Calming down the seas: the near collapse of an Atlantic coastal fishery

For years now the estimates of the consequences of overfishing for marine ecosystems have differed greatly within the scientific community^1^. The use of commercial catch statistics to estimate tendencies has been much criticised^2^, but alternative information sources with long time series are rare. Here we employ the historic archive (1953-2007) of the recreational spearfishery in Galicia (NW Spain), which does not have the problems common to other fishery registers, to estimate long-term changes in coastal ecosystems. Using generalized additive regression models (GAM) we estimated decreases of around 83% in the abundances of coastal fish over the last 50 years. In the same period the average body size decreased by 36%. In addition, the relative catch frequency has decreased for the most valuable commercial species. Commercial overfishing has brought these ecosystems so close to the brink of collapse that it is necessary to implement measures that ensure their recovery

Movimientos de tres grandes peces depredadores costeros del Noreste Atlántico: un estudio preliminar mediante telemetría

Labrus bergylta, Dicentrarchus labrax and Conger conger are common predators of northeast Atlantic coastal ecosystems and are studied here for the first time with ultrasonic telemetry in their natural environment. We demonstrate the viability of using this technology with these species and used movement information to obtain preliminary short-term results on site fidelity, diel activity patterns and home range sizes. Two complementary telemetry methods were used: manual and automatic tracking along a stretch of coast characterized by its high wave exposure (A Coruña, NW Spain). C. conger stayed in the area for the longest periods of time (17 days), occasionally leaving their refuges at dusk or during the night to search for food. Their home range was very small (604 m2). L. bergylta were not detected by the automatic receivers but the size of their home range (between 2874 and 5184 m2), shows that they are highly sedentary with very limited movements. D. labrax left the area for the longest periods (9 days) and were detected during both night and day. Their home range was the largest (up to 26396 m2), evidencing complex spatial behaviour on a large scale.Labrus bergylta, Dicentrarchus labrax y Conger conger son depredadores habituales de los ecosistemas costeros del Noreste Atlántico que en este trabajo se estudian por vez primera mediante telemetría ultrasónica en el medio natural. Se demostró la viabilidad del uso de esta tecnología con estas especies y la información sobre sus movimientos se usó para obtener resultados preliminares a corto plazo acerca de la fidelidad al hábitat, la temporalidad diaria de la actividad y el tamaño del área vital. Se emplearon complementariamente dos métodos de telemetría: seguimiento manual y automático en un tramo de costa caracterizado por su elevado grado de exposición al oleaje (A Coruña, NW Spain). Los C. conger permanecieron en el área durante los períodos más largos (17 días), abandonando periódicamente sus refugios al atardecer o durante las noches para buscar alimento. El tamaño de su área vital fue muy pequeño (604 m2). Los L. bergylta no fueron detectados en los receptores automáticos, pero el tamaño de su área vital (entre 2874 y 5184 m2), evidencia un elevado grado de sedentarismo y movimientos muy limitados. Por el contrario, los D. labrax abandonaron el área durante los intervalos más prolongados (9 días), detectándose igualmente durante el día o la noche. Su área vital fue la de mayor tamaño (hasta 26396 m2), evidenciándose un comportamiento espacial complejo y a gran escala

Evaluación del impacto de la pesca submarina mediante el uso de registros de concursos y censos visuales subacuáticos

