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Underwater noise has been identified as a relevant pollution affecting marine ecosystems in different ways. Despite the numerous studies performed over the last few decades regarding the adverse effect of underwater noise on marine life, a lack of knowledge and methodological procedures still exists, and results are often tentative or qualitative. A monitoring methodology for the behavioral response of bluefin tuna (Thunnus thynnus) when exposed to ship and wind turbine operational noises was implemented and tested in a fixed commercial tuna feeding cage in the Mediterranean sea. Fish behavior was continuously monitored, combining synchronized echosounder and video recording systems. Automatic information extracted from acoustical echograms was used to describe tuna reaction to noise in terms of average depth and vertical dimensions of the school and the indicators of swimming speed and tilt direction. Video recordings allowed us to detect changes in swimming patterns. Different kinds of stimuli were considered during bluefin tuna cage monitoring, such as noise generated by feeding boats, wind farm operational noise, and other synthetic signals projected in the medium using a broadband underwater projector. The monitoring system design was revealed as a successful methodological approach to record and quantify reactions to noise. The obtained results suggested that the observed reactions presented a strong relationship with insonification pressure level and time. Behavioral changes associated with noise are difficult to observe, especially in semi-free conditions; thus, the presented approach offered the opportunity to link anthropogenic activity with possible effects on a given marine species, suggesting the possibility of achieving a more realistic framework to assess the impacts of underwater noise on marine animals., AZIMUT IEO, SI

[EN] The method of fundamental solutions has been applied to evaluate the influence of fish models geometrical features on the target strength (TS) directivity and TS frequency response of swimbladdered fish. Simplified models were considered for two fish species: gilt-head sea bream (Sparus aurata, Linnaeus 1758) and Atlantic salmon (Salmo salar, Linnaeus 1758), and different geometrical details of their morphology were studied, such as backbone presence, and its curvature or the inclusion of vertebrae modulation. Swimbladder shape and tilt, together with the inclusion of backbone (and its realistic curvature) for dorsal measurements were the most important features for proper estimation of mean TS. The estimation of mean TS is considered including the effect of fish tilt, the echosounder frequency, and the fish-to-transducer distance., This work received funding from ACUSTUNA project ref. CTM2015-70446-R (MINECO/ERDF, EU). LG acknowledges the support by FCT-Fundacao para a Ciencia e a Tecnologia, I.P., within the scope of the research unit "Institute for sustainability and innovation in structural engineering-ISISE" (UIDP/04029/2020) and of Regional Operational Programme CENTRO2020, within the scope of the project CENTRO-01-0145-FEDER000006 (SUSpENsE). IP-A and VE acknowledge the financial support of Generalitat Valenciana by grants BEST/2018/119 and BEST/2019/008.

[EN] Anthropogenic activities are causing increased noise levels in the marine environment. To date, few studies have been undertaken to investigate the effects of different noise frequencies on the behaviour of juvenile fish. In this study, the behavioural changes of juvenile gilthead seabream (Sparus aurata) are evaluated when exposed to white noise filtered in third-octave bands centred at 63, 125, 500, and 1000 Hz (sound pressure level, 140-150 dB re 1 mu& x3a1;a) for 7 h. The group dispersion, motility, and swimming height of the fish were analysed before and during the acoustic emission. Dispersion of the fish was found to reduce immediately upon application of low frequency sound (63 and 125 Hz) with a return to control condition after 2 h (indicative of habituation), whereas at 1 kHz, dispersion increased after 2 h without any habituation. The motility decreased significantly at 63 Hz throughout the 7 h of sound exposure. The swimming height decreased significantly for all frequencies other than 125 Hz. The results of this study highlight significant variations in the behavioural responses of juvenile fish that could have consequences on their fitness and survival., This study was conducted in the framework of the Ph.D. program in the Mediterranean Biodiversity XXXII cycle (International) of the University of Palermo. I.P.-A., M.B.-C. and V.E. acknowledge the financial support of the European Comission-Project No. 11.0661/2018794607/SUB/ENV.C2, risk-based approaches to good environmental status (RAGES). The other founding support comes from the Ph.D. Innovative with Industrial Characterization Programma Operativo Nazionale (PON) 2014-2020 and the projects bilateral Research laboratory on marine and maritime Science Italy-Argentina (CAIMAR) Joint Laboratory Italy-Argentina (Laboratori Congiunti Bilaterali Internazionali of the Italian National Reseach Council, 2017-2019). Document

