Change in Elasmobranchs and Other Incidental Species in the Spanish Deepwater Black Hake Trawl Fishery off Mauritania (1992–2001)

From 1992 to 2001, by-catch that was landed from the Spanish deepwater trawl fishery for black hake off Mauritania was closely monitored. This is a highly specialised fishery, with two species of black hake (Merluccius senegalensis and Merluccius polli) constituting between 77–99% of total landings, which have annually averaged 9 300 tons over the past two decades. Landings of Sparidae were highest among by-catch species of commercial value, with the large-eye dentex, Dentex macrophthalmus being the most important until 1996, after which the family Lophiidae and others predominated. Next were the Elasmobranchii, including large demersal squalids and several species of rays, although their annual landings fell from 182 tons in 1992 to only 4 tons in 1999, rising to 37 tons in 2001. The present paper analyses these changes using by-catches retained in the black hake fishery. We believe that the decline could be due to a set of different factors: a change in depths fished, economic reasons and probable over-exploitation of both targeted species and by-catch. Elasmobranchs constituted only 0.1% of total landings in 1999, compared to 1.9% in 1992, although their contribution to total commercial by-catch was constant. Seasonality was clearly evident, with an absolute and proportional rise in elasmobranch by-catch during warm periods, reaching 75% of by-catch landings in some months, coinciding with a drop in total by-catch. These seasonal variations could be related to the migratory habits of the fishery's target species, black hake

Composition of Demersal Fish Assemblages in Deep-waters of the Western Guinean Gulf

Data from deep water hauls carried out during the Spanish Research trawling Survey 'GUINEA -90', conducted in Sierra Leone, Liberia, Ivory Coast and Ghana, between 100 and 700 m depth, were analysed. The taxonomic list of the survey showed a total of 91 fish species caught between 100 and 700 m depth. The maximum species richness and the highest abundances were found between 2000 and 300 m (60 species), depth range corresponding to the breaking of the continental shelf and to the upper part of the slope. Despite the local differences, the 'GUINEA -90' Survey showed the existence of fish assemblages

Nonlinear waves in a chain of magnetically coupled pendula

A motivation for the study of reduced models like one-dimensional systems in Solid State Physics is the complexity of the full problem. In recent years our group has studied theoretically, numerically and experimentally wave propagation in lattices of nonlinearly coupled oscillators. Here, we present the dynamics of magnetically coupled pendula lattices. These macroscopic systems can model the dynamical processes of matter or layered systems. We report the results obtained for harmonic wave propagation in these media, and the different regimes of mode conversion into higher harmonics strongly influenced by dispersion and discreteness, including the phenomenon of acoustic dilatation of the chain, as well as some results on the propagation of localized waves i.e., solitons and kinks.Generalitat Valenciana APOSTD/2017/042Umiversitat Politècnica de València PAID-01-14Ministerio de Economía y Competitividad (MINECO), Spain FIS2015-65998-C2-2-PJunta de Andalucía 2017/FQM-28

Multi-step approach for automated scaling of photogrammetric micro-measurements

[EN] Photogrammetry can be used for the measurement of small objects with micro-features, with good results, low costs, and the possible addition of texture information to the 3D models. The performance of this technique is strongly affected by the scaling method, since it retrieves a model that must be scaled after its elaboration. In this paper, a fully automated multi-step scaling system is presented, which is based on machine vision algorithms for retrieving blurred areas. This method allows researchers to find the correct scale factor for a photogrammetric micro model and is experimentally compared to the existing manual method basing on the German guideline VDI/VDE 2634, Part 3. The experimental tests are performed on millimeter-sized certified workpieces, finding micrometric errors, when referred to reference measurements. As a consequence, the method is candidate to be used for measurements of micro-features. The proposed tool improves the performance of the manual method by eliminating operator-dependent procedures. The software tool is available online as supplementary material and represents a powerful tool to face scaling issues of micro-photogrammetric activities.Frangione, A.; Sánchez Salmerón, AJ.; Modica, F.; Percoco, G. (2019). Multi-step approach for automated scaling of photogrammetric micro-measurements. The International Journal of Advanced Manufacturing Technology. 102(1-4):747-757. https://doi.org/10.1007/s00170-018-03258-w7477571021-

Screen-Printed Chipless Wireless Temperature Sensor

A chipless wireless sensor for temperature monitoring is described in this work. The sensor is fabricated by screen printing of an RLC circuit on a flexible substrate. The sensing element is a resistive carbon paste with positive temperature coefficient placed in a small area in the interconnection between the inductor and the capacitor. This sensing layer modifies the resonance frequency of the circuit when the temperature varies. We also show the influence of the sensor sensitivity with respect to the reading distance

UHF Printed Sensor for Force Detection

In this contribution, we show the advances in the direction of designing Radiofrequency Identification (RFID) antennas with sensing capabilities. In this particular case, we have integrated a force/pressure sensor made of a silicon-based organic polymer in one of the arms of a dipole antenna made of silver paste. The sensor response to external forces modifies the resonance frequency of the dipole antenna that can be detected by an external RFID reader, building up a wireless force sensor system.Pervasive Electronics Advanced Research Laboratory(PEARL), Department of Electronics and Computer Technology, University of Granada Institute for Nanoelectronics, Technical University of Munic

