Abiotic and biotic drivers shaping the schooling behavior of small pelagic fish in multispecies environments.

Small pelagic fish play a vital role in pelagic ecosystems and global fisheries, but their aggregative behavior poses challenges for accurate assessments. While the basic functions of schooling-defense, foraging, migrating and mating-are well-documented, the dynamics and variability of these aggregations are less well understood. This study analyzes data from the JUVENA survey (2013-2020) in the Bay of Biscay, examining 54,240 schools from 158 daytime fishing hauls.

Shrinking body size of European anchovy in the Bay of Biscay.

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 marine fish, changes in food availability or fluctuations in abundance, including those due to size-selective fishing, provide compelling mechanisms to explain changes in body size.

Variation in the levels of anisakid infection in the European anchovy Engraulis encrasicolus (Linnaeus) from the Bay of Biscay during the period 2000-2023 (ICES Subarea 8).

The European anchovy Engraulis encrasicolus is one of the most important commercial species in the Bay of Biscay (ICES Subarea 8), and our analysis focused on the analysis of the temporal mean abundance, prevalence, and intensity of Anisakis spp. larvae species in anchovies from ICES Subarea 8 in the years 2000, 2001, 2014-2016, and 2019-2023. Prevalence in adult individuals of anchovy was only 1% in 2000 but increased to 90% in 2014.

Understanding the impact of along-transect resolution on acoustic surveys.

Resolution can be defined as the minimum distance between two consecutive sampling points taken by an instrument. In acoustic surveys, the main parameter determining the resolution of sampling along a transect is the distance between successive echosounder transmissions or "pings". An increase in either the time interval between pings or the speed of the vessel increases the inter-ping distance, hence decreasing the effective sampling resolution.

The Simrad EK60 echosounder dataset from the Malaspina circumnavigation.

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 operating at 38 and 120 kHz. The cruise was divided into seven legs: leg 1 (14th December 2010, Cádiz-13th January 2011, Rio de Janeiro), leg 2 (17th January 2011, Rio de Janeiro-6th February 2011, Cape Town), leg 3 (11th February 2011, Cape Town-13th March 2011, Perth), leg 4 (17th March 2011, Perth-30th March 2011, Sydney), leg 5 (16th April 2011, Auckland-8th May 2011, Honolulu), leg 6 (13th May 2011, Honolulu-10th June 2011, Cartagena de Indias) and leg 7 (19th June 2011, Cartagena de Indias-14th July 2011, Cartagena). The echosounder was calibrated at the start of the expedition and calibration parameters were updated in the data acquisition software (ER60) i.

Towards acoustic discrimination of tropical tuna associated with Fish Aggregating Devices.

Tropical tuna support some of the largest and most valuable artisanal and industrial fisheries worldwide, conducted to a large degree with Fish Aggregating Devices (FADs). Yellowfin, bigeye and skipjack are the main tuna species found in mixed aggregations around FADs and they are simultaneously encircled by the purse seining operation. One of the key challenges that purse seine fleets fishing with drifting FADs face in all oceans is to be able to target species in healthy condition such as skipjack, while reducing impacts on bigeye and yellowfin in areas where there is a need to reduce fishing pressure on these species.

Detecting the presence-absence of bluefin tuna by automated analysis of medium-range sonars on fishing vessels.

This study presents a methodology for the automated analysis of commercial medium-range sonar signals for detecting presence/absence of bluefin tuna (Tunnus thynnus) in the Bay of Biscay. The approach uses image processing techniques to analyze sonar screenshots. For each sonar image we extracted measurable regions and analyzed their characteristics.