[EN] This paper presents measures of target strength (TS; dB re 1 m(2)) and models of TS vs. fork length (L; cm), i.e. TS = 20log(L) + b(20), for skip-jack tuna associated with fish aggregating devices (FADs) in the Central Pacific Ocean. Measurements were made using 38-, 120-, and 200-kHz split-beam echosounders on a purse-seine workboat during fishing operations. To mitigate potential bias due to unresolved targets, TS measurements were rejected if they were not simultaneously detected with multiple echosounder frequencies in approximately the same location. The filtered TS and concomitantly sampled L data were used to estimate b(20) = -76, -71, and -70.5 dB for 38, 120, and 200 kHz, respectively, using the method of least squares. For comparison, quasi-independent estimates of TS and b(20) were calculated from acoustic echo-integration and catch data representing entire aggregations around the FADs. The results differed by, We thank the following organizations and people for their support of this work: the governments of Kiribati, Tuvalu, and Tokelau which permitted this research in their EEZs; Albacora for allowing this work aboard F/V ALBATUN TRES; Fishing Master Euken Mujika; the captain and crew; the scientists and divers J. Filmalter and F. Forget are thanked for invaluable insight about fish behaviour, vertical stratification and non-target species composition at FADs; Hector Pena for providing instruction on the sonar setup and analysis; Yolanda Lacalle for the illustration in Figure 2; and Andres Uriarte for advice concerning transmission of statistical errors. The research reported in the present document was funded by the International Seafood Sustainability Foundation (ISSF) and conducted independently by the authors. The report and its results, professional opinions and conclusions are solely the work of the authors. This paper is contribution 843 from AZTI (Marine or Food Research).

Underwater noise is mainly produced by anthropogenic activities and has increased in recent years. The Marine Strategy Framework Directive aims to monitor “continuous low frequency sound” trends in ambient noise in particular at 1/3rd octave bands centered at 63 and 125 Hz. The aim of this work is to evaluate the possibility of using the results of Sparus aurata juvenile’s behavior for parameterizing a numerical model of the fish behavior. The fishes were stressed with white noise filtered with a band pass filter at 1/3 octave band centered respectively at 63 Hz, 125 Hz, 500 Hz, and 1 kHz (SPL: 140-150 dB re 1µPa). We performed three test replicas for the control (without any sound emission) and for each of the four frequencies. Each trial lasted 7:15 hours in total and included the following three periods in which two video cameras recorded: 30 min before the acoustic emission; 60 min in which the acoustic stress was dispensed; 6 hours after the acoustic emission divided into 6 periods of 1 hour. To obtain the behavioral data (cohesion, motility, swimming height) the fishes were video monitored 15 min before the sound exposure, one hour during the sound exposure and the final 15 minutes of each hour after the sound exposure. The bottom of the tank was divided into squares. Cohesion was evaluated by counting the number of squares occupied by the group; motility by counting the number of squares crossed by each fish; swimming height by counting the fish presence in three zones (deepest, intermediate, and highest). Using Kruskal-Wallis tests and multiple comparisons post-hoc tests we assessed different behaviors of the fishes reacting to different acoustic frequencies. Here, we propose the use of part of these data (the first hour of acoustic emission) for the parameterization of a numerical model using an adaptation of the Boids method. In the model the cohesion, motility and the swimming height are analyzed in the same way as they are analyzed for in vivo video recordings. Preliminary results showed that it is possible to reproduce in the new model the same qualitative behavior of the in vivo recordings with fish. In this way, it will be possible to understand the behavioural responses of fish in laboratory experiments and contribute to the prediction of the impacts of other possible acoustic sounds emitted by human activities through the application of the created numerical model.

