REPORT OF THE 2022 EASTERN ATLANTIC AND MEDITERRANEAN BLUEFIN TUNA DATA PREPARATORY MEETING (INCLUDING BFT MSE)

The 2022 Eastern Atlantic and Mediterranean Bluefin Tuna Data Preparatory Meeting including MSE was held online from 18 to 26 April 2022. The bluefin tuna Species Group reviewed the development of the current CMPs and recommended a Blim of 40% of dynamic SSBMSY and an overfishing metric. It was suggested to use two quilt plots with main and secondary performance metrics and "worm plots" on biomass and catches for narrowing down the list of CMPs. A Path forward was defined for the BFT MSE process and for continuing with the ambassador’s programme. The draft Terms of Reference for the E-BFT assessment were reviewed. Initial model setup for the three platforms to be used, Virtual Population Analysis, Age Structured Assessment Program and Stock Synthesis were presented. Initial data inputs and indices of abundance were reviewed by trying to harmonize the input data for this stock assessment and the current BFT MSE. Following the presentations of initial data and preliminary results for three modeling platforms a working plan was defined. GBYP matters and BFT growth in farms were addressed

Description of the ICCAT length at age data base for bluefin tuna from the eastern Atlantic, including the Mediterranean Sea

This study aims to describe the current length at age database available for Eastern Atlantic bluefin tuna management area. A total of 8 500 spines and 5 000 otoliths were read from specimens caught from 1984 to 2017 in both the Atlantic Ocean and Mediterranean Sea. Obtaining ALKs for this species is difficult, as it has a wide length range and spatial distribution, and sampling is costly. Unfortunately, there are practically no contributions to this database from the East Atlantic and Mediterranean Sea countries, and only thanks to the initiative of the GBYP has it been possible to increase the number of samples in the ICCAT database in the last 10 years. As a result, the current ICCAT length at age database has incomplete spatial, temporal and size range coverage. However, it may be suitable as conditional age-at-length data for the Stock Synthesis model

Forgotten treasures in the HST/FOC UV imaging polarimetric archives of active galactic nuclei. I. Pipeline and benchmarking against NGC~1068 and exploring IC~5063

Over its 13 years of operation (1990 -- 2002), the Faint Object Camera (FOC) on board the Hubble Space Telescope (HST) observed 26 individual active galactic nuclei (AGNs) in ultraviolet (UV) imaging polarimetry. However, not all of the observations have been reduced and analyzed or set within a standardized framework. We plan to reduce and analyze the AGN observations that have been neglected in the FOC archives using a consistent, novel, and open-access reduction pipeline of our own. We then extend the method to the full AGN sample, thus leading to potential discoveries in the near future. We developed a new pipeline in Python that will be able to reduce all the FOC observations in imaging polarimetry in a homogeneous way. Most of the previously published reduced observations are dispersed throughout the literature, with the range of different analyses and approaches making it difficult to fully interpret the FOC AGN sample. By standardizing the method, we have enabled a coherent comparison among the different observational sets. In this first paper of a series exploring the full HST/FOC AGN sample, we present an exhaustively detailed account of how to properly reduce the observational data. Current progress in data-analysis is implemented in and has provided state-of-the-art UV polarimetric maps. We compare our new maps to the benchmark AGN case of NGC~1068 and successfully reproduce the main results previously published, while pushing the polarimetric exploration of this AGN futher, thanks to a finer resolution and a higher signal-to-noise ratio (S/N) than previously reported. We also present, for the first time, an optical polarimetric map of the radio-loud AGN IC~5063 and we examine the complex interactions between the AGN outflows and the surrounding interstellar medium (ISM).Comment: 17 pages, 19 figures, to be published in Astronomy & Astrophysic

Standardized age - Length key for east Atlantic and Mediterranean bluefin tuna based on otoliths readings.

This paper presents an age-length key (ALK) based on age estimates from otoliths following a recent standardized reading criterion. Sampling of Atlantic bluefin tuna (Thunnus thynnus) otoliths comes from the “Biological and genetic sampling and analysis" (GBYP) project and was complemented with some samples from the Spanish institute of Oceanography. Using 2010 to 2012 data improves length range and monthly sampling coverage. Variability in length at age from ALK seems acceptable and although it was developed from data pooled over three years, the bias is likely to be small. Final age was adjusted to account for the date of capture and the timing of bands formation throughout the year. Monthly formation of edge type, translucent or opaque, was inconclusive and did not allow establishing an annual formation pattern. The confidence interval of the von Bertalanffy growth model curve fitted to ALK data included currently adopted growth function for eastern bluefin stock and western stock function up to age 8. From age 9, this last western function predicts slightly older ages than the present ALK growth model.Postprint0,000

Applying mixed-effects growth models to back-calculated size-at-age data for Atlantic bluefin tuna (Thunnus thynnus)

We fit growth models to back-calculated size-at-age data for Atlantic bluefin tuna (Thunnus thynnus) captured in the western Atlantic management area to inform alternative growth scenarios within the current management framework of the species. The Modified-Fry function was the best-performing of three back-calculation functions based on a leave-one-out cross-validation for within-cohort comparisons. We fit multiple growth models to the back-calculated growth trajectories, and demonstrated that growth parameters were highly sensitive to whether the lack of independence between back-calculated lengths from each individual was accounted for by the model. Non-linear mixed-effects modelling provides a suitable approach for accounting for this lack of independence and the autocorrelation between back-calculated lengths from the same individual. We further demonstrated the utility of mixed-effects models for predicting future growth of individuals using a forecasting test. We used this modelling approach to demonstrate that male bluefin tuna had greater estimated asymptotic length than females, and found that there was no significant difference in growth parameters between individuals assigned to genetically distinct spawning stocks.1,58

Age-length keys availability for Atlantic bluefin tuna captured in the eastern management area

This paper analyzes the available direct ageing information in the last decade from Atlantic bluefin tuna caught in the eastern management area. To investigate differences among ALKs, a standard Von Bertalanffy growth function (VB) was fit to length at age data for each stratum. A deficient convergence of VB fitting to the asymptotic length due to the scarcity of old specimens was found for all available ALKs. After these analyses some records were identified as outliers (reading methodological issues) and removed from the data base.En prensa0,000