Faunistic Composition of Catches from the Spanish Bottom-longline Fishery in Deep-waters of Mauritania

The Spanish bottom-longline fleet started fishing in Mauritania in the 1990s targeting the hakes. In November 2000, an experimental longliner survey was carried out. The data showed 85% of the catches were used commercially and 15% were discarded, 84% of the commercial catches belonged to two hakes, Merluccius senegalensis and Merluccius polli. The areas of greatest abundance and species richness seem to correspond to upwelling zones, located by satellite imagery, where the highest values of both chlorophyll concentrations and pelagic resources were detected

Time-space reproductive differences of black hakes, M. polli and M. senegalensis off the NW African Coast

PosterThe named black hake in the Northwest Africa, M. polli and M. senegalensis, are distributed in Saharan, Mauritanian and Senegalese waters, where they are target species of Spanish trawling fleet and by some longliners. The separation of both species is quite difficult in practice, hence they are usually considered as black hake (mixed) in commercial catch statistics. This fact and the considerable deep distribution range of M. polli, results in a marked scarcity of comparative detailed studies about these species. The aim of this work was to analyze detailed biological data, collected during research trawl surveys and scientific observations onboard of commercial trawlers and longilenrs in Mauritanian and Senegalese waters during 2003-2006. By macroscopic analysis of the gonadic stages and the seasonal evolution of gonadosomatic indices (GSI), it has been determined the spawning season of both species. In order to determine the size at first sexual maturity, a logistic model was fitted to the mature fraction by length separated by species, considering different time periods. In other hand, the monthly time series of commercial gonad yields between 1986 and 2006 were split up in the trend and the seasonal components using a X-12 ARIMA routine. The spawning took place during the cold season, from November to February with the strongest signal during December-January for both species, but it occurs quite early in M. senegalensis. Males consistently maturing earlier than females, but there was a little length difference of sexual maturity for the two species. M. senegalensis reached the first maturity (35,4 cm) at slightly lower length than M. polli (37,0 cm) for combined sexes model. The sex ratio was skewed to females in both species. Because these species inhabits into a highly dynamic oceanographic area, and taking in account that recently it has been suggested a strong dependence between the climate-environment proxy NAO and the black hakes adult abundance dynamics, we explored possible deterministic relationships between reproduction features and sexual maturity of both species in phase with NAO index. It was not possible to determine if the difference in length-maturity values with some previous analyses were related with changes in abundance, the environmental forcing, or due to calculus procedures. However there was synchrony between the pronounced negative NAO phase and decreasing amplitude of seasonal peak of gonad yields for both species. Finally, despite of there was a slightly asynchrony in spawning timing among both species, we believe that in general terms it is justified to consider one set of maturity parameter values to perform the assessment procedures.Instituto Español de Oceanografía (IEO

Over-Stretching Tolerant Conductors on Rubber Films by Inkjet-Printing Silver Nanoparticles for Wearables

The necessity to place sensors far away from the processing unit in smart clothes or artificial skins for robots may require conductive wirings on stretchable materials at very low-cost. In this work, we present an easy method to produce wires using only commercially available materials. A consumer grade inkjet printer was used to print a wire of silver nanoparticles with a sheet resistance below 1 W/sq. on a non-pre-strained sheet of elastic silicone. This wire was stretched more than 10,000 times and was still conductive afterwards. The viscoelastic behavior of the substrate results in a temporarily increased resistance that decreases to almost the original value. After over-stretching, the wire is conductive within less than a second. We analyze the swelling of the silicone due to the ink’s solvent and the nanoparticle film on top by microscope and SEM images. Finally, a 60 mm long stretchable conductor was integrated onto wearables, and showed that it can bear strains of up to 300% and recover to a conductivity that allows the operation of an assembled LED assembled at only 1.8 V. These self-healing wires can serve as wiring and binary strain or pressure sensors in sportswear, compression underwear, and in robotic applications.This work has been partially supported the TUM Graduate School (TUM GS), and the European Union through the fellowship H2020-MSCA-IF-2017 794885-SELFSENS. Additionally, this work was supported by the German Research Foundation (DFG) and the Technical University of Munich within the Open Access Publishing Funding Programme

Screen Printed Security-Button for Radio Frequency Identification Tags

Radio frequency identi cation (RFID) security is a relevant matter. The wide spread of RFID applications in the general society and the persistent attempts to safeguard it con rm it, especially since its use involves payments and the store or transmission of sensitive information. In this contribution, we present an innovative solution for improving the security of RFID passive tags through the use of a screen printed button, that allows the reception and transmission only when a certain level of physical pressure normal to its plane is applied. The materials and fabrication technology used demonstrate an easy to implement and cost-effective system, valuable in several scenarios where the user has straight contact with the tags and where its usage is direct and intentional.This work was supported by the fellowship under Grant 2020-MSCA-IF-2017-794885-SELFSENS