Human activities in the oceans, such as marine traffic and Deep Sea Mining (DSM), are increasing in the last years (Ross 2005; Calvo et al 2016). Underwater noise in the oceans, especially at lower frequencies, is mainly produced by marine traffic and DSM could increase this noise in the next future. Marine Strategy Framework Directive promotes the achievement of a good quality environmental status and aims to monitor “continuous low frequency sound” trend in the ambient noise level within the 1/3 octave bands centred at 63 and 125 Hz. The aim of this study is to evaluate the behavioural changes of Sparus aurata juveniles exposed to a four different acoustic signals in a tank. The emitted signal was white noise filtered at 1/3 octave band centred respectively at 63 Hz, 125 Hz, 500 Hz, and 1 kHz (SPL: 140-150 re 1μΡa). For each frequency we tested three independent groups of 6 specimens and video monitored them for a total of 7:30 hours (15 min before, one hour during and 6 hours after the sound exposition) using two cameras located above the tank and in the water column. Moreover, three control group (no acoustic emission) tests were performed (no sounds were dispensed). Behavioural data (cohesion, motility, swimming height) were collected from the 15 minutes of each hour except in during sound exposition, where we considered the entire hour. The bottom of the tank was divided into squares. Cohesion was evaluated counting the number of squares occupied by the group; motility counting the number of squares crossed by each fish; swimming height counting the fish presence in three zones (deepest, intermediate, and highest). Using Kruskal-Wallis tests and multiple comparisons post-hoc we assessed that the cohesion was significantly affected at 63,125 and 500 Hz. At 63 and 125 Hz, significant increase in cohesion was observed during and up to the third and sixth hour of exposition respectively; at 500 Hz cohesion increased only during the exposition. Significant increase in motility was observed during the 63 and 125Hz stimuli. For swimming height, all frequencies significantly increase the number of fish in the deepest zone and decrease in the intermediate zone. The juvenile of S. aurata exhibit different behaviours depending on the acoustic frequencies. This study evidences an impact at short and medium time on juvenile. This could determine an effect on budget energy and, consequently, a potential threat for their recruitment in a noise-polluted environment.

[EN] We propose the application of a numerical model based on the Method of Fundamental Solutions to the estimation of the target strength (TS) of single fish, a crucial parameter for evaluating fish abundance when using active acoustical techniques. We consider a realistic beam and the influence of the evolution of the scattered field with distance maintaining the target in the far field of the ultrasonic transducer. The cases of a fluid sphere and a prolate spheroid model for the swimbladder are used to verify the application of MFS against other analytical and numerical methods. Additionally, a model considering only the swimbladder and the fishbone is presented to evaluate the differences between dorsal and ventral aspect measurements, and to understand previous experimental works performed with Atlantic salmon (Salmo salar) in floating cages., I. Perez-Arjona and V. Espinosa acknowledge funding of ACUSTUNA project ref. CTM2015-70446-R (MINECO/FEDER, UE), and UPV grants of PAID-00-15 and GVA BEST/2015/270. L. Godinho acknowledges the funding by FEDER funds through the Competitivity Factors Operational Programme - COMPETE and by national funds through FCT - Foundation for Science and Technology within the scope of the project POCI-01-0145-FEDER-007633. The authors would like to thank Dr. Manuel Bou and Carlos Albino for the technical assistance with work-station procedures.

[EN] The possibility of detecting uneaten food pellets in aquaculture floating cages using a scientific single beam echosounder is demonstrated. The applied methodology is based in a basic scheme with the ultrasonic beam facing upwards the sea surface from the cage bottom. The target strength of single pellets is measured resulting in a linear relationship between target strength and pellet size. These results are the basis to quantify the uneaten food falling and to develop an automated feeding system based on demand. (C) 2017 Elsevier B.V. All rights reserved., This work was developed with the financial support of project ARM/1790/010 of the Tecnological Develoment Program of MAGRAMA, Spanish Government. E. Soliveres acknowledges support of Spanish Government grant AP2009-4459 FPU Subprogram. The authors would like to,acknowledge Prof. Helge Balk of the University of Oslo for his assistance with the software and license's access to Sonar 5 Pro, and the collaboration of Simrad Spain S.L. for lending the used EK15 echosounder.

The earth’ resources are running out, the population will increase and further sources will be needed. These, were found in the deep ocean. To date the mining activities (Deep Sea Mining, DSM) they have not started. One impact of DSM could be underwater noise. Considering the noise frequencies of anthropic activities in the ocean, and the European directive on underwater noise control, we stressed the animals with four acoustic 1/3 band noises around: 63 Hz, 125 Hz, 500 Hz, 1kHz. We study the effects on Sparus aurata juveniles, and on Mytilus galloprovincialis. We will analyse behavioural., molecular and biochemical responses Los recursos de la tierra se están agotando, la población aumentará y se necesitarán más fuentes. Esaos fueron encontradas en el océano profundo. Hasta ahora, las actividades mineras (Deep Sea Mining, DSM) no han empezado. Un impacto del DSM podría ser el ruido subacuático. Teniendo en cuenta las frecuencias de ruido de las actividades antrópicas en el océano, y la directiva europea sobre el control del ruido submarino, molestamos los animales con cuatro ruidos acústicos de 1/3 de banda alrededor: 63 Hz, 125 Hz, 500 Hz, 1kHz. Estudiamos los efectos en juveniles de Sparus aurata y en Mytilus galloprovincialis. Analizaremos respuestas comportamiental,moleculares y bioquímicas.

