Guillermo Boyra
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View article: Seasonal and inter-annual dynamics in the energy seascapes of a marine top predator
Seasonal and inter-annual dynamics in the energy seascapes of a marine top predator Open
Ecosystems are undergoing global changes that disrupt energy transfer across trophic levels, reducing energy availability and destabilizing predator–prey interactions. In marine systems, small pelagic fish (SPF) are key energy vectors to h…
View article: ITSASDRONE, an autonomous marine surface drone for fish monitoring around wave energy devices
ITSASDRONE, an autonomous marine surface drone for fish monitoring around wave energy devices Open
One of the primary foundations of the EU Blue Growth policy is the development of ocean energy. While the technological development of devices is advancing quickly, little is known about their possible environmental implications. The SafeW…
View article: A Web-Based Interactive Application to Simulate and Correct Distortion in Multibeam Sonars
A Web-Based Interactive Application to Simulate and Correct Distortion in Multibeam Sonars Open
Multibeam sonars are advanced scientific tools for estimating fish school volume and density, using multiple beams to provide comprehensive size measurements of detected targets. However, challenges remain in accurately estimating target d…
View article: Weakly supervised classification of acoustic echo-traces in a multispecific pelagic environment
Weakly supervised classification of acoustic echo-traces in a multispecific pelagic environment Open
In trawl-acoustic methods, machine learning can objectively assign species composition to echo-traces, providing a reproducible approach for improving biomass assessments and the study of schooling behaviour. However, the automatic classif…
View article: Exploring Growth Patterns of Maurolicus muelleri across Three Northeast Atlantic Regions
Exploring Growth Patterns of Maurolicus muelleri across Three Northeast Atlantic Regions Open
Maurolicus muelleri is an important component of mesopelagic ecosystems; nevertheless, we possess only limited knowledge about its biological features. We collected samples of M. muelleri from six scientific surveys between 2019 and 2021 i…
View article: Northward range expansion of Bay of Biscay anchovy into the English Channel
Northward range expansion of Bay of Biscay anchovy into the English Channel Open
European anchovy Engraulis encrasicolus is a widely distributed, warm-water species which has been postulated to be a climate change ‘winner’. For decades, the northern-most stock resided in the Bay of Biscay, where it typically spawned du…
View article: Target strength measurements of yellowfin tuna (<i>Thunnus albacares</i>) and acoustic discrimination of three tropical tuna species
Target strength measurements of yellowfin tuna (<i>Thunnus albacares</i>) and acoustic discrimination of three tropical tuna species Open
Tropical tuna fisheries support some of the largest artisanal and industrial fisheries worldwide. Approximately 37% of the tropical tuna catch by industrial purse seiners is obtained from tuna associated with drifting fish aggregating devi…
View article: Shrinking body size of European anchovy in the Bay of Biscay
Shrinking body size of European anchovy in the Bay of Biscay Open
Decreased body size is often cited as a major response to ocean warming. Available evidence, however, questions the actual emergence of shrinking trends and the prevalence of temperature‐driven changes in size over alternative drivers. In …
View article: Role of material properties in acoustical target strength: Insights from two species lacking a swimbladder
Role of material properties in acoustical target strength: Insights from two species lacking a swimbladder Open
[EN] Acoustic target strength (TS) is a key parameter for species identification and stock assessment in fisheries. The TS of fish is influenced by the contrast in acoustic impedance between their tissues and the surrounding water. While t…
View article: ITSASDRONE, an autonomous marine surface drone for fish monitoring around wave energy devices
ITSASDRONE, an autonomous marine surface drone for fish monitoring around wave energy devices Open
The ocean energy development is one of the main pillars of the EU Blue Growth strategy. However, while the technological development of devices is growing fast, their potential environmental effects are not well-known. The nascent status o…
View article: Influence of seasonal variability on the trophic structure of pelagic communities
Influence of seasonal variability on the trophic structure of pelagic communities Open
Seasonal variations in hydrodynamic conditions play a critical role in prey availability at the base of the food web and thus have implications for trophic interactions at higher trophic levels. Here we use the combination of stomach conte…
View article: Variation in the levels of Anisakis spp. infection in the European anchovy Engraulis encrasicolus (L. 1758) from the Bay of Biscay in the period 2000-2023 (ICES Subarea 8)
Variation in the levels of Anisakis spp. infection in the European anchovy Engraulis encrasicolus (L. 1758) from the Bay of Biscay in the period 2000-2023 (ICES Subarea 8) Open
The European anchovy Engraulis encrasicholus is one of the most commercial important species in the Bay of Biscay (ICES Subarea 8). We analysed the temporal mean abundance of Anisakis spp. larvae species in anchovies from ICES subarea 8 in…
