnologías en los estudios ha mejorado enormemente el conocimiento de la geometría de los artes de pesca de debajo del agua, pero, al mismo tiempo, surge la pregunta de la fiabilidad de los datos obtenidos. Los sistemas de seguimiento más comúnmente utilizados en los artes en el Mediterráneo usan la velocidad constante del sonido cuando calculan la distancia horizontal de un sensor a otro. Sin embargo la velocidad del sonido en el agua marina no es constante ya que depende de la temperatura del agua, de la presión y la salinidad. Se sabe que esto afecta al rendimiento de los sonares que transmiten en horizontal, y es razonable suponer que si se compensan adecuadamente, las lecturas de los monitores de seguimiento del arte pueden ser incorrectos, dando lugar a estimaciones sesgadas del área barrida por el arte, y en consecuencia potencialmente producir sesgo en bastantes estimaciones. Conociendo que la velocidad del sonido depende de la temperatura, salinidad y presión, se ha usado la ecuación de Del Grosso (1974) para calcular el coeficiente de compensación en series de datos de profundidad teórica y temperatura. A continuación, un modelo simple se ha propuesto en el presente artículo para la corrección manual de la obertura horizontal de la red y estimación del área de barrido. Se han usado los datos de temperatura y profundidad obtenidos del proyecto MEDATLAS para mostrar la variación estacional y espacial en la velocidad del sonido cerca del fondo marino, y los resultados demuestran que, a no ser que se compense adecuadamente, el error en la obertura horizontal de la red varía entre –1.5 a 2.9%

    Dinámica diaria vertical de comunidades de peces asociados a un arrecife artificial (Mar Adriático Norte)

    Get PDF
    The vertical diel activity of a fish assemblage inhabiting the Senigallia artificial reef (northern Adriatic Sea, Italy) was evaluated from July to November 1996 using enhanced hydroacoustic techniques. Extensive seabed mapping of the area was done using a multibeam echosounder to obtain background imagery of the reef structures and identify the most suitable locations for placing stationary acoustic transducers. Three acoustic transducers were placed inside the reef area, while a fourth was located in the open sea outside the area. Data analysis was conducted on three different depth layers: surface, midwater and bottom. In each layer, diel fish biomass inside the reef showed two peaks, one in the early morning and the other in the late evening. Slightly different behaviour was observed outside the protected area. Comparison of the layers showed that fish biomass was not homogeneously distributed along the water column throughout the sampling period. There were high values in the middle and bottom layers until the end of August. However, no significant biomass variations in time were observed outside the reef where low values were always recorded in each layer.La actividad diaria vertical de la comunidad de peces que habitan en el arrecife artificial Senigallia (Mar Adriatico Norte, Italia), se evaluó desde julio a noviembre de 1996 utilizando técnicas de hidroacústica. Se realizó un mapaje extenso del fondo marino utilizando una ecosonda multihaz para obtener imágenes de las estructuras del arrecife e identificar las áreas más adecuadas para emplazar los transductores acústicos. Tres fueron colocados dentro del área del arrecife, mientras que un cuarto fue situado en mar abierto, fuera del área. El análisis de datos se realizó a tres profundidades: superficie, profundidad intermedia y fondo. En cada profundidad la biomasa diaria de peces en el arrecife mostraba dos picos, uno por la mañana y otro al anochecer. Pequeñas diferencias en el comportamiento de los peces se observaron fuera del área protegida. Comparando entre las distintas profundidades mostramos que la biomasa de los peces no estaba uniformemente distribuida a lo largo de la columna de agua, durante el período de muestreo, con valores altos en las profundidades intermedias y en el fondo hasta finales de agosto. Por otro lado no se observaron variaciones de biomasa significativas en el tiempo fuera del arrecife donde siempre prevalecieron valores bajos en cada profundidad

    Otterboard hydrodynamic performance testing in flume tank and wind tunnel facilities

    Get PDF
    © 2017 Elsevier LtdTwo pelagic otterboards, previously tested in a wind tunnel, have been tested in a flume tank prior to their analysis in real working conditions in sea trials. This intermediate step aims at providing guidance for sea trial planning and a basis for otter board performance analysis from real campaign data. The doors were rigged in working-like conditions in the flume tank, with onboard-mounted attitude sensors to provide at the same time a noisy environment as expected in sea trials and accurate measurement of all quantities relevant to precise determination of hydrodynamic angles and forces. The trends found in flume tank experiments closely match wind tunnel results, although systematic offset has been observed that can be ascribed to deviations between nominal and real water velocity, due to inhomogeneous velocity distribution in the cross-section.Peer ReviewedPostprint (author's final draft

