Data and initial model set-up for the 2022 VPA stock assessment of the eastern Atlantic and Mediterranean bluefin tuna

This document presents the data and initial model set-up for the 2022 Stock Assessment for the Eastern Atlantic and Mediterranean bluefin tuna stock. During the 2017 Data Preparatory meetings, several changes in the data used for previous assessments have been presented, among which the revision of the Task 1 and Task 2 statistics and the selection of the indices of abundance. This led to completely revisiting the catch at age matrix and the model specifications for the 2017 assessment. For the present document, the data over the historical period (1968-2015) were nearly identical, whereas the data for the years 2016-2020 and abundance indices were updated. As agreed in previous meetings, the initial model specifications were kept identical to the 2017 assessment as no change has been agreed on since then

Final data, explorations, model set-up and diagnostics for the 2022 VPA stock assessment of the eastern and Mediterranean Atlantic bluefin tuna stock

This document presents the modeling work done for the 2022 stock assessment for the Eastern and Mediterranean Bluefin tuna stock, during informal modeling subgroup meetings in June 2022. This document presents various runs built upon the base case for the 2017 stock assessment. These runs aim at addressing issues identified in the 2020 update assessment and aspects discussed during the informal meetings held in june 2022, regarding the inclusion of updated catch at age data, improvement of model stability in relation to Fratio estimates, the selection of the age for the plus group, inclusion of the WMED_GBYP_AER index. Following several explorations, the present work contains two runs that displayed improved diagnostics compared to previous runs. These models have improved retrospective patterns and no problematic issue was found through jittering the random number generator, jittering the starting values for the terminal F estimate, bootstrapping or through jackknife analysis

Seascape connectivity of European anchovy in the Central Mediterranean Sea revealed by weighted Lagrangian backtracking and bio-energetic modelling

Ecological connectivity is one of the most important processes that shape marine populations and ecosystems, determining their distribution, persistence, and productivity. Here we use the synergy of Lagrangian back-trajectories, otolith-derived ages of larvae, and satellite-based chlorophyll-a to identify spawning areas of European anchovy from ichthyoplanktonic data, collected in the Strait of Sicily (Central Mediterranean Sea), i.e., the crucial channel in between the European and African continents. We obtain new evidence of ecosystem connectivity between North Africa and recruitment regions off the southern European coasts. We assess this result by using bio-energetic modeling, which predicts species-specific responses to environmental changes by producing quantitative information on functional traits. Our work gives support to a collaborative and harmonized use of Geographical Sub-Areas, currently identified by the General Fisheries Commission for the Mediterranean. It also confirms the need to incorporate climate and environmental variability effects into future marine resources management plans, strategies, and directives

Guideline to apply hedging to mitigate the risk of construction materials price escalation

Accurately forecasting cost is vital to the success of any construction project. Cost estimation encompasses uncertainty, since construction projects are exposed to many forms and degrees of risk. Materials price volatility and shocks constitute one aspect. Most current approaches for material risk assessment are deterministic and do not take into consideration material price fluctuation. The application of hedging, to mitigate the risk of construction material price fluctuations, is proposed in this research. Although it is known that using hedging as a risk management tool adds value to a financial firm, limited knowledge has been established about using hedging for construction material price risk mitigation. Hedging has also been a practice applied in the airline industry for a long time, and substantive research has been completed in the field of airline fuel hedging. The objective of this research is to identify best practices in the area of airline fuel hedging to provide an outline for implementation in the construction industry, and to develop a step-by-step guideline to applying materials hedging in the construction industry. This is considered to be the first attempt to match construction material hedging with the airline fuel hedging application. The guideline presented herein helps construction companies to apply hedging to mitigate the risk of construction material price fluctuations. This guideline improves construction companies’ ability to submit a very competitive bid on a specific project.Non UBCUnreviewedFacultyOthe

Data and model set-up for the 2020 update stock assessment of the Eastern and Mediterranean Atlantic bluefin tuna stock

Peer reviewe

Data and initial model set-up for the 2022 VPA stock assessment of the eastern Atlantic and Mediterranean bluefin tuna