Recreational fishers are increasingly competing for space and resources with commercial fishers worldwide, but have been poorly studied. In particular, the impacts of spearfishing competitions on the temperate fish assemblages have seldom been analysed. In Galicia (NW Spain), there are currently 5000 spear fishers, and 500 of them participate in spearfishing competitions. An historic archive of spearfishing competitions was used to assess their influence on the subsequent competitions in the area and to analyse their effect on the fish abundances estimated by underwater visual censuses. The annual recreational catch of the spear fishers was also estimated and comparisons with the commercial landings were performed. The spear fishers targeted 29 species, although six accounted for 95% of the catch. Most of the species show low vulnerabilities to fishing pressure and only Dicentrarchus labrax, among frequently caught species, can be considered as moderately vulnerable. The overall impact of spearfishing competitions on fish populations was limited, although some competitions temporarily reduced the abundances of Labrus bergylta, the main target species, by up to 83%. Spear fishers caught a large proportion of the total catch of common species, with recreational catches of some species (e.g. L. bergylta) matching or exceeding the commercial catch. The inclusion of this fishery in the management models of the coastal ecosystems is strongly recommended.Los pescadores recreativos compiten cada vez más intensamente por el espacio y los recursos con los pescadores comerciales en todo el mundo, pero han sido poco estudiados. En particular, rara vez se han analizado los impactos de los concursos de pesca submarina sobre las comunidades de peces propias de las regiones templadas. En Galicia (noroeste de España), en la actualidad hay 5000 pescadores submarinos, y 500 de ellos participan en concursos. Se utilizó un archivo histórico de competiciones de pesca submarina para evaluar su influencia sobre los concursos celebrados posteriormente en la zona y para analizar su efecto sobre las abundancias de peces, estimadas mediante censos visuales subacuáticos (UVC). Además, se estimaron las capturas recreativas anuales de los pescadores submarinos y se realizaron comparaciones con los desembarques comerciales. Los pescadores submarinos capturaron 29 especies, aunque seis representaron el 95% de sus capturas. La mayor parte de las especies muestran bajas vulnerabilidades a la presión pesquera y sólo Dicentrarchus labrax, de entre las especies capturadas con frecuencia, puede ser considerada como moderadamente vulnerable. El impacto global de los concursos de pesca submarina sobre las poblaciones de peces fue limitado, aunque algunos concursos redujeron temporalmente las abundancias de Labrus bergylta, la principal especie objetivo, hasta en un 83%. Los pescadores submarinos obtuvieron una relevante proporción de las capturas totales sobre las especies comunes, con las capturas recreativas sobre algunas de ellas (e.g. L. bergylta) siendo equivalentes o superiores a las comerciales. Se recomienda encarecidamente la inclusión de esta pesquería en los modelos de gestión de los ecosistemas costeros

Como asignar valor económico a bancos de pesca cuando las estadísticas de pesca no son espacialmente explícitas

Fishery statistics do not usually include small-scale spatial references to assess the effects of natural or human disturbances. We present a methodology which assigns a geographical origin to the catches and assesses the total revenue of the fishing grounds. Market statistics are combined with the results of an ethnographic survey to provide a spatial allocation of the fishing effort. In the present case study, which corresponds to the Galician coast (NW Spain), 253 vessels from 14 base ports that fish in 80 fishing grounds were identified. The annual total revenue of the catches was 8.28 M€ and ranged from a minimum of 4928 € to a maximum of 0.60 M€ with a mean value per fishing ground of 0.104 M€.Las estadísticas pesqueras no suelen incluir referencia espacial a pequeña escala que permita evaluar los daños causados por perturbaciones naturales o humanas. Se presenta una metodología que asigna un origen geográfico a las capturas y permite estimar un valor de explotación de los caladeros. Se combinan estadísticas de comercialización con los resultados de un análisis etnográfico para proporcionar una localización geográfica al esfuerzo de pesca. En particular, se ha estudiado una situación en la que se identificaron 253 embarcaciones de 14 puertos diferentes, que pescaban en 80 caladeros de la costa de Galicia (NW de España). Los ingresos brutos anuales resultantes de las capturas realizadas fueron de 8.28 M€, con un importe promedio por banco de 0.104 M€, oscilando entre un máximo de 0.60 M€ y un mínimo de 4928 €

Dissolution kinetics of cellulose in ionic solvents by polarized light microscopy