[EN] In this work, acoustic and computer vision techniques are combined to develop an automatic procedure for biomass estimation of tuna during transfers. A side scan sonar working at 200¿kHz and a stereo camera, positioned facing towards the surface to record the ventral aspect of fish, are set as acquisition equipment. Moreover, a floating structure has been devised to place the sensors between cages in transfers, creating a transfer canal that allows data acquisition while fish swim from donor to receiving cage. Biomass assessment is computed by counting transferred tuna and sizing a representative sample of the stock. The number of transferred tuna is automatically deduced from acoustic echograms by means of image processing techniques, whereas tuna size is computed from the stereo videos using our automatic computer vision procedure based on a deformable model of the fish ventral silhouette. The results show that the system achieves automatic tuna counting with error below 10%, achieving around 1% error in the best configuration, and automatic tuna sizing of more than 20% of the stock, with highly accurate Snout Fork Length estimation when compared to true data from harvests. These results fulfil the requirements imposed by International Commission for the Conservation of Atlantic Tunas for compliant transfer operations., This work was supported by funding from the BIACOP project, ES13/41, from the EU Fisheries Control Programme through the Secretaría General de Pesca, Ministerio de Agricultura, Alimentación y Medio Ambiente (MAGRAMA), and by ACUSTUNA project ref. CTM2015-70446-R (MINECO/ERDF, EU). The BIACOP project has been possible thanks to the collaboration of the Spanish company Grup Balfegó S.L. that also supplied boats and divers to acquire underwater video in the Mediterranean Sea. Special personal acknowledgements to Manuel Guijarro and Antonio López, and to David Baizán from IMA – Acuicultura Integrada Multitrófica S.L.U., for their assistance with the design and construction of the floating structures.

[EN] Horizontal hydroacoustics is a technique of remote fish detection that has proved to efficiently determine fish density and biomass in shallow or superficial waters. This non-intrusive technique could render better results than those obtained by conventional sampling when monitoring shallow waters. To apply this technique, we need equations that relate the amount of sound returned by fish, known as target strength (TS in dB), with their length (mm) or weight (g). This study presents horizontal conversion equations for the species gilt-head bream (Sparus aurata) and sea bass (Dicentrarchus labrax), two of the most important species bred in aquaculture. Moreover, this study presents a new formula to calculate a mixed equation adjusted to the percentage of distribution of those species in case of mixed populations. The results in this research have been obtained by applying a simple setup that allows for high-quality acoustic data. These new equations will enable the application of this technique in order to estimate these species' density and biomass in shallow aquatic systems such as aquaculture ponds with semi-intensive production densities., This study's authors would like to thank the Superintendent of Economy and Knowledge (Andalusian Government) for the funding provided as part of the project (PI_57052) developed in collaboration with CTAQUA. We would like to thank the researchers Carlos Orduna Marin and Juan Ramon Cid Quintero for their selfless work to obtain the field data and to the company PIMSA for generously allowing us to use their facilities and fish. We would also like to thank the veterinarian JR Rodriguez for being kind enough to perform X-rays on the studied fish and Cristina Ocana for her careful proofreading of the English text.

[EN] Fish anatomical vertical dimensions are extracted from a time-of-flight analysis of fish echo shape using narrow bandwidth echosounding of swimming individuals. These vertical dimensions fit a Gumbel distribution model and are successfully correlated with fish weight. The proposed method can be used to estimate the mean weight of fish in aquaculture cages as an alternative to target strength measurements. Full-waveform acquisition and signal correlation techniques permitted to increase the signal-to-noise ratio and to improve the performance against traditional envelope-based echosounding., This work was developed with the financial support of project ARM/1790/010 of the Tecnological Develoment Program of MAGRAMA, Spanish Government. E. Soliveres acknowledges support of Spanish Government grant AP2009-4459 FPU Subprogram.