This document presents the data and initial model set-up for the 2022 Stock Assessment for the Eastern Atlantic and Mediterranean bluefin tuna stock. During the 2017 Data Preparatory meetings, several changes in the data used for previous assessments have been presented, among which the revision of the Task 1 and Task 2 statistics and the selection of the indices of abundance. This led to completely revisiting the catch at age matrix and the model specifications for the 2017 assessment. For the present document, the data over the historical period (1968-2015) were nearly identical, whereas the data for the years 2016-2020 and abundance indices were updated. As agreed in previous meetings, the initial model specifications were kept identical to the 2017 assessment as no change has been agreed on since then.Ce document présente les données et la configuration initiale du modèle pour l'évaluation du stock de thon rouge de l'Atlantique Est et de la Méditerranée de 2022. Lors des réunions de préparation des données de 2017, plusieurs modifications des données utilisées dans les évaluations précédentes ont été présentées, parmi lesquelles la révision des statistiques de la tâche 1 et de la tâche 2 et la sélection des indices d'abondance. Cela a entraîné la révision complète de la matrice de prise par âge et des spécifications du modèle pour l'évaluation de 2017. Dans le présent document, les données de la période historique (1968-2015) étaient presque identiques, tandis que les données des années 2016-2020 et les indices d'abondance ont été mis à jour. Comme convenu lors des réunions précédentes, les spécifications initiales du modèle étaient identiques à celles de l'évaluation de 2017.En este documento se presentan los datos y la configuración del modelo para la actualización de la evaluación de 2022 del stock de atún rojo del Atlántico este y Mediterráneo. Durante la reunión de preparación de datos de 2017 se presentaron varios cambios en los datos utilizados para las evaluaciones anteriores, entre ellos la revisión de las estadísticas de Tareas 1 y 2, así como la selección de los índices de abundancia. Esto llevó a revisar completamente la matriz de captura por edad y las especificaciones del modelo para la evaluación de 2017. Para el presente documento, los datos del período histórico (1968-2015) fueron casi idénticos, mientras que se actualizaron los datos de los años 2016-2020 y los índices de abundancia. Como se acordó en reuniones anteriores, las especificaciones iniciales del modelo se mantuvieron idénticas a las de la evaluación de 2017, ya que no se ha acordado ningún cambio desde entonces

Preliminary 2017 stock assessment results for the eastern and Mediterranean Atlantic bluefin tuna stock

Compared to 2014, the present assessment differs on several respects. During the 2017 data preparatory meetings, number of changes have been presented, among which the revision of the task I and task II statistics, the selection of the indices of abundance. In particular, this led to completely revisit the catch at age matrix. As a consequence, previous model specifications could not be used anymore. Whereas the 2014 assessment updated the catch and abundance index data up to 2013 and used the same model specifications as in the 2012 stock assessment, the present assessment present a complete revisitation of these. VPA2-Box was used to estimate the stock status, using a broad spectrum of settings. The resulting models were tested and compared on the basis of their diagnostics, so that the best models could be identified. In particular, different scenarios for Fratio, variance scaling for indices, recruitment constraints and vulnerability were tested. This document will serve as a basis for the 2017 EBFT stock assessment.En comparación con 2014, la presente evaluación difiere en varios aspectos. Durante la reunión de preparación de datos de 2017, se presentaron varios cambios, entre ellos la revisión de las estadísticas de Tarea I y Tarea II y la selección de los índices de abundancia. En particular, esto condujo a reexaminar completamente la matriz de captura por edad. Como consecuencia, las especificaciones previas del modelo ya no pudieron utilizarse. Mientras que la evaluación de 2014 actualizaba los datos del índice de abundancia y de captura hasta 2013 y utilizaba las mismas especificaciones del modelo que en la evaluación de stock de 2012, la evaluación actual presenta una completa revisión de ellas. Se utilizó el VPA2-Box para estimar el estado del stock, utilizando una amplia gama de ajustes. Se probaron los modelos resultantes y se compararon basándose en sus diagnósticos, para poder identificar los mejores modelos. En particular, se probaron diferentes escenarios para Fratio, varianza escalada para los índices, restricción del reclutamiento y la vulnerabilidad. Este documento servirá como base para la evaluación del stock de atún rojo del Atlántico este de 2017.La prospección aérea francesa en el golfo de León proporciona un importante índice independiente de la pesquería para la evaluación del stock de atún rojo del Atlántico este (EABFT, Thunnus thynnus). El presente documento recuerda la metodología empleada para la prospección y proporciona la actualización del índice para el año 2021, que muestra un ligero descenso respecto a 2020, que fue el año con el valor más elevado hasta la fecha, pero ocupa el tercer puesto en cuanto al valor más alto. Lo que confirma la tendencia al alza de los últimos años