Aiming to increase the scarce information available on the kinetics of cellulose dissolution, we have applied an image-assisted technique based on the luminance evolution as cellulose dissolves to study this process under different experimental conditions. This protocol was validated via direct determination of the cellulose dissolved. In all cases datapoints were linearly fitted assuming a pseudo-zero order reaction which facilitates the comparison between datasets. To study the solvent effect we have used three ionic liquids with large basicity and found significantly different rates of dissolution, from faster to slower: [C2 C1 Im][OAc]>[C1 C1 Im][DMP]>[C2 C1 Im][DEP]. Solvatochromic parameters and viscosity of the solvent media were determined and the latter was identified as a key factor slowing the process as it reduces ionic mobility. The weight of viscosity was estimated by removing the viscosity effect with a tuned solvent media doped with DMSO. Activation energy was 70% lower at constant viscosity. On the substrate side, particle size is the main factor affecting the dissolution rate. All samples were milled to homogenise the starting material and minimise the distortions caused by the size distribution. After, dissolution of three cellulose substrates under the same experimental conditions was analysed. Dissolution of natural fibers took twice as long as dissolving pulp which dissolves slower than lyocell fibers. This trend correlates with the roughness of the samples obtained by optical perfilometry which is consistent with the dissolution mechanism proposed in the literature.Xunta de Galicia | Ref. ED481A 2021/341Xunta de Galicia | Ref. ED481D-2022-022Agencia Estatal de Investigación | Ref. RYC2021- 033826-IUniversidade de Vigo/CISU

A State-of-the-Art Review of Marine Ecosystem Services in the Rías Baixas Natura 2000 Network (Galicia, NW Spain)

Humans are deeply connected to the oceans, who provide us vital ecosystem services (ES) (climate regulation, control of natural threats, wealth of its biodiversity, etc.), but the oceans are the first to suffer from human activity (climate change, destruction of ecosystems, overexploitation of marine resources, pollution, endangered species, etc.). Marine biodiversity is a fundamental natural capital in the generation of marine ecosystem services (MES), fundamental elements for the maintenance of human wellbeing. The objective of this article is to empirically demonstrate the role of marine ES in natural protected areas in Nature 2000 Rías Baixas (N2RB) (Galicia, NW Spain) in order to (1) to improve the knowledge on natural capital and ES associated to conserved coastal areas, (2) to analyze the contribution of these conserved coastal areas to the provision of sustainable business opportunities, and (3) to analyze if green-oriented policies can revert the current unsustainable exploitation model by providing real opportunities for business development. By creating an inventory, we gathered detailed information collected up to October 2020 of scientific literature, research projects, press releases, information on business initiatives and public policies regulations on ES and conservation of marine biodiversity in the N2RB (Cíes Islands and Island of Ons, including the Ons–O Grove Complex). Better protection of marine natural capital needs coordinated efforts among all sectors of government, business, and international institutions. It is a priority to generate a greater degree of social and business commitment that promotes the conservation of marine biodiversity, through the design of social and business participation strategies in the planning and use of ES in the N2RB areasThis work has been carried out within the framework of the ECOSOCIETY Project (Citizen participation for the improvement of conservation of marine biodiversity in the areas Rías Baixas Natura 2000 Network), with the support of the Ministry for the Ecological Transition and the Demographic Challenge, through the Biodiversity Foundation. PP received funds from the Xunta de Galicia under the modality of Grupos de Referencia Competitiva (Grant ED431C2019/11), and RECREGES I and II projects under Grants ED481B2014/034-0 and ED481B2018/017S

Relevancia de la pesca recreativa desde la costa en el archipiélago de Madeira, Portugal (Atlántico nororiental)