    Fisheries Bycatch of Chondrichthyes

    Get PDF
    This chapter reviews the current state of knowledge about global chondrichthyes bycatch, including how the combination of biological characteristics of these species and the impact of different fishing methods reflect their vulnerability to bycatch. Specifically, it summarizes the present status of elasmobranchs and chimaeras bycatch worldwide. Following this, it illustrates the main ecological consequences behind such incidental captures. Hence, it provides a description of how chondrichthyes bycatch occurs across broad fishing gear categories. Moreover, it outlines potential mitigation options available to reduce bycatch. As such, the main technical measures tested and applied in different fishing practices are listed. In addition, an overview about which are the current management measures implemented at international level to ensure long-term conservation of cartilaginous fish is reported. Then, two case studies summarize how chondrichthyes bycatch occurred in some of the most exploited fishing areas. Finally, the chapter ends with relevant considerations about potential for new research needed to monitor and reduce chondrichthyes bycatch

    Scientific, Technical and Economic Committee for Fisheries (STECF) - Landing Obligation - Part 6 (Fisheries targeting demersal species in the Mediterranean Sea) (STECF-15-19)

    Get PDF
    Sala, Antonello ... et al.-- This report was reviewed by the STECF during its winter plenary meeting held from 9 to 13 November 2015 in Brussels.-- 269 pages, 166 figures, 7 tables, 5 annexesThis report presents the responses of the Scientific, Technical and Economic Committee for Fisheries to requests from the Eur opean Commission for advice on the implementation of the EU Common Fisheries Policy. Advice is given in relation to the following: Landing Obligation (Fisheries targeting demersal species in the Mediterranean Sea)Peer Reviewe

    Effect of a lateral square-mesh panel on the catch pattern and catch efficiency in a Mediterranean bottom trawl fishery

    Get PDF
    The current legal codends used in Mediterranean bottom trawl fisheries are at high risk of retaining undersized individuals of several commercial fish species. This entails that codends alone are unable to provide the desired exploitation pattern. A simple technological measure that potentially can provide higher release efficiency of undersized fish are Square-Mesh Panels (SMPs). SMPs are often applied in the upper section of the trawl belly, just ahead the codend. However, recent studies in the Mediterranean have demonstrated that SMPs mounted in this position provided limited release efficiency, because very few fish came into contact with their meshes. In attempt to improve SMPs efficiency in the Mediterranean bottom trawl fisheries, we applied them on the lateral sides of the last tapered section of the trawl belly, just ahead of the codend, and fitted two guiding panels in the trawl belly to enhance fish-SMP contact. We compared the catch performance of a standard commercial trawl with a 52 mm diamond-mesh codend and of a similar trawl fitted with lateral SMPs (70 mm mesh size) in the belly using a twin trawl. The study focused on red mullet (Mullus barbatus), a commercially important species, but data for gurnard (Chelidonichthys lucerna and Chelidonichthys cuculus)  were also obtained and analysed. In contrast to previous research on SMPs mounted in the top panel of the trawl, in this study SMPs induced a significant effect on catch performance for red mullet, demonstrating that their lateral position involved greater fish-SMP contact. However, since the test trawl lost a significant amount of legal-sized red mullet compared with the standard trawl, the effect was not wholly positive, possibly due to an excessively large mesh size. Therefore, future studies should be encouraged to test lateral SMPs with smaller mesh sizes

    Escape Survival and Scale Damage Assessment of Red Mullet (Mullus barbatus Linnaeus, 1758) during Bottom Trawling in the Central Mediterranean Sea

    Get PDF
    Stock assessments routinely evaluate the status of commercially harvested species, but seldom account for the possible mortality of released or escaping fish. This study presents a method for estimating the escape survival of the red mullet (Mullus barbatus) from demersal trawling in the Central Mediterranean Sea. Fish escaping from the trawl codend were collected in a detachable cage, which was lined to reduce water flow and protect the sampled fish from further fatigue and injury. Control fish (from an open codend) showed high survival, 94% (87–97%, 95% Confidence Interval), and minimal injuries, while fish escaping through codend meshes had significantly increased injuries and reduced survival, 63% (55–70%). During 7 days of captive monitoring, treatment group mortality was highest in the first 24 h and ceased for both groups within 48 h. Conflicting length-related mortality was observed, where larger treatment fish had a higher probability of dying, while the opposite was observed in the controls. Analysis showed that treatment fish were significantly more injured than control fish, with treatment fish predominantly injured in the head zone. In conclusion, this improved methodology should be repeated to provide accurate escape mortality estimates for the improved stock assessment of the red mullet in the Central Mediterranean
    corecore