View article: Differences in nutrient and undesirable substance concentrations in Maurolicus muelleri across the Bay of Biscay, Norwegian fjords, and the North Sea
Differences in nutrient and undesirable substance concentrations in Maurolicus muelleri across the Bay of Biscay, Norwegian fjords, and the North Sea Open
Introduction We are having pressing issues of global food insecurity and malnutrition. Mesopelagic communities in the North Atlantic have been estimated to have high biomasses of organisms. Some of these low-trophic organisms are known to …
View article: Understanding the impact of along-transect resolution on acoustic surveys
Understanding the impact of along-transect resolution on acoustic surveys Open
The distance between successive echosounder transmissions or “pings” is the main parameter determining the resolution of sampling along a transect in acoustic surveys. An increase in either ping interval or vessel speed increases the inter…
View article: Life History Strategy of Maurolicus muelleri (Gmenlin, 1789) in the Bay of Biscay
Life History Strategy of Maurolicus muelleri (Gmenlin, 1789) in the Bay of Biscay Open
Maurolicus muelleri is a significant component of the marine ecosystem and has the potential to be a valuable fishery resource. However, in the Bay of Biscay, its primary biological traits remain unclear. This study presents data on the le…
View article: Correction of beam overlap-induced athwart distortion in multibeam sonars
Correction of beam overlap-induced athwart distortion in multibeam sonars Open
A method is proposed to estimate and correct athwart-beam distortion of multibeam sonars to advance sonar-based abundance estimation. We illustrate its application using data from a Simrad SN90 multibeam sonar aboard a tropical tuna purse-…
View article: Ecological risk assessment of a pelagic seabird species in artisanal tuna fisheries
Ecological risk assessment of a pelagic seabird species in artisanal tuna fisheries Open
Fishery bycatch is a serious threat to several protected, endangered, and threatened species (PETs), requiring urgent action to develop and implement conservation measures. This study performs an Ecological Risk Assessment for the Effects …
View article: Probabilistic School Classification of Multiple Species in Acoustic Echograms Based on Machine Learning
Probabilistic School Classification of Multiple Species in Acoustic Echograms Based on Machine Learning Open
Multifrequency trawl-acoustic surveys are used worldwide for continuous monitoring of pelagic ecosystems. Acoustic backscattering energy partitioning in different species is typically done by visual scrutiny of the echograms with the aid o…
View article: A standard processing framework for the location data of satellite-linked buoys on drifting fish aggregating devices
A standard processing framework for the location data of satellite-linked buoys on drifting fish aggregating devices Open
Satellite-linked buoys used by tropical tuna purse-seine vessels on drifting fish aggregating devices (DFADs) provide a continuous stream of information on both the ocean characteristics and the presence and size of fish aggregations assoc…
View article: The Simrad EK60 echosounder dataset from the Malaspina circumnavigation
The Simrad EK60 echosounder dataset from the Malaspina circumnavigation Open
We provide the raw acoustic data collected from the R/V Hesperides during the global Malaspina 2010 Spanish Circumnavigation Expedition (14th December 2010, Cádiz-14th July 2011, Cartagena) using a Simrad EK60 scientific echosounder operat…
View article: Niche segregation mechanisms in marine apex predators inhabiting dynamic environments
Niche segregation mechanisms in marine apex predators inhabiting dynamic environments Open
Aim Understanding the mechanisms that allow the coexistence of species is key to preserve full ecosystem functioning. In dynamic environments, the study of ecological niches faces the complexity associated to the three dimensionality of th…
View article: <i>Ex situ</i>and<i>in situ</i>target strength measurements of European anchovy in the Bay of Biscay
<i>Ex situ</i>and<i>in situ</i>target strength measurements of European anchovy in the Bay of Biscay Open
This study measures the dorsal aspect target strength (TS; dB re 1 m2) and TS–length (standard length, SL; cm) relationships for European anchovy, attained both ex situ and in situ in two different seasons across 7 years in the Bay of Bisc…
View article: Raw EK60 echosounder data (38 and 120 kHz) collected during the Malaspina 2010 Spanish Circumnavigation Expedition (14th December 2010, Cádiz - 14th July 2011, Cartagena)
Raw EK60 echosounder data (38 and 120 kHz) collected during the Malaspina 2010 Spanish Circumnavigation Expedition (14th December 2010, Cádiz - 14th July 2011, Cartagena) Open
These data consist of raw echosounder observations collected during the Malaspina 2010 Spanish Circumnavigation Expedition (14th December 2010, Cádiz-14th July 2011, Cartagena). The cruise was divided into seven legs: leg 1 (14th December …
View article: Integrated daytime EK60 echosounder data from Malaspina-2010 cruise
Integrated daytime EK60 echosounder data from Malaspina-2010 cruise Open
Daytime acoustic data (nautical area scattering coefficients, in m2/nmi2) integrated over 2 m vertical bins, from 200 to 1000 m depth. Data in each “pixel” is the average of all cleaned and valid data recorded at that depth range, in a tim…