In 2017, a total of 4825 licences were issued for shore angling in Madeira. Surveys were conducted on 734 anglers, some in the government fisheries office during the licence request and others during the fishing activity. Shore angling is practised throughout the year, mostly at weekends and during day time, and with an increase in summer. More than 60% of the anglers are unemployed, have low incomes, and spend on average €254 per person per year on this activity, adding up to a total of €1.16 million per year. Shore angling average number of fishing days per year per fisher was 65.1±62.0 and the average catch per unit of effort was 0.35±0.26 kg/angler/hour. The estimated total annual catch was 520.7 t. Forty-three teleost species, 2 elasmobranchs and 6 invertebrates were identified in the catches. Despite the limitations and inaccuracies inherent to the surveys, they still provided valuable information and gave a general perception of the recreational shore fisheries in Madeira. The possible impact on the most captured species, such as the white seabream, Diplodus sargus (Linnaeus, 1758), and the parrotfish Sparisoma cretense (Linnaeus, 1758), should be analysed because high fishing pressure could affect populations and ecosystems.En 2017 se tramitaron un total de 4825 licencias para la pesca recreativa desde la costa en la Región Autónoma de Madeira. En este periodo se realizaron 734 encuestas a los pescadores de esta modalidad, algunas en las oficinas, durante el trámite necesario para obtener la licencia y otras a personas mientras estaban pescando. La pesca desde la costa es una actividad que se practica durante todo el año, principalmente los fines de semana y normalmente durante el día, con un aumento de pescadores durante el verano. Más del 60% están desempleados o tienen bajos ingresos, y gastan en promedio 254 € por persona al año en esta actividad, contabilizándose un total de 1.16 millones de € por año. El numero medio de días de pesca por pescador al año fue de 65.1±62.0, mientras que la CPUE media fue de 0.35±0.26 kg/pescador/hora. La captura anual total estimada fue de 520.7 t, y se identificaron 43 especies de teleósteos, 2 de elasmobranquios y 6 de invertebrados en las capturas. A pesar de las limitaciones e imprecisiones inherentes a las encuestas, por primera vez se ha logrado obtener una valiosa información, que nos permite tener una percepción general de la pesca recreativa desde la costa en Madeira. El posible impacto sobre las especies más capturadas, como el sargo Diplodus sargus (Linnaeus, 1758) y la vieja Sparisoma cretense (Linnaeus, 1758), debe ser analizado ya que están sujetos a una importante presión pesquera que podría afectar a sus poblaciones y al ecosistema

Planning Large Single Frequency Networks for DVB-T2

[EN] The final coverage and associated performance of an SFN is a joint result of the properties of all transmitters in the SFN. Due to the large number of parameters involved in the process, finding the right configuration is quite complex. The purpose of the paper is to find optimal SFN network configurations for DVB-T2. Offering more options of system parameters than its predecessor DVB-T, DVB-T2 allows large SFN networks. However, self-interference in SFNs gives rise to restrictions on the maximum inter-transmitter distance and the network size. In order to make optimum use of the spectrum, the same frequency can be reused over different geographical areas - beyond the reuse distance to avoid co-channel interference. In this paper, a methodology based on theoretical network models is proposed. A number of network architectures and network reference models are considered here for different reception modes in order to study the effects of key planning factors on the maximum SFN size and minimum reuse distance. The results show that maximum bitrate, network size and reuse distance are closely related. In addition, it has been found that the guard interval is not the only limiting parameter and that its impact strongly depends on the rest of DVB-T2 mode parameters as well as on the network characteristics (Equivalent Radiated Power, effective height, inter-transmitter distance). Assuming that the C/N requirements are in the vicinity of 20 dB and bitrates over 30 Mbps, it has been found that the network can be as large as 360 x 360 km (delivering 39.2 Mbps) or even 720 x 720 km (delivering 37.5 Mbps). The reuse distance will also have a complex dependency on the DVB-T2 mode and especially the network parameters, ranging from below 100 to 300 km.This work has been financially supported by the Beihang University, IRT, the University of the Basque Country UPV/EHU (UFI 11/30 and program for the specialization of the postdoctoral researcher staff) and by the Spanish Ministry of Economy and Competitiveness under the project HEDYT-GBB (TEC2012-33302)